Crane.| Prospecting, Mining and Milling Machinery. 255 
the latch or trip, H, is pulled out (to the left), by means of 
a hook, which the operator holds in his hand. As soon as 
the latch is drawn back the bottom falls, thus emptying the 
bucket through the bottom. 
Fig. 42. Dumping Ponte. ou shaft. Used with 
One advantage of this form over the other mentioned is 
that the bucket always remains in an upright position, but with 
large boulders, as are often sent to the surface in the buckets, 
it is not as good as the other forms. Boulders often clog in 
or break and deform the bottom of the bucket, thus causing 
delay in removing and sometimes causing extensive repairs 
t made. 
A dumping board acts as a shield for the shaft, and also 
guides the material dumped upon it into the crusher room. 
The construction and working of adumping board are shown 
in figure 42. While hoisting, AB, which is hinged at G, rests 
against the supporting prop, D; when the bucket has been 
raised above the board, AS, it is swung over and assumes 
the new position, BE’; the bucket is then dumped and the 
dirt slides from the platform, BH, over its prolongation, BC— 
AB and BC forming a continuous inclined plane. After 
dumping, the bucket is raised, BH thrown back into its former 
position, AB, and the bucket is again ready to be lowered. 
Cars.—The cars employed in transferring the ore, both 
above and below ground, but especially above ground, con- 
