SHELTER-BELTS. 55 
ond fallacy is that shelter-belts can effect climatic changes 
only through their power to send off an ‘exodium of 
warmth.’ While the writer of this article may have 
aimed at a very good thing, he has certainly missed the 
point as far as shelter-belts are concerned. 
“ Holding that forest-culture in Kansas can be made 
a success, and that it is necessary to the prosperous set- 
tlement of the state, we desire to prove that forest-cult- 
ure in the form of extended and carefully arranged 
shelter-belts must have efficient climatic influence. In 
proof of this let us state some of the simple laws which 
govern the radiation of heat and the motion of the at- 
mosphere. 
“LAWS OF HEAT. 
“1. Heat is radiated from all bodies and in all direc- 
tions, the angle of incidence and of reflection being equal. 
“9. Heat of high intensity passes almost unobstructed 
through some bodies, while thé same bodies are opaque 
to heat of a lower intensity ; thus the sun sends its in- 
tense heat through the glass into the green-house, while 
the plants cannot radiate that heat back again through 
the glass into the open air. This fact can be illustrated 
by a heated ball and a plate of glass, showing the heat 
of low intensity is almost entirely retained by the glass. 
The vapor of water operates almost like the plate of 
glass, permitting the free passage of the heat from the 
sun, but checking very largely the radiation from the 
earth. Thus an atmosphere saturated with vapor will 
check radiation with seventy times the power of a dry 
atmosphere. 
“3, The point of saturation varies with the tempera- 
ture of the atmosphere. Then the cooler the atmosphere 
the drier it will be, and hence the more rapid the radia- 
tion of heat; or, the drier the atmosphere under any cir- 
cumstances, the more rapid the radiation of heat. It is 
calculated by Professor Tyndall that one tenth of the 
