370 



CEMENTS, LIMES, AND PLASTERS. 



is a comparatively fixed affair, located far enough away from the work- 

 ing-face to avoid damage from blasting. Here the cars are attached 

 to a cable or to a locomotive and hauled to the mill. 



r 



FIG. 74. Cableway in cement-rock quarry. 



Occasionally an aerial cableway is used for transporting the mate- 

 rial to the mill. This is shown in the two views of a cement-rock quarry 

 given in Figs. 74 and 75. 



Working in levels. In quarries containing several beds of rock 

 differing greatly in composition and lying horizontally, tracks are often 

 run in on different levels, so as to insure that each car or cart shall con- 

 tain only one kind of rock. This practice is exemplified in the shale-pit 

 shown in Fig. 76. A similar plan is followed in working the quarry 

 partly shown in Fig. 77, which contains several heavy beds of limestone 

 intercalated with workable but thinner layers of shale. 



Use of steam-shovels. In a few limestone and cement-rock quarries 

 a steam-shovel is employed to load the blasted rock into the cars, and 

 in shale quarries this use of steam-shovels is more frequent. In cer- 

 tain clay- and shale-pits, where the material is of suitable character, the 

 steam-shovel can be employed to do all the work, both excavating and 

 loading the materials. 



