466 Proceedings of Learned Societies. 



The recent experiments of Foucault with the turning mirror, and 

 the parallax observations of the planet Mars which have been made 

 during the past three months in both 1ST. and S. hemispheres, were 

 alluded to, as bearing upon the distance of the sun, which is the 

 basis of all measures of the heavens. 



i^l The smaller velocity of light deduced by Foucault, linked to the 

 sun's distance by its aberration, was shown to be supported by some 

 of M. le Yerrier's recent investigations, while the extreme doubtful- 

 ness of some of the most important observations of the transit of 

 Venus on 1769, on which the received distance of the sun depends, 

 renders the success of the observations of Mars doubly desirable. 

 And although the distance of Mars, and not of the sun, will, in the 

 first instance, be obtained by this method, they are boixnd together 

 by a proportion which has been accurately known since the days of 

 Copernicus and Tycho. 



Professor Selwyn communicated a note relative to an apparent 

 notch in the sun's limb, observed by him some little time ago. 

 From the note we learn that he now ascribes the appearance to the 

 low power employed, as the complete limb was observed on the 

 same day by the Rev. W. R. Dawes, in his larger instrument. 



Several other papers, among them a valuable one on eye-pieces, 

 by the distinguished observer we have just named, and on the 

 diameters of Mars, by the Rev. R. Main, were communicated to the 

 Society. 



The latter paper was accompanied by some drawings of Mars, 

 from observations made in the Oxford heliometer. Another series 

 of thirteen drawings, chosen from twenty-five made during the 

 past opposition of the planet, and embracing a complete rotation, 

 was exhibited by Mr. Lockyer. 



This latter series, the result of observations made by an equa- 

 toreally mounted refractor of Q\ inches aperture, the workmanship 

 of Messrs. Cooke and Sons, of York, was remarkable not only on 

 account of the details of the planet shown, but also of the exact 

 agreement of the broad features of the drawings with a similar 

 series taken by Beer and Madler, in 1830. 



CHEMICAL SOCIETY, December Uh. 



Recent Formation of Rocks.— A paper was read by Mr. A. H. 

 Church on " Certain Processes of Rock Formation now in Action." 

 The author's attention was directed in the summer of 1860 to an 

 instance, at Bude-Haven, in Cornwall, of the consolidation of sea- 

 sand by means of land-springs, and he endeavoured to trace the 

 chemical causes of the phenomenon. From numerous analyses of 

 the loose and of the consolidated sand, and also of the water of the 

 district, the author came to the conclusion that the cementing 

 action was often due to the reprecipitation, between the sandy 

 particles of carbonate of lime — this substance being originally de- 

 rived from the shelly debris of the sand itself, and being held in 

 temporary solution by carbonated water. The absence of marine 

 salts from the consolidated sand supports this hypothesis. Mr. 



