148 Anali/ses of Books, [Feb. 



opinion is promptly assumed that the hitter small experiment is 

 susceptible of the greater accuracy, and the numbers m its result 

 gratuitously adopted as nearer the truth than that of the former. 

 As this is an opinion which I have never been able to bring my 

 mind to acknowledge, and as it is a matter of oreat importance 

 in the present state of physics, I have been desirous to draw the 

 attention of philosophers to a closer consideration of the subject, 

 with a view to a more deliberate and impartial decision of this 

 point. 



" From the closest and most scrupulous attention I can 

 employ on this question, the preference, in point of accuracy, 

 appears to be decidedly in favour of the large or mountain expe- 

 riment over that of the small balls." 



From the Schehallian experiment. Dr. H. thinks, that the mean 

 density of the earth is five times that of water, but not more ; 

 while, from his experiment, Mr. Cavendish has assumed the mean 

 density to be = 5*48. Dr. Hutton afterwards points out some 

 of the errata in Mr. Cavendish's paper ; and concludes that the 

 medium of the first six of his experiments is 6*19, and of the 

 other 2o experiments 5*43, and the mean of both these means, 

 he observes, is 6*31, instead of 5-48, the error arising from the 

 sum of the numerical calculations. The difterence of 0*31, or 

 about the 17th part of the whole, Dr. Hutton thinks must be 

 ascribed to the inaccuracy of making and reading off experi- 

 ments with such intricate and inadequate machinery as that 

 used by Mr. Cavendish. 



Dr. Hutton observes, " that he cannot conclude this paper of 

 inquiry without expressing a hearty wish for the repetition of 

 the large or mountain experiment, in some other favourable 

 situation, and with improved means, if possible." For this pur- 

 pose, the Doctor suggests an idea, that one of the large pyramids 

 m Egypt might profitably be employed, instead of a mountain, 

 for this experiment. 



XX. On the Separatio7i of Iron from other Metals. By 

 J. F. W. Herschell, Esq. FR^. &c. 



This paper is given in the present number of the Annals. 



XXI. On the Re-estahlishment of a Canal in the Place of a 

 Portion of the Urethra which had been destroyed. By Henry 

 Eai'le, Esq. Surgeon to the Foundling, and Assistant Surgeon to 

 St. Bartholomew's Hospital. (Communicated by Sir Humphry- 

 Davy, Bart. PRS.) 



. For the particulars of this paper, which is entirely surgical, we 

 must refer to the original volume. 



XXII. Calculations of some Observations of the Solar Eclipse 

 on Sept, 7, 1820. By Mr. Charles Rumker. (Communicated 

 by Thomas Young, MD. For. Sec. to RS.) 



For this paper, which can hardly be abridged, we must also 

 refer to the volume. 



XXIII. An Account of the Uemeasurement of the Cube, Ct/lin- 



