88 SOME COMPARISONS RELATING TO ELECTRIC PROPULSION, ETC. 



turbines in the Vespasian and by test with torsion meter showed much improvement. He put 

 her under similar conditions of trim and showed a definite comparison. 



Then Sir Charles Parsons made another determination. That is, he took a ship called 

 the Caimgowan, an engine-driven ship, and tested her in comparison with the Cairnross, a 

 turbine-driven ship, similar propeller speed, a sister ship and identical in all respects. The 

 comparison as published would lead us to believe that these tests are comparable. These 

 ships are something like 1,700 or 1,800 horse-power. The Cairngowan used for all purposes 

 17.3 pounds per shaft horse-power. Under similar conditions the Cairnross used 14 pounds. 

 The steam consumption of the Jupiter, under exactly the same conditions as the Cairngowan, 

 would be 11.97 pounds; that is, against 17.3 on this engine-driven ship. This is the only 

 comparison that I know which is a just one, made properly. 



It is extremely hard to test water rates of apparatus. You must have all the facilities 

 and everything absolutely right and be able to get consistent results, over and over again, 

 to be sure that you are right. Of course, in Schenectady we have done more of that in our 

 work than has been done anywhere else in the world; we have been developing the art of 

 prime movers so very rapidly that we have needed immense facilities for testing. The Jupi- 

 ter's turbine was put right on a condenser, the degrees of vacuum produced, the output of 

 electrical energy was exactly measured, and everything determined in the most scientific man- 

 ner, so that there can be no question at all about the results. 



The question of the maximum speed of the California is another matter concerning 

 which I am not informed. We were required under the specifications to make guarantees 

 of speed and very heavy penalties imder certain test conditions, and one of these test con- 

 ditions was the highest speed which the ship could produce. In another part of our specifi- 

 cations we were required to furnish 25 per cent more power than the ship was supposed to 

 require at a certain speed, 21 knots. That, as I understood it, required us to furnish 36,400 

 horse-power to the propellers of the California and to produce this guaranteed water rate at 

 that maximum output. As I understand it, the government is at liberty to run that ship 

 as fast as it can and penalize us if our water rate goes above that point. We have had to 

 make our curve turn up a good deal at the maximum to take care of that very extreme 

 condition. 



Now, as to the question of the California's propeller efficiencies which has been raised, 

 I can give no information. I simply have stated what Captain Dyson has told me, that our 

 speeds are advantageous and there is a certain gain. As to the actual comparison made 

 here, I cannot exactly blame him for it — it is the result of certain information obtained 

 largely through him, and it is approximately in accordance with a certain curve which he sent 

 me, giving the possibilities of different speeds of propellers and different numbers of pro- 

 pellers in this ship and certain other ships. It may be right or wrong, but there is certainly 

 a considerable advantage in these lower speeds. 



The President : — I am sure we are all much indebted to Mr. Emmet for his interesting 

 paper. I will mention that Paper No. 6, which is on the program for today, will be post- 

 poned until tomorrow morning. Paper No. 12, on the program for tomorrow afternoon, 

 will be read in the morning. 



