298 DESIGN AND CONSTRUCTION OF PASSENGER STEAMERS. 



placement, 19,550 tons; cargo oil, 10,000 tons; shaft horse-power, about 8,000; speed, about 

 15 knots. 



The electric propulsion apparatus is being constructed at the works of the General Elec- 

 tric Company. 



Electric propulsion is only an experiment in our navy, and its success depends largely 

 upon this ship, which requires therefore the greatest care in its construction. As one of 

 the inspectors of this work, I must express my appreciation for the splendid spirit with which 

 everyone is cooperating to make it a success. Undoubtedly electrically propelled ships are 

 going to play an important part in future naval construction, and it is gratifying to know 

 that our Japanese Navy is getting its first lesson in this development from the United States. 



Mr. Ernest H. B. Anderson, Member: — I think the Society is greatly indebted to Mr. 

 Rigg for this paper, but it seems to me that its value would be greatly enhanced if a second 

 paper could be written describing the machinery in the various ships that Mr. Rigg has re- 

 ferred to. As Mr. Rigg points out, one class has reciprocating engines, while the other class 

 has geared turbines. We all know there are many types of geared turbines; there are also 

 various types of gears, and it would certainly improve matters in finally arriving at the econ- 

 omy and overall performance of these ships if some particulars of the machinery could be 

 published. We have had a certain amount of discussion regarding the different types of boil- 

 ers, and this is just another phase of the question. 



Mr. McFarland referred to the types of boilers in the large German ships. My impres- 

 sion is that the Thomycroft-Schulz has three lower water drums connected by tubes to one 

 large steam drum ; in other words, this gives a formation of two fireboxes or combustion 

 chambers, whereas the German ships really have a modified Yarrow boiler with one large 

 steam drum and two lower water drums. A complete description, with illustrations, of the 

 boilers in the Imperator was published in Engineering of June 12, 1914. 



Mr. Elmer A. Sperry^ Member: — I think the Society is to be congratulated upon the 

 paper just presented. This paper gives a forward look and I think it is good for the Society 

 also to have such a view. Our friend Mr. Smith says that the Diesels were not considered 

 in his remarks, because they have not yet risen to the occasion. Neither has this ship. So, 

 inasmuch as they are both futures, is it not perfectly proper to stop for half a minute and 

 consider the Diesel? We have to face the facts, and as surely as we are here, Diesels will 

 do our work — the direct combustion of the fuel in the cylinder, where it has absolutely direct 

 application to the delivery of power to the crank shaft, is just as sure to supersede other 

 power as anything in the world. 



Now there is nothing insuperable about the size of the gear, because sizes are in sight 

 now oi over 12,000 horse-power per engine, with only six combustion cylinders in line, and 

 these are limited to our present knowledge as to the sizes and thickness of the walls of com- 

 bustion cylinders. Within our present knowledge of the limitations of these vital points, it 

 is possible to make a 12,000 horse-power direct consumption oil engine now. Compounding 

 makes all this easy and simple. Suppose we take this 115,000 horse-power which the author 

 suggests on page 279, and suppose we take the same cruiser, four shafts, and use geared 

 Diesels. These Diesels only require about 7,200 horse-power each, and just think of what 

 we are accomplishing in the point of weight. I venture to say that these Diesels will not 

 weigh as much as the water in the system with steam. We need the weight thus saved to put 



