CORRESP ONDENCE. 



5*3 



Unlike but mutually-adapted physical 

 growth and expenditure, including the func- 

 tions of reproduction, are held to balance 

 and equalize the physical well-being of the 

 sexes. It is further claimed that their psy- 

 chical powers, dependent upon and working 

 through adapted organisms, are also thereby 

 maintained in a perpetually-adjusted equi- 

 librium. The hypothesis assumes true men- 

 tal equivalence, which is secured through 

 inherent, varying, constitutional provisions. 



My sole claim to originality must lie in 

 the attempt to briefly and insufficiently in- 

 dicate how Nature has wrought to achieve 

 a continuous and progressive balance of 

 the sexes from the beginning until now. 

 It remains to complete the work ; to deter- 

 mine how much of one set of characters is 

 the mathematical equivalent of counter- 

 balancing quantities. 



Extremely accurate and detailed esti- 

 mates are doubtless out of the question. 

 The simplest computations are so inexact 

 that even the mean distance of the earth 

 from the sun still awaits revision. How- 

 ever, " in time," science must be able to 

 offer sufficiently accurate, incontrovertible 

 proof that men and women are, or are not, 

 intellectually peers. 



A. B. Blackwell. 



Somerville, N. J., March, 1876. 



THE "NEW PHILOSOPHY" OF HEAT. 



To the Editor of The Popular Science Monthly. 



In opening a copy of Bailey's Dic- 

 tionary, published in London in 1*775, my 

 eye fell upon the following : " Heat (ac- 

 cording to the New Philosophy) very much 

 consists in the rapidity of motion in the 

 smaller parts of bodies, and that every 

 way ; or in the parts being rapidly agitated 

 all ways. Its operation upon the senses 

 we call Heat, and is estimated according to 

 its relation to the organs of feeling, which 

 motion of its small parts must be brisk 

 enough to increase or surpass that of the 



parts of the sentient, for if it be more 

 weak or languid, it is said to be cold." 



I was under the impression that the 

 theory concerning heat which involves this 

 definition is of modern development. What 

 is the truth on the subject ? 



E. K. Craven. 



The doctrine which makes heat consist 

 in molecular motion, or in an agitation of 

 the minuter parts of which material things 

 are constituted, is old as a speculation, but 

 modern as a scientific demonstration. Locke 

 said, more than a hundred years ago, " Heat 

 is a very brisk agitation of the insensible 

 parts of an object, which produces in us 

 that sensation from which we denominate 

 the object hot, so that what in our sensa- 

 tions is heat, in the object is nothing but 

 motion." Similar views may be vaguely 

 traced in the writings of Galileo, Bacon, 

 Newton, Leibnitz, Descartes, Bernoulli, and 

 Laplace. But they were unverified con- 

 ! jectures, and could not take their place 

 among the principles of science until ex- 

 perimentally proved. This was first done 

 by Count Rumford, in his celebrated experi- 

 ments at the Munich Arsenal, and published 

 in the " Proceedings of the Royal Society 

 for 1*798." But Rumford's results were ig- 

 nored for half a century. Dr. Whewell 

 published the history of thermotics in 1837, 

 without mentioning him. He was far in 

 advance of his age, both in his philosophi- 

 cal views regarding heat and the experi- 

 mental evidence by which he sustained 

 them. When, from 1840 to 1850, various 

 physicists and chemists entered upon lines 

 of research that led to the general doctrine 

 of the convertibility or correlation of forces, 

 the labors of Rumford began to be appre- 

 ciated, and the truth concerning the nature 

 of heat being proved in various ways, be- 

 came accepted in science and part of a 

 " new philosophy," in a sense quite differ- 

 ent from that in which these terms were 

 used in the last century. 



