253 



lies, or acids, produced very little effect, although they are better con- 

 ductors. 



Lastly, some general applications of these singular facts are pointed 

 out by Mr. Davy ; such, for instance, as the application of electricity 

 to the analysis of animal and vegetable substances. Muscular fibre 

 being electrified for some time, became dry and hard ; and it left, 

 upon incineration, no saline matter. Potash, soda, ammonia, lime, 

 and oxide of iron, were collected on the negative side ; and the sul- 

 phuric, nitric, muriatic, phosphoric, and acetous acids, on the posi- 

 tive. Laurel-leaf was rendered brown and parched ; green colouring 

 matter, with resin, alkali, and lime, appeared in the negative vessel, 

 and prussic acid in the positive. 



By using charcoal and plumbago, or charcoal and iron, as the ex- 

 citing powers, along with neutro-saline solutions, large quantities of 

 acids and alkalies might be procured with little trouble or expense. 



It is very probable that many mineral formations have been mate- 

 rially influenced or even occasioned by the agency of the electricity ; 

 and the electrical power of transference may thus be applied to the 

 explanation of the principal points in geology. 



On the Precession of the Equinoxes. By the Rev. Abram Robertson, 

 M.A. F.R.S. Savilian Professor of Geometry in the University of 

 Oxford. Read December 18, 1806. [Phil. Trans. 1807, p. 57.] 



The Professor observes, that Sir Isaac Newton was the first ma- 

 thematician who endeavoured to estimate the quantity of the pre- 

 cession from the attractive influence of the sun and moon on the 

 spheroidal figure of the earth. His investigations relating to this 

 subject evince the same transcendent abilities that are displayed in 

 other parts of his Principia ; but it is admitted, that, from a mistake 

 in his process, his conclusion is erroneous. 



The investigations of other mathematicians in attempting the solu- 

 tion of the same problem are arranged by the author under three 

 general heads. The first arrive at wrong conclusions, in consequence 

 of mistake in some part of their proceedings ; the second obtain just 

 conclusions, but rendered so by balance of opposite errors ; the third 

 approach as near the truth as the nature of the subject will admit, 

 but, in the author's estimation, are liable to the charge of obscurity 

 and perplexity. 



The defects in all their investigations Professor Robertson ascribes 

 to the same cause the uncultivated state of the doctrine of com- 

 pound rotatory motion. 



The author's endeavours are, consequently, first directed to the 

 investigation of the principles of compound rotatory motion from 

 principles which he considers clear and unexceptionable. 



He next proceeds to calculate the disturbing solar force on the 

 spheroidal figure of the earth, and thence the angular velocity which 

 it produces. 



The quantity of annual precession is then computed ; and, lastly, 



