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a) Introduction to First Edition.

This report sets out to give as comprehensive a survey as possible on the different types of lights available for cave purposes, and on the different makes and types of safety helmets that are on the market. In the report will be found, where it has been possible to ascertain such figures, details of approximate initial cost and, in the case of lights, running costs, and figures giving strengths, sizes, weights, etc. where the manufacturers have provided these. It will be found that part of this report is factual statements on specifications and the like and part .consists of comments on the product in question. The author has tried to make as much as possible of the report fact only, but where personal opinions have been included he has been careful to make it obvious that the statement is one of opinion and not necessarily fact. It is hoped that even cavers who are fully equipped in this field and have no intention of making any further purchases will be able to find a few tips and will also be more conver¬sant with the state of the market. The report will probably be of greatest interest to those wishing to purchase either, or both, of these items of equip¬ment, as it will put before them a survey of what is available and some of the pros and cons of each.

Although not necessarily followed in every section of this report, the general plan has been to give an introduction which will include the author's comments and comments from other sources, followed by a survey of what is avail¬able en the market. The latter is based on manufacturer’s figures and information, and/or that obtained as far as possible, by the author from tests he has carried cut personally.

After the two principal sections on helmets and lights, will be found app¬endices giving a list of the references and suppliers quoted in the text, a summary of the British Standards Institution Specifications for industrial safety helmets, and a brief survey of some of the legal aspects and dangers associated with acetylene and calcium carbide.

The reason for preparing this report was that the author could not remember having seen anything published in this field, and a search of well over 600 caving books and Club Journals brought forward one article on lights, another short article on one make of helmet, and a few brief references to either topic; but no survey.

Admittedly; by far the majority of journals searched were those of Southern caving clubs and something may well have been published by a Northern club; this report is more likely, however, to be read by cavers than potholers. This one article found during the literature search was a survey of cave lighting equip¬ment (1) by H.A. Bamber, and was a general article on many of the forms avail¬able. The present author has used this article as a basis for the second section of this report, but has added to, and removed from it, certain sections.

Although Mr. Bamber's article was used as a basis. Section C of this report is by no means a re-hash of it, and has been compiled quite independently, except where specifically stated.

The method of obtaining the information for this report, having come to a full stop after searching the literature, was to contact as many suppliers and manufacturers as could be found in a variety of directories, and from advertise¬ments in mining and similar journals. This involved correspondence with well over four dozen firms; and while it certainly does not cover the entire field, it must cover a large part of it.

As there is a definite possibility of bias amongst the opinions expressed in this report, it would be as well to show in which direction this bias lies by describing the author's own equipment and preferences. The helmet used is a "Texolex" Model 2. For lighting, an acetylene lamp (Premier Brand) is used for general caving with an electric lamp and a twin-cell cycle battery mounted on the helmet as a secondary a source of illumination. The electric lamp is focused to give a long beam so that it can be used for illuminating distant objects as well as an emergency lamp in the event of the carbide lamp failing for any reason. This electric lamp is used alone for photographic trips because of its beam, and the ease of switching on and off, but the author would prefer to use an accum¬ulator powered lamp for this purpose (provided there was little climbing or tight crawling in the cave) if he possessed one.

(b) Introduction to Second Edition. Revised 1967

Since the first edition of this report was produced in 1958 there have been many changes in the field of lighting and headwear equipment, and although many of the tried and tested items are still available, a good number have disappear¬ed from the market. The range of carbide lamps has been considerably reduced, and some accumulator sets (such as the Edison) are no longer manufactured, although second hand supplies of some of these items are available.

On the other side of the coin there is a considerable number of newer lines available. Some of the plastic helmets are becoming more popular, but the author is surprised that other items, such as Mallory cells, etc., are not used more. Presumably cost is the reason for this conservatism.

A good deal of material has been written of the subject of lighting since 1958, and the bibliography appended to the report has been considerably extended. There still appears to be no other paper with the comprehensive nature of this report.

Throughout the report it has been the authors intention to give as many references and names of suppliers as possible in order to make it easier for anyone wishing to read further into the subject or to purchase any of the items mentioned. It will be found that all references have been numbered in Roman numerals and are given in the text in the form (1); suppliers and manufacturers have been numbered using a Arabic numerals i.e. (1 ). Where an alternative source of supply in known this is the second of the two references, viz. (6) (33). A complete list of all these references will be found in Appendix I.

As the scope of this report has been increased slightly, and on the whole the variety of items available has also increased, it has been necessary to present the information in condensed form. Information given in introductory notes is not necessarily repeated in the body of the text. Before ordering any item, read the relevant sections carefully and quote any manufacturers refer¬ences given.

The author of the first edition ended his introduction by stating his prejudices. The present author records that his equipment is very similar. It is to be hoped that this has not made any resulting, bias too great.

NOTE: - The prices quoted in this report were correct at the time of the preparation of this manuscript.  Some of these may have increased up to the time of Publication.


(a) Introduction.

A good helmet is an important part of a caver's equipment, not only as a protection for the head, but as a means of carrying his light - leaving the hand free while still allowing the light to be directed (within limits) where it is required.

In the author's opinion the ideal caving helmet would possess the following qualities:-

(a) Strong enough to protect the wearer from hard knocks and reasonable rock falls,
(b) Durable.
(c) Unaffected by water.
(d) Lightweight.
(e) Comfortable to wear.
(f) Easy to replace parts liable to wear.
(g) Easily carries ones lights.
(h) Relatively cheap initial cost.
(i) As small as practical, i.e. no wide brim, or high crown.

It is of course important that the helmet should not only stand up to a heavy blow cut should absorb as much as possible of the shock, transmitting the force to the wearer as evenly as possible in order to avoid injury. It is reasonable to assume that those conforming to the British Standard Institutions specifications will meet this requirement, but it should be realised that B.S.S. 2095 requires a shock absorption test of only 28 lb/ft. while B.S.S. 2826 requires a 40 lb/ft. impact test. It is recognised by the National Coal Board that B.S.S. 2826 is the appropriate standard for men working in shafts, and it is the author's opinion that this is the more suitable standard for caving, par¬ticularly where there are any pitches involved.

A drawback of the B.S.S's. is that they make no mention of ageing prop¬erties. Synthetic materials particularly tend to become brittle with age and les able to withstand shock loads. Others are subject to impact fatigue. Some also show a poor performance at low temperatures and though there is a low temperature test in B.S.S. 2826, it is not obligatory for a helmet to pass this in order to achieve the standard. So far as the author is aware, there is no quantitive data available on these points, so that direct comparison is not possible between the various materials employed. Variations even between batches being possible.

An attempt therefore has been made in the text to asses these points qualitativ¬ely for the different materials.

An important feature of some helmets is that they are not constructed of a waterproof, material, and once the protective coating has been removed (which does not take long under caving conditions) they absorb water and begin to deteriorate in strength and become very pliable. Whereas helmets made of a water¬proof material are extremely durable and should last a lifetime, once the paint of the others has been removed they soon deteriorate and finally become unusable, unless great care is taken, attention is drawn to this in two British Standards Institutions Specifications for industrial safety helmets (i) and (ii), and while these specifications were not drawn up with caving in mind, the question is even more important for us, due to the greater incidence of water. The paragraph, which is identical in both specifications, reads as follows: -

"The particular attention of users of safety helmets is directed to an important feature of certain kinds of safety helmets which are made of materials which, if unprotected, are liable to absorb moisture and thereby lose their mechanical strength. The outer surface of helmets made of such materials should be protected against moisture. If this protective coating is damaged by abrasion in use and the material of the helmet is allowed to become wet, a serious reduction in strength may result. It should be appreciated therefore that the strength of many helmets when used in wet conditions may depend on the mainten¬ance of this protective coating, which should be renewed at regular intervals, especially if the helmets are likely to become wet".

The importance of this quotation lies in the last sentence, and anyone who has used the familiar black miner's helmet on more than just a few caving trips will know exactly what is meant.

Comfort in use depends largely on the cradle, and since, this is a part of helmet which is liable at some time to need replacement, some consideration should be given to the types of cradle available.
Broadly there are two types:-

    1. Leather or leatherette cradles. The headbands are usually of fixed sizes, though some are adjustable. The concussion tapes are usually adjustable by a common, lace at the crown. All the examples of this type mentioned here are laced into the helmet and thus are easily removable.
    2. P.V.C. adjustable cradles. These fall, into four types: - .

(i) The fixed type where the headband only is detachable; the concussion tapes being riveted to the shell.

(ii) The laced-in type (as employed by Texolex) the entire cradle is removable, but in the author's opinion it is a little "sloppy" in use

(iii) The "Snap-in" type cradle. The cradle has a number of wedges around its base which snap into moulded slots in the shell. The entire cradle is removable but the slot mouldings make external bulges around the base of the shell, above the brim. Fixed and adjustable crown straps are incorporated in the cradle and the entire helmet is among the heaviest reviewed here.

(iv) Various clip-in types. Panorma (1 ) use three variations:-

I 65 D. - six straps pass through the shell, thickened portions providing fixing stops. These are exposed and might be liable to abrasion.

I 65. - fastens by the same method, but the fastening stops are not exposed.

PP 63. - six nylon studs pass through the shell from the outside and clip on to the cradlo internally.

Some cradles employ fixed concussion tapes, which cannot be adjusted, so that the minimum wearing clearance cannot be reduced. Some manufacturers give a recommended minimum wearing clearance, Malcolm Campbell ''Caps" (9) for instance recommend 1.1/2 on their Texolex helmets. This space should not, of course be used for carrying items, although often it may be the only, dry place available. The danger of reducing the clearance should not be forgotten.

The comfort of a helmet can often be improved by inserting a lining of foam rubber between the headband end the shell. Ventilation is another factor which can contribute towards comfort, though this is a personal point, though, one thing, unventilated helmets make good substitutes for buckets when bailing, so if you do not want your helmet ''borrowed" for this purpose, be warned!

Although it is often claimed by the manufacturers that the P.V.C. cradles eliminate the need for chin straps by hugging the back of the neck, this is not so under caving conditions. There is also the danger aspect of using a helmet without a chin strap; dropping down a pitch for example. Most manu-facturers will supply chin straps out these are usually of leather, which is quite unsuitable as it hardens and rots after wetting. Only webbing or elastic chin straps have therefore been mentioned in the text. Prices of chin straps will be found in the list of common parts, at the end of this section.

In the following pages are listed details of all the helmets that it as been possible to trace. They have been divided into types, depending on the materials used in their construction.

All the helmets listed here are, or have been, fitted with a lamp bracket, which should be specified when ordering. Unless otherwise stated this is suitable for electric or carbide lamps with prong, rather than wire clip fittings.

All weights quoted are approximate.

B. (b) Metal Helmets.

The day of the ex-army "tin-hat" has passed and, with one exception, this is the only type, of helmet known to the author that comes under this heading. The fact that "tin-hats" are a thing of the past is not to be regretted as not only do they make unsatisfactory headwear for caving, but they can be very formidable weapons. However, to make this survey as complete as possible, they are mentioned here. As issued they are heavy, not provided with any method of fixing a cap lamp, and although the brim is reasonably small, it is surprising how much it gets in the way. It will be found that a hacksaw will make little or no impression on the helmet, but anyone deter¬mined to remove the brim will find that it can be done either by using an oxy-acetylene cutting torch, or by placing the brim in a vice and bending the helmet back and forth, and so fatiguing off the brim. Either method leaves a sharp rough edge which must be removed, and a file will not make much impression. Similarly, it is very difficult to fix any form of lamp bracket. It can easily be imagined that anything as heavy as a "tin-hat", falling, even from only a small height, makes a dangerous weapon, and for this reason many clubs frown upon, and some even forbid, the use of these helmets. From this it will be seen that they do not make a suitable form of caving headgear and they are definitely not recommended.

The following is one exception.


Sureguard. In bright anodised aluminium to B.S.S. 2095, the helmet has a narrow brim, a peak and ribbed unventilated crown. A chin strap is available. Clip-in adjustable P.V./C. head cradle (165D); sizes 6.1/2 – 7.1/2 approx.; weight 12.34 oz.

Price 27/6

A wide brim is available.

B. (c) Vulcanised Fibre.

These helmets are the familiar "black, miner's helmets" which are the ones most commonly used for caving. They have the advantages that they are light in weight and are the cheapest of all helmets to purchase but, they are presumably the type referred to in the introduction to the British Standards Specifications. Although very strong when new, after use for caving they soon become softer and after a time have to be replaced. For this reason they are probably not the best buy for people taking up caving "seriously".


These are the helmets most commonly used for caving on Mendip and are now sold as conforming to B.S.S. 2095. They are also the only type of helmet suitable for carrying the wire clip fastening type of carbide lamp. Fitted with leather headbands in fixed sizes, all have a 1.3/8" peak.

Type 100. 1/2" brim; vented by four holes; weight 12 oz.

Price 10/-

Type 107. Brimless; vented by four louvres over 1/2" holes; weight 12 oz.

Price 10/6.

Type 110. 1/2" brim; vented by four raised louvres over l/2;; holes; weight 11 oz.

Price 9/6.

The manufacturers of Huwood helmets are now Thetford Moulded Products and are referred to as such throughout the rest of this text.

CROMWELL (3) (32).

M 8/11. To B.S.S. 2095; 1/2" brim; peak; fluted, vented crown; fixed P.V.C. adjustable cradle; sizes 6.3/8 - 7.5/8; black or white

Price 14/9.

M 9/04. To B.S.S. 2095; plain unvented crown; damp proofed, adjust¬able leatherette headband; three sizes of moulding 6.1/2 -7.1/2; weight 11 - 13 oz.; black or white.

Price 14/3.

M 8/04. To sane specification as K 9/04, but with fluted vented crown.

Price 14/3.

L 8/04. As M 8/04 but sides and peak of lighter material; weight 10 - 12 oz.

Price 13/3.

A wide brim model is available.


B 8/11. To B.S.S. 2095: 1/2" brim; peak; heavily fluted crown; fixed P.V.C. adjustable cradle; two mouldings, 6.3/8 – 7.5/8; black or white.

Price 14/-.

M 605. Not to B.S.S..; 1/2" brim and peak; fluted crown with ventilating louvres; cradle in rexine, or as above; weight 8 oz.: black or white.

Price 12/6

B. (d) Glass Fibre.

The strength of glass fibre is well known and as it is impervious to water these helmets should recommend themselves for caving; yet very few are seen in use. One disadvantage is that the resin tends to crack when knocked hard.


Peakguard. To B.S.S. 2826; 1/2" brim; large peak; flat fronted, high domed, unvented crown: P.V.C, cradle (PP63) or leather (PP 25; alternative; sizes 6.1/2 - 7.1/2 approx.; weight 15 oz. Spray painted in B.S.S. Colour range.

Price 24/6.

Gapguard. To B.S.S. 23 26; 1/2" brim; peak; flat fronted, unvented crown; cradles as above; weight 14.1/2 oz. pigment, or spray painted, black, white and colours.

Price 20/9.

Skullpeak. To B.S.S. 2095; brim; peak; flat fronted, unvented crown; P.V.C. (PP 63) or leather (CL 4/1) cradles available; sizes 6,1/2 - 7.1/2 approx.: weight 13.1/4 oz . colours as Capguard.

Price 20/9.

Wide brim models are available.


Centurian 200. To B.S.S. 2826; 1/4" brim; 1.1/2" peak; webbing chin strap available; ribbed, vented crown; fixed P.V.C. adjustable cradle; weight 13 oz.

Price 18/-.

CROMWELL (3) (32)

5/11. To B.S.S. 2826; 1/2" brim: peak, flat fronted, ribbed crown; fixed P.V.C. adjustable head cradle; two mouldings; sizes 6.3/8 – 7.5/8; weight 13 - 15 oz; black, white and colours.

Price 17/5-


F 5/11. To B.S.S. 2826. T his helmet appears to be identical to the Cromwell F 5/11.

Price 17/6.


Fibreglass model. Brim and peek; flat fronted, ribbed crown; adjust¬able leather cradle available.

Price 20/-.

EVEROAK (6) (33).

These helmets have an adjustable, laced in, headband of padded rayon twill. P.V.C. is available as an alternative. The cradle has fixed, and adjustable, concussion tapes; heavy duty models having 1 .1/2" tapes. They are fitted with a webbing chin strap and are available in black, white and colours.

Model B. To B.S.S. 2095; 1/2'" brim; peak; flat fronted, ribbed crown; weight 14 oz.

Price 17/6.

Model HB. As above but to B.S.S. 2326.

Price 17/6.

Model D. To B.S.S. 2095; 1/2" brim; no peak; flat fronted, ribbed crown; weight 15 oz.

Price 17/6.

Model HD. As above but to B.S.S. 2626.

Price 19/6.

Wide brim models are available.


Fibreglass Helmet. To B.S.S. 2826; brim; peak; plain or ribbed crown styles; unvented; elastic chin strap available; clip in P.V.C. adjustable cradle with nape strap; black, white and colours.

Price 24/3•

NORTH (8).

SH 1501. To B.S.S. 2826; brim; 1.1/2" peak; plain unvented crown; lamp bracket in moulded plastic; elastic webbing chin strap available; six point strap-in P.V.C. adjustable cradle; sizes 6.1/2 - 7.3/4; weight 16 oz.; white and colours.

Price 21/11 .

B. (e) Cloth Laminated P.F. Resin.

Since the introduction of these helmets to cavers on Mendip early in 1953, they have become more and more popular due to their robustness and the fact that they are completely impervious to water, even when the cloth laminate is exposed.


This make has been used by the author (B.M.S.) for many years and alth¬ough it has been sadly abused, the helmet is still as good as new apart from some superficial scratches on the crown. The helmets are ventilated by four holes in the plain crown. The lamp bracket is suitable for electric or wide pronged acetylene lamps only. Laced in P.V.C. adjustable cradles, sizes 6.5/8 - 7.3/4, or leather or leather cloth alternatives, in fixed or adjust¬able sizes, are available. Leather brow bands for P.V.C'. cradles, and cork linings, can be fitted. They are available in natural brown, or spray painted. Pegram (iv) in a short article quotes some tests made on these helmets.

Medium Dome Model No. 2.

To B.B.S. 2826; virtually brimless; small peak.

Price 21/9.

Low Dome Model No. 1.

Exceeds B.S.S'. 2095; 1/2" brim; larger peak and lower done than No. 2. above, otherwise identical.

Price 23/5.


Miners "Saycap". To B.S.S. 20 95; 1/2" brim;-peak: plain crown; adjustable leather cradle available.

Price 20/-.

B. (f) Laminated Plastic.

While these helmets would appear to be ideal for caving because use of the water resistant .material used, unfortunately this is not so. As far as the author is aware, only the "Oldham-Sorbex" has been used for caving but at least four of those helmets have cracked for different reasons;- one of them when it was dropped from a height of three or four feet onto a wooden floor. It appears that once there is a crock or cut in the P.V.C., the helmets soon crack when submitted to shock. The material also becomes very brittle at low temperatures.


To B.S.S. 2826; 1/2" brim; peak; ribbed, unvented crown; P.V.C. harness (l 65 D); sizes 6.1/2 - 7-1/2 approx.; weight 11.1/2 oz. in natural brown only. 

Price 30/-


Safety Helmet.

In P.V.C. to B.S.S. 2095; V2" brim; peek; ribbed crown; bracket suitable for electric lamp; chin strap available; adjustable cradle of P.V.C. faced cloth or leather; in fixed sizes 6.1/4 – 7.1/2 or large, medium and small, white only.

Price 23/3

B. (g) Moulded Plastics.

Much the sane considerations apply to these helmets as to the laminated plastic ones above. Although several of them have been seen whilst caving they seem liable to cracking; also most of them have a fairly high dome, being designed for industrial, rather than mining uses.


Light Guard.

In A.B.S. to B.S.S. 2826; has a "gutter" brim (which might be use-full for protecting the lamp cable) peak; ribbed, unvented crown; adjustable P.V.C. cradle (I 65); sizes 6.1/2 - 7.1/2 approx.; weight 13.1/2 oz.; pigmented white and colours.

Price 23/9.

Top Vent.

To B.S.S. 2095; gutter brim; peak; ribbed crown; the only Panorma helmet which is vented, it has four holes which can be adjusted from open to closed; cradle (I 65); sizes 6.1/2 - 7-1/2 approx.; weight 10.3/4 oz.; white and colours.

Price 17/6.


Centurion 300.

In Polypropylene to B.S.S. 2095; 1/4" brim; 1.1/2" peak; vented crown; adjustable P.V.C. cradle; sizes 6.1/2 - 7.1/2; weight 10 oz.

Price 15/-.

Centurion 500.

In A..B.S. to B.S.S. 2826; 1/4" brim; 1.1/2" peak; vented crown; adjustable P.V.C. cradle; weight 12 oz.

Price 18/-.

CROMWELL (3) (32)

P 10.

In Polypropylene to B.S.S. 2095; 1/2" brim; peak; flat fronted, ribbed crown; cradle, alternatives of leatherette or leather in fixed sizes, or adjustable, leatherette in sizes 6.1/2 – 7.1/2 or fixed P.V.C. adjustable 6.3/8 - 7.5/8 (leather brow band for P.V.C. cradle available); two shell mouldings; weight 10 - 12 oz. black, white and colours.

Price 11/6. - 13/-

DP /2. ;

In Polythene to B.S.S. 2095; 1/2" brim; peak plain, unvented crown; fixed P.V.C: adjustable cradle; weight 10 - 12 oz.; black, ' white and colours. .

Price 21/6.

A wide brim version of the DP /2. is available.



To B.S.S. 2826; 1/2" brim; wide peak; ribbed, unvented crown; elastic chin strap available; clip in adjustable P.V.C. cradle with nape strap; three mouldings; sizes 6.1/3 - 8; white and colours.

Price 21/-.

NORTH (8).

SH 1511.

To B.S.S. 23-26; brim; peak; plain, unvented' crown; six point snap-in adjustable P.V.C. cradle; sizes 6.1/2 - 7.3/4; white and colours

Price 21/5.

M.S.A. (11)

V - Guard Cap.

In A.B.S. to B.S.S. 2826; brim; peak; V-ribbed crown; webbing or elastic chin straps available; four point snap-in adjustable cradle with P.V.C. leatherette head-band; sizes 6.1/2 - 7.3/4; weight 11 oz.

Price 20/-

S.G.B, (12).

Safety Helmet.

To B.S.S. 2826; bring peak; plain, unvented crown; six point snap-in adjustable P.V.C. cradle; sizes 6.1/2 – 7.3/4; weight 15 oz. white , yellow and blue.

Price 23/3,


Safe - t - Cap.

In Polycarbonate to "North American safety standards'''; brim; peak; ribbed, unvented crown; four point snap-in adjustable P.V.C. cradle sizes 6.1/2 - 7-7/8; weight 16 oz.; pigmented black, white and colours.

Price 24/9.



To B.S.S.. 2826; brim; peak; plain unvented crown; eight point snap-in adjustable P.V.U. cradle; sizes 6.1/2 - 8; weight 14.1/2 oz.; white and colours. 'The manufacturers make special claims of the "off centre impact 'and compression load resistance", and low temperature performance of the helmet.

Price 13/-.

B. (h) List of Common Parts.

Manufacturer Part. Catalogue Number Price.
      s. d.
    I 65 9. 6.
Pyrene – Panorma.  (1 ) Harnesses I 65 D. 9. 6.
  CL 4/1 7. -
    C 5/3 7. 6.
    PP 25 7. 3.
    PP 63 8. -
  Chin straps C 523 1. 6. +P.T
  C 407 1. - + P.T.
  Headwarmers   7. 6.
  Lamp Bracket and cable loop   2. 6.
  Self adhesive sweat band     10. +P.T.
  39" White Teryiene cord     6. +P.T.
  6" Laces     3. +P.T.
  Spray Painting (per- helmet)     5.
Thetford Moulded        
Products.  (2) Leathercloth covering for plastic lining   2. -

Cromwell.  (3)

Replacement linings (spare lining and lace). -/89 4. 6.
  -/04 4. 6.
    -/64 5. 6.
  Spare Polythene headband -/11 2. -
  Leather browband for -/11      
  headband   2. 6.
  Plastic draught excluder for      
  -/11 headband   1. 3.
  Lamp brackets      
  light pattern with cable clip C   6.
  Universal pattern with cable clip U   9.
Bathgate    (4) Spare polythene headband for      
  -/11 linings   2. -
  Leather browband for same   2. 4.
  Lamp Brackets      
  “C” type with cable clip     3.
  “U” type with universal cable clip     6.
  “B” type acetylene     9.
  “BC” type acetylene and electric   1. -
Crook. (5) “Skycap” No Information      
Thomas Townsend Lamp bracket     6.
“Everoak”  (6) Lamp bracket and cable lop   1. -
  Cork inserts   1. 6.
  Neckstrap     6.
  Drop linings (for warmth)   1. 3.
  Linings complete with laces and chin strap   4. -
  Laces – 41”, per doz.   2. - +P.T.
  Laces – 17”, per doz.   1. - +P.T.
Acrow  (7) Elastic chinstrap and assembly studs AT/C 2. 9.
  Lamp bracket and cork clip   4. 6.
  Internal suspension AT/IS 7. 6.
  Set of main studs for above AT/MS 1. -
  Set of harness collar studs AT/CS 1. -
  Headband 6.1/2 – 7.1/2; 6.1/8 – 7.1/3; 7 – 8 AT/H 4. 6.
  Drawstring   4. 5.
George Angus Complete headgear SP/160    
“North”     (8) Elastic webbing chinstrap (breakaway      
  attachment operates if caught in a fall) REF  “A”    
  Lamp bracket and cable clip REF  “B”    
  Winter liners – Half liner SH/1531    
                           Full liner SH/1530    
  When ordering helmet with chinstrap, and/or lamp bracket, quote Ref. No., E.G. SH/511 A/B.      
Malcolm Capbell Headcradles      
“Texolex”   (9) Polythene adjustable 6.5/8 – 7.3/4      
  Basil leather individual sizes 6.1/4 x 1/8 – 7.3/4      
  Leather cloth; sizes as for Basil leather type      
  Helmet retainer with Basil leather cradles   1. 3.
  Leather browband for polythene cradles   1. 6.
Oldhams   (10) See page 11      
Mine safety Grey webbing chin strap 257271 2. 6.
Appliances  (11) Black plastic chin strap 257335    
  Nape strap with studs 257272 2. 3.
  Replacement harness with P.V.C. leatherette sweat band 257589 11. 6.
  Cold guard winter liner; small, mediums and large 257262 7. 8.
  Foam back winter liner (small) 257275 8. 3.
      “      “         “         “    (large) 257276 8. 10
  Terylene winter liner 257277 11. -
  Yellow P.V.C. cape for V-guard 257273 7. 2.
  Reflective cape for V-guard 257274 18. 9.
S.G.B.   (12) Lamp bracket and clip   2. 3.
Safety Products Spare head harness   7. -
Ltd.   (13) Lamp bracket   2. -
Siebe Gorman        
Ltd.  (14) Lamp bracket   1. 6.

B. (i) Conclusions.

The helmet most suitable for caving are probably those sold for mining w2here the conditions are closest to those met in caves. Messrs, Thetford (Huwood); Malcolm Campbell (Telolex) and Oldhams manufacture helmets for the N.C.B.; Helmets Ltd., (Cromwell), Bathgate and Mine safety Appliances make helmets specifically for mining.

In the author’s opinion, only the helmets made to B.S.S. 2826, Heavy Duty, are acceptable. Vulcanised Fibre, Plastics and Glass Fibre all have disadvantages already stated. This leaves laminated P.F. Resin helmets, and of these, Texolex is the best known and most tried among caving circles.



(a) Introduction.

As lighting is the most important item of caving equipment, it is very surprising that so little has been written about it in caving .journals and books. Although one can go (if determined) without helmet, boots, ladders, etc., exploration is limited to the shortest of rock shelters without some form of illumination, although a candle may give sufficient light to see one's way, it is not powerful enough to show cave formations to their full beauty, as it is seen realised on burning some magnesium ribbon or visiting a commercialised show cave, with their powerful electric lights; nor does one have sufficient light for complete safety.

No one form of lighting is universally accepted by cavers, but there are two definitely predominant forms: -the acetylene miner's cap lamp, and the accumulator powered electric cap lamp. Neither of those are perfect, each having many features of the ideal lamp but neither of them all - some cavers preferring the disadvantages of one to the disadvantages of the ether and vice versa. In the author's opinion, the ideal caving light would posses the following features:-

    1. Reasonably cheap initial cost.
    2. Cheap running costs.
    3. Will give a beam or diffuse: light, as required.
    4. Easy to clean and maintain.
    5. Light in weight and of small bulk.
    6. Easy to affix to helmet.
    7. Unaffected by water or shock.
    8. Easy to recharge anytime and anywhere.
    9. Safe and foolproof.
    10. Capable of giving many hours of light at any one time.

Which type of lamp a cover will use depends on several conditions. Thus, when he starts, the chances are very high that if he hasn't been able to borrow a lamp from someone else he will use a torch, because even if one is not available the cost is small. Having decided that he is going to do some more caving, the decision then usually rests between acetylene or accum¬ulator. Which way he will decide depends on many factors, and as neither of them is ideal, and one does not surpass the other by much, there is no point in the author giving an opinion - he will state the pros and cons of each later in the report, together with a few comments.

Lamp brackets were mentioned earlier, all accumulator operated cap lamps and some carbide lamps (see details of carbide lamps) have a flat metal prong which is quite strong and will fit nearly every kind of helmet fitting. Some carbide lamps however, have wire clips which are not so strong and will fit only "Huwood" helmets. A Terry clip can be used to fasten the lamp to the helmet, but this makes the lamp project slightly more than in front of the helmet, which the author considers a disadvantage.

In the following pages, lighting has been divided into a number of categories, as with the helmets, and each type is first discussed before giving details of the lamps available. In addition the three usual forms of lighting - acetylene, accumulator and dry battery, these types of ill¬umination have been included to make the survey complete and also a section on methods of ignition. This last section has be on included in the hope that even experienced cavers, may be able to pick up a tip or two.

C. (b) Methods of Ignition.

Because the majority of types of lighting available for cave explorat¬ion require some form of ignition, it would be as well to consider the more practical idea's that are available in this field. The necessary conditions for a means, of ignition to be used underground are that it must be robust and capable of being, used when wet, or capable of being water proofed by some reasonably easy method.

Matches and ships' Lifeboat Matches.

Matches are the easiest method of ignition for all types of lighting but they are very susceptible to damp and must be waterproofed. Of the two types of ordinary match available (the safety, on, non-safety, the former is to be preferred because it ignites by means of a chemical reaction rather than by friction, and for this reason it is slightly less susceptible to damp). There is the disadvantage, however, that should the striker become wet but the matches remain dry, one is more likely to find dry striker for a non-safety match (e.g. the inside, of a caving helmet) than for a safety match. There are several others available for waterproofing matches, of which dipping the heads in wax is the easiest, but unfortunately not the most satisfactory. Not only does this method make no provision for waterproofing the striker, but if you have a dry striker, it is soon rendered useless as it becomes clogged with wax from the matches.

A more satisfactory method is to carry the matches and a striker in a waterproof container. Small plastic containers capable of carrying a doz¬en or so matcher are available (38) for a few pence and those are quite satisfactory, an alternative method is to seal matches and striker in rubber or polythene. A method of making a small rubber pouch with sheet rubber and rubber solution has been describe1 in the British Caver (v). The easiest and a very effective method of sealing polythene is to place the two edges between two flat surfaces, e.g. two rulers, leaving 1/8" sticking out, and then run a flame back and forth to melt the protruding polythene back to the rulers, care being taken not to heat the polythene too much so that it burns. Even opening a container to the very damp air found in caves will cause matches to become damp, and hence difficult to light, so it is a good idea to carry a number of small containers, each containing a few matches and a striker, rather than one large container.

The best of all, when they are available, is to use ships' lifeboat matches, such as are made by Bryant and May (39). These matches are sold in a watertight plastic container, and the matches themselves are. Reasonably impervious to water. Once alight, it is impossible to blow them cut and they are not effected by water spray; they can even be totally immersed in water for a fraction of a second and still keep burning. Unfortunately, Bryant and May have recently ceased making these matches.

Cigarette Lighters and Flint Wheels

The manufacturers of acetylene cap lamps provide flint strikers an their lamps, but while these are useful for lighting the lamp before enter¬ing the cave, or for re-lighting the damp in a dry cave, they are soon rendered useless under wet conditions. The same disadvantages applies to a cigarette lighter, but this may be kept dry in a waterproof container fairly easily. Bamber (i) mentions the possibility of catalytic lighters and also says he has experienced difficulty with the velatization of the fuel under damp, cold cave conditions. The latter can be overcome by using a lower boiling fuel such as 60° - 80° petroleum ether, but for lighting an acetylene lamp only a spark is necessary. It is preferable to use an automatic lighter of the Ronson type, as this does away with the necessity of putting a wet and/or muddy thumb directly onto the flint wheel.

Other Methods.

The author has seen a caving helmet fitted with a two way switch so that the battery could be connected either to the stand by lamp or to an electric gas lighter element. Unfortunately he has not tried this system himself but it does appear, at first sight, to have possibilities - it depends how susceptible the element is to water, another possibility is the use of a mixture of calcium carbide and calcium phosphide in an acetylene lamp, the latter producing phosphine with water, which is spontaneously inflammable in air. This mixture was used for self-lighting rescue flares during the last war.

C. (c) Magnesium Ribbons and Flares.

This class of lighting can in no way be considered as a permanent form of cave illumination, but they do have a very definite use for temp¬orary and brilliant illumination of a chamber. They cannot be considered permanent lighting because it would be found that they are expensive, in¬convenient, and produce considerably more light than necessary when used for this purpose.

Magnesium Ribbon.

Can be bought (40) for about 2/6d. an ounce reel and it will be found that a reel will illuminate a large number of chambers – if the remainder has has not been lost between caving trips.

A few hints for using magnesium ribbon; - Use two lengths of ribbon at a time and twist them loosely together to make it a little more rigid and less likely to curl. Fix the ribbon to a suitable point on the wall or the roof of the chamber so that there is no tendency to become en¬raptured by the view, and allow the ribbon to burn your fingers. Before lighting, scrape an inch of the ribbon to remove the oxide film and to expose the shiny metal, the ribbon will then be found much easier to ignite. But, choose a position for the ribbon such that the cave is not disfigured by the resulting white ash.

Magnesium Flares.

Also available (40) for taking cine pictures but these are considerably bulkier and heavier than ribbon and they also have the disadvantage that, unlike ribbon, they are susceptible to water. Bamber (i) mentions that self-striking varieties have been produced for purposes, but the present author has been unable go find any on the market.

Photographic Flash Powder.

Not suitable because, as the name suggests, it is burnt in a flash, but the author has heard of some made flares being produced from a mixture of photographic flash powder and potassium chlorate, held together and the burning slowed down by paraffin wax. While the author has not, as yet, tried these himself, he is assured that they are effective.

Coloured Bengal Lights.

As available for Guy Fawkee Night will be fount to produce an inter¬esting and unusual experience when used to illuminate a chamber; Tolson (yi) mentions that they were used for this purpose luring the 1870's in the commercialised American cave of Wyanlotte.

All these, forms of illumination suffer from the disadvantage that they give rise to clouds of dense, acrid smoke, which as well as being trouble¬some, by causing coughing, also obstructs future viewing until air currents remove the smoke.

C. (l) Candles and Night Lights.

Once the main source of illumination for cavers, candles still hold a place in every caver's equipment. They are cheap, light, easy to use, float if dropped - into water, and have many other advantages which make them
a very suitable emergency light. They possess many of the features of the ideal lamp, but unfortunately, on the points where they fail to meet these requirements, they do so with a vengeance. Thus as everyone who has used them in a cave knows, they are easily blow out by draughts or falling water, and they do not give an exceptionally good light: but as an ordinary candle burns at the rate of over half an hour per inch in calm surroundings, they will last quite a times, when being carried around a cave however, the burning rate is considerably faster. ...

Despite these disadvantages however, they do, as already mentioned, have a very definite use as emergency light, route markers and re-lighting points for acetylene lamp users, after very wet sections, such as waterfall pitches or sumps. For the last two purposes night lights are preferable as they are sturdier and a single night light will last for about eight hours if left in draught free surroundings.

Long life candles lasting about 7 hours in still air, are also available (38).

C. (e) Paraffin Lamps.

Although paraffin lamps do fulfil several of the conditions required for the ideal lamp, their few points which are contrary to this ideal im¬mediately severely restrict their use underground. These leaps can be divided into two groups (i) liquid paraffin fuel and (ii) vaporized paraffin fuel, and each will be considered separately.

Liquid Paraffin Burning Lamps.

This class of lamp included the old oil lamp with the tall glass chimney, as used in houses before the advent of electricity, and the hurricane lamp. The former type is much too bulky and fragile to be worth considering - any¬one who managed to get one of them any distance down a cave without break-ing it would be doing very well indeed. The hurricane lamp, while still being bulky, is not so fragile, and will stand a considerable amount of knocking about, but it is a very poor source of light. It is, however, cheap to purchase initially, and cheap to run. A medium sized lamp with a 5/8" wick will burn for about two hundred hours on one gallon of paraffin, at a cost of 2/9d. This factor alone may recommend the lamp for cave use as a semi-permanent fixture where a very cheap, but by no means powerful, source of light is required.

Vaporized Paraffin Purriing; lamps.

These lamps have all the disadvantages of the hurricane lamp (bulky, heavy, etc.), plus the fact that as they use an incandescent mantle, they are even more susceptible to shock and water than the liquid paraffin burning type. They have, however, the very real advantage that they are a very good source of reasonably white light, as anyone will know who has used one. This type of lamp will be found in some of the less commercialised show caves, such as the Michelstown Caves, Ireland, where they are used by the guides to show the beauties of the cave to an admiring audience. This type of lamp may be, and sometimes is, used in what the Americans would call a "wild cave" for illuminating large chambers or particularly fine formations; they also have a limited use as a semi-permanent fixture for illumination of "digs". One further disadvantage of lamps burning vaporized paraffin, is that they require priming in the form preliminary heating before lighting. It must also be remembered that they cannot be used unless there is a reasonable ventilation; while this does not affect their use in a large chamber, it should, be borne in mind if it was used to light a "dig" in a restricted space.

Details of the vaporized paraffin lamps available are listed in the table below.

Lamp Dimensions Weight empty Duration Capacity Output Cost
  in inches lbs hours pints C.P. £.  s.  d.
Alladin (15)            
“Bialladin” 13.1/2          
Pressure X 4.1/2 11 1.3/4 300 4.  15.  -
Lantern 315. 6.1/4          
Tilley (16)            
“X 246 B” 3.1/2 x 7. 5. 12 1.1/2 300 4.  12.  6.
“FL6” 26 x 14.1/2          
  X 22.1/2 48 6 5,000 15.  7.  6.

A 12” reflector is available for the Tilley “X 246 B”.. Two stands, raising the “FL6” floodlight 8” of 5’ 8” (adjustable) above the ground, respectively, are available, but size, weight, and initial cost would rule this lamp out for most caving purposes.

Spare mantles for the lamps cost 2/6d. each.

C (f) Calor Gas Light.

Although coming nowhere near the ideal light source for caving purposes, the Calor Gas (17) "Streamlite" may have a place for any person or club having control of a cave and wishing to install floodlighting. The "StreamLite" has a light output of 630 foot candles, and will run for a total of 30 hours from a Mk. 10 gas cylinder. The cylinder and lamp, they are designed for use together, stand 2' 0" high and weigh 29 lbs., there is a hire charge of 22. 10s. 01. on the cylinder, and the gas costs 15/3-. The lamp itself costs 29. 0s. 6d.

C (g) Acetylene Lamps and Flares.

The author has no intention in this report of entering into the eternal argument of acetylene versus electric. Below are given a few facts and the choice is left to the reader.

The acetylene miners cap lamp is the more popular source of illumination on Mendip, and it will be found that these lamps are not as trouble¬some as expected, once you have used one a few times and learnt their idiosyncrasies. As with most things, they have to be looked after and it is most important that they are kept clean if one is to be given the best of service. The carbide chamber should be emptied immediately on it’s returning to the surface to prevent corrosion, and, although it is not usually required, a solvent for spent carbide is a solution of ammonium chloride. The felt filter pad should be cleaned after every trip and replaced as soon as it becomes hard.

When an acetylene lamp is being used underground the user must carry a jet brush or pricker with him for cleaning the jet, and it is advisable to carry a spare jet and rubber washer.

The advantages of the acetylene lamp are, its low purchase price and low running costs. One fill of carbide - usually 2.1/2 oz. - will last up to 6 hours under static conditions, though under caving conditions 4 hours is more of an average figure. Even this latter time gives about twenty five hours of light to the pound of carbide (cost 2/6 - 3/6d. per pound, unless bought in bulk) which shows that the acetylene lamp is the only practical source of light for very long underground trips, as an accumulator will only last about fifteen hours and a spare accumulator weighs about at 5 lbs. with a relatively high initial cost.

The disadvantages of acetylene lamps is that while they require quite a strong wind to put out the flame, they are very susceptible to water, and also have a habit of going cut if knocked hard. The lamp can only be protected from falling water to a certain extent by fixing a shield ever the top of the reflector. Another disadvantage, for some people, is the smell of acetylene when the lamp is not burning.

Apart from cap lamps, a number of acetylene hand lamps are available, and while they are too cumbersome for general caving, they are useful for illuminating ''digs", etc. A surprising amount of light can be obtained from an acetylene lamp, especially if the reflector is kept clean and periodically replaced.

Cap Lamps.

The nly cap-lamp, that appears to be currently available is the.-

PREMIER (18) (35).

Lamp No .65 (code word CAPA)

This lamp was the most commonly used, even before other makes disappeared from the market, and is most satisfactory. It stands 3.3/4" high; weighs 6 ozs.; takes 2.1/2 oz. charge of carbide; gives 12 candle power, and lasts about 4.1/2 hours. It is available generally with wire clips. Two kinds of flat back clips have been made, - narrow and wide - and lamps with these fittings are available by special order from the manufacturer, though this will extend the delivery period.

Hand Lamps.

The following hand lamps are available:-

Lamp & make Height Weight empty Charge of carbide Duration Output Cost
  Inches lbs.  ozs, ounces Hours C.P. £.  s.  d.
PREMIER (18)            
No. 67 (AKIE) 8.1/2 1.   10 6 8 – 10 20 1.  12.  6.
No. 61 (AKIN) 8.1/2 2.    6 10 10 – 12 20 1.  17.  6.
WOLF (19)            
No. 854 9.3/4 2.    7 8 10 – 12 20 1.   9.   -
No. 60 A 8.3/4 2.  14 9 10 – 12 25 2.   2.  3.
No. 60 AB 8.3/4 3.    3 9 10 – 12 50 3.   3.  9.
No. 60 AMPH 9.3/4 3.    4 9 10 – 12 50 3.   5.  6.


The PREMIER lamps No. 67 (“Cleveland”) and 61 (“King”) are made in steel, and use burners No. 110 and 105 respectively. The “Cleveland” has a large flat back clip and a flint and a wheel. The “King” has a hook on the bridle.

The WOLF No, 854 is made of tinned steel, with a 3.1/2” brass reflector above the body of the lamp, and a wire handle. No. 60A is also made is tinned steel but with a 5.1/2” reflector in the normal position. No. 60APH has a ‘milk pail’ handle instead of the hook of the 60A, and a bonneted reflector after the fashion of all cycle lamps.

Acetylene Flares.

Apparently, only one manufacturer now produces those. They would not be very useful underground because of their size, but might be useful on the surface, e.g. on a rescue.

ATOZ Flares.

Made of galvanised steel, they have parabolic chromium plated reflectors; extension pipes can be fitted to raise the reflector further. It is stated that the 1,000 c.p. model costs about 1. l/2d. per hour to run. Two models are available, from (20).


Size Approximate C.P. Tank Dimensions Carbide Charge Price
        £.     s.   d.
No. 1 1,000 28” high x 10” diameter 6. lbs 24.  10.  -
No. 2 2,500 31” high x 14” diameter 12. lbs 33.   -     -


C (h) Accumulator Powered Cap Lamps.

Contrary to the belief of most acetylene lamp users, these lamps are not as heavy and cumbersome as expected. When a person has used one of them for a few trips he soon gets into the habit of moving the accumulator into the most convenient position for a climb; but all the same their bulk and the cable running from the helmet to the back are at times a nuisance. While the initial cost of the lamps is high, their running cost is negligible, if one has ones own battery charger and power supply. They also have the advantage of giving a very good light and requiring very little maintenance, though it is necessary, as with all lamps, to keep them clean and checked. Perhaps the main disadvantage of this type of lamp is on very long trips, or when making a number of trips away from a power supply, because as already mentioned in the previous section, the capacity of most batteries is about 10 ampere-hours, giving a useful life of about 15 hours. It is possible however, to charge an accumulator lamp from a car battery, when away from home. For normal charging, Knibbs (xvi) describes the construction of a charging set. The method the author uses, however, is to reduce the output of a standard car battery charger by wiring a length of resistance wire (from an electric fire element) in series with the battery while charging. The appropriate current is obtained by adjusting the length of resistance wire in circuit and reading the ammeter incorporated in the charger.

There are two principle types of accumulator available for cap lamps, these are the lead-acid battery and the alkali-nickel. Each has its own characteristics, but of the two the latter is to be preferred because it is
very much more robust, both electrically and mechanically. An acid accumulator will be ruined by short circuiting or overcharging, but while it is not recommended, this treatment will do very little harm to an alkali battery.

Accumulator lamp sets, if purchased, new, are expensive; second hand supplies, generally ex-N.C.B., however are often available. Second hand alkaline accumulators can generally be purchased with confidence, giving 90% or better of their original capacity, in the author's experience, after refurbishing. Second hand acid accumulators however tend to be less reliable as their total life is about 2 years. Their capacity and age should, be checked, before purchase.

A further disadvantage of acid accumulators is that when not in regular use, they must be charged and discharged occasionally to avoid sulphating. Some authorities also recommend this treatment for alkaline cells, but it is not so vital in their case.

Second hand accumulators are often available from caving clubs, and through the “Exchange and Mart”: they may also be obtained from G.W.George (21) and R.Stewart (36).

A final general point is that, particularly after topping up a battery, any liquid spilt should be washed off and electrolyte should not be allowed to come in contact with clothes, skin, eyes, etc.

NIFE (22).

NC 113 G. This is a three cell alkaline battery with a steel case. The weight complete is 51b. 15oz. The case measurers 7.1/2" x 5" x 1.1/2", and the reflector is 3" in diameter. The duration on main beam is 10 hours, and the cost new is £3. 15. 0.; second hand £1 . - £2.

Some replacement parts are: -


Part No. Component Price
    s.   d.
67416 Steel vent, complete       11.
55146 Cell rubber jacket 2.    6.
70132 Cable reinforcing tube clip        3.
70133 Cable reinforcing tube        8.
70134 Cable, complete 10.  6.
70126 Fuse 1.    3.
70207 Armour plate glass 1.    9.
70208 Reflector washer for use with above        9.
70263 Reflector – standard 2.    3.
70289 Reflector – spot 2.    3.
70240 3.6 volt  1.0 amp. Main bulb 3.    0.
70242 4.0 volt  0.9 amp. Pilot bulb        5. +PT
- Electrolyte, liquid, type 3 – per pint. (specific gravity 1.160 – 1.2000) 13.  0.


The second hand lamp, when received, may need some attention, procedure is as follows:¬ -

To open the battery lid, remove the solder from around the head of the locking, nut with a small file. Remove the nut and turn the whole battery up side down, the spring and plunger will then fall out. If you then cut a groove in the head of the nut for a screwdriver, or drill through the bottom of the catch plate and replace the entire plunger assembly with a split pin. This will avoid using a spanner each time you open the lamp. Do not rely on just the catch without some sort of plunger though, as it will tend to open in use.

If the cell vents are the plastic type, replace them with the steel items. Clean up the cell tops and grease with Vaseline.

The electrolyte is a mixture of potassium hydroxide and lithium hydroxide in the ratio of 14:1. If the light dims when the battery is in¬verted, this is a sign that topping up is needed. Use distilled water and fill till the plates are just covered, over filling will cause spillage. The manufacturers used to recommend topping up with a weak electrolyte, but this is not so any longer.

The specific gravity of the electrolyte should be between 1.160 and 1.200; when it falls below this, the capacity of the battery will be reduced. The electrolyte should then be replaced. Discharge the battery, drain for not more than half an hour, do not wash out with water, refill with the manufacturers electrolyte.

To open the headpiece, remove the locking screw on the bezel; this is superfluous for caving use. To remove the cable, undo the gland nut. Avoid touching the reflector. If necessary, clean it with a soft cloth or camel hair brush, do not use metal polish.

Charge the lamp at 1.75 amps, for 3 hours, or 16 hours after electro¬lyte renewal. Charging for too long is unlikely to damage the battery it will merely bubble off more gas, causing some loss of electrolyte.

As the battery will continue giving off gas for some while after charging, keep it upright for a few hours. It is best to slacken off the vents during charging, as this prevents a gas pressure building up.


The Patterson Company is, or was, a subsidiary of Fife Batteries Ltd. and the lamps should be treated as "Nife" lamps.


These items are no longer manufactured, but the details below are given as some are still about.

The A5 battery is a two cell, 2.4 volt model, weigh's 41b. 4oz., should be charged for 8 hours at 1.5 amps, after discharge and gives 11 hours light.

The A7 battery is a three cell, 3.6 volt model, weigh's 6lb. 8oz., should be charged for 8 hours at 1-75 amps'., and gives 12 hours light.

Both batteries have a stainless steel case, and two headpieces are available; a Bakelite one having a 3.75 volt. 1.0 amp. double filament krypton bulb; and a stainless steel headpiece fitted, with a 3.6 volt. 1.0 amp. single filament krypton bulb. A pilot emergency bulb could be fitted to the latter.

The electrolyte 24% potassium hydroxide; should, be maintained between a specific gravity of 1.17 and 1.23 in the battery. Topping up should be done with electrolyte diluted with distilled water to a specific gravity of 1.020. If however, the electrolyte in the battery becomes too strong, dis¬tilled water should be used until the specific gravity falls to within the above limits.

The electrolyte should be renewed when the battery is received and then every 13 months. This should be done while the cell is discharged. Empty the battery and wash out with tap water several times. Do not leave the battery standing for any length of time empty or with tap water in it. Fill with electrolyte of specific gravity 1.20 - 1.21. Charge the battery at 1.75 amps, for 12 hours.

A few general tips:-
A flickering light could be due to the bulb being loose in the socket, in which case, bent up the contacts, or to dirty bulb contacts or dirty/ worn switch contacts. If cleaning these does not help, look for a short circuit.

Leaking electrolyte can be caused by perished stopper sealing washers, battery sealing pad, or terminal bushes or cracked ebonite bushes under the battery terminals. As spares are apparently no longer available, a little ingenuity would be required to remedy these faults.


The "Concordia" lamps used to be -manufactured by the company now known as Transformers (Vales) Ltd. They are no longer made but some of the lamps re still in use.

Two and three cell models have been made. The charging rate should be 2 amps until the voltage on charge of the batteries reaches 1.3 volts per cell. This appears to take about 8 hours (or longer after electrolyte renewal).

The electrolyte is a potassium hydroxide and lithium hydroxide mixture. The specific gravity of the electrolyte in the battery should be maintained between 1.18 and 1.23 after use by topping up with dilute electrolyte or distilled water, as necessary. The electrolyte should be replaced when the electrolyte falls below 1.18. This should be done when the battery is discharged: empty and wash out the cells ad refill with an electrolyte mixture of specific gravity 1.19 - 1.20. The cells should be done individually, as it is harmful to expose the plates to air for longer than necessary. The lamps should be totally discharged every three months, and given a long (10 - 12 hours) charge at the normal rate.

The batteries should be allowed, to bubble freely for about an hour and a half after charging, and the headlamp should not be switched on luring this time. The lamp top should be removed when the lamp is out of service for more than a day.


These lamps are now out of production.

The model "L" lamp, is a three cell alkaline, battery in a steel case, with a Bakelite headpiece. The headpiece contains a rotary switch. The-weight is 51b. and the duration 10 hours. The charging rate is 10 hours at 2.0 amps. Two bulbs can be used, either a 3.6 volt 1 .0/0.5-amp or-3.75 volt 1.0/1.0 amp. type.

The electro magnetic case lock has to be modified and some lamps have no switches when received! ex-N.C.B. The electrolyte is a mixture of 25% potassium hydroxide and 1.5% lithium hydroxide. The specific gravity should be between 1.16 and 1.25 and the level is 11/16” above the plates.

SAFT (23)

Portable Miners Lamp Typo 3VR10.

The author has never seen this French made lamp in use; however, from the details below it will be seen that if a second hand source could be located, it would compare favourably with other makes. 

Weight 3.3/3lb. complete.
Dimensions of Battery 3.1/4” x 42 X 1.1/2”.
Battery Three cylindrical sealed Cadmium Nickel “Voltabloc” VR10 in moulded case.
Duration Over 10 hours on main bulb, or 20 hours on pilot bulb.
Output Main beam 180 lux. At six feet.
Charging Charge at 5 volts, final charging current being 800 milliamps. after nine hours use the battery will be charged in 15 hours.An "individual" automatic charger is available.
Price New £18


This is a two cell, four volt, lead acid battery. It is non spill able and has a hard rubber case. The main bulb is 4 volt 1 amp., and the pilot bulb is 4 volt 0.46 amp. The duration on main beam, when new, is 12 hours, but the second hand lamp may only last about 10 hours. If the lamp lasts less than 9 hours it is unreliable, and should not be used (Richardson (xv)).

The new lamp, together with an individual automatic charger and a “Tools and Spares Kit” costs £12. 6. 6.

A full range of spares is available from the manufacturers. A brief list of which is shown below.

Oldhams  Component Price
Code No.    s. d.
2.001.21. Lens ring, Black.
(White, red, yellow and blue available, same price). 
3. 1
2.001.31. Headpiece glass (clear). 1. 5.
2.014.27. Diffused reflector - Non focussing. 2. -.
2.025.27. Soft beam reflector - Men focussing. 2. -.
6.174.04.  Soft beam reflector focussing kit.
(For conversion from non focussing.
5. 9.
2.024-55  Soft beam reflector - Focussing.
(For replacement only).
4. 9.
6.174-02  Specular reflector - Focussing kit.
(For conversion from non focussing).
 5. 9.
2.023.55  Specular reflector - Focussing.
(For replacement only).
4. 3.


Charging and Maintenance.

    1. Topping up. This should be done with distilled water (NEVER BATTERY ACID). Remove filler cap in the front of the battery case and pour in the distilled water through the filler holes exposed. A syringe is useful here. The correct level is found by tilting the battery forward 10 degrees.
    2. Do not let the battery stand in a discharged condition when not in use.
    3. Charging. If the manufacturers automatic equipment is in use this presents no problem. Otherwise, charge at 0.3 amps. for a length of time20% in excess of the time that the lamp was used.
    4. To remove the battery top the nut in the side must be undone. A small pair of round nosed pliers are suitable. A groove cut in the top of the screw will enable an ordinary screwdriver to be used in future.


CgL2 Cap Lamp.

This is a two cell lead acid battery of 10 amp. hour capacity. The battery container, which is also the cell wall, is of hard moulded rubber. The lamp top will fit any standard battery. The headpiece is available with semi-matt, or fully polished reflector, and is fitted with a toggle switch. The main bulb is rated at 4 volt 1 amp., and the pilot bulb at 4 volt 0.8amp.

The battery should be charged at an initial voltage of 5 volts, which at no time during the charging should be allowed to exceed 3.05 volts. Experience will no doubt enable the user to determine the appro¬priate amperage. Charging takes about ten hours. Top up frequently with distilled water only. This should be done during the actual charging, through the vent plug in the side of the battery. The level should just cover the plates. Care should be taken to avoid spilling the electrolyte.

If there is a leakage of acid from the vent plug in the side of the lamp, check the fitting of the plug ande sealing rubber, and the level of the electrolyte.

To remove the lamp top, prise out the sealing wax from the locking screw. Unscrew this and pull off the locking piece. The lamp top can now be removed. To remove a blown fuse (which is fastened to the lamp top) undo the two screws which secure it.

To open the headpiece the wax must be removed from the locking screw, unscrewing this then enables the bezel to be removed. If the reflector (anodised aluminium) is dirty, wash in warm soapy water and dry with a soft cloth. Do not use abrasives etc. When assembling, ensure that the reflector notches are located on the headpiece mouldings.


Now out of production, the following details of the Concordia Type F lamp are given for completeness.

The basic battery is an "Exide" battery which is topped up through the vent in the side of the casing, as with other lead, acid lamps. The charging rate is 1.5 amps, for 10 hours.

There is a magnetic locking device op the headpiece which would have to be replaced with some form of grub screw. The external charging term¬inals, a brass button on the case top (+ ve.) and the case top itself (-ve.) are best disconnected from the battery as they tend to short out under water (Johnson (xxi)).

C. (i) Dry Battery Powered Cap Lamps.

These lamps are used to a limited extent for caving but they have, the disadvantage met with in all dry battery equipment - high running costs. The general arrangement is a headpiece which has an adjustable strap for fixing round the head, and a cable leading to the battery container carried in the pocket, or on a belt.

"EVER READY'" produce a well made battery powered cap lamp which sells at about 30/-. Three U2 batteries are used in series with an 0.5 amp. pre-focus bulb to give a very powerful beam. The lamp can be fitted either to the battery case, or the head band supplied. The battery case has a belt clip, button loop, carrying handle and stand, all of which fold or slide away independently of each other when not in use The battery case has an internal clip, for carrying a spare bulb (one is supplied) and takes the spare flex to the head lamp. The lamp is well designed, but it would be difficult to fasten the lamp to a caving helmet satisfactorily and it is not as robust as a damp designed for miners.

The same damp is also sold under the trade names "BEREC" and "EXIDE".

The "G.E.C." and "WOLF" lamps mentioned in the first edition of this report are no longer available.

"PIFCO" manufacture a similar lamp: to the "EVER READY" model above, taking four U2 batteries; and cap damps taking the small flat 4.1/2 -volt batteries are available at some camping shops. Neither of these appear to be very robust.

C. (j) Battery Powered Hand Lamps.

Ordinary torches come in this category and these of course need no introduction. They are often used by the "novice" cavers as they are eas¬ily acquired and therefore the initial cost is small. Although useful as an emergency source of light the ordinary torch is not very convenient because it is frail, cannot be fitted to a helmet and the running costs are high. In another article (vii) the author of this report (first edit¬ion) describes experiments he performed, to determine the lengths of use¬ful life of a number of batteries when run continually and using a 3-5 volt 0.3 amp. bulb. A summary of the results are given here.

“Ever Ready” Battery Catalogue No. Type of Battery Useful Life in Hours
800 Cycle front lamp 7 – 7.1/2.
2 x U2 in series Cycle rear lamp 6 – 6.1/2.
2 x 1839 “Baby” battery 1.1/2 – 2.
No. 8 “Bijoux” battery 1
1289 4.1/2 volt pocket battery 2.1/2 – 3.
126 4.1/2 volt bell battery 3 – 8.1/2.

Both the "Ever Ready" and the "Vidor" companies produce water proof torches using two or three U2 batteries and of the two, .he latter is to be preferred as the water proofing is better. These torches will operate completely submerged in water, and being rubber cased will stand up to a certain amount of rough treatment. A Japanese made rubber torch is also available, but one owned by the author soon developed a faulty switch.

Although dry batteries do not deteriorate electrically by being submerged in water, they definitely do deteriorate mechanically and multi-cell batteries tend to fall apart. "Leak proof" batteries encased in metal are worth the extra cost for the more robust batteries.

There are several heavy industrial torches on the market which are made for use in inflammable atmospheres and are therefore watertight. They are however heavy, but very robust. The makes that are known to the author are given below. Prices are exclusive of batteries.


Made from heavy gauge solid drawn copper tube, chromium plated, the torches are fitted with armour plated clear glass and screw/press button switches. Spare parts, are available from the manufacturers and dimensions and prices of the three models are given in the table on the following page.

Model Length Head Body No. of Cells Price  
  Overall Diameter Diameter   £.  s.  d. +PT
PB2 8” 2.3/8” 1.1/2” 2 1  17  6 6/2
PB3 10.1/4” 2.3/8” 1.1/2” 3 1  19  6 6/5
td Mines Pattern            
PB2M 8” 2.3/8” 1.1/2” 2 2   2   - Nil
PB3M 10.1/4” 2.3/8” 1.1/2” 3 2   3   6 Nil
td Anti Explosive            
A.E.T. 11” 2.3/8” 1.1/2” 3 3   2   6 Nil

Mines pattern torches incorporate a locking device.

The Anti-explosive torch has a grill over the glass.

OLDHAM. (10)

TD3A. Safety Torch.

This also has armoured glass protected by a grill, press/screw button switch, and weighs 21b. 4oz. complete. There is a shock protector between the 3.5 volt 0.3 amp. bulb and the cells. Made in die-cast alloy, it has a cell retaining tube for easy removal of corroded batteries. Fitted with locking device. Earlier models in brass without a cell re¬taining tube are available from some ex-Government stores, e.g. (41).

CEAG (24)

3-Cell Universal Torch.

The solid drawn brass body is 12” long overall, the diameter of the body being 1.1/2” and the head 2.1/2”. The reflector is aluminised and focusable. The switch is of the press/screw button variety.

Price £3. 8s. 0d.


SA 6060 safety Torch.

A cast aluminium alloy body 10.1/4" x 3.1/4"; weighing, with batter¬ies 1lb. 14oz.; is fitted with armour plated glass protected by a grill; has an interior battery container. The torch takes three U2 cells.

Price £2. 5s. 01.

SA 622 Safety Torch.

The body of this torch is injection moulded in high density Polyethylene. The dimensions are 10.3/3"' x 3" and the weight, with batteries 1lb. 2oz. The torch is packed with 43 spare seals, key, and instructions.

Price £1. 17s. 4d.

A full range of spares is available for both these torches.

The author did, on one occasion, find a divers torch at the bottom of the "Forty Foot" in Swildons, presumably dropped by someone, although extremely robust, I should think that the person who dropped it was glad to have done so because it was extremely heavy, although it was only powered by three U2. batteries.

There are various large dry battery powered hand lamps on the market, designed largely for motorists' use. Although their size and weight rules them out for normal caving purposes, the good beam they give could be use¬ful on occasions. The "Ever Ready" range is tabled below.

Model and Price



Reflector Diameter



“Space Beacon”

7.1/2 x 5.3/4” 8” excluding wire handle

Cylindrical, pivots on base.  Dome light and reflector



6 volt

Round spotlight 5.5v  0.3amp

“Space Beam”

£1.  3.  3.

8.11/16 x 4.3/4” x 6.1/4” overall

Rectangular battery box, reflector pivots on handle


As above

Pre-focus 4. 75v  0.5amp

“Space Ray”

8.7/8 x 4/3/4” x



As above

As above

£1.  15.  -.

6.1/4” overall





One further type of lamp coning in this category, is, the accumulator powered hand lamp as produced for use in mines and other inflammable atmospheres, or where at high power, portable, light source is required. They are heavy and cumbersome, but could be put to use where a good light is required at one place, e.g. a "dig".

NIFE. (22)

These are alkaline batteries.

NH 10 A

Made of steel; weight 41b. (approx.); dimensions 2.3/4" x 4.1/4" x 5.1/2" excluding handle. Rectangular battery box; screw switch; focusing device. Give ten hours of light with a 0.75 amp bulb.

Price £4. 19s. 0d.

Hand Lamps NB 07 and NH 113.

Similar in appearance to the NH 113 cap lamp, these lamps have short cables and suitcase type handles. Both have krypton filled main bulbs and emergency pilot bulbs. Other details are given in the table below.

  NH 07 NH 113
Weight 5lb.   40z. 5lb.   11oz.
Dimensions 8.1/2” x 1.1/2” x 8” 8.1/2” x 1.1/2” x 9”
Duration  7 hours 10 hours
Price £7.  15s.  0d. £8.  15s.  0d.

Searchlight S 6.

This -lamp has a rectangular battery box with the reflector built into the case. Its dimensions are 7.1/2" x 5.5/3" x 3.1/2", and the weight is 131b. A very powerful beam, designed to be equivalent to a motor car headlamp, is given by the 18 watt dual filament bulb (3.0/ 0.5 amp.). The: duration of the lamp is 3 - 4 hours on main beam or 20 hours on reserve. On an alternative bulb (l.0/l.0amp) the duration is 9-10 hours. The six cell, 6-8 volt, 11 amp. hour battery should be charged at 1 .5 amp for 12 hours. The lamp is operated by a push button switch.

Price new £19. -. -.

Floodlight Set FL 6.

The battery is housed in a welded steel container size 13.1/4” x 12” x 11” into which a lamp standard also packs, when not in use. The unit gives 6 hours of light with a 24 watt bulb, and 18 and 38 watt bulb are also available. An even spread of light is given by the lamp on a standard which can be raised to 5’ 6” in height. The total weight is 42lb.

Price new £24. 19. -

CEAQ. (24)

2 - Volt Inspection Lamp.

The cylindrical battery case is made entirely of non-ferrous mater¬ials. Including the handle the height is 3.1/2" and the diameter 3.1/2”. The reflector casing is on the side. The total weight is 51b. 8oz. 4 2 volt 1.3 amp bulb is used. The lamp switches by rotating the top.
The electrolyte is non-spill Jellac Acid, the charging rate being 1,5 amps, for 8 hours.

Price, new £6. 16. -.

C. (k) Other Cells.

So far we have considered mainly the conventional dry batteries and miner's accumulators of the acid and alkaline types. There are on the market several other types of cell suitable for lighting sets, such as the "Voltabloc" cells used in the SAFE miner's damp, and consideration of these and other types of primary and secondary cells is given below.

The main .disadvantage of most of these cells seem to be their cost, but some comfort can be drawn for the fact that the prices have in some cases come down! The general advantage of the cells lies in their great¬er output per unit of weight. This of course results is smaller batteries and/or longer life. Some average figures quoted by one manufacturer, may be of interest:-

Lead - Acid 10 AH/lb.  18-20 WH/lb.
Nickel - Iron alkaline  10 AH/lb. 12 - 13 WH/lb.
Silver - Zinc  40 AH/lb. 50 - 60 WH/lb. '

DEAC Cells. (26)

These are permanently sealed Nickel - Cadmium accumulators.


The cells should not be discharged below 1 volt, especially when mounted in batteries. The cells should not be discharged continuously at more than ten times the average 10hr. discharge rate (I10)(20 times for cells with sintered electrodes).


The charging voltages are listed under. 1.4 times the capacity taken out must be replaced. Permissible occasional overcharge rates are: -

Up to 24 Hours with I10

Up to 48 Hours with 1/2I10

Up to 100 Hours with 1/3I10

The last rate has no immediate ill effect, but should be avoided. Similarly, when charging with constant current (i.e. normally) the rate 'of I10 amps, should not be exceeded. If a 'tapering' current is used, the starting rate may be 1.2 x I10, but at the end should not be greater than I10. If the state of discharge is unknown, charge for 12 hours only at I10 and then after a rest period, give a normal 11 hour charge.

The cells should not be mounted in parallel but may (except for the 20 DK and 50 DK) be mounted in series to form a battery. The manufactur¬ers will supply cells mounted in battery cases and this should avoid contact troubles. Soldering should be avoided, as should copper contacts


Although the manufacturer states that these are suitable for torches their small capacity must limit their usefulness. All but the 20 and 50 DK are suitable for mounting in batteries.

The full range of standard button cells is shown in the table below.


Some of .these cells correspond to standard dry battery sizes and the corresponding "Ever Ready" size is given where appropriate in the table below.

Type   20DK 50DK 100DK 150DK 225DK 450DK 1000DK 2000DK 3000DK
Capacity - 10 hr.  rate Milli amp hrs 20 50 100 150 225 450 1000 2000 3000
Discharge current 10hr. rate Milli amps 2 5 10 15 22 45 100 200 300
Average discharge voltage – 10hr. rate Volts 1.22 1.24
Cut-off voltage – 10hr. rate Volts 1.10
Charging rate (14hr. charge) Milli amps 2 5 10 15 22 45 100 200 300
Charging voltage Volts From 1.35 to 1.50
Cell weight Grams 1.1 3.5 9.0 11.0 12.5 33.0 57.0 95.0 135..0
Ozs 0.04 0.12 0.31 0.38 0.44 1.2 1.9 3.3 4.7
Dimensions in mm Diam. 11.4 15.5 - - 25.0 - - 43.0 - - 50.3 - -
Height 5.1 5.85 6.1 6.6 8.6 7.6 10.0 18.0 25.0
Dimensions in inches Diam. 0.45 0.62 - - 1.0 - - 1.7 - - 2.0 - -
height 0.20 0.23 0.24 0.26 0.34 0.30 0.40 0.64 1.0
Price   4/9 3/6 3/11 4/2 4/9 7/5 12/9 22/3 28/8


Type 450D 900D 151D 451D BD2.5
Capacity – 10hr. rate Milli ampere hours 450 900 150 450 2000
Discharge current rate Milli amperes 45 90 15 45 200
Average discharge voltage – 10hr. rate Volts 1.20
Cut-off voltage 10hr. rate Volts 1.10
Long term discharge rate – maximum Milli amperes 450 900 150 450 2000
Charging current (at 10hr. rate) Milli amperes 45 90 15 45 200
Charging voltage Volts From 1.35 to 1.50
Cell weight Grams 23 40 12 23 150
Ounces 0.80 1.4 0.42 0.80 5.2
Dimensions in millimetres Diameter 13.5 13.5 12 13.5 34
Height 50 50 29 50 62
Dimensions in inches Diameter 0.53 0.53 0.46 0.53 1.3
Height 1.9 3.5 1.1 1.9 2.4
“Ever Ready” size    - - - D23 U7 U2
Price   10/9 13/9 15/6 10/11 29/8



These cells should also be operated in an upright position normally. The 3/SD. batteries have solder tags; the other individual cells being fitted with screw terminals. The sintered plate design permits a higher current drain.

Technical data is shown in the table below.

Type SD1.6 SD2.6 SD4 SD7 SD15 3/SD1.6 3/SD2.6
Capacity – 10hr. rate Milli ampere hours 1.6 2.6 4 7 15 1.6 2.6
Discharge current rate Milli amperes 0.16 0.26 0.40 0.70 1.5 0.16 0.26
Average discharge voltage – 10hr. rate Volts 1.24 3.7
Cut-off voltage 10hr. rate Volts 1.10 3.3
Charging current (at 14hr. rate) Milli amperes 0.16 0.26 0.40 0.70 1.5 0.16 0.26
Charging voltage Volts From 1.35 to 1.45 From 4 to 4.35
Cell weight Grams 115 180 260 360 715 360 570
Ounces 5.25 6.3 9.1 12 26 12 20
Dimensions in millimetres Length 16.8 16.8 24.2 38.2 77 52 52
Width 41.2 30 43 43
Height over terminals 65.7 102 115 67.5 110
Dimensions in inches Length 0.66 0.66 0.95 1.5 3 2.2 2.2
Width 1.6 1.2 1.7 1.7
Height over terminals 2.6 4 4.5 2.6 4.3
Price   31/5 35/11 47/2 72/8 120/2 99/6 114/6

VOLTABLOCK Cells. (23) ;

These are stated by the manufacturer to be suitable for use in torches. Cells may be combined in series to form batteries. The cells are completely sealed, requiring no maintenance and the electrolyte is Potash. The rated voltage of the cells is 1.2 volts, and they may be discharged steadily at rates up to C. amps. (C = the nominal capacity in amp. hrs.). The cells are rechargeable. The rates are given with the cell data in the following table. They may be stored indefinitely and have good charge retention, but for the best results, discharge slowly to 1 volt per cell, and store in a cool place.

Type VO1 VO2.5 V04 VO4US VO9 VO9LM VO12LM
Nominal capacity.  C. # 0.8 2.7 3.8 4.4 9.9 11 13.2
Dimensions in millimetres Depth 8.6 20 15.3 16 15.3 32.7 32.7
Width 42 45 60 60 92 44.2 39.2
Height overall 76 69 76.4 73.3 104 115.5 152.5
Dimensions in inches Depth 0.3 7.8 6 6.2 6 12.7 12.7
Width 1.6 1.8 2.4 2.4 3.6 1.7 1.5
Height overall 0.3 2.7 2.3 2.4 2.3 5 5
Weight in grams   50 150 170 190 390 450 560
Weight in ounces   1.7 5.2 6 6.6 13.6 16.5 19.6
Container   Nylon Steel
Price       47/3   69/6  

# These nominal capacities are obtained when discharging fully charged cells at the 5 hour rate down to 1.1 volt final voltage.


Venner manufacture a wide range of Silver-zink accumulators. Extremely small and light, these cells have a rectangular perspex case, and for caving, would probably need to be enclosed in a battery box, although they are shock and vibration proof. The manufacturers state that they are suitable for portable lighting equipment, and the range of operating temper¬atures easily covers our requirements. They are supplied empty with the electrolyte in a separate container. Filling instructions are given.

The nominal voltage is 1.5 volts, and the charging rate C/10 (where C - the nominal capacity). The cell is fully charged when its voltage, while charging, reaches 2.10 volts.

Information on some of the individual cells is given in the table below.

Characteristics. Cell Type
   H075. H105- H4. H705. H10.
ELECTRICAL. td   td   td   td   td   td  
Nominal capacity (Ah). 0-75 1 «5   4 ,7*5  i :10
Maximum rate for            
complete dis charge (Amps). 1-75 4-5   10 ¦12 20
APPLICATION DATA             -  
at 20 °C.                
Discharge rate (amps). 0.75 1.4 0.4 4 0-75 5 1 5
Discharge time (Mins)o 53 60 128 80 600 90 640 131
td PHYSICAL.                
Weight .      (grms). 21.3 31.9 106 128 192
Height (overall)  (mms) 39 51 82 75 81
Width.                  ( " ) 28.5 28.5 42 52.5 57
Depth.                  ( " ) 14 16 20.5 21 27
Weight.               (ozs) 0.76 1.1 3.7 4.5


Height (overall) (lns) 1-5 2 3.2 2.9 3-2
Width.                 ( " ) 1.1 1.1 1.6 2.1 2*2
Depth.                 ( " ) 0.5 0.6 0.8 0.8


PRICE. 18/3 19/9 33/- 59/6 49/6

In addition to these, Venner make other Silver-zimk cells of up to 60 amp. hr. capacity, at a price of £7.15. 0.

Also manufactured is a Silver-cadmium accumulator (CD 5); nominal capacity 5 amp. hrs.; charging rate 0.5 amps.; duration at discharge rate of 1 amp. is 330 minutes; weight 121 grams.

Price: £2. 3. 6.


These cells are normally sold mounted in batteries. The standard batteries are 2 – 10. VO1., VO4., VO4US. ,or VO9. cells Information on the individual cells are given below in the table.

Charging. * .

Fully discharged cells should be charged for 16-18 hours at the following rates. The duration of charging at this rate should be suitably reduced for partially discharging cells.

Type V01 . V02.5 V04. VG4 US V09. V09 LM. V012 LM
Rate. M.A. 75 250 350 400 900 1 Amp 1.2 Amp

If the state of discharge is unknown, the cells may be permanently charged at a current of C/50, fully discharged cells will take about 80 hour at this rate.


These cells are designed as far as possible to be interchangeable with standard dry batteries. All except the VR1-RR. therefore have a cover with a central boss. The cell cover is +ve. and the container -ve.

The container is made of nickel plated steel.


The cells should be charged at a rate of C/10 for 15-16 hours, and at this rate, can withstand considerable overcharging (up to 200 hours), it is thus possible to recharge cells whose state of discharge is unknown at this rate. Alternatively, fully discharged cells' may be re re-charged at a rate of C/5 for 7 hours.

Type Format RatedCapacity # Weight Dimensions Equivalent type ofprimary cell Price
Grams Ozs. Height Diameter
          mm ins mm ins
VRO45 AA 0.45 23 0.8 50 1.9 14.6 0.6 U12/D14/U7 19/9
VRO65 ½ C 0.65 36 1.3 25 0.87 26 1.0    
VR1 RR 1 47 1.6 41 1.6 22.8 0.9   23/-
VR1.6 C 1.6 72 2.5 49 1.9 26 1.0 U11/LPU11/HP11 28/6
VR3 Dm 3 124 4.3 61 2.3 32 1.2 U2/LPU2/HP2 37/-
VR3.5 D 3.5 144 5.1 61 2.3 34 1.3 U2/LPU2/HP2 41/-
VR5 Fm 5 195 6.8 91 3.5 32 1.2   50/-
VR6 F 6 229 7.2 91 3.5 34 1.3   56/3

# the rated capacity C is for discharge at the 5 – hour rate at a temperature of about +20O C after normal charge for a final voltage of 1.1 volts.

All the cells are fitted with a cover with central boss, except the VR1 – RR which has a flat cover. The following cells can also be supplied with a flat cover on request: -

VR3 – Dm, VR3.5 – D, VR5 – Fm and VR6 – F. In this case the overall height of these cells in 3mm less. The diameters are given for cells covered with an insulating sheath.


Although the supplier states that these cells are suitable for torches, their small capacity must limit their usefulness in this direction.

The cells can be supplied in batteries of up to 20 cells. The output terminals should not be used for supporting or fixing the battery, and soldering should not be made direct to the cell itself.


The cells must be charged at constant current. Fully discharged cells should be charged at the C/10 rate for 15 - 18 hours. If a cell is part¬ially discharged, it may be charged at the above rate provided that the time is reduced. In this case the charge replaced should be approximately 1.5 times that withdrawn. If the state of discharge is unknown, it can be recharged at the C/10 rate provided that it has been discharged at a current of C down to a terminal voltage of 1 volt. Alternatively, the cell may be overcharged at a rate of C/50, but the cell will only regain 70% of its full charge at this rate.

Type Rated Capacity (mAh) Weight Dimensions Price
    Gr. Ozs. Thickness Diameter  
        mm. ins. mm. ins.  
VB10S. 90 6.5 0.2 5.2 0.2 22.7 0.9 3/10
VB18S. 200 11 0.3 7.4 0.3 24.8 1 4/6
VB25S• 275 16.5 0.5 5.2 0.2 34.4 1.3 4/6
VB50S• 550 28.5 1.0 9.45 0.4 34.4 1.3 7/-
VB100 900 64 2.2 8.3 0.3 50.5 2 13/-
VB200 1750 100 3.5 14.90 0.6 50.7 2 20/6

The rated capacity is for discharge at the 5 hour rate at a temperature of about + 20°C, af"cer normal charge and for a terminal voltage of 1 '1 V.


Manufactured by Vidor Ltd. (28), these cells are stated (xiv) to have improved output characteristics over standard dry cells. At present however, only two Kalium cells are available, which although suitable for use in torches, are rather too small for general use. The initial voltage of the cells is 1 .3 volts as opposed to the 1 .5 volts of the normal Leclanche dry cell.

Number Description Dimensions Dis.     Length Price.
V107 Penlight. •555"x 1 .985" 3/3
VI09 Half Weight Penlight •555"x 1" 2/6

The above table gives details of the two cells.


These cells are available from (30).


These are primary cells i.e. they are not rechargable, they have the advantage though that they last three to five times as long as ord¬inary dry batteries. They also have 2 years storage life and are of leak proof construction. The nominal voltage is 1 .5 volts and they are inter¬changeable with standard batteries (Ever Ready U2 etc.).

Mallory Type No. Corresponding "Ever Ready" Battery Size. Capacity Ah. Price.
Mn1300 U2 10,000 7/-
Mn1400 U11 5,000 4/9
Mn1500 U7 1 ,800 2/9
Mn2400 U16 750 2/4
Mn9100 D23 580 1/10

It will be seen that these batteries are at the moment more expensive to use than ordinary batteries. However, if considerations of weight and space are important, and there is no source of power available for accum¬ulators (vis. on an expedition), these batteries could well be very useful.


A wide range of Mercury cells (these are also primary cells) is also manufactured, but these are designed for much smaller current drains than would be required for lighting a bulb. Some of the largest only are dis¬cussed here.

Mercury cells have a very high ratio of energy to volume and weight (3-4 times that of a conventional, cell), uniform discharge character¬istics, similar to those of a secondary cell, strong construction, long shelf life and reliability

They are designed to be connected in series to form a battery, and the normal voltage is 1.35 volts per cell.
Some of the types available are:-


Cell Type No :- RM.1R RM.502R RM.4R RM.12R RM.42R
Capacity MAh 1000 2400 3400 3600 14000
Max Current Drain M Amps 100 200 80 250 1000
Dimensions in   mm Dia. 15.75 13.47 30.22 15.8 30.18
Height 16.38 49.61 16.51 49.61 60.3
Dimensions in ins. Dia. .6 .5 1 .2 .0 1.2
Height .6 1.9 .6 1.9 2.3
Weight G-ms. 12.2 29.77 42.52 39.69 165.89
ozs. .9 1.0 1.4 1.4 6.4
Price. 2/9 4/6 6/- 5/9 24/-

These cells would doubtless be very useful for emergency radio equipment or other communication devices, but for general lighting purp¬oses would be much too expensive. The RM.42R for instance, approximates in size to an ordinary U2.

Mallory also manufacture a range of Silver oxide batteries for use in Planar transistor devices. Dalforso (xvii) discusses further the technical nature of Mallory cells«


Ever Ready also manufacture ranges of conventional, sealed Manganese and Mercury batteries.

Sealed batteries are recommended rather than standard types because of their greater strength and corrosion resistance. Their sealed Manganese batteries (sold as "High Powered") they claim, last twice as long in torches than ordinary batteries, giving brighter light. Prices for their Mercury batteries are about the same as Mallory, but as they do not cover so wide a range as the latter, no details are given here.

Cat. No Price Typical use Dimensions (inches)
U2 -/8 Torches 1.11/32 - 2.13/32
U7 -/7 Torches 9/16 - 1.63/64
D14 -/4 Torches 9/16 - 1.63/64
U11 -/5 Torches 1.1/32 - 1.31/32
8 -/7 Torches (3 volt) 27/32 - 2.29/32
U16 -/5 Torches 13/32 - 1.3/4
U10 -/5 Torches 51/64 - 2.19/64
72 1/2 Torches 9/16 - 3.31/32
126 3/- Bells (4.1/2 volt) 4.1/16 1.3/8 3.7/16
481 12/6 Lamps (4.1/2 volt) 4.7/16 2.19/32 6.1/2
800 1/6 Cycle lamp (3 volt) 2.11/16 1.7/16 3.3/16
996 4/- Hand lamp (6 volt) 2.21/32 2.21/32 4
1289 1/3 Pocket lamp (4.1/2 volt) 2.7/16 7/8 2.5/8
1839 -/10 Torches (3 volt) 1.1/32 - 3.15/16
1915 -/8 Torches (3 volt) 9/16 - 3.11/32
D20 -/7 Hearing aids 37/64 - 63/64
D22 1/2 Hearing aids 13/32 - 1.3/4
D23 -/9 Hearing aids 15/32 - 1.3/16
LP U2 -/10 Torches 1.11/32 - 2.13/32
LP U11 -/11 Torches 1.1/32 - 1.31/32
HP2 1/6 Torches 1.11/32 - 2.13/32
HP11 1/3 Torches 1.1/32 - 1.31/32
HP16 1/- Torches 13/32 - 1.3/4


Many of these cells could usefully be applied to caving purposes; the Voltablock YR series, Venner, and Manganese batteries particularly. Some of the secondary cells must be charged at constant current, and the proper equipment is needed to do this. The button type cells however, generally do not have the capacity required, though they might be use¬ful for a supplementary or emergency light.

(C) (1) Bulbs.

The standard ranges of torch bulbs are too well known to need dis¬cussion here. The bulbs used in most accumulator sets however, are Krypton filled. These are 20% more efficient than ordinary bulbs, thus giving more light for no increase in drain on the battery. The range of Osram (30) miners bulbs is given in the table on the next page.


For use in Volts Amps Shape Dimensions Cap Finish Price
Dia. mm O/L length mm
Hand lamps # 2.5 1.75 Pear 18 ±2 43.5 ±2 953 $ Pearl 3/-
Hand lamps # 2.5 1.75 Pear 18 ±2 45.5 ±2 S.E.S Pearl 3/-
Cap lamps 3.6 1.0 Round 18 ±1 30.5 ±1 M.E.S. Clear 2/6
Cap lamps 3.75 1.0 & 1.0 Pear 18 ±2 40 ±2 S.B.C Clear 3/6
Cap lamps 4.0 0.8 Round 18 ±1 30.5 ±1 M.E.S. Clear 2/6
Hand lamps 4.0 1.0 Pear 18 ±2 43.5 ±2 S.E.S. Pearl 3/-
Cap lamps 4.0 1.0 Round 18 ±1 30.5 ±1 M.E.S Clear 3/-

# These bulbs have fuses in the caps.
$ Special S.C.C. Made in accordance with B.S. 535 where applicable.


For use in Volts Amps Shape Dimensions Cap Finish Price
Dia. mm O/L length mm
Cap lamps 2.5 0.75 Round 15 ±1 27.5 ±1.5 M.E.S Clear 2/-

C . (m) Making an Electric Lighting Set.

Having given the details of separate batteries and bulbs available, it seems only logical to make some recommendations for assembling them into a working unit, especially as inefficient home made sets cam be positiv¬ely dangerous.

First the battery box. The purpose of this is to protect the batteries, and provide a terminal point for the lead. It should be as small as possible, strong, easily opened, but not liable to open accidentally, rustproof, and perfectly waterproof.

The flex should be a heavy duty cab lay type, and should be protected from chaffing by a grommet, wherever it passes through a hole in the battery box or lamp. The wire should be soldered firmly, either direct to the terminals, or to tags which are themselves screwed to the terminals. The terminal should never take any strain from the cable, and to avoid this, pass it through a hole and knot it, or hold it by a clamp, near to the terminal.

The lamp itself is difficult to make and these may be bought separately from the accumulator manufacturers. If you wish to make your own, the simplest way is probably to modify a cycle front lamp.

In this case the lamp may be removed from the battery box without distorting, by drilling through the small spot-welds (usually five) with a small bit. The terminals must then be made so that they are properly insulated, and protected from accidental damage. The glass should be re¬placed, preferably with armoured glass, or alternatively with plastic. The surface of the plastic will soon be badly scoured and it will need regular replacing, but ordinary glass will be broken even sooner.

If the lamp is to be fastened to the helmet rigidly, it must point in the proper direction - downwards - and the mounting: must be designed to do this. It should also project as little as possible from the helmet, or it will be too cumbersome.

Toggle type switches are seldom satisfactory for long, as there is no way of preventing water and dirt from entering. A screw down arrangement will probably last longer, and even a simple crocodile clip can be used. The author has tried using two switches in parallel, one acting as an emergency switch. The result looked rather like something from science fiction, but it worked. Plugs in the system are probably best avoided, suitable heavy duty ones can be obtained, but they are cumbersome, heavy and expensive.

One other point worth remembering, when connecting N cells of cap¬acity C. and voltage V in series to form a battery, then:-Nominal Voltage of battery - V.N. Nominal Capacity of battery = C. Whether your system is home made or bought, do not forget to dry it out, grease the terminals after use, and always check it the day before you want to use it.



For personal lighting no lamp is ideal, each having its advantages under different circumstances. No purpose would therefore be served by recommending one type rather than another. Nor should it be necessary to emphasise the need, whatever the lamp, for proper care and maintenance. No equipment will give reliable service for long, under caving conditions, without some attention.

High powered light sources are sometimes needed for such occasions as surface lighting on a night rescue, filming, digs, etc.. Though it is not claimed that the lamps mentioned in the text are necessarily suit¬able for such purposes, several high powered sources have been included to show what is actually available in this line. A brief resume of these lamps, in the order mentioned in the text, is given below:-

Paraffin Vapour Lamps and Flares.
Calor Gas.
Acetylene Flares.
Accumulator powered Hand Lamps
and Flood Lights.


The author would like to record his thanks to the persons who have helped in various ways with the compilation of this report. These in¬clude all the firms mentioned in the report who supplied information and answered innumerable questions about their products, and also a large number of other firms who were contacted, only to find that they did not mention products in which the report was concerned. Of the firms, acknowledgements go particularly to Thomas Townsend Ltd., and Helmets Ltd., who sent free samples of their products so that the report could be as complete, as possible. Finally, the author wishes to thank the British Standards Institution for permission to quote the paragraph about helmets made from non-waterproof materials from their Specifications.2095 and 2826.

In revising this report, the present author adds his thanks, particularly to the previous, editor Mr. B.M. Ellis, for his comments, and to the production team.



(i) H.A.Bamber. “Cave Science" Vol.3.No.21. pp 228-234.
(ii) British Standards Specification 2095:1954.
(iii) British Standards Specification 2826:1957.
(iv) J.Pegram. "Westminster Speleological Group Bulletin11 Vol.1 .No.38, pp-2-3.
(v) "MOT" "British Caver" Vol.23. 1952. page 41.
(vi) P.Polson. "Exploring American Caves" page 76.
(vii) B.M.Ellis. "Westminster Speleological Group Bulletin" Vol.2.No.3. pp 2-3.
(viii) Petroleum (Carbide of Calcium) Order 1929.
(ix) Post Office Guide.
(x) Southern National Omnibus'Co. Ltd., Regulations and Conditions. Section 18.
(xi) Western National Omnibus Co. Ltd., Regulations and Conditions. Section 18.
(xii) Bristol Omnibus Co. Ltd., Regulations and Conditions. Section 10.
(xiii) A.Cumming and J.Horn. "Journal of Applied Chemistry" Vol.1 . pp 198-202.
(xiv) A.J.Knibbs. "Lighting Miscellany", "Mendip Caving Gi-oup Journal" No.2.1960. pp 28-62.
(xv) D.T.Richardson. "Lighting Equipment & Care & Maintenance" "White Rose Pothole Club Journal" Vol.1. December, 1961. pp 48-63.
(xvi) A.J.Knibbs. "An Accumulator Charging Set", "Mendip Caving Group Journal" No.3. 1962. pp 52-58.
(xvii) J.L.Dalfonso. "Miniaturisation and the Primary Cell" "Electrical Manufacture” (March, 1962).
(xviii) D.Kemp. "Nife Cells", "South Wales Caving Club News¬letter" No.45- (December,- 1 963 ).
(xix) R.Johnson. "Edison Overhaul", "White Rose Pothole Club Journal" Vol.2. Section 1. (June, 1964). pp 25-28.
(xx) A.D.Benn. "Ceag Do's and Don'ts", "Bradford Pothole Club Journal" Vol.4.
(xxi) R. Johnson. "Exide Concordia Lead Acid Lamp", "White Rose Pothole Club Newsletter" No.45. (September, 1964) pp 6 – 9.
(xxii) R.J.Staynings. "Edison Safety Lamps", Wessex Gave Club Journal. No-.102. Vol.8. (July, 1965) PP 271-272.
(xxiii) J .Church. "The Nickel Iron Accumulator11 -, Wessex Cave Club Journal No.103. Vol.8. (October,.. 1965) PP 321-323.


HanwortheAir Park, Feltham, Middlesex.

Thetford, Norfolk.

Moat Factory, Wheathampstead, St. Albans, Herts.

Marlborough Street, Liverpool, 3«

High Level Factory, Gateshead, 8.

32, Great Pultney Street, Golden Square, London, W.1.

South Wharf, London, W.2.

300, Gray's Inn Road, London, W.C.I.

5, Great James Street, London, W.C»1«

Denton, Manchester.

Queenslie Industrial EastatGlasgow E.3.

(i) Mitcham, Surrey.
(ii) Howes Road, Newfoundland Road, Bristol.
(iii) 46 other depots.

Holrnethorpe Avenue, Redhill, Surrey.

Davis Road, Chessington, Surrey.

Alladin Building, Greenford, Middlesex. (Do not supply direct to the public).

Dunmufry, Belfast, Northern Ireland.

178-202, Great Portland Street, London, W»1.

Pleco Works, Barras Garth Road, Leeds, 12.

Saxon Road Works, Sheffield, 8.

Sagma House, 23, Princes Gate, London, S.W.7.

The Oaks, Rettendon Common, Chelmsford, Essex.

Union Street, Redditch, Worcs.

Spedant Works, Park Royal Road, London, N.W.10.

Queens Road, Barnsley, Yorkshire.

Mellngriffith Works, Whitchurch, Cardiff.

Elmbridge Works, Island Farm Av., West Molesey Trading Estate, East Molesey, Surrey.

Kingston By-Pass, New Maiden, Surrey.

Vidor House, Petts Wood, Kent.

Gatwick Road, Crawley, Surrey. (Do not supply to the public).

Coronation Road, Park Royal, London, N.W.10.

(i). Sales Office:- Lena Gardens, Hammersmith, London, W.6.
(ii). Distribution Depot (London) :- East Lane, Wembley, Middlesex.
(iii). Distribution Depot (Bristol) :- Victoria Street, Bristol.

Spa Lane, Derby.

41-43, East Dulwich Road, London, S.E.22.

Coronation Road, Park Royal, London, N.W.10.

Midsomer Norton, Bath.

132, Barnwood Road, Gloucester.

20, Dock Street, London, E.1.

38) Camping Equipment Manufacturers,
20-24, Gray's Inn Road, London, W.C.1.

39) Ships Chandlers,
20, Brood Quay, Bristol, 1.

40) Photographic Dealers,
127, New Bond Street, London, W.1.

41) Ex. Government Stores,
62-64, Hampstead Road, London, N.W.1.

2, Park Street, London, W.1.

49, High Holborn, London, W.C.1.



Summary of the British Standards Specifications 2095 & 2826. (42).

The two Specifications dealing with safety helmets are the B.S.S. 2095: 1954 and B.S.S.2826s 1957, the former being for light-duty helmets and the latter for heavy-duty. While the compilers of these two Specifications did not have caving in mind when they were drawing up these Specifications they do give a good indication of the strength of helmets used, as all helmets available on the market are sold primarily as in¬dustrial safety helmets, or as mining helmets.

Common to both Specifications is the paragraph already quoted in the introduction to the section on Helmets, regarding the importance of maintaining the waterproof coating on helmets that are made of non-water proof materials. Then follows details regarding the construction of the helmet, the finish, and the construction of the head cradle. A table of helmet sizes and the circumference inside the headband is also given.

(i) British Standard Specification 2095 for Industrial Safety Helmets (Light Duty)
For evidence of compliance with the Standard, it is necessary for ten helmets to be taken at random and submitted to the following tests. If all the helmets pass, then the Standard has been complied with. If any of the helmets fail the tests, then a second random batch of ten shall be taken, and if one of this second batch fails, then the Standard has not been complied with.

(a) Proof Test for Resistance to Moisture.
The helmet is continuously wetted at room temperature for four hours and then tested for mechanical strength.
(b) Proof Test for Mechanical Strength.
The helmet is placed on a wooden block in the shape of a head, on top of which has been placed a five inch disk of white paper, and then a four inch diameter disk of carbon typing paper with the carbon facing the white paper. After settling the helmet on the block by means of a 25 lb. weight, an 8 lb. iron sphere is allowed to fall 3'6" on to the centre of the crown. There must be no marking on the white paper caused by the helmet touching the carbon paper,
(c) Proof Test for Inflammability.
After applying a 1/2" gas flame to the end of a 1/2" wide strip of the helmet material for 10 seconds, the material must not burn faster than 3" per minute.

(ii) British Standard Specification 2826 for Industrial Safety Helmets (Heavy Duty)
The method of sampling is similar to that for B.S.S. 2095 except that no one helmet is expected to pass more than one of the following tests.

(a) Shock Absorption Test.

Sample helmets are set up as for the mechanical strength tests of B.S.S. 2095, after being prepared in one of the following ways: -

(i) Four hours at 18° - 22° P. (-7.8° to -5.6° C.)
(ii) Four hours at 118° - 122° P. (47.8° to 50° C.)
(iii). Four hours continuous wetting at room temperature.

An 8 lb. iron sphere is then dropped from 5'0" onto the centre of the crown of the helmet, and afterwards the amount of shock transmitted to the wooden "head" block must not exceed a certain amount (measured by
the indentation made on a strip of aluminium of definite hardness), nor must any part of the helmet be found to be broken.
(b) Penetration Test.
A plumb-bob with a steel point of inclined angle of 30 and a maximum/point radius of 0.02" must not penetrate the helmet by more than 3/8" (this measurement includes the thickness of the helmet) after being, dropped vertically through a height of ten feet.
(c) Inflammability Test.
This is exactly the same as that specified in B.S.S. 2095.


Legal Aspects and Dangers of Acetylene and Calcium Carbide.

Acetylene, being so highly inflammable a gas, gives rise to a number of legal points, and these are applied to Calcium Carbide due to the ease with which it will generate Acetylene gas.-

Storage of Calcium Carbide (viii); obtainable from (43).

(a) Up to 5 lbs. weight of carbide may be kept, provided it is kept in separate hermetically sealed metal containers holding not more than 1 lb. each. Each container must be labelled "Carbide of Calcium" "Danger¬ous if not kept dry", together with the caution "The contents of this package are liable if brought into contact with moisture to give off a hjghly inflammable gas".

(b) Up to 20 lbs. of carbide may be stored, provided the following conditions are observed:-

1) The carbide shall be kept only in a metal vessel or vessels hermetically closed at all times when the carbide is not actually being placed in or withdrawn from such vessel or vessels.
2) The vessels containing carbide shall be kept in a dry and well ventilated place„
3) Due precautions shall be taken to prevent unauthorised persons from having access to the carbide.
4) Notice of such keeping shall be given to the Local Authority.
5) The vessels are labelled as in (a) above.

Transporting Calcium Carbide.

Due to the potential danger of Calcium Carbide, there are regulations forbidding its presence at certain places. Thus, it is not permissible to send carbide through the post (ix), and some 'bus companies forbid pass¬engers from carrying it on their busses, e.g„ (x), (xi), and (xii).

While on this subject, it would be as well to mention that some 'busses forbid the carrying of accumulators, e.g. (xii), while others will only convey them on certain conditions being fulfilled, such as their being in a proper carrier and being placed on the floor of the 'bus, e.g. (x), and (xi).

Danger of Carbon Monoxide Poisoning from use of Carbide Lamps.

Cumming and Horn (xiii) have shown that there is a danger of Carbon Monoxide poisoning.' from Carbide Lamps in an enclosed space. They have shown that two Acetylene lamps burning with "two inch flames (the maximum that would normally be used) in an unventilated volume of 1,000 cubic feet, are likely to produce a large enough concentration of Carbon Mon¬oxide after a period of eight hours, to cause death if exposed to the atmosphere for two hours. While these: conditions will not be met with on ordinary caving trips, the necessary circumstances could occur during a long session of digging in a confined space; obviously the smaller the space, the quicker the danger will arise. Provided there is sufficient ventilation to keep the percentage of Oxygen in the atmosphere above 17% there appears to be no danger, however long one is working.

Carbon Monoxide poisoning will cause deep breathing, dizziness or fainting, on exertion, and most important of all, it will cause a sudden failure of ones sense of judgement.