PHYSICS OF NINETEENTH CENTURY 155 



industrial development which is still in progress had 

 already begun. One of its chief instruments, the 

 steam engine, reached a serviceable form when, in 1769, 

 James Watt patented the principle of the condenser. 

 The steam engine was a practical invention, to which 

 scientific principles were applied at a later stage to 

 carry out developments and improvements. But the 

 electric telegraph, the other great agent in revolu- 

 tionizing the social conditions of the world, was a 

 direct consequence of research in pure science. 



To some people, the practical applications of science 

 stand for its main achievement. But their effect on 

 the human mind and its thought, though great, is 

 indirect. That effect is slow and cumulative. The 

 gradual and apparently inevitable extension of man's 

 power over the material resources of nature gives 

 applied science, by which the advance is chiefly 

 secured, an importance in the eyes of the outside world 

 with which no amount of abstract thought endows 

 pure knowledge. Indeed, in the eyes of the world, 

 applied science attains the position which Francis 

 Bacon foresaw and desired. As one triumph after 

 another is won, the effect to all appearance is that 

 of an invincible if slow advance. It seems that no 

 limits can safely be assigned to the extension of man's 

 mastery over nature ; it comes to be assumed that 

 the mechanical principles by the application of which 

 that extension is made are competent to account for 

 and explain the whole of the Universe. 



Save in this indirect way, with the technical applica- 

 tions of science we shall have little to do. It is indeed 

 a very grave question whether the consequent advance 

 in material wealth and resources has produced any 



