Mance: Quarry Industry of Southern Indiana 91 



current motors especially has become widespread. The relative 

 value of the two types of equipment (direct and alternating- 

 current motors) in plants where the current has to be carried but 

 a short distance is still a question, but where the current is trans- 

 mitted any considerable distance the alternating current is 

 undoubtedly the better. The advantages of the use of alternat- 

 ing current lie in the fact that there is less heating, and that no 

 high voltage is carried thru sliding contacts. Probably the best 

 results are obtained in this type of work by three-phase sixty- 

 cycle motors. Many of the operators who were using direct- 

 current motors and generators in their plants, and have since 

 begun to purchase power from the local power companies have 

 installed motor-generator sets instead of putting in alternating- 

 current motors. In most plants the alternating-current motors 

 have been installed with the stone-working machinerj^, but 

 small motor-generator sets are used to furnish direct current 

 for the motors on the cranes. 



A type of machine that should be of interest to the manu- 

 facturer who uses but a medium amount of power is the self- 

 contained engine and boiler equipment known as the locomobile. 

 The engine of this equipment is set upon the boiler with the 

 cylinders projecting into the smoke box so as to minimize piping 

 and radiation losses. These engines are built in units up to 800 

 horse-power. They are widely used in Europe but are just 

 beginning to be developed in this country. One German firm 

 alone has built over 1,000,000 horse-power of these machines. 

 The following description is taken from the catalog of an American 

 manufacturer of locomobiles: 



It consists of a compound engine mounted on an internally-fired boiler, 

 the engine cylinders being inclosed in the smoke box which also contains a 

 superheater, a reheater, and all high pressure piping and valves as well as 

 the intermediate piping. A special casing compels the hot gases to traverse 

 the superheater and reheater before emerging into the smoke box proper 

 on their way to the stack. The engine drives a pump which feeds the boiler 

 through a tubular heater in the exhaust line. The engine exhausts into a 

 suitable condenser equipped with an air pump also directly driven from the 

 main engine. The boiler is of the internally-fired type and the machine 

 doCs not need elaborate brick work further than a firm foundation. The 

 engine is of the tandem compound center crank type. 



Among the advantages claimed for this type of power generator 

 are the following: 



1. Small floor space. 



