164 Britain's Heritage of Science 



with a view to elucidating problems of geology. By studying 

 sections of rocks he laid the foundation of modern petro- 

 graphy and, devising methods for the examination of metal 

 surfaces, he originated a new era in the science of metal- 

 lurgy. He became interested in metals because he wanted 

 to examine the structure of meteorites. Not being able to 

 cut sections sufficiently thin to be transparent, he applied 

 acid to the polished surfaces, which then showed patterns 

 indicating the manner in which the crystallized parts of 

 the body hang together. The same method applied to ordi- 

 nary metals, and more especially to steel, has led to results 

 of far-reaching importance in practical engineering. 



It is difficult to assign a correct position in the history 

 of science to a man whose work is entirely neglected and 

 buried, to be brought to light only when its novelty has 

 disappeared. Such a man has had no influence in shaping 

 scientific thought, yet his merits are as great as if his 

 discoveries had been acknowledged at the time. John 

 Waterston (1811-1884) probably furnishes the most con- 

 spicuous example of a long-continued neglect of work 

 which would have marked a great advance in knowledge, 

 had it been recognized at the time of its maturity. A paper 

 which contains results of the highest value in the theory 

 of gases was presented to the Royal Society, but only a 

 short and insufficient abstract was printed. In the words 

 of Lord Rayleigh : " the omission to publish it at the time 

 was a misfortune which probably retarded the development 

 of the subject by fifteen years." In the complete investi- 

 gation discovered in the archives of the Royal Society by 

 Lord Rayleigh and published in the Philosophical Trans- 

 actions fifty years after it had been communicated, it is 

 shown how the kinetic theory can explain in a simple 

 manner the physical behaviour of perfect gases. It is proved 

 that the kinetic energy of a molecule is a measure of its 

 temperature, whatever the nature of the gas, and it contains 

 the discovery though imperfectly demonstrated that " in 

 mixed media the mean square molecular velocity is inversely 

 proportional to the specific weight of the molecules." The 

 ratio of the specific heats of constant pressure and volume 

 is calculated for molecules exhibiting internal motions, only 



