330 



CEMENTS, LIMES, AND PLASTERS. 



been carried straight down, until now they are narrow and deep pits, 

 from which the material is hoisted vertically. The Bonneville Port- 

 land Cement Company's quarry is an extreme example of this type. 



FIG. 67. Tunnel, Lawrence Cement Co., Siegfried, Pa. 



In .quarries opened on a side-hill, so as to have a long and rather 

 low working-face and a floor at the natural ground level, the rock is 

 commonly blasted down in benches, sledged to convenient size for 

 handling and crushing, and carried by horse carts to a point in the 

 quarry some distance from the face where the material can be dumped 

 into cars, which are hauled by cable to the mill. Occasionally the 

 material is loaded at the face into small cars running on temporary 

 tracks. The loaded cars are then drawn by horses or pushed by men 

 to a turntable, where they are connected to the cable and hauled to the 

 mill. While these methods seem clumsy at first sight, they are capable 

 of little improvement. The amount of rock used every day in a large 



