KILN-DRYING HARD WOOD. 379 



stock of the same thickness, if sawed and piled during the months 

 of extremely hot weather, would have to be carried over until the 

 approach of another summer, the effect of the season of extremely 

 damp atmosphere seeming to be to liberate the internal moisture, 

 which somehow appeared to be imprisoned by some (at that time) 

 unknown force, and which, being so liberated, was rapidly car- 

 ried off by the cool, dry days of the following spring. 



It had probably always been known that lumber would dry, 

 and did dry, most rapidly during the season of high winds, but 

 the fact had been generally accepted without asking for a scientific 

 reason. But when it dawned upon the minds of the experimenters 

 that there must be one, it led to the further discovery that air in 

 motion of a low temperature would produce better results than air 

 of a high temperature if kept stagnant, and that the ordinary 

 atmosphere, with its natural temperature, if above the freezing 

 point and with a low degree of humidity, if kept in constant mo- 

 tion or circulation, would dry lumber well and rapidly without 

 the aid of artificial heat. 



These points once definitely settled and understood, led to re- 

 searches that immediately led into the domain of wood chemistry 

 and physiology, and the experimenters and inventors became to a 

 degree chemists and physicists. Thus a special education was ob- 

 tained before they were able to say they had solved the problem 

 of drying lumber artificially ; fairly accurate knowledge on the 

 following points being gained : 



1. (a) Different varieties of wood, and (b) wood of the same 

 variety grown in different localities, requiring radically different 

 treatment. 



2. (a) That too high a degree of heat applied at any stage, and 

 (6) especially during the first, injured the lumber more or less, 

 according to kind, and retarded or prevented perfect drying. 



3. That with a perfect circulation of air of a low degree of hu- 

 midity, a high temperature was not necessary to produce good 

 results except as to time. 



4. That the results, good or bad, depended very largely upon 

 the chemical changes produced by heat upon the natural gums 

 and juices of the wood. 



5. That all these points became much more pronounced in the 

 case of hard woods, and hence the necessity for special machinery 

 and arrangement of the kiln. 



THE calculation of the orbits of the newer asteroids has been greatly facili- 

 tated at Nice and Bordeaux, France, by astronomical photography, which makes 

 it possible to follow them long enough to give a sufficient number of observations 

 on which to base the computations. 



