Crane.| Prospecting, Mining and Milling Machinery. 259 
B, while the other end of the rod is clamped to the plank 
C, which supports the lower end of the upper chute bottom, 
D. The rods are further braced by the crosspiece LE, to which 
they are sometimes fastened by means of staple bolts. The 
crosspieces, B, C, and EL, are made fast to the chute by bolts 
and straps of iron, Ff, as seen in 7 and 2. 
Another method often employed is shown in 2. One end 
of a rod is bent at right angles and set in the cross plank A; 
the other end is placed in holes bored in the plank B. Any 
pressure upon the bars or rods tends to hold them more firmly 
in place. Occasionally no intermediate cross brace is em- 
ployed, in which case the rods must be shorter, in order to 
prevent sagging and spreading. That too much care cannot 
be taken to keep the bars straight, and, therefore, parallel, is 
shown by the large number of much distorted, and conse- 
quently useless, screens seen in the district. 
i) 
Fig. 46. Construction of grizzly screens. 
