THE SUBMARINE OF TO-DAY AND TO-MORROW. 221 



ent engine so heavy. At the present time I am engaged in the design of an engine based 

 upon my theories, which differ very materially from the theories of the late Dr. Diesel. As a 

 result of correspondence with the Navy Department relative to the discrepancy of data 

 quoted last year for the two ships, the Cyclops and Jupiter, my theories were mentioned 

 and I was invited by the Navy Department to design an engine to illustrate my theory. 

 The option was given the Department to select as a problem either a large sized engine or 

 a submarine engine. The submarine engine was selected. In this selection I was somewhat 

 limited in size and power. However, I decided to conform to requirements as far as 

 possible, but not to sacrifice any desirable elements of my design to conform to the re- 

 strictions. 



The type of engine selected to submit was the low-pressure type. In this engine the 

 clearance of the cylinder is about 17 per cent in place of 8 per cent, as is used in the Diesel 

 engine. In order to produce initial ignition of the fuel it is proposed to use steam in the 

 jackets of the cylinder. The explosion pressure can be allowed to run up from a pres- 

 sure of 175 pounds to around 500 pounds. In this case the engine would at first thought 

 appear to be no lighter than the Diesel. This is not the case, however, as the weight of the 

 engine is due in no small degree to the bearing areas. In the Diesel, with its high pressure of 

 compression, a lower bearing pressure per square inch must be used than in the proposed 

 type where this stress, if it exists at all, will exist for only a short time. It is my opinion that 

 much of the massiveness of the present Diesel engine is unnecessary. This applies to the 

 cylinder. The part of the cylinder exposed to the maximum stress is the top. Here we 

 have a solid ring of metal where the head and cylinder join. This is a great aid in resisting 

 the bursting effect of the cylinder. As for the holding-down effect it is necessary only to 

 assure a ring of metal sufficient to resist the effect of the maximum stress on the piston as a 

 tensile stress. As for the head of the cylinder its depth necessary to allow for passage 

 makes it well reinforced. The problem seems to be more one of design to assure maximum 

 reliability in regard to the quality of the castings. As for the cylinder barrel I have con- 

 sidered the use of cast steel cylinder castings with cast iron liners forming the wearing sur- 

 face. By some such care as this it seems no more than reasonable to lighten the engine to a 

 considerable degree. It hardly seems feasible to lighten the engine by anything which will 

 approach the constant pressure type which I worked on for some time and concerning the 

 undesirability of which I have assured myself. The weight of the engine must not be reduced 

 at the expense of its efficiency or general utility. 



The other point was that brought up by Mr. Donnelly in regard to the possibility 

 of in some way storing up air in a highly compressed form for the purpose of running on 

 oil power submerged and also to increase the mean effective pressure. I was much pleased 

 to have Mr. Donnelly bring this point up. He very correctly said that in a given cylinder 

 only a certain amount of atmospheric air could be compressed. With this amount of 

 atmospheric air but a certain amount of fuel can be used. If more fuel were injected 

 the results would be imperfect combustion without any increase in the power. This is one 

 of the points which I have recognized and worked on, and this is the reason for my taking 

 up the low-pressure type of engine. Let us assume that we have a Diesel engine of such pro- 

 portions that the piston displacement is but one cubic foot. Then with the clearance space 

 filled with pure air the contents of the cylinder will be 1.08 cubic feet. This is the most 

 favorable case where the scavenging air is used to good effect. The limit of power in this 

 engine will be that which can be derived from the use of that oil which will require 1.08 



