OCR Text |
Show ELECTRICITY CLEANS BLACKBOARD BLACK-BOARD ERASERS. Cleaning chalf dust from blackboard black-board erasers was formerly a task saved for the misbehaved schoolboy to do after school hours. The punishment was often as great to those who wore not guilty but still within range of the flying dust. Today a new device operated op-erated by electricity on the principle I of a vacuum cleaner removes the I chalk by strong suction, cleans thai erasers with a bristle brush, and still j allows no dust to escape in the room where it is used. The work is done by a compact motor of 1-25 horse-power which is attached to a plug and cord making the device serviceable wherever central station lighting is used. Tho chalk is filtered out of the exhaust from tho tiny suction blower with fine muslin and rotained In the box on which the motor is mounted. |