464 Proceedings of Philosophical Societies . [June, 



they had descended : this penetrating foam acts on the lower 

 argillaceous strata, till the overhanging rock is undermined. 

 Lieut. Portlock remarks that there has been a gradual fall in the 

 level of the lakes at Canada. He also offers some considera- 

 tions on the proximity of the sources of several rivers which 

 flow in opposite directions. 



May 7. — A paper on the Geology of the Ponza Islands in 

 the Mediterranean, by G. P. Scrope, Esq., MGS. was read in 

 part. 



A letter was read from Thomas Borfield, Esq., MGS. accom- 

 panied by a collection of bones and horns of the Deer, and 

 bones of Man and other animals, found in a cleft of the rock at 

 a quarry at Hincks' Bay (near the Old Park iron-works) in the 

 parish of Dawley and county of Salop. Their adhesion when 

 applied to the tongue showed that the animal gelatine was 

 nearly gone, which does not take place till after a long period of 

 inhumation. 



METEOROLOGICAL SOCIETY. 



Feb. 11. — Dr. Burney communicated the results of a Meteo- 

 rological Journal, for January 1824, kept at his observatory at 

 Gosport, Hants. 



A note was read, on some curious effects of the Radiation of 

 Heat ; by Luke Howard, Esq. FRS. and M. Met. Soc. 



The reading was commenced of a " Memoir on the Varia- 

 tions of the Reflective, Refractive, -and Dispersive Powers of the 

 Atmosphere, &c. ; by T. Forster, MB. FLS. and M. Met. Soc." 



March 10. — The reading of Dr. Forster's memoir was con- 

 cluded. It relates to certain branches of the subject of 

 atmospheric refraction, belonging to the province of meteoro- 

 logy, which the author states to have been particularly neg- 

 lected : these are, the variation in the refractive, dispersive, and 

 reflective powers of the atmosphere, resulting from the diffu- 

 sion therein of different modifications of cloud, which are 

 themselves affected by local circumstances, and which vary 

 greatly at different times ; and the effects of that variation, on 

 the colour of the light transmitted by the planets and fixed 

 stars, and on the declination of the latter. After some general 

 remarks on reflection, refraction, and prismatic dispersion, the 

 author proceeds to consider the subjects just mentioned in three 

 sections. In the first, ' On the variation in the refractive 

 power of the atmosphere at different times of the night and day, 

 and on different occasions and seasons,' he ascribes that varia- 

 tion, principally, to the quantity and nature of the aqueous 

 vapour diffused in the air : and he supports this opinion by 

 various observations on the planets and stars, made at different 

 times and seasons. In observing the planets and brightest stars 

 through prismatic glasses, he found that the spectrum was less 

 oblongated, whilst the red colour was more distinctly apparent, 



