JACK PIKE. 23 



s/asoning unless care is exercised. It is more resinous than white 

 pine, hut less so than the yellow pines of the South. The heartwood 

 is fairly durable in contact with the ground, but the sapwood rots 

 quickly. 



A comparison of the mechanical properties of jack pine and other 

 species is shown in full in Bulletin 556, United States Department of 

 Agriculture.' That bulletin gives the results of tests which show 

 lower average values for jack pine than for Noi-way pine in cross 

 bending, stiffness, and work to the maximum load perpendicular to 

 the grain, and higher values in compression parallel and perpendic- 

 ular to the grain, in hardness, and in shearing strength. The differ- 

 ences, however, are not great. As compared with white pine, jack 

 pine shows somewhat higher average values in all the above proper- 

 ties except in stiffness and in cross bending, in which white pine 

 averages slightly higher. 



The specific gravity of oven-dry jack pine wood, based on volume 

 when green, is 0.39, which is intermediate between Norway at 0.44 

 and white pine at 0.36. The weight of a cubic foot of au'-dried wood 

 of jack pine is 29 pounds, that of Norway is 34, and that of white 

 pine is 27 pounds. 



The structure of jack pine wood, in gross and microscopic charac- 

 teristics, is not conspicuously different from that of other hard pines. 



UTILIZATION. 



Jack pine is used for railway ties, lumber, slack cooperage, pulp- 

 wood, mine timbers, poles, fencing, and fuel. (See Pis. XI and 

 XII.) 



RAILWAY TIES. 



The greatest consumption of jack pine for railroad ties is in Canada, 

 where in 1911 jack pine ^ replaced cedar as the leading species used, 

 and 5 J million jack pine ties (38 per cent of aU ties purchased) were 

 bought by consumers at an average price of 41 cents. In 1914, 

 8,379,064 jack pine ties, comprising 43.2 per cent of aU ties bought, 

 were purchased in Canada at an average price of 43 cents. In the 

 Lake States jack pine is used much less for ties than for lumber. 



Ties can not be produced from trees under 10 inches in diameter 

 breast high. Therefore, the proportion of the total stand of jack 

 pine from which ties can be cut is relatively small and only the older 

 trees can be used. Table 28 (appendix) indicates the number of ties 

 it is possible to cut from trees of different sizes, and Table 9 shows the 

 number of trees 10 inches and over in diameter in fuUy stocked stands 

 of different ages. 



1 " Mechanical Properties of Woods Grown in the United States," by J. A. Kewlin and Thomas R. C. 

 Wilson, of the Forest Products Laboratory. 

 2 Including somelodgepole pine [P. contorta) from Alberta and British Columbia. 



