THOUGHTS ON THE NATURE AND ORIGIN OF FORCE. 245 



ailel iu.stauce of a considerable body of water by its momentum raising 

 &, smaller quantity to a biolier level in the bydraulic ram. Similar in- 

 stances of water-power occur in nature, a*s at the mouths of rivers, aud 

 at estuaries, where the contracting channel transforms a large mass 

 movement into the potential of elevation. A magnificent example of this 

 is furnished in the Bay of Fundy, where a huge tide of seventy feet is 

 derived from an ocean- wave probably not exceeding two feet in height. 



As in visible or mass motion, the matter may be either falling to a 

 lower state of power, (as in the descending weight of a clock or the 

 falling water of Niagara,) or rising under a superior external propulsion 

 to a higher state of power, {as in a clock being wound i^^ or ocean- water 

 being evaporated by the sun,) so in molecular movements, the matter 

 maybe either running down, (as in combustion, or in the decomposition 

 of quaternary or ternary compounds into more stable binary compounds,) 

 or the matter may be raised to higher power, (as in the vegetable de- 

 oxidation of carbon by the sun's rays, or in the building up of animal 

 substance to more complex and unstable conditions, by the power derived 

 frojn other matter running down.) 



Now, in all these wondrously varied and complex transmutations of 

 force, while it is certain that the sum of all the static and kinetic forms 

 of energy in the universe is a constant, which the human race with all 

 its endless appliances of machiuer}^ can no more increase or diminish 

 than it can add to or subtract from the quantity of matter, yet it is 

 equally true that the store of the former, or the potential in Nature, is 

 being in the aggregate diminished by transfer to the condition of the 

 latter or the dynamic ; and that in this transfer the general tendency is 

 to a form of temperature of greater diffusion, and less capability of fur- 

 ther transformation. So that solar and planetary systems are con- 

 stantly running down to a lower plane of power — the former by the 

 radiation of high heat, the latter by the radiation of low heat — into 

 empty celestial spaces.* There is on the whole, therefore, as Professor 

 Sir William Thomson has well designated it, a "Dissipation of En- 

 ergy." 



In a paper " On a Universal Tendency in Nature to the Dissipation of 

 Mechanical Energy," presented to the Royal Society of Edinburgh, April 

 19, 1852, Professor Thomson arrives at the conclusions, that " there is 

 at present in the material world a universal tendency to the dissipation 

 of mechanical energy :" and that " within a finite period of time past 

 the earth must have been, and within a finite period of time to come 

 the earth must again be, unfit for the habitation of man as at present 



* The whole amount of solar energy incessantly expended on our earth may be esti- 

 mated at the amount of 208 hillion 498,027 million " horse-power"— a horse-power 

 being equal to 550 foot-pounds per second. But as was shown by the illustrious Dr. 

 J. R. IMayer in his Beitrdge zur Di/namilc dcs Himmels, (Hoilbroun, 1848, ) the amount 

 of solar heat intercepted by the earth is to the whole amount radiated into space " as 1 

 is to 2,300 millions." {On Celestial Dijnmnics. Translated by Dr. H. Debus, L. E. D 

 Phil. Mag., April, 1863, Vol. XXV, p. 245.) 



