454 Proceedings of FhihsopMcal Societies. [Dec. 



the Scorching Effects of the Sun's Rays." The author began by 

 stating some observations which had induced him to form the 

 opinion that the scorching effects of the sun's rays are produced 

 not merely in virtue of their heating power, but by the joint 

 agency of their heat and hght. To verify this opinion, he made 

 several experiments which showed that the face and hands may 

 be exposed to a temperature of 100°, or even 120°, without paiu 

 being produced, provided the light be excluded ; but that if the 

 same, or even an inferior degree of heat be produced by the 

 direct rays of the sun, the parts are scorched, and blisters are 

 produced. This effect he found to be completely prevented by 

 covering the hand or face with black kerseymere, and the same 

 purpose is attained by the black rete mucosum of the negro. In 

 those cases when a black covering was superimposed, perspira- 

 tion came on, and the same takes place on the skin of the negro 

 when exposed to the direct rays of the sun. 



The author observed also that the eyes of those animals ex- 

 posed to the strong light of the sun are furnished with a black 

 pigment apparently for the same purpose ; while others, which are 

 abroad by night, and consequently not needing such a protec- 

 tion, are not provided with it. 



Nov. 16. — A paper, by Sir H. Davy, was read, entitled, " On 

 the Magnetic Effects produced by Electricity." 



On repeating Oersted's experiments, the author stated that 

 with a voltaic battery of 100 four-inch plates, the south pole of 

 a magnetic needle placed under the communicating wire of pla- 

 tinum, the positive end of the apparatus being on the right, was 

 strongly attracted by the wire, which was shown to be itself 

 magnetic by its power of attracting steel filings. The wire also 

 was found to communicate permanent magnetism to steel bars 

 attached to it transversely, while such bars placed parallel to 

 the wire were only magnetic during their connexion with tlie- 

 apparatus. 



Actual contact, however, of the steel wires with the platinum 

 or other metal forming the conductor was found not to be neces- 

 sary ; for magnetism was imparted to a needle placed trans- 

 versely to the connecting metal, but at some distance from it. 



Sir H. n^xt related some experiments, showing that the mag- 

 netic power is proportionate to the quantity of electricity 

 passing through a given space without any relation to the trans- 

 mitting metal, and that the finer the wires the stronger the 

 magnetic e§ect. 



The author found that an analogous effect was produced by 

 the discharge of a Leyden phial through a wire; and by passing 

 the discharge of a Leyden battery of 17 square feet through a 

 silver wire ivith a steel bar transversely attached to it, of two 

 inches in length, the latter became powerfully and permanently 

 magnetic. The same effect was produced at a distance of five 

 inches through air, water, and even through thick plates of glass. 



