20 



Das Verhaltniss der chemischen Verwandtschaft zur galvanischen 

 Elektricitat, in Versuchen dargestellt. Von N. W. Fischer, M. et 

 Phil. Doct. 8vo.— The Author. 



The reading of a Paper, entitled, On the Equilibrium of Fluids ; 

 and the Figure of a Homogeneous Planet in a Fluid state. By James 

 Ivory, Esq. M.A. F.R.S. — was commenced. 



January 20. 



HIS ROYAL HIGHNESS THE DUKE OF SUSSEX, 

 President, in the Chair. 



William John Elake, Esq. M.A. was elected a Fellow. 

 The following Presents were received, and thanks ordered for 

 them: — 



Transactions of the Society for the Encouragement of Arts, Ma- 

 nufactures, and Commerce, for the year 1829. 8vo. — Presented 

 by the Society. 



Proceedings of the Committee of Science and Correspondence of 

 the Zoological Society of London. (Nov. 9, to Dec. 4?, 1830.) 

 8vo. — The Society. 



On the Probable Connection of Rock Basins, in Form and Situation, 

 with an internal Concretionary Structure in the Rocks on which 

 they occur: introduced by Remarks on the alleged Artificial 

 Origin of those Cavities. By E. W. Brayley, Jun., Esq. 8vo. — 

 The Author. 



Tabulae Regiomontanse Reductionum Observationum Astronomi- 

 carum ab Anno 1750 usque ad Annum 1850 computatae. Auctore 

 F. W. Bessel. 8vo. — The Author. 



The reading of Mr. Ivory's Paper was resumed and concluded. 



The author considers the essential property of a fluid, and that on 

 which its definition should be founded, as consisting in the perfect 

 mobility of its particles among one another. If abstraction be made 

 of the force of gravity, or other accelerating force, when a conti- 

 nuous fluid is at rest, and consequently in a state of equilibrium, 

 all its particles are equally pressed in every direction, are equally 

 distant from one another, and are similarly arranged about every in- 

 terior point. No fluid is absolutely incompressible; but the degree 

 of compressibility may be conceived to be so small as not to affect the 

 results ; and it is accordingly disregarded in the investigations which 

 occupy the present paper. 



These investigations are built on the assumption that the hydro- 

 static pressure at every point of the fluid is the same function of 

 the three rectangular co ordinates of the point drawn to three planes 

 intersecting one another at right angles. The author shows that the 

 algebraical expressions of the accelerating forces producing the pres- 

 sure are not entirely arbitrary • because they must necessarily be 

 equal to the partial differential co-efficients of a function of three in- 

 dependent variables, and therefore they are likewise the same func- 



