906 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



after liquefaction are also ice of their kind ; yet are tliey so hot that 

 combustible bodies brought in contact with them are set on fire." 



Let us see how he disposes of the primum frigidum and sitmmum 

 frigidum of other philosophers, of and before his time. He says : " Since 

 the air is always and ev^ery where observed to be fluid, and therefore (as 

 demonstrated) warm, it follows that all bodies encompassed by the terres- 

 ti'ial atmosphere are warm, although they may appear cold to the senses ; 

 and thus an ultiynate degree of cold in our terraqueous glohe is not given.''^ 

 Can anything be more precise and more philosophical ? 



Here, indeed, in Michael Lomonosow's splendid memoir, do we discover 

 the doctrine of heat energy and the kinetic theory of gases, traced hith- 

 erto, by recent writers, only as far back as 1811 to Avogadro. The history 

 of thermodynamics must now contain a long and deeply-interesting 

 chapter referring to the speculations and close reasoning of Russia's 

 Goethe — a poor fisherman's son, afterward a linguist, rhetorician, poet, 

 dramatist, historian, physicist, and professor of chemistry in the Academy 

 of St. Petersburg — nevertheless forgotten ! 



D.— DEFINITION OF AN ICE-MACHINE. 



I shall only briefly allude now to the laws of heat which control the 

 operations that are to be studied in ice-machines or cold-generators. 

 Cold being only less heat, the entire subject is one of pure thermody- 

 namics, and the labors of Joule, Mayer, Rankine, Clausius, Sir AViUiam 

 Thomson, Tait, Tyndall, and others have unfolded the truth of the 

 action of heat-engines, and of the methods by which heat may be ab- 

 stracted from cold bodies by the energy of heat at higher temperatures. 

 Mr. Alexander Carnegie Kirk, in a paper read in 1874, before the Institu- 

 tion of Civil Engineers in London, defined the mechanical production of 

 cold to be "the removal of heat from a body without the intervention of 

 a colder body, by a continuous circle of operations. Any arrangement 

 for effecting this was merely a heat-engine, whose temperature of absorb- 

 ing heat was lower than its temjierature of ejecting heat, the motive 

 power in this state of things being negative. An air-engine was the type 

 of all refrigerating-machines in which the medium used was incondensa- 

 ble gas. A steam-engine with a surface condenser might be taken as the 

 tyi^e of those in which the medium was a vapor or condensable gas. 

 Harrison's ether-machine was the best known of this type." 



The analogy Avith a heat-engine is notaltogetUer simple, since in this the 

 useful work done is the equivalent of heat which disappears during the 

 process, whereas the intervention of motive power to raise heat from 

 water to be frozen to the condenser of an ordinary ice-machine, when 

 abstracted heat is thrown off with a large amount of water going to 

 waste, suggests at once that in an ordinary ice-machine there are two 

 elements to be considered, first, the heat-engine proper, viz, the steam-en- 

 gine, which operates the second element of the machine, viz, the circulat- 

 ing-pump, dealing with air or liquefiable gases. The same power and the 



