SCIENTIFIC MEMOIRS. 
VOL. I.—PART I. 
ArTIcuE I. 
Memoir on the Free Transmission of Radiant Heat through 
different Solid and Liquid Bodies ; presented to the Royal 
Academy of Sciences of Paris, on the 4th of February, 1833, 
by M. MEttont. 
From the Annales de Chimie et de Physique, t. u111. p. 1. 
Maniorre was the first, so far as I am aware, who attempted to 
appretiate the action of diaphanous substances in transmitting or inter- 
cepting the calorific rays which emanate from terrestrial sources. After 
having observed that solar heat concentrated at the focus of a metallic 
mirror, suffered no sensible diminution of intensity by being made to 
pass through a glass plate, he took and placed his apparatus before the fire 
of a stove, and found, that at the distance of five or six feet the tempe- 
rature of the reflected image at the focus, when the rays were allowed to 
meet there without impediment, was such as the hand could not bear ; 
but that when the plate of glass was interposed there was no longer 
any sensible heat, although the image had lost none of its brilliancy. 
Whence he concluded that none *, or certainly but a very small portion, 
of the heat of terrestrial fire passes through glass. 
About a century after Mariotte’s time, the same experiment was re- 
peated by Scheele, who, instead of imitating the cautious reserve of his 
predecessor, asserted that from the moment when the glass was inter- 
posed there was no longer any heat whatever at the focus of the mirror +. 
* Mariotte, Traité de la Nature des Couleurs; Paris, 1686, part 2, at the 
end of the Introduction. 
¢ Scheele, Traité del Air et du Feu ; Paris, 1781, § 56.—The original work 
of Scheele was published in 1777. Mariotte died in 1684. 
Vou. I— Parr 1. B 
