394 ANNUAL REPORT 



of wood from different species of trees of the same size; strike 

 each with a hammer, and we hear different sounds. If we could 

 have an adjustment delicate enough, the same phenomenon 

 would be observable in the same sized blocks clipped from trees 

 of the same species and the same variety, proving no two things 

 are alike in all respects. If we ask for the cause of this, we shall 

 have to content ourselves with the fact, that by some mysterious, 

 molecular structure, some bodies are more sonorous than others, 

 and keyed unlike. So it is relative to the ether-conveyance of 

 heat and cold waves. Some bodies are good radiators, and some 

 are bad radiators; that is, some are so constituted and keyed as 

 to communicate their motion freely with strong undulations of 

 the ether that conveys such motion, while other bodies do not 

 so powerfully communicate their wave-action. With a sun-glass 

 focalize a solar beam in the air, not a particle of heat is sensibly 

 evolved; put your hand in the focus, it may draw a blister; put 

 wood in there and it bursts into a flame. Transparent bodies 

 like pure air, or colorless glass, or ice,, or snow, are incompetent 

 to absorb luminous rays. A purely luminous beam cannot harm 

 a single sj)ecula of an ice crystal. It is not the ''shine" but a 

 body of dark rs(^s emitted by the sun, that melts the snows and 

 the glaciers, and quickens slumbering forces into organic form. 



As the atmosphere is a poor absorber and radiator of heat, and 

 the ground a good one in this respect, the inference to be drawn 

 from these phenomena, is, that protection to the roots of a plant 

 is of more vital consequence than protection to its stem, as we 

 have experimentally learned. A black body, like our prairie 

 soil, absorbs and radiates heat more powerfully than a lighter 

 colored soil. This scientific fact suggests that the frequent loss 

 of our small fruit plants, such as raspberries and blackberries, 

 dirt-covered for the winter in our prairie country, is due, largely, 

 to the great heat-absorbing and radiating qualities of our black, 

 sticky soil, and that a lighter colored covering or mulching, 

 snow especially, or even sand, such as the Russians apply to 

 their orchards, or old, broken straw is more protective. We 

 have learned by a losing trial, that black tarred paper tied 

 round our fruit trees for the winter, kills more trees than rabbits 

 can; that white envelopes, such as newspapers, are safe every 

 way. The difference is owing, doubtless, to the law in question. 



Let us apply these simple discoveries relative to the wave ac- 

 tion of things. Here is a clump of apple trees, apparently of 

 the same degree of hardiness, healthful conditions beitig the 



