Chemistry and Physics. 423 
the apartment in which the lamp is burning and thus aid in the general 
illumination of the room. The meaning which Mr. King attaches to the 
term is however so perfectly evident that I have not hesitated to follow 
him in using it. For that matter, there can be no doubt but that the 
numbers given by us express as accurately as the circumstances of the 
case will admit, the actual diminution of the amount of light, falling for 
example upon the pages of a book held near to its source, which woul 
be occasioned by the interposition of the shades enumerated in our tables. 
Boston, April 20, 1860. 
[We cannot doubt that the great loss of light proved by the experiments 
above given, is to be, in part at least, accounted for by the conversion of a 
portion of the light into heat—an effect perfectly in harmony with the the- 
ory of transverse vibrations as applied to explain the phenomena of polari- 
zation of heat. On this theory, heat and light are different effects produced 
by one and the same cause, and they differ physically only in the rapid- 
Pe 
parency of the air as 4575 times greater than that of sea-water, and 
: publié 
* Traité tigae sur la Gradation de la Lumiere (ouvrage posthume) : pu 
par Mi fase Bs Canis Paris, 1760, 4to, pp. 368. 
