16 



Indiana University Studies 



of a guyed derrick or a traveling crane. The guyed derrick is 

 usually controlled hj power from the power plant of the mill 

 and is of the swinging-gear type. The mast is usually supported 

 by 6 wire ropes, 3 times its length and fii^mlj^ attached to the 

 ground. The boom should be slightly shorter than the mast, 

 and adjusted to swing freely under the guy wires at anj- angle 

 of elevation. The guy wires should be examined oftea, since 

 a broken guy may cause the collapse of a derrick, endangering 

 life as well as destroying property. 



The traveling cranes in use at most of the mills are of from 

 20 to 50 tons" capacity and the span is from 45 to 80 feet. The 

 most popular type is the Bedford Foundry and ^Machine Company 

 20-ton crane. In most of the mills in the district the crane 

 motors are of direct-current types, altho a few are operated on 

 alternating current without transformers. In many of the 

 larger mills small auxiliary handpower cranes are in use in the 

 carving departments. The crane is a piece of machinery that 

 should be built for the particular service it is to perform, and 

 any suggestion as to which kind is the best on the whole is im- 

 possible, because a crane that fits one case would not necessarily 

 do the work under other circumstances. Crane track-ruits u.p 

 to 400 feet are operated in some of the larger mills. A few steam- 

 operated cranes are still in use in the district, but these are 

 being rapidh^^ replaced by electric cranes. 



Most of the sawing is done with gang saws. The large blocks 

 are placed on the truck of the gang saw and cut down to the size 

 desired. The gang saw consists of a number of mild steel blades 

 set in a frame at distances apart to correspond with the thickness 

 of the slabs required. The blades are held tight by wedges set 

 at the ends. The frame is suspended by rods carried on shafts 

 attached to the uprights of the saw. A connecting rod attaches 

 the frame to the crank of a power-driven jack which drives the 

 entire frame backward and forward. Sand and water are fed 

 on to the surface of the stone, and the blades of the saw are driven 

 downward by a screw arrangement. The more rapidly the saw 

 is driven into the rock the rougher is the surface made, and the 

 greater is the work left for the planer. The Xew Albany saw 

 is the one most widely employed, but many other makes are 

 also in use. 



In some mills, slab-cutting to size is done b^^ the diamond 

 saw. This is a fixed circular saw with a number of diamonds 



set in its periphery. The slabs to be sawed are clamped on a 



