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Page:Popular Science Monthly Volume 90.djvu/603

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Popular Science Monthly


��Giving the Teeth a Clean Sweep with a Rotary Tooth- Brush

PRACTICALLY, the tooth- brush is a miniature scrub- bing brush. It works

���enough in cleaning the surfaces of the teeth. But in cleaning the spaces between them — the very parts that need cleaning most — it is deficient. Food will collect between the teeth before it will collect an>^vhere else. If not removed it starts to decay.

A rotary tooth-brush has been invented,

����When the handle of the brush is rotated certain bristles scrub the surface while others f>enetrate and clean the crevices

��Do You Know That We Americans Have Over a Hundred Volcanoes

MORE than a quarter of the active volcanoes of the world are on L'nited States soil. We have the distinc- tion of possessing about sixty volcanoes in Alaska and in the Aleutian Islands just off the coast. In the western United States, in the Philip- pines and in the Hawaiian Islands we have nearly as many more, making over a hundred volcanoes that we possess (not that X, we place any value

upon their possession). There are but four hundred and seventeen throughout the entire globe.

��A Machine Which Automatically Feeds Twine and Cuts It





��which cleans out the crevices between the teeth as well as the tooth surfaces. The brush is guided with Dne hand and turned with the other. The metal guard prevents the bristles from 'T^HE wrapping clerk who has learned the touching the inside of the mouth. The ± trick of breaking twine only after his turning bristles rotate parallel to the fingers have suflfered from cuts and burns,

revices, some scrubbing the surfaces of the will welcome the appearance of a machine

teeth and others penetrating into the which will not only cut twine at the point

desired, but which will feed it along under a cutter so that the end is always within convenient reach. The machine does its work with the faithful- ness of a human ; there is no need for the operator to watch it as he wraps his bundles. The twine is cut by pressing down a knob which operates the cutting blade. At the same time the twine is advanced by an arm which moves forward when the knob descends. In this way the twine is fed forward as fast as the knob is operated, leaving, with each stroke of the knife, a slight length on the side of the machine nearest the wrapper to be used for the next package.

The twine is held in a cup large

enough to accommodate several

You punch the sizes. It makes no difference how

Ke ?utt the ^^'^^ o-" «t0"g .the twine may be. twine and more ^^e machine will cut and feed it is pulled out along as fast as the operator works.

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