1918] 
ZELLER—STRENGTH AND DURABILITY OF PINE 113 
of specifie gravity or high percentage of summer wood, 
factors which function in the strength of the pieces. 
TABLE I 
STRENGTH AND DURABILITY OF SOUTHERN PINE HEART-WOOD 
" Strength tests 
agin Small Full-size Small 
CAM loss in blocks (wet) blocks (wet) blocks (dry) 
sember ка Strength Strength Strength 
о ЕЁ їп Рег сепї їп їп 
wood Чие | pounds | moisture | pounds 5520 pounds d Si 
to decay |per square per square per square 
inch inch inch 
Shortleaf pine (Pinus echinata) 
46 3.13 3375 58.1 3050 0.7 6052 0.8 
47 7.24 3207 63.8 2840 47.8 5080 ).8 
48 2.85 4055 61.9 3655 47.4 5765 б 
49 9.00 3380 47.5 3065 46.3 5962 0.4 
50 992 3432 55.9 3550 93:9 6447 9 
51 14 3332 40.1 3185 59.] 5605 1 
52 24 3822 50.0 3770 45.4 7211 0.2 
53 88 3812 50.7 3410 50; 6142 3 
54 12.02 2705 82.3 2440 43.6 3957 Хы, 
55 201 3692 67.5 3599 53.8 6160 4.0 
56 6.29 2902 79.9 2790 54.0 5202 ZR 
57 3.07 3795 56.9 3910 43.6 5817 3.8 
Longleaf pine (Pinus palustris) 
58 ELI 5130 25.2 5220 29:9 8032 259 
59 3.19 4255 50.7 4290 41.3 7312 5. 
60 5:12 5340 26.0 5270 24.0 8812 0.6 
61 5712 4342 65.6 3990 58.4 7012 4.5 
62 4.26 4240 67.1 4180 53.9 7817 5 
63 3.06 5695 42.0 5540 40.2 8272 4.0 
64 4.37 3720 TESTI 3570 47.3 6635 
65 6.76 3795 60.0 3690 56.1 6450 3 
66 1-43 3790 81.6 4020 64.6 6467 f 
67 3.50 4257 44.1 4130 39.6 7485 ) 
68 3.87 3897 43.4 3890 45.7 6897 0.3 
69 5.03 3962 42.4 3910 46.1 7147 11.3 
RESULTS AND CONCLUSIONS 
The curves in figs. 1, 2, and 3 graphically represent the 
results presented in table т. Figure 1 shows the relation be- 
tween strength and durability of pine heart-wood when the 
strength tests were made on ljxl1i-nch water-saturated 
blocks. Figures 2 and 3 show the same relation when 4X4- 
inch water-saturated blocks and lix1ji-ineh air-dry blocks, 
respectively, were tested for strength. The three strongest 
samples, 63, 60, and 58, show considerable loss in weight, 
which is not totally due to decay. They were highly resinous, 
