A HISTORY OF SCIENCE 



seeming thus, as viewed by the Martian, to rise in the 

 west and set in the east, and making the month only 

 one-fourth as long as the day. 



The Rings of Saturn 



The discovery of the inner or crape ring of Saturn, 

 made simultaneously in 1850 by William C. Bond, at 

 the Harvard observatory, in America, and the Rev. 

 W. R. Dawes in England, was another interesting op- 

 tical achievement; but our most important advances 

 in knowledge of Saturn's unique system are due to the 

 mathematician. Laplace, like his predecessors, sup- 

 posed these rings to be solid, and explained their sta- 

 bility as due to certain irregularities of contour which 

 Herschel had pointed out. But about 1851 Professor 

 Peirce, of Harvard, showed the untenability of this 

 conclusion, proving that were the rings such as La- 

 place thought them they must fall of their own weight. 

 Then Professor J. Clerk -Max well, of Cambridge, took 

 the matter in hand, and his analysis reduced the puz- 

 zling rings to a cloud of meteoric particles a " shower 

 of brickbats" each fragment of which circulates ex- 

 actly as if it were an independent planet, though of 

 course perturbed and jostled more or less by its fel- 

 lows. Mutual perturbations, and the disturbing pulls 

 of Saturn's orthodox satellites, as investigated by Max- 

 well, explain nearly all the phenomena of the rings in 

 a manner highly satisfactory. 



After elaborate mathematical calculations covering 

 many pages of his paper entitled "On the Stability 

 of Saturn's Rings," he summarizes his deductions as 

 follows : 



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