APPENDIX. 207 



arc, and to diminish the time of a given number of vibrations. 

 The influence of the sun's rays on a magnet oscillating in a 

 void, is to increase the time of a given number of vibrations ; 

 whilst the arc, if the retardation of the rate of vibration be 

 small, is not materially affected." Nearly the same pheno- 

 mena occur when bars of copper are vibrated in like manner. 



MELLONI. " Observations et Experiences relatives a la theorie 

 et a 1'identite des agents qui produisent la lumiere et la cha- 

 leur rayonnante," in Journ. des So. PJiys. de M. Julia de Fon- 

 tanelle, t. iv. p. 161. (1836.) In this remarkable paper, which 

 was, I think, presented to the Academy of Sciences of Paris, 

 the author, after proving that radiant light and heat have two 

 distinct causes, or are two distinct effects of one cause, endea- 

 vours to separate light completely from heat. His experiments 

 succeeded admirably. Absorbing all the heat either of the 

 solar rays or an artificial fire, by making the rays pass through 

 a system of diaphanous bodies, such as water or blue glass, he 

 succeeded in obtaining pure light. " This pure light" says 

 Melloni, " emerging from this system, contains much yellow, 

 and possesses moreover a bluish-green tint. It has no action 

 whatever on the most delicate thermometer, even when con- 

 densed by a lens until it is as brilliant as the direct rays of the 

 sun." This pure light has therefore all the properties hitherto 

 recognized in ordinary phosphoric light, such as that of the 

 glowworm, the Bologna-stone, etc. 



SUEIEAY. " Kecherches sur la cause ordinaire de la Phosphores- 

 cence Marine." Mag. de Zoologie de Guerin, 1836. 



BECQUEEEL (Ed.). On Phosphorescence after Insolation ; many 

 papers in Ann. de CJiim. Paris. Compare also MOEEEN, in 

 Convptes-Rendus, 1861 and 1862, on the Phosphorescence of 

 Gases. 



BECQUEEEL (Pere). Traite d'Electricite, t. vi. 



MOIGNO. Repert. d'Optique Moderne. (Paris, 1842.) 



These two authors have quoted several facts relating to Phos- 

 phorescence in their large works. 



AEAGO. " Notice sur le Tonnerre," etc., in his (Euvres Completes. 



