72 SOME COMPARISONS RELATING TO 



The details of the Jupiter's installation have been described in previous papers 

 presented to this Society. All predictions made by the writer in connection with 

 the Jupiter have been exactly fulfilled. The following quotation from a paper by 

 Lieut. S. M. Robinson, Chief Engineer of the Jupiter, shows the opinions of the 

 men who have had experience with this equipment : — 



"After all, the greatest test of the satisfactory working of any machinery is 

 whether or not the men who are actually handling it and caring for it are pleased 

 with it. If this test applies to the Jupiter's machinery, it certainly is an unquali- 

 fied success. In particular is this true if the matter is referred to the coal passers 

 in the fire-room who have to handle much less coal than do the men on sister ships. 

 The ship can make her contract speed of 14 knots without using forced draft at all." 



The generators for the California are bipolar alternators, and the motors are 

 arranged to be connected either for 24 poles or 36 poles. For economic cruising 

 at 15 knots or less, one generator will be used with motors on 36-pole connection. 

 For higher speeds the 24-pole connection will be used. The ship will be capable of 

 operating at a speed of about 18.5 knots with one generator. 



Speed variation with either motor connection will be eflfected by change of 

 turbine speeds through the agency of variable speed governors designed to hold au- 

 tomatically any desired speed within usual ranges. This arrangement, which is 

 also used in the Jupiter, entirely prevents racing and makes it convenient to hold 

 a fixed speed irrespective of variations in sea, weather or steam conditions. It is 

 thought that this feature will be valuable in fleet formations. 



The steam consumption guaranteed on the California covers the total steam 

 required for the main turbines and engine-room auxiliaries as described above. The 

 conditions are 250 pounds gage pressure, dry steam, with such vacuum as can be 

 produced under trial conditions. The guaranteed water rates per horse-power 

 delivered to the propeller shafts are as follows: — 



Lbs. 



At 10 knots 14.6 



At 1 5 knots 1 1 .4 



At 19 knots I I.I 



Maximum speed 11.9 



Very heavy penalties are imposed in case these guaranteed consumptions are 

 exceeded in trials, $25,000 per pound for the two lower speeds and $20,000 per 

 pound for the two upper speeds. 



At full speed the California propellers will make 175 revolutions per minute, 

 this being about the lowest speed of propellers which is practicable within the space. 

 The propeller speeds proposed for the sister ships with Parsons turbine drive is 240 

 revolutions per minute, and comparisons by Dyson's method indicate that this 

 speed difference will give the California an advantage of about 9 per cent in pro- 

 peller efficiency. 



