260 



FELLING AND CONVERSION. 



iutroduced, or some other arran^'ement made for firin<jj the blast. 

 Fij,'. 130 shows a simple detonating' apparatus, the riuj,' (d) bein^ 

 for the insertion of a handle for screwing,' it into the bore-hole, 

 whilst (h) is a simple trigger for striking the cap. Urich improved 

 p ..^„ matters farther by using an ap])a- 



ratus with a needle for firing tlie 

 cap, which was placed on the 

 top of the powder, as shewn in 

 figs. 131, 132, the former giv- 

 ing its external form, and the 

 latter a section through its 

 axis. The apparatus has a bore 

 suificient for working of the 

 needle {ni o). It is closed by a 

 scrcAv-lid (b) in which the cap (n) 

 is placed. In order to prepare 

 the apparatus for firing, the 

 needle is raised by means of the 

 ring (m), and a steel pin is placed 

 in the aperture {d). The lid 

 (h) is then removed, and screwed 

 on again after a cap has been 

 inserted. The charge is fired on the removal of the pin by 

 means of a long cord, the needle being driven down on to the 

 cap by a strong spiral spring placed above the ledge (in). The 

 advantage of this apparatus consists in the fact that it is not 



Fio. 130. 



necessary to fill it with powder, but a cap only is required, and the 

 firing of the charge follows immediately on the release of the 

 needle which can be done from a distance with perfect safety, 

 whilst no tamping is required for the blast, the strong apparatus 

 screwed into the bore-hole serving instead ; the results are ex- 

 cellent, the largest stumps being split into two or more pieces. 

 Whenever only a fuse is used, after less than half the powder 



