12 THE INTERNAL-COMBUSTION ENGINE, ETC. 



amount earned on investment from 17.4 per cent to 18.73 per cent or 67 per cent better than 

 the steamer. 



The above figures can be used as a basis for working out a comparison for any route 

 which will vary directly with length of voyage and the size of the vessels employed. 



A brief description of the motor ship William Penn will be given, as it was the first large 

 vessel of this kind owned by the United States Shipping Board. The performance of this 

 vessel in service will be of particular interest, as it is to be operated over the same route and 

 by the same operating company as the electrically driven ship Eclipse, recently put into 

 service. 



The hull, having been originally intended for a 3,000 shaft horse-power single-screw 

 turbine installation, is not exactly suitable to the Diesel engine installation of 4,500 indi- 

 cated horse-power, or 3,500 shaft horse-power. For best efficiency, due to its high block 

 coefficient, the vessel should not be driven over 10^^ to 11 knots in service. The screws 

 have accordingly been designed for lower turns than that for which the engines were in- 

 tended, so that the designed mean indicated pressure, upon which the efficiency of engines 

 somewhat depends, will be maintained. 



The William Penn has a length between perpendiculars of 439 feet 6 inches, beam of 

 60 feet, depth moulded to shelter deck of 36 feet 8 inches, and draught of 28 feet 4^ inches, 

 corresponding to 12,375 tons deadweight The length of engine-room space was maintained 

 the same as for the steam-driven sister ships. A built-up column was added to tie the middle 

 of the engine-room double bottom to the shelter and bridge decks, to prevent possible sjoi- 

 chronous vibrations being set up between the main engines and the hull's structure. 



The main engines are, as previously stated, six cylinders, each of a bore and stroke of 

 740 mm. and 1,150 mm., respectively. Along the port side are arranged the three auxiliary 

 engines each driving 65 kilowatt generators, and along the starboard side the maneuvering 

 compressor and bilge and ballast pumps. The lubricating and salt-water cooling pumps are 

 placed near the forward bulkhead and the fuel oil pump and reserve air compressor aft, 

 between the main engines. In this vessel a fresh-water closed cooling system, with cooler 

 and fresh-water pump, has been added for the cooling of the cylinders and covers. This is 

 a precaution against mud being deposited in the spaces, which is liable to occur with deep- 

 draught vessels when navigating shallow waters and rivers. The salt cooling water is main- 

 tained for the main compressors and piston cooling, which is also used for cooling the fresh 

 water. 



The Chairman : — For the benefit of those who have come in since we opened these 

 proceedings, let me say that it was thought desirable to have both papers before there was 

 any discussion; that the discussion should then take in both subjects. At the close of the 

 discussion some pictures will be thrown upon the screen by Mr. Shaw, by Mr. Warriner 

 and by some others. 



Paper No. 2, by Mr. Robert Warriner, is entitled, "Reduction Gears for Ship Propul- 

 sion." 



Mr. Warriner presented the paper. 



