DISCUSSION ON MAY MEETING PAPERS. 49 



While theoretically a little economy may be experienced by the adoption of 20 de- 

 grees of superheat on reciprocating engines, as Mr. Warriner mentioned, it must be ap- 

 preciated that approximately 150 degrees superheat are required to eliminate the initial 

 condensation in the high-pressure cylinder. The present practice in the leading maritime 

 nations with which the vessels of the United States are in competition (this includes Eng- 

 land, Holland, Denmark, Norway, Sweden, Japan and Germany) is toward the use of 

 high-degree superheat on all steam-propelled vessels, regardless of the type of the steam- 

 propelling unit, and the performance of these vessels is very favorable when compared 

 with the performance of the saturated steam vessels of the United States. 



It is pleasing to note that Mr. Warriner has designed and is building a vessel which 

 may be operated at a reduced cost and thus place the owner in an advantageous position 

 with relation to his foreign competitors, and that another progressive step has been made 

 towards the successful realization of an efficient merchant marine in the United States. 



Mr. J. W. Atkinson, Member (Communicated) : — In reference to the latter part 

 of Mr. Warriner's paper dealing with the testing of gears for efficiency, it is stated that, by 

 the method adopted, "it is possible to put the same load on the bearings and to run the gears 

 at the same tooth pressures and under the same conditions as when operating on board ship." 



I should like to ask what revolutions were obtained on the tests, with the full power 

 tooth pressures and bearing loads, since it is also stated that the power developed by the 

 motor represents only the friction of all the gears and bearings in the two units. 



Messrs. Metten and Shaw: — The Sperry oil engine is very interesting, and the 

 authors only hope the rather unusual claims that have been made can be made good on 

 commercial engines. The high-speed experimental model shown is not considered justly com- 

 parable with proven performance of engines designed for low revolutions to meet the par- 

 ticular requirements of the motor ship. To prove his statement that this experimental en- 

 gine is lighter per horse-power than a Burmeister & Wain engine, two slides were shown 

 by Mr. Smith illustrating the two types coupled to a generator, with the remark that the 

 'generator so coupled to the B. & W. engine "absorbs the whole power of the engine." 

 This is incorrect, as the generator shown was used for absorbing the power of three cyl- 

 inders out of the six at one time to save purchasing a new generator of sufficient capacity 

 for the full brake load. 



Mr. Fernald has furnished an estimated performance of a comparatively small ves- 

 sel having triple-expansion engines, geared turbines, and Diesel engines, and for the last 

 has selected engines of the B. & W. type. He states that his comparison was worked up 

 some time ago when he was connected with the Shipping Board, and from which we are 

 led to infer the Shipping Board based its decision not to embark on motor ship construc- 

 tion at that time. If this is correct, this important decision was based upon incorrect data, 

 as the B. & W. engines used in the comparison are two sizes larger than those in service 

 on vessels of the same size and speed. The size assumed for the comparison is known as 

 B. & W. type 6-275 and designed for 4,000 indicated horse-power (total). The engine size 

 that should have been employed in the comparison is actually two sizes smaller and known 

 as B. & W. type 6-200, designed for 2,800 indicated horse-power (for the two engines). 

 These latter engines are the same as installed on the motor ship Oregon and several simi- 

 lar vessels which have the same designed sea speed as the Fernald vessel but have 5 feet 

 more between perpendiculars, 1 foot more beam, and 6 inches more draught. The total 



