Treatment of Cotton Seed 
33 
fitted as to be readily removed for loading and unloading the drum. The 
shaft (d) which passes along the longitudinal axis of the drum is fastened 
at one end to a system of reducing gears which in turn is connected by a 
belt to a small motor of y 8 horsepower. By means of the reducing gear, the 
speed is reduced from 1800 revolutions per minute at the motor to about iy 2 
revolutions per minute at the drum containing the seeds. 
The heat is supplied by 8 C-H electric space heaters* (h) placed in the bot¬ 
tom of the machine and directly under the drum for the seeds. In order 
to prevent lint and sand from accumulating on the heaters, a ventilated 
removale shield (k i) is inserted between the heaters and the seed in the 
drum. The temperature is regulated automatically by means of a thermostat 
which controls a circuit-breaker. 
The sensitive element of the thermostat was made by firmly riveting 
together two strips of iron and zinc to make a tongue of metal 11 inches long 
and tapering gradually from 1 inch at the widest end to % inch at the tip. 
This strip of metal was bent into the shape of a narrow letter U with one 
side twice as long as the other. The end of the short arm was attached to 
a metal base and a point of platinum metal was attached to the tip of the 
long arm. A second platinum metal point was fastened into the tip end of 
an adjustable screw and the two parts bearing the metal points were set in 
such relative positions that when the temperature of the oven arose or fell, 
the two points made or broke contact respectively. The adjustable screw 
made it possible to increase or diminish the distance between the two points 
and thus to regulate the temperature of the oven. The thermostat is fastened 
to the inner surface of the front asbestos wall of the oven and suitably in¬ 
sulated wire connects its two parts to proper poles on the circuit breaker. 
The circuit breaker (Fig. 5) is mounted on a slate base. It consists of two 
glass cups (e) containing a small amount of mercury and two electro mag¬ 
nets (d) capable of raising or lowering a U-shaped piece of metal (g). 
Tinned iron nails dipping into the cups of mercury are connected to the 
source of power and the bar of metal carries a short copper wire (f) to the 
ends of which other tinned iron nails are soldered. These nails are so ad¬ 
justed in height above the mercury surface in the cups that when current is 
flowing through the thermostat they are held out of the mercury, but when 
the oven temperature falls and current ceases to flow through the thermostat, 
their points drop into the mercury cups, thus closing the heating circuit. 
A signal light burns when current is flowing through the heaters. Since the 
current which flows through the thermostat and operates the circuit breaker 
is taken from the same source as that which supplies the heaters, no bat¬ 
teries are needed. A condenser is connected across the contacts of the 
thermostat to reduce arcing at that point and consequent clatter of the circuit 
breaker. The motor which rotates the drum is operated independently of the 
heating circuit. The wiring diagram is shown in Fig. 5. 
Thermometers inserted through the walls of the machine have made it 
possible to obtain a knowledge of the temperatures obtaining at different 
places in the machine while the seeds are being treated. In practice, it is 
^Manufactured by Cutler-Hammar Mfg. Co., New York. 
Foot-note page 55. 
