Discovery of the Cause of Gravitaiion, 147 



surface, it is required to know what resistance this plate will be 

 capable of making against a force applied to this arm as a lever, 

 considering the material, as well of the plate as of the arm and 

 surface, as a perfect mathematical abstraction ; that is to say, as 

 perfectly rigid or non-elastic, as infrangible or incapable of break- 

 ing, &c. ? 



Second Question. — A body being suspended from the extre- 

 mity of a cord, the other extremity of which is fixed to the roof 

 of a room: if this body is made to describe an arc of a certain 

 circle round the fixed extremity ; and if, besides, a movement 

 of projection is given to it, — it is required to know the nature 

 of the curve, or rather double curvature, which this body will de- 

 scribe, according to the hypothesis As is the resistance of the 

 air, so the square of velocity ? 



Third Question. — If there is an identity between the forces 

 which produce the electrical phsenomena, and those which pro- 

 duce the galvanic phaenomena, — whence is it that we do not find 

 a perfect accordance between the former and the latter ? 



Fourth Question. — Many modern authors believe in the iden- 

 tity of the chemical and galvanic forces : — it is required to prove 

 the truth or falsity of this opinion ? 



Fifth Question. — What is the true chemical composition of 

 sulphurets, as well oxidized as hydrogenized, made according 

 to the diflferent processes ; and what are their uses in the arts ? 



The answer must be supported as far as possible with new 

 facts, and experiments easy of repetition. 



XXVIII. Intelligence and Miscellaneous J.rticles^ 



DISCOVERY OF THE CAUSE OF GRAVITATION. 



M[Froin a Correspondent.] 

 R. John Herapath of Bristol has lately completed the solu- 

 tion of the celebrated problem respecting the cause of gravitation, 

 m which he has been engaged at different times for several years. 

 His researches for the solution of this problem (which was some 

 years ago the object of ardent inquiry by the Royal Society and 

 the contmental mathematicians) show that gravitation is only 

 a particular case of a general principle, which comprehends all 

 the great phaenomena of nature. It is remarkable that this de- 

 duction exactly coincides with the opinion of some of the greatest 

 philosophers of modern times; and, in particular, with that of the 

 late Professor Playfair, in his " Outlines of Natural Philosophy." 

 In the general theorem which Mr. H. has brought out' to express 

 the law of gravitation, it is found that the intensity of the at- 

 tractive force between two ultimate atoms, varies inversely as the 



K 2 square 



