78 



THE WHITE PINE. 

 Average strength of the wood of White Pine of different treet at IS per cent moisture. 



o Insufficient data for a fair average. 



In the above table the data for trees 101 to 116 are insufficient. Both material and tests for 

 trees 001 to 609 -were satisfactory in every respect, and the results, therefore, of far greater value 

 than those for trees 101 to 116. 



In keeping with its greater weight, the wood of the butt logs is slightly stronger than that of 

 the top logs, and there is generally a regular difference between different parts of the same cross 

 section, the center, as appears usual in pine, beiug the weakest, the heavier intermediate portion 

 the strongest, and the peripheral part lying between the two. 



For a more careful study of this relation, tests were made of a set of 2 by 2 inch sticks cut out 

 of one log from each of three trees, in such a manner that the centers of the logs formed one set, 

 the part midway from center to bark another set, and the outer portion of the logs a third or outer 

 set, the latter two being all quarter-sawed pieces. The tests furnished the following average 

 results : 



Strength of 2 J>y 2 pieces at 12 per cent moisture. 



It is apparent from the above that the perfect quarter-sawed material confirmed the other 

 test results in showing the great similarity of the wood of these three trees. It also shows, how- 

 ever, that the effect of defects in an unselected lot reduces the strength values markedly in this 

 species. 



Arranging the results according to the position of the test pieces in the log, it is found that in 

 compression endwise the strength was: Center pieces, 5,o20 pounds, or 78 per cent; intermediate, 

 7,000 pounds, or 100 per cent; outside pieces, C,6SO pounds, or 95 per cent; showing that the 

 heart pieces, as has been found in other conifers, are always the weakest, thus verifying the results 

 of the general series. The slight decrease from the intermediate to the outside pieces is in keeping 

 with the smaller weight of the latter and need not be ascribed to the fact that these pieces con- 

 tained small proportions of sapwood. As might be expected, the uniformity of results in this 

 properly selected and prepared material was greater than in the ordinary series. Of 58 tests, all 

 fell within '2~> per cent of the average strength and 76 per cent within 10 per cent of the average. 



In connection with a general study into the maximum uniformity of wood, three scantlings of 

 White Pine, with an average specific gravity of about 0.34 and an average compressive strength 

 at 8 per cent moisture of 4,900 pounds, were examined, two being tested air-dry (8 per cent) and 





