262 



The Rev. Samuel Haughton on the 



Table IV. 



On comparing the observed ellipticities with the limits calculated in the 

 preceding Table, it appears that the ellipticity of Mars exceeds tlie major limit 

 admissible on the fluid hypothesis; the inference from which fact is, either 

 that gravity is not perpendicular to the surface of ISIars, or that his interior 

 structure is not that which would be assumed by a fluid body. The first of these 

 suppositions appears inadmissible from the fact, that there is reasou to beheve, 

 that there are degrading and disintegrating forces at work on the surface of that 

 planet, similar to those now in operation on the Earth, and which would render 

 the surface perpendicular to gravity, if not so originally. The second suppo- 

 sition would appear to be inconsistent with the idea that Mars derived his pre- 

 sent fio-ure from having been originally fluid; at least, we are scarcely justified 



* Transactions of Royal Society of London, for the year 1784. The ratio of the axes of the 

 planet Mars, deduced from observation, is 1355 : 1272. 



t Exposition du Systeme du Monde, p. 37- The ratio of axes deduced from observation by 

 Arago is 194 : 189. 



X Exposition du Systeme du Monde, p. 39. The ratio of axes is 177 : 167. 



§ Transactions of Koyal Society of London, for the year 1 790. The ratio of axes is 2281 : 206 1 . 



