950 KEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



S.— THEEMO-GLACIAL ENGINE. 



This is based on the ascertained fact that a liquefiable gas or vapor 

 may be cooled and liquefied by the transformation of its heat into 

 mechanical energy. I avail myself of this by causing the gas or vapor 

 in its passage to the refrigerator — or that jjortion of the api^aratus where 

 it acts upon the substance to be refrigerated — to exert its energy against 

 a resisting body, such as the piston of an engine, whereby it i^arts with 

 its heat and is liquefied to a great extent, if not entirely; in which con- 

 dition it passes from the engine to the refrigerator, where it acts as the 

 refrigerating agent. In the refrigerator it is, by the heat, abstracted 

 from the substance to be cooled, again converted into vapor or gas, 

 which is, by a pump or compresser (driven by the engine above named) 

 returned to the starting j)oint and there suppUed with sulficient addi- 

 tional heat to overcome inertia and friction, so as to cause it again to 

 pass on to the engine and through the same cycle of operations. 



The apparatus requisite to effectuate the foregoing method of opera- 

 tion consists of the following leading parts : 



I. A heater or boiler, in which the gas or vapor is raised to the proper 

 degree of heat. If we suppose that the material employed be anhydrous 

 or pure liquid ammonia — a substance which I prefer, and in practice 

 use — then the heater or boiler is heated by suitable means to raise the 

 ammonia to, say 125° Fahr., which wiU give a pressure of about 300 

 pounds to the square inch. 



II. An engine, preferably a rotary engine, in which the piston has a 

 continuous rotary movement on its axis in one direction. The gas from 

 the boiler is through a suitable conduit led to the engine, w^here it is 

 worked expansively, through the instrumentality of a proper cut-off", to 

 drive the piston. In this way the heat is used up by conversion into 

 mechanical energy, and the gas thus fi-eed from heat assumes the liquid 

 form more or less completely, according to the extent to which the heat 

 has been transformed into energy. I prefer to use a double engine; that 

 is to say, one having two cylinders. The gas enters the first or high- 

 pressure cylinder and is there worked expansively, so as to abstract 

 much of its heat. It thence exhausts into the second or low-pressure 

 cylinder, where it is worked exi^ansively still further. The expansion 

 in each case is determined by the usual cut-off', which can be regulated 

 by the engineer, according to conditions of nse and the nature of the 

 hquefiable gas or vapor employed, in such manner as to admit at each 

 stroke or revolution, as far as practicable, only that amount of gas whose 

 heat can be all, or nearly so, transformed into mechanical energy, the 

 object being to bring the gas to a liquid condition by the time it has 

 done its work in the second cylinder. 



III. A refrigerator, into which the liquefied gas or vapor is led from 

 the engine, and where it is brought into contact with or caused to act 

 directly or indhectly upon the object to be cooled or frozen. The refrig- 



