ANNUAL ADDRESS. IX. 



In the first place, the water of the ocean at 62 degrees might 

 be used as fuel if it were pumped through an evaporator and 

 discharged at 32 degrees, because then 30 degrees of its tempera- 

 ture could be communicated to evaporate such medium, and 

 make the necessary gas or vapour for the engine, instead of 

 requiring the heat to be obtained from the combustion of coal. 

 In the second place, only one-fourth part of the quantity of water 

 at present required for condensing, would be necessary as such 

 iuel ; and the coal would be altogether unnecessary. 



With all the substances at present known which are capable 

 of being used as the medium in a heat engine, their pressure as 

 a gas or vapour diminishes under expansion in such a different 

 ratio to their reduction of temperature (the range of pressures 

 approaching relatively so much closer to the practical zero of 

 pressure than the range of temperatures does to absolute thermal 

 -zero) that, when fully expanded, they still retain so much heat as 

 to require cooling or condensing water to take it away. In the 

 case of air, or so called caloric engines, simply to reduce the 

 volume; in the case of other engines in a lesser way to produce 

 liquefaction of the medium, and in a greater way to reduce the 

 volume. 



It is the simplest thing in the world to bring a pound of water 

 at 212 degrees into intimate contact with another pound at 

 32 degrees, and produce two pounds at say 122 degrees, but it is 

 quite another matter to attempt to separate the commingled 

 waters into two separate pounds at their original temperatures. 

 Will that problem ever be solved? Will a medium ever be 

 found that will enable a heat engine to be run entirely below 

 normal temperatures, as recent statements would imply 1 



It is no doubt true that the bare suggestion of such proposi- 

 tions, in the light of established theories, lays one open to 

 ridicule. The mere idea, almost but yesterday, would not have 

 been considered worth a second thought ; yet, in the light of 

 recent events, it will not be wise to dogmatise as to what im- 

 provements are possible in the heat motor of the future. 

 Ohemical action, as we understand it, seems to cease at low 



