ON ARTIFICIAL REFRIGERATION. 927 



for the vapour, say at least one-lialf. Tlie progress of tlie evaporation 

 of the liquid in the vessel h will depend on the quantity of vapour drawn 

 off by the vapouv-piunp, as well as the quantity of caloric talcen up from 

 the liquid surrounding the vessel b, and thereby will its teniperature be 

 cooled down even to freezing." 



I have been informed by Mr. Loftus Perlvins, nephew of Mr. Jacob 

 Perkins, that the great success of his uncle's first freezing-machine, as a 

 matter of experiment, alarmed his partners lest he neglected the very 

 lucrative business they were engaged in, and he was compelled to aban- 

 don a i^ursuit most congenial to his tastes. All that lacked to complete 

 the ether-machine, was that extension of surfaces for the effectual freez- 

 ing of a sufficiently large body of water whilst supplying heat to the 

 ether for evaporation. Three inventors practically completed the work of 

 Perkins, ^-iz. Twining, Harrison, and Daniel Siebe. It were invidious 

 to discriminate against either of these, but the ablest mechanic of the 

 three, Mr. Siebe, having had all the fundamental principles laid before 

 him, competent for any task he undertook, was limited to the engineer- 

 ing question, and to his skill in this respect we have to ascribe the prac- 

 tical success of ether-machines throughout the world. 



Prof Alexander C. Twining, of Xew Haven, has been justly regarded as 

 having designed the first ai)paratus being an advance or improvement 

 on the earlier invention of Mr. Jacob Perkins. His first patent was 

 taken out in England on the 3d of July, ISoO, and hi the United States 

 on ]N^ovember 8, 1853. The last was afterward extended to 1871. Pro- 

 fessor Twining has permitted the publication of a statement of the steps 

 taken in the progress of his invention. From 1848 to 1850 he was en- 

 gaged in repeating Cullen's original ether experiments in vacuo, and 

 found that one pound of ether, by its evaporation, was adequate to pro- 

 duce one pound and one-fifth of ice from water at 32° Fahr., besides 

 cooling the ether 28^. He then determined that only 200 superficial feet 

 of thin copper pipe would form an adequate surface for the production 

 of 2,000 pounds of ice in twentj'-four hours, even employnig Avater of the 

 temperature at the earth's equator. Ether was found to pass into vapor 

 within a quarter as fast as water in locomotive-boilers ; in a partial 

 vacuum, 1 superficial foot of metal supplied heat even at the low temper- 

 ature of 4"^ above zero to 5.J pounds of ether per hour. 



In relation to the method of freezing water, it was ascertained that the 

 rate of freezing was not appreciably obstructed by the thickness of ice 

 already formed; a congelation of one-eighth of an inch in thickness could 

 be realized per hour; 240 superficial feet would be a sufiicicnt surface on 

 which to freeze one ton of ice per day of twenty-four hours. 



" The first attempt at a complete freezing construction was made in 

 the summer of 1850. The machine had only capacity to freeze a pail- 

 ful of water at one operation. It embraced the evaporating, the con- 

 densing, and the freezing parts" as afterward used. "But the mode of 

 applying the freezing i)ower was widely different. Six months were 



