SllOOTINCJ 



Fig\ 34. Fuse. Fig 1 . 35. Magnetic Exploder. 



A Platinum Bridge. 

 B Copper Wire. 

 C Plug Holding Fuse. 

 D Primary Composition . 

 E Charge of Fulminate. 



destroyed. One of John Davis and Sons' magneto-exploders is 

 shown in Fig. 35. Exploders are classified according to the 

 number of shots they can fire at a time. 



A five -foot seam in an eight-yard bord, when undercut, 

 may require three shots to fetch down the coal ; one in the mid- 

 dle, and one 011 either side on the top, the holes being given an 

 upward slant. Thick seams require more shots to fetch down 

 the coal than thin seams ; also more powder is required for 

 shooting when the holing is done in the top of the coal instead 

 of in the bottom. Custom requires that the shooters find their 

 own powder, but it is stored at the mine. Sometimes coal is 

 shot down without holing: this is known as "shooting fast/ 



