Page:Popular Science Monthly Volume 91.djvu/948

This page needs to be proofread.


��Papular Science Monthly


��A Steel Boring Mill Tool-Holder Requiring Little Material

WITH the price of high speed tool steel soaring, devices for the conservation of this kind of material are being sought. With this thought foremost the device for holding a bor- ing mill tool, as illustrat- ed, was developed and a great saving in material effected. The entire tool, made of high speed steel, will weigh about \Yi lb. The piece of steel used in the holder weighs about 4 oz. This holder can be made in a variety of shapes, and different tools can be used. Pressure exerted by the set-screw on the round-pin holds the tool in place. The round pin is roughened or knurled on the end to hold on the steel surface. — J. R. Minter.

����A Treadle for an Automobile Foot Accelerator

ON a great many cars the accelerator consists of a plunger rod, with a metal disk at the end, for the foot to rest upon. As it is often difficult to keep the foot pres- sure steady up- on the button, a constant in- crease and de- crease of speed is the result.

With this in mind, I con- structed a treadle along the lines shown in the sketch, which overcomes, to a great extent, the uneven pressure, and also gives an easier position for the foot.

The under side of the treadle was chan- neled so as to keep it always in place on the button. The top surface was furnished with corrugated rubber and the lower end hinged to the car floor. As a result the car ran much more smoothly and the leg muscles were relieved from the constant strain of adjusting the pressure upon the accelerator. — L. B. Robbins.

��Treadle to ease the foot on accelerator pedal

��An Improvement on the Old-Time Back to Back Card Trick

THIS trick originally consisted in read- ing off the cards one by one as they were shown to the audience without your having had a chance, apparently, of seeing them at all. The secret consists in placing two halves of the pack back to back, so that one half faces one way and the other in an opposite position. Notice what the face card is on one side and hold the pack up so that the audience can see it. While you are doing this you will have a chance to notice the rear card, that is the card facing toward yourself. As soon as you have done this place the pack behind your back or under the table and transfer the rear card to the front of the pack, thus bringing into view the one you have just named and at the same time disclosing the next card in the rear. On holding the pack up to the audience you will be en- abled to name the card next to appear. It is needless to say that no one should be allowed behind the performer while this trick is in progress.

The variation of this trick employs a mirror in order to deceive the "knowing ones" who are familiar with the older method of working it. For this newer method, the pack is not cut and put back to back, but the cards all face in one direction. Somewhere overhead a mirror is placed where it will reflect the cards to you, but in such a position that it will not be seen by the spectators. As the cards are reflected in this you will be able to read them off without lowering the cards. Be careful to hold the pack between your eyes and the spectators so that the di- rection of your glance is not detected.

��Newspaper as a Substitute for Chalk Talk Lecturers

CHALK talkers, lecturers and teachers who use paper and crayons to show diagrams, sketches, figures, etc., now find the prices of large sheets a serious con- sideration. Their outlay may be materially reduced if they will use old newspapers that have a comparatively even gray appearance from a distance. Select the sheets that have no dark or heavy cuts, headings and the like, such as the "Help Wanted" pages, and use the regular "chalk talker's" crayons. The printing will not detract from the drawing; in fact it can scarcely be noticed by the audience. — A. B. Wagener.

�� �