236 



against, he proceeds to describe his apparatus, which consisted of two 

 thermometers, A and B, of large and nearly equal bulbs graduated to 

 quarters of centigrade degrees, one whitened with a wash of chalk 

 and water, the other blackened with Indian ink. In other experi- 

 ments a differential thermometer was used, one ball being only ex- 

 posed to the heating influence under various coatings, and the other 

 carefully screened, so as to reduce the effect as much as possible to 

 that on a mere air thermometer. 



A variety of experiments on the heating effects of various flames, 

 incandescent metals, &c., on these thermometers so prepared, and 

 both screened and unscreened with glass plates, are then detailed ; 

 and the author then draws his general conclusions, which may be thus 

 stated. 



1 . That the heat radiated from all luminous hot bodies is divided 

 or analysed by a glass screen into two portions, one of which is 

 stopped by the screen, and employed in increasing its temperature, 

 and the other passes through it without raising its temperature. 



2. That besides this difference in the nature of the two portions of 

 the total radiation, they differ in their capabilities of being absorbed 

 by the surfaces of bodies. That portion which passes freely through 

 glass being absorbed much more readily by blackened surfaces, while 

 the other, or non-transmissible portion, is nearly equally well ab- 

 sorbed by black and white surfaces. The texture of surfaces, rather 

 than their colour, he supposes to exercise the chief influence in de- 

 termining the absorption of this latter portion, though this last-men- 

 tioned opinion is, perhaps, rather adopted in conformity with the 

 language of others, than in consequence of any experiments detailed 

 in the present paper. 



On the Anatomy of the Mole-cricket. By J. Kidd, M.D. and F.R.S. 

 Reg. Prof, of Medicine in the University of Oxford. Read Febru- 

 ary 3 and February 10, 1825. [Phil. Trans. 1825, p. 203.] 



The insect described in this paper is common in certain peat bogs 

 a few miles west of Oxford, and is found within 18 inches of the 

 surface. Like the mole, its limbs are particularly calculated for bur- 

 rowing; and to prevent the necessity of its excavating a passage large 

 enough to admit of its turning round, it has the power of moving as 

 easily in a retrograde as in a progressive direction. Its colour closely 

 resembles that of the mould in which it lives ; and in common with 

 many other insects, it has the power of assuming a lifeless appearance 

 when suddenly disturbed. Having kept some of them in glass ves- 

 sels for several weeks, the author remarked that they preferred the 

 potatoe to other vegetable food, but that they attacked raw meat with 

 especial greediness, and upon emergency attacked each other, in which 

 case the victor soon devoured the fleshy and soft parts of the van- 

 quished. But although they are very voracious, they are equally 

 remarkable for their power of abstaining from food, and have been 



