8 - BULLETIN 676, U. S.. DEPARTMENT OF AGRICULTURE. 
the equation values and another “species-locality” fall far below 
them. 
In figure 5 are plotted the curves of the equation for modulus of 
rupture in static bending in green material, M=18500 4/g°, and of 
the equation for the same property in air-dry material, M=26200 4/¢°. 
In order to give a graphical idea as to the reliability of these 
equations, the specific gravity and the modulus of rupture of each 
“‘species-locality”’ have been plotted asa point. The reference num- 
ber placed near each plotted point is assigned to the ‘‘species-locality”’ 
in the order of its respective specfic gravity as determined from 
compression parallel to grain specimens of green wood. In figures 
6, 7, and 8 the data are given for the curves on shrinkage in volume 
from green to oven- dry condition, maximum crushing strength in 
compression parallel to grain, and fiber strength at elastic limit in 
compression perpendicular to grain. 
Under each property is listed in this second portion of Table 1, for 
both green and air-dry conditions, those percentages of the equation 
value above which were one-tenth of the ‘‘species-localities.”’ Simi- 
larly, there are listed those percentages above which were one-fourth 
of the ‘‘species-localities,’’ those below which were one-fourth, and 
those below which were one-tenth. For instance, in static bending 
(green), one-tenth of the “‘species-localities”’ tested had a modulus of 
rupture of more than 114 per cent of what the specific gravity equation 
indicated they should have had; one-fourth of them had a modulus of 
rupture greater than 108 per cent of the equation value; one-fourth 
of them less than 91 per cent of the equation value; and the lowest 
one-tenth had a modulus of rupture less than 84 per cent of what-the 
equation indicated they should have had. It follows from these 
figures that one-half of the ‘“species-localities” had a modulus of 
rupture of between 91 per cent and 108 per cent of the value given by 
the equation, and that the other one-half were evenly divided between 
those that were more than 108 per cent and those that were less than 
91 per cent. 
The third portion of Table 1 gives the actual value of each property 
for each ‘‘species-locality”’ as determined by the tests, expressed as a 
percentage of the value computed from the specific gravity by the 
use of the equation at the head of the column. For instance, it is 
found from the table that air-dry Biltmore ash has a models of 
rupture 98 per cent as great as that of the average wood of its specific . 
eravity, the modulus of rupture of the average wood of this specific 
gravity being the figure given by the equation. These percents are 
given for for green and air-dry wood. 
