ON THE HISTORY OF TERRESTRIAL PHYSICS. 589 



to emitting and receiving radiant heat, is in every respect highly interesting ; 

 and the multiplicity and diversity of his experiments would have entitled 

 him to still higher commendation than he has obtained, if they had heen 

 more simply and circumstantially related. Perhaps, however, none of 

 the modern improvements in speculative science deserves a higher rank 

 than Dr. Herschel's discovery of the separation of heat from light by re- 

 fraction. Mr. Prevost has made some just remarks on the experiments of 

 other philosophers respecting heat ; and his own theory of radiant heat, 

 and his original investigations, on the effect of the solar heat on the earth, 

 have tended materially to illustrate the subject of his researches. 



The general laws of the ascent and descent of fluids in capillary tubes, 

 and between plates of different kinds, had long ago been established by 

 the experiments of Hauksbee, Jurin, and Musschenbroek ; many other 

 circumstances, depending on the same principles, had been examined by 

 Taylor, Achard and Guyton ; and some advances towards a theory of the 

 forms assumed by the surfaces of liquids, had been made by Clairaut, 

 Segner, and Monge. In an essay on the cohesion of fluids, read before 

 the Royal Society in the year 1804, I have reduced all effects of this 

 nature to the joint operation of a cohesive and repulsive force, which 

 balance each other ; assuming only that the repulsion is more augmented 

 by the approach of the particles to each other than the cohesion ; and I 

 have had the satisfaction of discovering in this manner a perfect corre- 

 spondence between many facts, which had not been supposed to have the 

 slightest connexion with each other. Almost a year after the publication 

 of this paper, Mr. Laplace read to the National Institute a memoir on capil- 

 lary tubes, in which, as far as he has pursued the subject, he has precisely 

 confirmed the most obvious of my conclusions; although his mode of 

 calculation appears to be by no means unexceptionable, as it does not in- 

 clude the consideration of the effects of repulsion. Had my paper been so 

 fortunate as to attract Mr. Laplace's attention before his memoir was pre- 

 sented to the Institute, he would perhaps have extended the results of my 

 theory with the same success, which has uniformly distinguished his 

 labours in every other department of natural philosophy. 



When we reflect on the state of the sciences in general, at the beginning 

 of the seventeenth century, and compare it with the progress which has 

 been since made in all of them, we shall be convinced that the last two 

 hundred years have done much more for the promotion of knowledge, than 

 the two thousand that preceded them : and we shall be still more encouraged 

 by the consideration, that perhaps the greater part of these acquisitions 

 has been made within fifty or sixty years only. We have therefore the 

 satisfaction of viewing the knowledge of nature not only in a state of ad- 

 vancement, but even advancing with increasing rapidity ; and the universal 

 diffusion of a taste for science appears to promise, that, as the number of 

 its cultivators increases, new facts will be continually discovered, and those, 

 which are already known, will be better understood, and more beneficially 

 applied. . The Royal Institution, with other societies of a similar nature, 

 will have the merit of assisting in the dissemination of knowledge, and in 

 the cultivation of a taste for its pursuit ; and the advantages arising from 



