Object in Focus: No. 9

Explosives were an integral part of mining in this country during the 20^th as well as the 19^th century. The use of explosives, including one based on T.N.T helped the acquiring of the ‘black diamonds’, which is of course- coal. The following explosives and explosive devices were used in mining during the 20th century:

The Polar Ajax

The explosive was jelly-like (gelatinous), had good water resistance and therefore worked well; despite the ever-increasing chances of damp conditions, the deeper the mine was. The explosive’s high density meant it was packed with explosive material and so good for use at the back of the shothole (a narrow cut in the rock face where explosives were placed) which I presume had great impact, partly due to the Polar Ajax’s high density. However on the down side, non-sheathed explosives like these could well have been responsible for a tragedy at Woodhorn Colliery in July 1902 when two men- George Johnson and James Douglass as well as a 16-year-old boy- James Henry Huntley died in an explosion caused by explosives.

Sheathed Explosives

Sheathed explosives were used from 1934 in this country and were much safer than their non-sheathed counterparts. The Ajax had a sheathed version that, like all sheathed explosives, used sodium bicarbonate as a cooling agent which increased safety but had very little effect on the power of the explosion it created and was used for hard rippings and hard coal.

The Unirend

Unirend is an E.qS explosive and is based on Trinitrotoluene also known as T.N.T. Developed after 1934 due to further development to make mining safer by the NDRD (the Nobel Division Research Department), It has the safety element of sheathed explosives but without the costs and considerations of them, such as displacement or loss of the explosive’s sheath and used for medium-hard coal and soft rippings.

The Electric Detonator

The device which releases the destructive potential of the objects above. An electric detonator is like a capped fuse but instead of a fuse, an ‘Electric Detonator’ uses two insulated wires. Through a small cord an electric charge is sent to the detonator cap and ignites the explosive material. In future versions of the detonator, a delay powder was used which consequentially allowed the development of a pre-programmed electric detonators and the delaying of explosions. Given the date of a Coal Mines order, insisting the use of an electric detonator in 1951, I would say it was then, later and still earlier then 1951 that electric detonators were in use. The delaying technology in the later, pre-programmed, version of the ‘Electric Detonator’  contributed to the world as well mining. This technology inspired the later and safer ‘EBW’ which replaced the similar but more unsafe ‘Electric Detonator’ and is suggested to have contributed to the development of the nuclear weapons and the timing of nuclear blasts.

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