155 
Fic. 56.—Shot 91; 500-Ibs. of eanpowder 344 feet below the surface. showing 
the first effect of the arrival of the burnt gases at the surface ; the mound 
‘ot water is 18 feet high. 
Fie. 57.—Shot 92: showing the “plumes” (90 feet high) threwn wp by & 
500-Ib. charge of ganpowder 10 feet helow the sarface. 
Fic. 58.—Shot 64 ; 300-Ib. charge of 40/60 Amatol fired on the surface ; the 
cloud, whieh ix 100 feet high iu the photograph, eventually rose to 300 feet. 
