124 GEOLOGICAL SURVEY OF ALABAMA. 
the engineman to hoist away, and goes back to his room 
with the empty car to get another car load, thus requiring 
only one trip to deliver a one ton car of coal. The “emp- 
ties” are taken from the “slope tram,” and the full car 
bodies placed upon the same, by means of an iron post 
crane placed at the angle of the room road. At this point 
the slope pillar, instead of coming out to an angle, is cut 
away sufficiently to give space called a “siding” (but which has 
no side track), for the empty car to be swung from the slope 
tram and held suspended out of the way, while the full car 
body is being placed upon the slope tram, after which the 
empty is swung still further around and lowered upon the 
platform of,the room truck, from which the loaded car has 
just been removed. This necessitates at each room entrance, 
two cranes (upon a swivel post). The crane for the empty 
car body being of a lighter construction and placed on the 
upper side of the post; that for the loaded car, heavier and 
on the lower, or room entrance side. [See Diagrams, one 
opposite, and two followiug p. 126.] From the end of each of 
the cranes there is suspended by a swivel joint in the centre, 
a light beam of the length of a car body. This beam has a 
small pulley at each end, over which passes a wire cord 
terminating in a hook and fastened at the other end to run- 
ning nuts on a double screw, actuated by a crank, on the 
same principle as the screws of the log carriage of a circu- 
lar saw. This arrangement is for raising and lowering the 
car bodies. ‘The screw for the “empties” is coarser, giving @ 
a more rapid lift, than that for the loaded cars. The second 
diagram opposite p. 126, shows the arrangement of the screw 
threads and crank for raising the mine car body from the room 
tram or from the slope tram. A catch lever is arranged at 
the side of the slope track opposite the room road, to ena- 
ble the miner to stop the “slope tram” at either one of the 
four platforms or scaffolds on which the mine ears rest in 
their transit up or down the slope. The mine car body is 
raised up from the tram truck, or up from the “slope tram” 
by means of a screw, which the miner turns by a crank as 
above described; the screw, when rotated, pulling a light 
wire cord above described sufficient to raise the car body a 
few inches, by a few turns of the crank; the crane is then 
