What's does the embossed number "15" stand for on certain N.C.B. Explosive Canisters Identification Tags?

Two explosives canister identification tags from Staffordshire both with an embossed number "15" on them- Lea Hall, Cannock Chase and Norton, Stoke-on-Trent.

The image above is of two explosive canister identification tallies or tags. I'm sure many collectors will have come across such checks before. They are very distinctive in that they are always of brass, are uniface and of 43 mm diameter plus have two pierced holes orientated as shown.  These holes were used for riveting the tags onto the top of the lids of the N.C.B.'s standard design of 5 lb. capacity explosive carrying canister. Such canisters were tagged with numbered tallies as a form of identification and probably as a means of controlling their issue and return to and from the pit's magazine. I have seen such tokens form many Yorkshire, Staffordshire, Co. Durham and Welsh pits. 

An sketch of a typical 5 lb Explosives Carrying Canister taken from a 1950s N.C.B. shot firing manual

During the NMMA's first field trip to Big Pit Colliery Museum in Wales a group of us found two such canisters on the spoil tip of the now abandoned private drift mine site of Cwm Glo (see A.J. Booth's book "Small Mines of South Wales", Vol. I, pages 24-25). One of these canister, post cleaning, is shown below.

A standard sized (22 cm dia. by 27 cm tall) Explosives Carrying Canister found at Cwm Glo Drift Mine, South Wales - Note the brass identification tag (numbered "559") still in-place on the canister's lid.

Both the canisters found that day still had their brass identification tallies attached and were constructed to conform to what appears to be the N.C.B.'s standard design for such boxes. The bodies of both canisters were formed from multiple plied canvas/rubber conveyor belting material and they each had a similar metal lid lock (which can only be opened with a shot firer's brass safety key). Each canister also had a carrying handle and strap complete with a buckle fastener. Both of the Cwm Glo examples probably originated from Big Pit and only found their way to down the valley at a later date in their working lives. 

Many of the explosive canister tags I have seen simply carry hand stamped identification numbers on them. However, others do carry the name of their respective pit of origin, often hand or occasionally machine stamped into their fabric. The two illustrated examples above are from two of three pits known to me (the other being West Cannock No.5) which used embossed tally/tag designs. All three of these examples from Staffordshire contain the embossed number "15" in their legends. I believe that this number signifies that the 5 lb. capacity canister, to which they were originally attached, were suitable only for holding up to "15" sticks of explosives. Can anyone confirm this or give me an alternative answer to this mystery? I'm sure a retired N.C.B. shot firer could tell us the answer to this enigma.

Submitted By : Mark Smith.
Date: August 2003
In the Yorkshire pits around Barnsley that I worked in we used half pound sticks of explosives. This would make 10 sticks to the normal 5 lb measure that could be carried in the standard sort of carrying canisters you mentioned. I do remember us using smaller sticks at one time but they would have had to have been of be a third of a pound each (i.e.  5.33 ounces each) to have made up the number of "15" to the canister that you implied. I certainly don't recall us ever using such small explosives measures as that. 
Submitted By: Tony Lewis 
Date: August 2003
The following information is taken directly from Part I of the N.C.B.'s booklet entitled "Handbook of Shotfiring in Coal Mines". Although this information doesn't mention the canister tags themselves it does confirm that in 1952 (the date of this publication) at least the N.C.B. were not using 5 1/3 oz sticks of explosive plus that it was a recommendation that each canister should be marked with a serial number.
5. Diameters and Weights of Cartridges. 

(i) At N.C.B. collieries there are two standard diameters of cartridges: 1 1/4 in. and 1 7/8 in., both inclusive of sheath, if any. In general, cartridges of very small diameter are less satisfactory than larger ones, and diameters less than 11/4 in. are not recommended. 

(ii) The standard weights of cartridges supplied for use at N.C.B. collieries are:- 
Gelatines                     ... ... 4 oz., 6 oz. and 8 oz. 
Powders                      ... ... 2 oz., 3 oz., 4 oz. and 6 oz. 
Eq.S. explosives             ... ... 4 oz. and 6 oz. 
6. Canisters for Explosives. (Article 7.) 
(i) Explosives must be conveyed into the mine. in closed canisters, stoutly constructed. Except where explosives Are conveyed in bulk in an explosives carriage, the capacity of the canister is limited to 5 lb. of explosive. It is recommended that they should be marked with a, serial number so as to assist in the recording of explosives issued and used, etc. Where different types of explosives are used in the same mine, canisters of different shapes or colours help to prevent inadvertent mixing of the different types. 
(ii) The Minister proposes to introduce a requirement that all canisters must be constructed so as to comply with certain requirements after a date to be announced (which will probably be 1 st February, 1955, or three years after the Order comes into effect). The requirements which the Minister has in mind are:- 
(a) The canisters should be made of a material, such as tin plate, galvanised iron, leather, moulded rubber or wood, sufficiently strong to protect the explosive inside from such blows or crushing as may be expected during use in the pit, the joints, if any, being closed to prevent the entry of water.
(b) The interior of the canister should be of such size, shape and construction that the cartridges of explosive can be packed in it without risk of deformation or damage.
(c) The lid of the canister should be, self-locking in the sense that the lid must lock automatically when it is placed in the fully closed position. This excludes a detachable padlock, but allows a hinged flap-and-hasp type of lock, provided that the hasp is automatically engaged and held when the flap is pressed into the closed position. 
It is desirable to ensure that all new canisters purchased should comply with these requirements.
Submitted By: Mark Smith  
Date: August 2003

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