SEQUEL TO THE GENERALIZATION 115 



the same problem, by supposing a solid nucleus 

 covered with a fluid of different density. No pecu- 

 liar novelty has been introduced into this subject, 

 except a method employed by Laplace for determin- 

 ing the attractions of spheroids of small eccentricity, 

 which is, as Professor Airy has said 11 , "a calculus 

 the most singular in its nature, and the most power- 

 ful in its effects, of any which has yet appeared." 



12. Capillary Action. There is only one other 

 problem of the statics of fluids, on which it is neces- 

 sary to say a word, the doctrine of Capillary At- 

 traction. Daniel Bernoulli 12 , in 1738, states that he 

 passes over the subject, because he could not reduce 

 the facts to general laws: but Clairaut was more 

 successful, and Laplace and Poisson have since 

 given great analytical completeness to his theory. 

 At present our business is, not so much with the 

 sufficiency of the theory to explain phenomena, as 

 with the mechanical problem of which this is an 

 example, which is one of a very remarkable and 

 important character; namely, to determine the 

 effect of attractions which are exercised by all the 

 particles of bodies, on the hypothesis that the 

 attraction of each particle, though sensible when it 

 acts upon another particle at an extremely small 

 distance from it, becomes insensible and vanishes 

 the moment this distance assumes a perceptible 

 magnitude. It may easily be imagined that the 

 analysis by which results are obtained under con- 



11 Enc. Met. Fig. of Earth, p. 192. " Hydrodyn. pref. p. 5. 



12 



