U. S. GEOLOGICAL SURVEY 
BULLETIN NO. 263 PL. VIII 
• - ' ip? 
■'• '. 
' v 1 - "*rf^BBi > /i JJ 
.1. SKIDS FOR DERRICKING. 
Bf^ 
II P 
p 
JUjl 
* ■ 0" 
i: 
■J^* 1 
i ■ 
p 
: 'H- - 
I 
. , -Jj * - ^ 
I ^ Hi 
»-j-;^ , fc 
' 
^^^MMHV 
1 
[ lV »r**S^B^B By 
■ 
■ ^*u 
^ 
t apt '. eL^BCV ' 
' 4. •■ \- ' ' 
B. DERRICK BUCKET. 
