Gl-1 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



sun, it would take many uiillions of years to cool dovrn to any 

 perceptible degree when once in a white hot condition. 



Modern experiments prove that no motion can be obstructed 

 without the generation of heat, from there the use of lubricators 

 preventing heating of the parts, and the consequent loss of motive 

 power; that heat is generated when a bodj^ falls from a height on 

 the 2:round, and that any small amount of heat, developed by the 

 shock, may be measured to a small fraction of a degree, is one of 

 the triumphs of modern philosophy. 



The Doctor here explained Melloni^s metJiod of measuring the one- 

 tliousaMdth part of a degree by the thermo-electric pile and midtipli- 

 cator; illustrating the explanations by experiments. 



If now we see that w^e cannot drop this leaden ball on the floor, 

 from the height of a few feet, without raising its temperature, we 

 can imagine what will be the result of the falling down to a com- 

 mon centre of gravity of millions of billions of masses, through 

 spaces of millions of miles, with, velocities far surpassing anything 

 we can produce, and we must conclude that an enormous rise of 

 temperature must take place, of which we cannot possibly have 

 any conception. 



This force is now radiating into space, and is giving l^ack slowly, 

 in the form of caloric and luminous undulations, a part of the 

 power expended by the falling down or evalescence of the masses. 



Heat, as we know now, is a state of matter, a molecular motion, 

 vibratory or rotatory, and the motion of the masses once pro- 

 duced by gravitation toward certain centres, is uow^ returning into 

 space, producing molecular motion, all around, at enormous dis- 

 tances. We say vibratory, rotatory or undulatory motions, as the 

 hypothesis of Newton, that light and heat is propagated by fine, 

 material particles, emanating from and propelled by the luminous 

 body, is just as absurd as it would be to assert that sound is pro- 

 duced by fine material particles driven out by the sounding body. 



A small fraction of the waves continually produced by the 

 molecuLnr motion or heat from the sun reaches our earth, less than 

 one-ten-thousand-millionth part, and this small fraction of its heat 

 and light is the source of all vegetable and animal life, of all the 

 motive power, of every movement we see on the surface of our 

 planet, except the tide-wave in the ocean and in the atmosphere. 

 We may, in fact, trace back to the sun all water power, as it is 

 produced by atmospheric evaporation ; all wind power produced 



