a: 
N. C. Experiment Station 
Fig. 5. The circuit breaker and wii'ing diagram; a, wires from the source of elec¬ 
trical supply; b, switch in heating circuit; c, switch in motor circuit; d, two electro 
magnets; e, glass cups containing mercury; f, conductor which connects the two mercury 
cups when current is flowing through heaters and which is raised out of mercury when 
the electro magnets raise the armature, g; h, electric heaters; i, shield, to prevent lint 
from falling on heaters; j, supports for heaters; k, apei'tures to facilitate circulation of air; 
1, galvanized iron hood; m, slide for regulating ventilation. 
