ELECTRIC PROPULSION OF THE U. S. S. JUPITER. 193 



was excessive. The condensed water was much discolored by boiler compound, 

 and water was at frequent intervals forced from the valve packings. 



The operation of the apparatus during these runs was exactly in accordance 

 with expectations. The turbine ran with a very perfect balance, and ran just as 

 steadily in rough water as in smooth. The governor held its speed perfectly. The 

 lifting of propellers to the surface at no time caused any perceptible speed varia- 

 tion. The only effect of such lifting of propellers was a fall of current on the 

 instruments showing a diminution of power delivered to the propellers. Examina- 

 tion of the turbine after several such runs had been made showed it to be in per- 

 fect condition, and free from rust, scale, or dirt. 



After this period of preliminary trials, the ship was docked, and since that 

 time she has made a set of standardization runs and a 48-hour unofficial trial with 

 a clean bottom. On this 48-hour trial the ship averaged 14.78 knots, the average 

 power delivered by the generator was 5,000 kw., corresponding to about 6,300 

 indicated horse-power. The average revolutions of the propeller were 115. The 

 Cyclops in her official 48-hour run made 14.61 knots with an average of 6,705 

 indicated horse-power. 



The power required by the Jupiter in this 48-hour run is somewhat less than 

 would be expected from the Cyclops performances, and the slip of the propellers 

 is also less than was expected. It has been suggested that this difference might, in 

 some degree, be attributable to the fact that in the Jupiter the torque delivered to 

 the propellers is continuous, while with the reciprocating engines the impulses are 

 intermittent. Careful investigation would be necessary to ascertain whether there 

 could be anything in such a theory. It has also been suggested that there would be 

 some advantage in the fact that the Jupiter's propellers were entirely free from 

 racing, but since some of these tests were made in quite smooth water, this could 

 hardly have had any effect. If no advantage is gained through these causes, it 

 would certainly seem that the performance of the Jupiter's propellers is very cred- 

 itable to Captain Dyson, who designed them. 



Through a misunderstanding, the steam pipe on board the Jupiter was made 

 much too small, so that the normal pressure at the turbine cannot be attained. The 

 vessel will not give her best performances until this is corrected, and until an ef- 

 fective separator is put between the boilers and the turbine so that the efficiency of 

 the turbine will not be affected by priming. It is believed that when these changes 

 are made, the Jupiter can, if desired, be operated at a much higher speed than that 

 which has been attained, and that her economy will prove to be far better than 

 that of any vessel afloat. 



The steam consumption of the Jupiter turbine and the efficiency of all of her 

 apparatus have been determined by exhaustive tests at Schenectady, and are also 

 accurately known through knowledge of the performances of other similar appa- 

 ratus. These results are shown by the accompanying curve, and they cannot fail to 

 be accomplished in the ship herself when all conditions are normal. 



Since the preliminary trials above mentioned, the Jupiter turbine has been in- 



