ELECTRIC PROPULSION ON THE U. S. S. JUPITER. 



By W. L. R. Emmet, Esq., Member. 



[Read at the twenty-first general meeting of the Society of Naval Architects and Marine Engineers, held in 



New York, December 11 and 12, 1913.] 



The contract for propelling machinery of the U. S. collier Jupiter was awarded 

 by the Government to the General Electric Company in June, 191 1. The designs 

 had been made during the previous year when it was expected that the ship would 

 be built in a private yard. The ship was built at the Mare Island Navy Yard, 

 and was put in commission September 15, 19 13. Since that time she has made a 

 number of trial runs in San Francisco Bay and at sea, but she has not yet had her 

 official trials. 



The Jupiter is a very large vessel of about 20,000 tons displacement, and is 

 designed to carry about 12,000 tons of coal and oil. The length of her deck over 

 her cargo space is occupied by a line of derricks, which must add considerably to 

 the weight and wind resistance of the ship. 



She is a sister ship of the colliers Cyclops and Neptune. The Cyclops was 

 equipped with reciprocating engines and has been in operation for some years. 

 The Neptune was equipped with turbines connected to the propellers by helical 

 gearing. 



The Jupiter is equipped with one turbine generating unit and two induction 

 motors, one driving each of the propeller shafts. There is also a board carrying 

 switches and instruments. 



A comparison of the equipment of these three vessels is given by the follow- 

 ing table: 



