158 
BULLETIN" "711, U. S. DEPARTMENT OF AGRICULTURE. 
head pole, then through another block of the same size on the tail 
pole, and thence to the fall block of the hoisting line, where it is 
attached. With crotch lines attached to the fall block, the largest 
logs can be lifted from the landing and moved toward or away from 
the car. 
In one case, the power is furnished by a 9J by 10 inch double cyl- 
inder engine, steam being supplied by a 50 by 120 inch vertical 
Fig. 63. — Overhead loading system. 
boiler, having a working pressure of 175 pounds. The upper or 
main drum carries the hoisting line. On the front shaft are two 
drums, one of which carries the trip line, the other the straw line. 
By means of the straw line, cars can be moved at the pleasure of the 
engineer, the power furnished being ample to " spot " six loaded 
cars on a 2^ per cent grade. The three drums are operated by three 
separate friction devices, making them independent of each other. 
The car and the load are under the control of the loading engineer 
at all times. The load is lowered by means of a powerful steam 
brake, thus eliminating the danger of dropping a log, which might 
injure a loader or break a car. 
In some cases the" J-inch hoisting line, leading from the main 
drum, passes through a 14 by 3 inch single-sheave corner block at 
the top of the head pole, then through a fall block of the same size, and 
thence to the gin pole, where a tail hold is taken. The scheme is 
shown in figure 61. In other cases, one of the trip-line corner blocks 
is hung on a 1\ or 1J inch guy instead of a tail tree, the guy line, 
which is called the front guy line, being strung from the top of the 
head pole to a stump at the back of the landing. The scheme is 
shown in figure 64. 
The fixed investment in equipment at one side with this method, 
when a double-sheave corner block is used, is about $1,193, as follows : 
