Processes in the Useful Arts. 843 



or put in practice ; and that, by a little perseverance, so as to become more 

 perfect in the plan, the blowing of rocks may be rendered as safe as the 

 letting off of a fowling piece. 



The cone was not found for six weeks, because, being buried among the 

 great masses of stone, it could not be got at until these were worked up 

 and removed ; when brought to me it was, by the violent percussion, 

 broken in two, and its surface rubbed and scratched as if it had been soft 

 lead. 



The shortness of the lower bore seemed to be the cause of its breaking, 

 for the workman informed me that he found it fast in the bottom of the 

 lower tube, conseqnently this points out the propriety of having it fully 

 of the dimensions that I have before stated. And, whether the cone be 

 used or not, it seems to me to be a matter of great importance, that the 

 gunpowder (whether inflamed at the top or bottom) should not be allow- 

 ed to go to the bottom of the bore, but have a certain space filled only with 

 common air, which can be done in a variety of ways, and therefore requires 

 no explanation from me. By the adoption of this plan, I have no hesita- 

 tion in saying, that half the quantity of gunpowder will be saved, and that 

 the same, if not a greater effect, will be produced, than is at present effect- 

 ed by such an enormous quantity of gunpowder, as a pound to the foot 

 of depth of bore. 



Thus I have detailed all that has occurred to me as far as I have, gone, 

 yet I am aware that my method is not yet perfect ; nevertheless it is satis- 

 factory to know, that the principal part is quite conclusive as far as respects 

 the destructibility of the rock, in a greater degree than has hitherto been 

 done. 



The whole process, therefore, may be summed up under the three 

 following heads, viz. 



I. To inflame the gunpowder at the bottom of the charge, by means of 

 sulphuric acid, charcoal, and sulphur. 2. To take advantage of the pro- 

 pelling power of gunpowder, as is done with a cannon-ball, only„reversing its 

 mode of action, and instead of a spherical, to apply one of a conical form, 

 by which the full effect of the wedge is given in every direction at the low- 

 er part of the charge, but particularly downwards. 3. And, in the last 

 place, to add to the effect of the whole, to insure a fourth part of the depth 

 of the bore at the bottom to be free from the gunpowder, so that when 

 inflammation ensues a red-heat may be communicated to the air in the 

 lower chamber, whereby it will be expanded to such a degree as to have 

 the power of at least one hundred times the atmospheric pressure, and 

 thereby give this additional momentum to the explosive power of the 

 gunpowder. 



Explanation of the figure* Injure alluded to. Fig'. 1 of Plate VI. is meant 

 to represent the tube with its ramrod, the lower part of which is drilled with 

 a small hole, as represented at A, of sufficient size to admit the end of the 

 ball B, containing the sulphuric acid, which end, if too small for the aper- 

 ture, is to be wound round with a little thread, so as to remain fail when 

 once introduced. The dotted line represents the portion of coppei thai 



