112 Mr. F. A. Ahel [April 28, 



whereby a charge of guncotton or dynamite is rendered of little value 

 as a means of getting coal when used in the ordinary way, the 

 distribution of the explosive force in all directions by the column of 

 water causes it to exert a cleaving or splitting action even superior to 

 that exercised by ordinary blasting powder. The farther develop- 

 ment of this method of applying detonating agents to blasting purposes 

 in coal-mine workings aj)pears therefore well worthy of attention. 



Another method of getting coal, which, though not new in itself, 

 has been applied in a novel manner and with most promising results 

 by Messrs. Smith and Moore, has the great advantage of dispensing 

 entirely with the use of explosive agents, and of any but the most 

 simple mechanical appliances. 



It consists in applying the force which quicklime will develop if 

 confined, and made to combine under that condition with water, 

 whereby it undergoes very considerable exiDansion, a large amount of 

 heat being at the same time developed. Messrs. Smith and Moore 

 convert the freshly burned and crushed quicklime into very compact 

 cylindrical masses, or cartridges, having a small groove on one 

 side, so that when the requisite number of cylinders are inserted 

 symmetrically into the mechanically drilled hole in the coal, which 

 they fit accurately, a narrow pipe, with perforations along its entire 

 length, enclosed in a tight-fitting stocking of open webbing, and 

 provided with a stopcock, may be inserted into the side of the charge, 

 which is afterwards tamjDcd in the usual manner. The proportion 

 of water necessary to slake the lime, plus an excess of about 

 one-sixth, is then forced into the hole through the pipe by means 

 of a simple hand syringe, and the stopcock of the pipe being 

 closed, the operation is complete. In a brief space of time sounds 

 indicative of the cracking of the mass of coal which contains the 

 cartridge show that the expansion of the lime by its union with 

 the water, and the very considerable development of steam within the 

 cartridges, are performing their work, and after an interval of time 

 varying with the strength of the part of the seam operated upon, the 

 coal is detached in large blocks. The holes can be charged so rapidly 

 that a considerable number may be put into operation in quick suc- 

 cession by one or two men.* As the action of the charge occupies 

 some little time (fifteen or twenty minutes), they really come into 

 operation together, and in this way large faces of hard coal, in long- 

 wall workings, are brought down with ease and certainty. Whether 

 these compressed lime cartridges can be applied with any success in 

 stone still remains to be determined, but in point of cost, simplicity, 



* In one of several operations of this kind recently witnessed by the Lecturer 

 at Shipley Collieries, Derby, in the "deep hard seam," which is nearly 3 ft. 

 thick, ten shots were fired together, bringing down a block of coal .39 ft. long by 

 3 ft. thick and 2 ft. 10 in. high, weighing about ten tons. The average time 

 occupied in boring a hole (by mechanical drill), charging and tamping it, and 

 watering the charge, was twenty minutes. The usual operation of bringing down 

 this very hard coal, by wedging, is exceedingly slow and laborious. 



