162 SCIENCE AND THE HUMAN MIND 



calculated independently by John Couch Adams of 

 Cambridge and the French mathematician Leverrier. 

 Turning his telescope to the position indicated by 

 Leverrier, the astronomer Galle of Berlin detected 

 a planet to which the name of Neptune was given 

 (1846). These researches give the final verification 

 of Newton's fundamental hypothesis that each particle 

 of matter in the solar system may be supposed to 

 attract every other particle with a force proportional 

 to the product of the masses, and inversely pro- 

 portional to the square of the distance between 

 them. The probability in favour of the hypothesis 

 as the embodiment of a correct relation is possibly 

 as great as that in the case of any other physical 

 theory hitherto propounded. 



Newton's theory, as developed by himself, Lagrange 

 and Laplace, proved sufficient to co-ordinate all the 

 The Nebular observations made concerning the solar 

 Hypothesis, system as now in existence ; it was 

 therefore natural to try to extend its sway over the 

 past, and to adapt it to an attempt to explain the 

 origin of that system. Hence Laplace framed a 

 " nebular hypothesis," which pictured the primordial 

 chaos as filled with scattered matter like a diffused 

 cloud, spread throughout the space now occupied 

 by the solar system. Laplace showed that known 

 dynamical principles were consistent with the drawing 

 together and gradual solidification into distinct 

 fiery masses of such space-scattered particles. He 

 thus made conceivable to the human imagination the 

 formation of the sun and planets from a formless 

 chaos. The existence of luminous nebulae in the 



