1 6 IntroauSlion 



one portion of the surface is numerically equal to the whole negative charge 

 on the other portion. 



Now if the density (on the cylinder) were inversely as the distance 

 from the charged body, a transverse section of the cylinder whose distance 

 from the charged body is the geometric mean of the distances of the ends, 

 would divide the charge into two equal parts (both of course of the same 

 kind of electricity), but if the density were inversely as the square of the 

 distance, the distance of the section which would bisect the charge would 

 be the harmonic mean of the distance of the ends. In all this he tacitly 

 confounds the point of bisection of the charge with the neutral point. 



He then shows by experiment that the actual position of the neutral 

 point agrees sufficiently well with the harmonic mean, but not with the 

 geometric mean, and from this he concludes (p. 65), 



Consequently, it evidently appears, from what was said above, that the 

 Density of the Electricity, of the electrical Atmosphere (in which the said 

 Body A , B was immersed) was in the inverse Ratio of the square of the Distance. 



It is evident from this that Lord Mahon was entirely ignorant of every- 

 thing which Cavendish had done. 



About the close of the century Dr Thomas Young, whose acquaintance 

 with all branches of science was as remarkable for its extent as for its 

 profundity, says of this neutral point : 



It was from the situation of this point that Lord Stanhope first inferred 

 the true law of the electric attractions and repulsion':., although Mr Cavendish 

 had before suggested the same law as the most probable supposition. 



The same writer, in his "Life of Cavendish," in the Supplement to the 

 Encyclopedia Britannica*, gives the following account of the first paper on 

 electricity. 



3. An Attempt to explain some of the principal Phenomena of Electricity by 

 means of an Elastic Fluid. (Phil. Trans. 1771, p. 584.) Our author's theory of 

 electricity agrees with that which had been published a few years before by 

 jEpinus.but he has entered more minutely into the details of calculation, showing 

 the manner in which the supposed fluid must be distributed in a variety of cases, 

 and explaining the phenomena of electrified and charged substances as they are 

 actually observed. There is some degree of unnecessary complication from the 

 great generality of the determinations: the law of electric attraction and repulsion 

 not having been at that time fully ascertained, although Mr Cavendish inclines 

 to the true supposition, of forces varying inversely as the square of the distance : 

 this deficiency he proposes to supply by future experiments, and leaves it to 

 more skilful mathematicians to render some other parts of the theory still more 

 complete. He probably found that the necessity of the experiments, which he 

 intended to pursue, was afterwards superseded by those of Lord Stanhope and 



[* Reprinted, at the end of this volume, from Young's Miscellaneous Works, vol. n.] 

 Lectures on Natural Philosophy, London 1807, vol. I. Lecture liii, p. 664. 



