252 Forestry Quarterly. 



The Air-seasoning of Timber. By William H. Kempfer, U. S. 

 Forest Service. Reprint from Bulletin 161, American Railway 

 Engineering Association. 1913. Pp. 163-231. 



This valuable publication comprises the various data collected 

 by the Forest Service in regard to the air-seasoning of cross-ties' 

 and, to a less extent, of poles and sawed timbers. Much of this 

 has already been published in various circulars and bulletins, but 

 the present work brings all of it together in comparable form 

 and adds considerable data not previously made public. It is all 

 too evident, however, that much remains to be done before our 

 knowledge of this important subject is satisfactory. 



The cross-ties tested were procured at monthly intervals 

 throughout the year and each month's cut piled in different ways 

 so as to ascertain the effect of the form of pile on the rate of 

 seasoning. The piles of 50 ties each were exposed to the weather 

 without cover other than that afforded by the solid tier of ties on 

 top. The progress of the seasoning was determined by weighing 

 each tie at intervals usually of a month. The data from these 

 experiments is presented graphically in numerous curves. 



Seasoning experiments on western yellow pine, white fir, and 

 Douglas fir were conducted at Pecos and Rociata, New Mexico, 

 where the elevation is between 7,000 and 8,000 feet above sea 

 level. Ties cut in January and February required from 4 to 5 

 months to reach a constant moisture content ; those cut in May 

 and June only 2 months at Rociata and i month at Pecos ; those 

 cut in November and December, 6 months. There was not much 

 variation in the rate of seasoning of the different species. 



Lodgepole pine, Douglas fir, and western larch of the North- 

 west were tested. Lodgepole cut in Montana in May, June or 

 July was practically air-dry in 3 months, and even when cut in 

 September became fairly well seasoned before winter; but if 

 started in winter it required until the next July to become dry. 

 Larch in Idaho and Douglas fir in Idaho and Washington, when 

 cut in early spring, required from 4 to 5 months to season, while 

 if cut in July they lost almost as much moisture in the succeeding 

 2 or 3 months as they did by holding them until the following 

 summer. 



Local climate effects on seasoning were shown by tests at 

 Tacoma in the western and at Pasco in the eastern part of Wash- 



