NOTES AND COMMENTS 1059 



upon which the Commission of Conservation has been engaged during 

 the past four years, has proved of great immediate value in this con- 

 nection, since the Commission was able to furnish the Imperial Muni- 

 tions Board with specific information as to the location and owner- 

 ship of all the large bodies of spruce in that province suitable for 

 airplane manufacture. The fact that this information had previously 

 been collected enabled the Munitions Board to take up without delay 

 the matter of securing the necessary supplies of this vitally important 

 material. 



Mr. H. R. MacMillen, former Chief of the British Columbia Forest 

 Service, is acting as the Pacific coast representative of the official cor- 

 poration of Canadian Aeroplanes, Limited, under the Imperial Mu- 

 nitions Board. 



Kiln Drying of Airplane Stock 



Most of the air-seasoned wood available in the United States having 

 been bought for airplanes for the Allies abroad, the procuring of 

 wood for this purpose is a problem, now that the United States has 

 entered the war, airplane manufacturers hesitating to use stock kiln- 

 dried under the methods ordinarily used, having frequently found it 

 unsatisfactory. 



Before this situation developed, however, the Forest Products Labo- 

 ratory at Madison, Wis., had been making a scientific study of the 

 drying of wood and had developed a method which has been very 

 successful, using for preliminary tests partially air-seasoned ash and 

 spruce plank, these being the woods most generally employed in air- 

 plane construction. 



This material was kiln-dried without injury. Thoroughly green 

 Sitka spruce, white ash (northern and southern), white oak, Douglas 

 fir, western white pine, and mahogany were secured in the log for 

 testing. The spruce and ash logs were cut up and the green material 

 from each species divided into three matched groups. One group of 

 each soecies was tested green, another has been set aside to be tested 

 when it has air-dried, and the third group was kiln-dried by several 

 methods and then tested. Only the results of the tests on the spruce 

 have so far been analyzed. Comparison with standard tests shows 

 that Sitka spruce can be kiln-dried from the green condition with no 

 more, perhaps less, injury to its mechanical properties than by air- 

 seasoning. Definite specifications have been prepared for kiln-drying 

 spruce green from the saw for airplane construction, and it is stated 



