GRAVITATION. 83 



which is to be overcome, the whole apparatus is called 

 the torsion balance. When a similar contrivance is re- 

 sorted to to detect and measure weak forces in Electri- 

 city or Magnetism, little circles of paper in the former, 

 and small magnetic bars in the latter case, are substitut- 

 ed for the leaden balls. For these purposes, a single 

 silk worm's thread, is generally used for the line to which 

 the bar is suspended.* 



By these and similar experiments, the last remaining 

 link is furnished to that beautiful chain of inductive rea- 

 soning, by which universal gravitation is established; 

 and the whole series is abundantly sufficient to satisfy 

 any mind by which it is attentively considered, that the 

 great Creator has made it an unvarying and universal 

 law, that every particle of matter draws towards itself 

 every other, and is itself reciprocally and equally drawn. 

 How simple is the principle; how immense the variety 

 and greatness of its effects ! If this single principle, con- 

 sidered in connexion with the unconceivable multiplicity 

 of useful effects which result from it, were the only proofs 

 of design which the creation afforded, the Atheist would 

 be compelled as he is now, to abandon reason and argu- 

 ment, and rest his cause on the bad passions and propen- 

 sities of the human heart. 



THE CAUSE OF GRAVITATION. 



The question has very often arisen, what is the nature 

 of the connexion between one particle of matter and 

 another by which this tendency to approach is produced ? 

 Jupiter and Saturn go out of their respective paths to 

 approach each other. Why do they do it 1 How is the 

 effect produced ? When the stem decays, the apple 

 rapidly goes to the earth. Is there any intervening sub- 

 stance which communicates an effect from one to the 

 other? Can an explanation of the kind like the first 

 described in the introductory remarks, be given of this 



* The writer has a torsion halance, constructed to be used as an 

 electrometer, in which the line suspending the bar of shelleac, is 

 of glass, a very attennuatcd thread, spun from window glass by a 

 blow pipe and a lamp. 



