948 



AMERICAN FORESTRY 



War Department with the General Staff, the Bureau of 

 Aircraft Production, Ordnance Department, Quarter- 

 master General, Surgeon General, Engineer Corps, and 

 Panama Canal ; in the Navy Department with the Bureaus 

 of Construction and Repair, Steam Engineering, Yards 

 and Docks, and Supplies and Purchase; with the Ship- 

 ping Board, Fleet Corporation, Fuel Administration, 

 Director General of Railroads, Advisory Commission of 

 Aeronautics, War Industries Board, War Trade Board, 

 with several of our Allies, and with large numbers of 

 war manufacturers. 



Advice and assistance were rendered members of these 

 organizations on foreign and domestic timber resources, 

 their location, quality, production, and means of increas- 

 ing production, on manufacturing processes, on the 

 strength properties of wood and physical and chemical 

 properties, the best substitutes, methods of drying, storing, 

 finishing, and 

 preserving 

 woods, prepa- 

 ration and re- 

 view of speci- 

 fi c a t i ons, in- 

 s p e c t ion and 

 the training of 

 men, and final- 

 ly, on various 

 economic ques- 

 t i o n s relating 

 to the wood- 

 producing and 

 wood-using in- 

 dustries. The 

 activities of the 

 organization in 

 ad d i t ion in- 

 cluded what- 

 ever field and 

 laboratory in- 

 v e s t i g ations 

 were necessary 

 to secure basic 

 information. 



Many things 

 have been given 

 the credit for winning the war food, ships, money, and 

 occasionally even fighting men and guns. No one ques- 

 tions the place of the airplane. The field was so new, the 

 requirements so exacting, and ?o much was needed that 

 the Forest Service centered its research largely on air- 

 plane problems. For the airplane the question of artificial 

 drying of wood loomed early as one of first importance. 

 Three-inch green spruce dries in the air in from one to 

 two years. During our neutrality our Allies-to-be prac- 

 tically exhausted the reserve stock of dry Sitka spruce. 

 Airplane authorities insisted that only air-dried stock was 

 acceptable. The pressure of the Kaiser's armies, how- 

 ever, required some other answer. Forest Service kiln- 

 drying specifications reduced the required period by 



CROSS GRAIN OR STRAIGHT? 



Straight to any but the closest ocular inspection but shown to be worthless for _ 



the splitting test, the surest method of detecting cross grain in Sitka spruce. This apparently perfect 



piece of spruce would probably have broken in the air during the first maneuver. 



twelve times, from years to an equal number of months, 

 and the supply of dry spruce lost its sinister place as the 

 controlling factor in airplane construction. These speci- 

 fications were based on several years' investigative work 

 mainly on other woods and for other purposes, and they 

 have since been checked intensively. Theoretically, 

 properly kiln-dried material should be better than air- 

 dried material for the simple reason that it is possible 

 in properly regulated kilns to maintain optimum con- 

 ditions throughout the entire period of seasoning, where- 

 as air-drying permits limited regulation only. If prac- 

 tice sustains theory, the result becomes one of first im- 

 portance. The advantage in strength and toughness per 

 unit of weight of spruce over its best substitutes is sur- 

 prisingly small ; but such as it was England crossed an 

 ocean and a continent to secure her critically-needed 

 supply, and the United States organized for its exploita- 

 tion a body of 

 men which in 

 former wars 

 would have 

 been a large 

 army. The 

 work of the 

 past year and a 

 half has dem- 

 onstrated that 

 properly < kiln- 

 dried spruce is 

 in fact strong- 

 er than that 

 dried in the air 

 even under the 

 best conditions. 

 Vehicle mak- 

 ers in the Unit- 

 ed States be- 

 fore the war 

 depended to a 

 very large ex- 

 tent upon air- 

 dried material. 

 S p e cifications 

 for escort wag- 

 ons called for 

 stock which did not conform to the standard sizes. The 

 accumulated air-dried material on hand was available, 

 therefore, only in small part, and it was necessary to go 

 back to the sawmill to secure what was needed. Oak in 

 large sizes for vehicle manufacture seasons naturally in 

 two or three years. Dry material had to be secured in 

 weeks. The kiln was again the only solution. The indus- 

 try, however, did not have enough kilns, did not know 

 proper methods of drying, and did not have trained 

 operators. Losses from poor kilns or even good kilns 

 inefficiently operated reached from 10 to 50 and even 

 100 per cent. The Rock Island Arsenal Record of 

 December 26 shows what can be done by suitable kilns 

 operated by competent men. Spokes for 56" artillery 



airplane construction by 



