B BULLETIN 2*72, U. S. DEPARTMENT OE AGRICULTURE. 



Table 3. — Average strength values of green cypress in compression endwise and in bending 

 for pieces of different weight. 1 



Wood (air-dry). 



Compression 



parallel to 



grain (crushing 



strength at 



maximum 



load, per 



square inch). 



Bending. 



Specific 

 gravity. 



Weight per 

 cubic foot. 



Fiber 

 stress at 



elastic 

 limit per 



square 



inch. 



Modulus of 

 rupture per 



square 



inch. 



0.58 

 .54 

 .50 



.44 

 .41 

 .37 

 .35 



Pounds. 

 36.2 

 33.7 

 31.2 

 27.5 

 25.6 

 23.1 

 21.9 



Pounds. 

 6,500 

 4,800 

 4,700 

 4,200 

 3,800 

 3,200 

 2,900 



Pounds. 

 6,S00 

 5,600 

 5,000 



Pounds. 

 7,800 

 7,100 

 6,300 



4,500 

 3,800 

 3,600 



5,800 

 5,100 

 5,000 



1 Forest Service Circular 19. Strength tests on cypress have not yet been made at the Forest Products 

 Laboratory in connection with the series for commercial woods of the United States, and the figures given 

 in Tables 3 and 4 can not be compared with those for other kinds of wood so far obtained in the latter series, 

 since conditions of test were different. 



In the above tests the varying strength values of green cypress are 

 shown to be correlated pretty closely with the varying weights and 

 densities of the wood. Trees on adjacent but dissimilar sites are 

 known to produce wood differing markedly in strength. The first 

 test was with a small cypress over four centuries old, grown in a 

 "pond" in South Carolina, which proved to be the heaviest and like- 

 wise the strongest and stiffest timber tested. 



Similar tests made with air-dry wood (12 per cent moisture) from 

 16 cypress trees selected from various portions of the range show, in 

 Table 3, the variation in strength values and their general correlation 

 with weight. 



Table 4. — Average strength values of air-dry {12 per cent moisture) cypress. 1 



Wood (air-dry). 



Average strength in pounds per square inch. 



Specific 

 gravity. 



Weight per 

 cubic foot. 



Compres- 

 sion par- 

 allel to 

 grain 

 (crashing 

 strength at 



elastic 



limit, per 



square 



inch) . 



Bending. 



Fiber 

 stress at 



elastic 

 limit per 



square 



inch. 



Modulus of 



rupture 



per square 



inch. 



Modulus of 



elasticity 



per square 



inch. 



0.58 



.55 

 .52 

 .51 

 .50 

 .49 

 .48 

 .47 

 .46 

 .45 

 .44 

 .43 

 .42 

 .39 

 .37 

 .35 



Pounds. 

 36.2 

 34.4 

 32.5 

 31.9 

 31.2 

 30.6 

 30.0 

 29.4 

 28.8 

 28.1 

 27.5 

 26.9 

 26.2 

 24.4 

 23.1 

 21.9 



Pounds. 

 7,860 

 6,510 

 7,290 

 6,270 

 6,100 

 7,660 

 7,170 

 6,890 

 7,740 

 6,070 

 6,760 

 5,470 

 5,520 

 5,200 

 4,770 

 6,070 



Pounds. 

 9,000 

 6,920 

 8,730 

 6,490 

 6,470 

 8,380 

 7,770 

 7,230 

 7,670 

 6,550 

 7,710 

 5,000 

 . 5,990 

 4,900 

 5,120 

 6,550 



Pounds. 

 8,480 

 8,120 



11,350 

 7,540 

 8,160 

 9,710 

 9,350 

 8,880 



10, 370 

 8,180 

 8,900 

 6,240 

 7,030 

 5,750 

 6,210 

 6,250 



1,000 lbs. 



1,774 



1,355 



1,734 



1,173 



1,173 



1,786 



1,275 



1,163 



1,768 



1,406 



1,660 



892 



1,075 



841 



996 



925 



1 Forest Service Circular 19. 



