A Practical Treatise on Coal Mining Volume 1
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1876 edition. Excerpt: ...of gunpowder is retained in this fuse, but the details of its arrangement are changed so as to fully satisfy all the conditions previously laid down as necessary. It consists of a flexible cord covered with waterproof materials, having a central core of fine gunpowder, surrounded by hempen yarns twisted up into a tube, and called the countering. The outer casing is made of different materials according to the circumstances under which it is intended to be used. A central touch thread passes through the core of gunpowder. This fuse, which in external appearance resembles a piece of plain cord, is very certain in its action: it may be used with equal facility in holes bored in any direction; it is capable of resisting considerable pressure without injury; it may be used without special means of protection in wet ground; and it may be transported from place to place without risk of damage. The combustion of the train of powder in a fuse takes place gradually, and the rapidity of the process greatly depends upon the dimensions and nature of the envelope or covering. In consequence of the compression, the gases liberated by the combustion of the first grains of powder cannot extend themselves in a backward direction, and hence the grains below become ignited only in consequence of the conductability of the several elements of the fuse as their temperature is brought up to the requisite degree. In the safety fuse, the conditions of slow burning are well provided for, and certainty is ensured by the touch thread through the centre of the core. As the covering of the core is indestructible, and as, moreover, the combustion of the core leaves in the small space occupied by it a carbonaceous residue, there is no passage whatever left through the...
- 189 x 246 x 9mm | 322g
- 13 Sep 2013
- United States
- black & white illustrations