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On the basis of the durability of the different woods, the same rail- 
way company divides them into two classes, ties which need to be treated 
and those which do not, with subclasses under each of these based on 
relative natural durability of the wood, as follows: 
Crass U. Tres wHicH MAY BE UsED UNTREATED 
Group Ua Group Ub ~ Group Uc Group Ud 
Black locust “Heart”’ pines “Heart” cedars Catalpa 
White oaks “Heart” Douglas fir “Heart’’ cypress Chestnut 
Black walnut Redwood Red mulberry 
Crass T. TIES WHICH SHOULD BE TREATED 
Group Ta Group Tb Group Tc Group Td 
Ashes “Sap” cedars Beech Elms 
Hickories “Sap’’ cypress Birches Soft maples 
Honey locust “Sap” Douglas fir Cherry Spruces 
Red oaks Hemlocks Hard maples Sycamore 
Larches Hackberry Butternut 
“Sap”’ pines Gums 
The board-foot contents of a cross-tie eight feet long (Chapman ’21) 
may be found by looking up the log scale for a log of that length and 
diameter inside the bark, just as if the log were being scaled. Or the 
cubic-foot contents of the tie may be calculated from the basal areas of 
the top and bottom, converting this into board feet by the use of a con- 
verting factor. For ordinary purposes we may consider that a cubic 
foot is equivalent to 5.5 board feet, since in sawing a log quite a large 
amount is lost in edgings and sawdust. Mill men estimate that a tie eight 
feet long with a 6-inch by 8-inch face (a No. 3 tie) scales about 32 board 
feet and that 30 of such ties will make 1000 board feet of lumber. Ties 
which are 8% feet long and have a 7 by 9-inch face (No. 5 tie) contain 
from 40 to 44 board feet each, or we may say that it takes from 23 to 25 
of them to make a thousand board feet of lumber. Switch ties are cut 
about twice the length of ordinary ties and consequently with this greater 
length would have a still greater content. 
Out of a total of 280,077 railroad ties purchased by one road in IIh- 
nois in 1921, we find that 155,940 came in class Ta, comprising such 
species as the ashes, hickories, honey locust, and red oaks. This shows that 
over half of the ties came from species that were not durable by nature, 
but were used because of the growing scarcity and high price of white oak 
and other durable species. It also shows the increasing value of many of 
our bottomland species which have until very recently been considered of 
little value for ties. The reason for this will be discussed later under the 
head of wood preservation. 
In the summer of 1919 prices received for ties as well as the price 
for making them, reached their peak, the former varying near Jonesboro 
from $1 to $1.90, the higher price being received for a No. 5 tie (7 by 
9-inch face) of such species as hackberry and soft maple, delivered at the 
ate 
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