926 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



ter of the cuiTent century for a practical step in the direction of artificial- 

 ice-machines. JacobPerkins, whilst a resident in London, devoted him- 

 self to the determination of the compressibility of gases and fluids, and 

 as I have stated elsewhere, he undoubtedly recognized that gases and 

 vapors might be condensed into liquids. This property he took advant- 

 age of in 1834, in his "Apparatus for Producing Ice and Cooling Fluids." 

 " The object of my invention," said Perkins in his English patent, " is so 

 to use a volatile fluid that the same (having been evaporated by the heat 

 or caloric contained in the fluid about to be reduced in temperature) shall 

 be condensed and come again into the vessel to be again evaporated and 

 carry off further quantities of caloric." 



^^Description of the drawing. — a is a cistern for containing the water or 

 other fluid from which it is desired to remove the caloric, and thus 

 reduce its temperature, and even produce ice. This vessel should be 

 well covered in and surrounded by a non-conducting material, in order 

 to prevent the atmosphere or surrounding bodies giving oft' heat to the 

 water or other fluid contained in such cistern ; & is a vessel which is to 

 contain the volatile fluid to be evaporated, and I chiefly recommend ether 

 as the material to be evajjorated, owing to the low degree of tempera- 

 ture at which, under ordinary circumstances, it becomes aeriform, but 

 under the circumstances hereafter explained it will evaporate at still 

 lower degrees of temperature ; c is an ordinary pump, which I term the 

 vapour-pump, it being intended to withdraw the vapour as it is gener- 

 ated in the vessel b, and to force it through the refrigerating-pipes d, con- 

 tained in the cooling-tank e. There is to be a constant supply of cold 

 water to the refrigerating-tank or vessel e, in order to cool down and 

 condense the vapour in the pipes d. f is a pipe leading from the vessel h 

 to the pump, having a valve to close the entrance into the pump, in order 

 to prevent the vapour being forced back into the vessel h on the return 

 stroke of the piston ,• g is a pipe having a valve opening outwards from 

 the pump. This pipe g connects the pump with the refrigerator-pipes d ; 

 consequently the vapour, on coming into the pump, will be forced into 

 the pipes rf, and be there condensed, and tlieuce return again into the 

 vessel h to be again evaporated. But in order to secure a perfect con- 

 densation, I emploj^ a valve, 7<, modefately weighted, say about atmos- 

 I)heric pressure, which prevents the return of the condensed ether till 

 the same has become compressed and forced to give off its caloric to the 

 condensing water on the outside of the condensing-tube d. The valve 

 li is placed between the condenser and the vessel 7>, as shown in the 

 drawing. It will be seen that most of the parts are shown in sections, 

 in order that their construction may be evident. 



"Tlie apparatus being arranged as above described^ and as shown in 

 the drawing, I now prepare it for commencing work by filling every part 

 of the apparatus with the volatile liquid to the utter exclusion of the 

 atmospheric air, after which a sufficient quantity of the liquid is drawn 

 off by the small pumx) attached to the valve /<, to make sufficient space 



