ON ARTIFICIAL REFRIGERATION. 927 



for tliG vapour, say at least ouc-half. Tlic pro^^rcss of the evaporation 

 of the liquid in the vessel b will dei)en(l on the quantity of vapour di-awn 

 off by the vapour-piunp, as well as the quantity of caloric taken up from 

 the li<]nnd surrounding^ the vessel b, and thereby will its temperature be 

 cooled down even to freezing*-." 



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

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

 matter of exi)eriment, alarmed his i)artners lest he neglected the very 

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

 dou a pursuit 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 sufliciently large body of water whilst supplying heat to the 

 ether for evaj)oration. Three inventors practically comi)leted 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 tlie world. 



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

 having designed the first apparatus 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, 1850, and in the United States 

 on November 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 1818 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 twenty-four hours, even employing water 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 4P above zero to 5i i)ounds 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 sufiicient 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- 

 fid of water at one oiDcration. It embraced the evaj^orating, the con- 

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

 ^-PPlyi^g the freezing power was widely difterent. Six months were 



