NATURAL HISTORY. 
395 
conducting the electric fluid, I cannot for a moment entertain, when 
I consider the simple fact, that silk, wool, and feathers, are all non¬ 
conductors, and yet become dewed as readily as plants. 
G. I. T. is no doubt fully aware, that it is possible for the surface 
of the earth to become colder than the surrounding air; for owing to 
the transparency of the atmosphere to the rays of heat, those rays 
which are given off by the earth are not again radiated to it by the 
surrounding air, but are lost in space ; and thus it is that the tempera¬ 
ture of the surface is lowered. 
By your Correspondent’s leave, I beg to make a remark or two on 
the arguments by which this theory is supported. And first, the sur¬ 
face of the ground is thought to be changed by some secret agency, 
in one case it is the attraction, and as the source of heat is etherial 
fire” (which I suppose is but another name for caloric)” that fire is 
first attracted by the points of vegetable bodies.” Now I suspect the 
most likely circumstance to attend this absorbtion of heat by any 
body would surely be, that the temperature of the absorbing body 
would be raised; yet in direct contradiction to this, we are told that the 
surface of the earth becomes colder! Also the abstraction of heat, 
when the clouds are suppossed to be the attracting bodies, causes an 
elevation in the temperature of the earth’s surface ! 
I should notice but one more of the arguments produced in support 
of this theory ; I allude to that part where the fact of metals not be¬ 
coming dewed is advanced in proof of this theory, when in truth they 
always appeared to me to furnish a most convincing proof of the 
correctness of the theory of Dr. Wells. We read in page 299, of 
plants “not being endued with the power of radiating or conducting 
heat in a degree by any means equal to that of metals, substances, 
which, it is said, do not become dewed at a time and under circum¬ 
stances wherein the circumjacent herbage is covered with minute 
drops of water,—a fact which is not only very remarkable in itself, 
but one which affords convincing proof that plants do not become 
dewed solely bv their power of radiating heat.” Here plants are said 
not to possess the power of radiating or conducting heat in an equal 
degree with metals; this to a person uninitiated would appear as though 
the powers of radiation and conduction were the same, when on the 
contrary they generally follow an inverse ratio. 
Also instead of metals being better radiators than plants, they are 
always considered to be the worst radiating bodies known ; and 
their not becoming dewed is, in my judgment, a fact no ways remark¬ 
able in itself but one which T should say affords convincing proof that 
plants do become dewed by their power of radiating heat. 
D d 3 
