Popular Science Monthly 



587 



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 



:revices 



MIL OF CORO 



WHEN IWOB ISDEPRESSEO 



TflEN ADVANClD 



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-" «t''0"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. 



