504 Prof. J. Lovering on the Mathematical and 



the constitution of matter has been a fruitful subject of debate, 

 and human science and philosophy have ever been dashing their 

 heads against the intractable atoms. The eagerness of the dis- 

 cussion was the greater the more hopeless the solution. For 

 every man who set up an hypothesis upon the subject there were 

 half a dozen others to knock it down, until at last speculation, 

 which bore no fruit, was suspended. A lingering interest still 

 hung around the question whether matter was not infinitely 

 divisible, and the atomic philosophers were not chasing a chi- 

 mera. From every new decision on this single point there was 

 an appeal; and the foothold which the atoms had secured in 

 chemistry was gradually subsiding. Of a sudden the atomic 

 theory has gained a new lease of life. But the hero of the new 

 drama is not the atom, but the molecule. In all the physical 

 sciences, including astronomy, the war has been carried home to 

 the molecules, and the intellectual victories of this and the next 

 generation will be on this narrow field. From the outlying 

 provinces of physics, from the sun, the stars, and the nebulas, 

 from the comets and meteors, from the zodiacal light and the 

 aurora, from the exquisitely tempered and mysterious aether 

 the forces of nature have been moving in converging lines to 

 this common battle-ground; and some shouts of victory have 

 already been heard. In the long and memorable controversy 

 between Newton and Leibnitz, and their adherents, as to the 

 true measure of force, it was charged against the Newtonian rule 

 that force was irrecoverably lost whenever a collision occurred 

 between hard, inelastic bodies. The answer was, that nature 

 had anticipated the objection and had avoided this kind of 

 matter. Inelastic bodies were yielding bodies; and the force 

 which had disappeared from the motion had done its work in 

 changing the shape. But unless the body could recover its 

 original figure by elasticity, there was no potential energy and 

 force was annihilated. It is now believed, and to a large extent 

 demonstrated, that the force, apparently lost, has been trans- 

 formed into heat, electricity, or some other kind of molecular 

 motion, of which the change of shape is only the outward sign. 

 The establishment on a firm foundation of theory and experi- 

 ment of the so-called conservation of energy, the child of the 

 correlation of physical forces, is one of the firstfruits of mole- 

 cular mechanics. 



It is no disparagement of this discovery, on which was con- 

 centrated the power of several minds, to call it an extension, 

 though a vast one, of Newton's law of inertia, of Leibnitz's vis 

 viva, and of Huyghens's and Bernoulli's conservation of living 

 forces — these older axioms of mechanics having free range only 

 in astronomy, where friction, resistance, and collision do not 



