Page:Popular Science Monthly Volume 90.djvu/114

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��Popular Science Monthly

��held in place by the brass edgings at the side of the contrivance.

It will be noted from the illustrations that the vertical lines on the glass are numbered serially from left to right. The hori- zontal ones are divided into two sets, each designated by similar groups of letters. The user of the device merely slides the metal plates around (using the handles projecting beyond the glass at each end) until, say, the upper left-hand corner of the good bill rests beneath the point A-i of the cross-hatching on the glass, and the remainder of the bill is correspondingly lined up and square with the rest of the cross-hatching. Similarly he brings the upper left-hand corner of the bad bill to rest beneath the point A of the lower section of the ruling — afterward like- wise bringing the other parts of the bill into agreement with the rest of the squares.

All of this has the effect of placing a good bill and a bad bill squarely before an ob- server, and because of the cross-hatching on the glass, of dividing up the surface of each bill into similar squares, each of which may be compared in detail. As is readily evident, if the bad bill is distorted in any particular, the defect will immediately become apparent under such close scrutiny as this sectionalizing into small squares makes possible.

The most valuable feature about the de- vice is the fact that the two oblong blotter- faced metal plates and their accompanying good and bad bills, may individually be moved up and down and round about by means of the handles at each side and a variety of comparisons made, all without disturbing the glass itself in any way.

The tests performed usually consist in com- paring the various orna- ments on a bill for ac- curacy of size and shape — the moving around be- ing a valuable feature, since the ornaments do not always happen to fall completely within a set of .squares.

���The various ornaments on the bills are compared for accuracy of size and shape. The plates are moved around by means of the handles at the sides to facilitate the comparisons

��Counterfeit coins are compared in the same way as bills, only a finer screen is necessary. Counterfeit money has to be good indeed to pass the kind of a test this machine can give it.

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���Spring-brass wire, bent as here shown, will convert any nib into an automatic fountain pen

��Providing Your Pen with an Automatic Fountain F course every boy wants a fountain pen. He will buy one the very first chance he gets; but good fountain pens are rather expensive for the purse that goes with "knickers," and an unreliable one is likely to prove such a disappointment that it is worse than none at all. However, you can add the advantages of a fountain-pen to any ordinary pen-point by a new at- tachment, made very simply of spring- brass wire. The main part of the attachment lies in two small coils which are fixed under the point of the pen to hold the sur- plus ink. These coil ends join at the rear, while those near the front of the pen are turned up and back to fit tightly against the top of the pen. The jaws so formed serve the purpose of clasping the attachment to the pen- point and of uniformly feeding the ink to the point as it is needed.

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