23 



of two sets of interior surfaces, that are equally pressed at all their 

 points by the action of the exterior fluid, is inconsistent with Clairaut's 

 theory, and is a proof of the insufficiency of that theory for deter- 

 mining the figure of a homogeneous planet. 



January 27. 

 GEORGE RENNIE, Esq. V.P., in the Chair. 



The following Presents were received, and thanks ordered for 

 them : — 



Views of the Pelvis, showing the Natural Size, Form and Relations 

 of the Bladder, Rectum, Uterus, &c. in the Infant and in the 

 Adult ■ taken from Preparations made for the Museum of the 

 Royal College of Surgeons in Ireland. By John Houston, Esq. 

 folio. — Presented by the Author. 



An Account of two newly discovered Muscles for compressing the 

 Dorsal Vein of the Penis, in Man and other Animals ; and also 

 of a similar Provision for compressing- the Veins of the Chame- 

 leon's Tongue. By the Same. 8vo. — The Author. 



Connaissance des Terns pour l'An 1833. 8vo. — The Board of Lon- 

 gitude of France. 



L'Annuaire pour l'An 1831. 12mo. — The Same. 



Bulletin de la Societe Francaise de Statistique Universelle. Pre- 

 miere Livraison. 4to. — The Society. 



Statuts, et Liste des Membres, de la Societe Francaise de Statis- 

 tique Universelle. 8vo et folio. — The Society. 



A paper was read, On the probable electric origin of all the phe- 

 nomena of Terrestrial Magnetism ; with an illustrative experiment. 

 By Peter Barlow, Esq. F.R.S. Corr. Mem. Inst. France, and of the 

 Imp. Acad. St. Petersburg!). 



The authorbeginshis paper by a retrospect of the several discove- 

 ries on terrestrial magnetism made since the commencement of the 

 present century. Humboldt, by his numerous and accurate observa- 

 tions on this subject, laid the foundation of all the scientific know- 

 ledge relating to it, which we hitherto possessed. The task of reducing 

 these observations to definite principles, by subjecting them to calcu- 

 lation, was undertaken by Biot ; and the conclusion which he drew 

 from them was, that on the hypothesis of the earth's being a great 

 magnet, the facts would best accord with the supposition that its 

 two poles are coincident, or indefinitely near to each other, at the 

 centre of the globe. The same result was also obtained, though by a 

 different process of reasoning, by M. Kraft of St. Petersburgh. It 

 followed as a necessary consequence, that terrestrial magnetism ob- 

 serves a law different from that of a permanently magnetic body, but 

 identical with that of a body in which transient magnetism is excited 

 by induction. The law which obtains in the case of a sphere of iron 

 rendered magnetic by induction was first investigated, in 1829, by 

 Mr. Barlow; and also, by Mr. Charles Bonnycastle, Professor of 



