THE DEVELOPMENT OF MECHANICS 247 



inclination which the planets have to approach the central body 

 round which they revolve, an inclination which is held in equili- 

 brium by the force of their forward motion." This is not much 

 nearer than Anaxagoras or Simplicius, though he offers an ex- 

 periment to clinch his idea. He avoids the use of the word 

 attraction, and he does not try to reduce the force of this 

 inclination to any mathematical expression. 



Along about 1660 there is a company of gentlemen meeting 

 in London to discuss all sorts of physical problems. Their head 

 is the Honourable Robert Boyle, one of the founders of pneu- 

 matics, the author of the Skeptical Chymist, and often referred 

 to as the founder of modern chemistry. Among others are Sir 

 Christopher Wren, the architect of St. Paul's, mathematician, 

 astronomer, and all-round man of science ; Edmund Halley, 

 future Astronomer Royal, then not long up from Cambridge ; 

 Robert Hooke, who begins as an assistant of Boyle's, reveals a 

 marvellous capacity for experiment, becomes the author of a 

 hundred inventions ; one of those restless-minded investigators 

 who scatter their fire and begin a hundred researches which 

 others will take up and complete. 



This company is the nucleus of the Royal Society ; in 1662 

 Charles II., restored to the throne of the Stuarts, gives it a 

 charter, and its great work is begun. In the very first year 

 after its founding, it appoints one of its earliest investigating 

 commissions to report on the subject of gravitation. Boyle is 

 a member of the commission ; already he is so thoroughly 

 interpenetrated with mechanical conceptions that he likens the 

 world to the wonderful clock in Strasburg that is to say, like 

 Descartes, he conceives it as a machine. 



But what is the force which makes this machine go ? 

 Evidently he does not see that it is gravity, about which the 

 commission is to report, for the inquiry bears no fruit. But 

 Hooke is restlessly fretting over the problem. As early as 1666 

 he has a paper before the Royal Society, " On the Inflection 

 of a Direct Motion into a Curve by a Supervening Attrac- 

 tive Principle." Seven or eight years later he had another 

 communication to make which contains this remarkable 

 passage : 



" I shall hereafter," he says, " explain a system of the world 

 differing in many particulars from any yet known, but answer- 



