Page:Popular Science Monthly Volume 88.djvu/841

 Popular Science Monthly

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��Floor Scrubber Propels Itself

A MACHINE for cleaning floors has been brought out, so quiet in its oper- tion that it can be used in hospitals and so gentle in its action that a frail woman can manipulate it without difhculty. Its chief feature of interest is that it departs radically from the suction or vacuum type of cleaner. Attached to the lower end of a long iron handle is an indus- trious but small electric motor. As the motor spins, it rotates a circular brush, which can be applied with any desired pressure to the floor surface. Behind the brush motor are two rubber wheels serving a double purpose — to act as a lever for regulating the pressure of the rotating bristles against the floor and as a carriage fcr rolling the equipment from one part of the building to another.

Because of the brush's rotary motion the machine is self-propelling. Various grades of brushes are supplied for various floor surfaces. For polishing hard- wood floors and mosaic or tile, brushes of other types are employed.

��No matter how swift a ball is thrown it is returned to the player with uniform speed.

��Detachable Blades for Hatchets

HERE is a hatchet with detachable blades, made possible by spring

���A

��Curved Spring Device Returns Bowling Balls RETARDING device consisting of a spring chute lead- ing from the gutter to the rack in the rear of a bowling alley serves the two-fold purpose of returning all balls to the player and return- ing them without the usual concussion resulting by the method now used. The curved spring has one end firmly fixed to the base of the housing and the other to an a d -

���A simple spring device retards the balls as they return to the player

��clips co-operating with apertures and

slots of the blades. When attached

each new blade

is as rigid and

stable as the main

body of the

hatchet itself, and

when it becomes

dull it can be

readily detached

and reground.

Thus the body of

the hatchet be-

���A detachable blade

��comes continuously serviceable, and one is always assured of a sharp blade. The blades can be economically made by stamping from sheet steel. From the standpoint of pure efficiency the hatchet makes a very eff'ective weapon.

��The motor

propels the

brush

���rnorjsJW*-

��JUS -

tor.

��Listening to an Electric Current AX interesting electrical experiment, xVillustrating the fact that sound accom- panies the passage of electricity through the body, can be shown in the following manner: Let two persons each hold an electrode from a small magneto or shock- ing-coil. Let one person, with his free hand, touch the other person behind and just below the ear. A buzzing sound, otherwise inaudible, can be heard. The tone of the sound depends upon the number of interruptions of the current.

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