Page:Popular Science Monthly Volume 91.djvu/224

This page needs to be proofread.


Popular Science Monthly

��How the Government Seals Unofficial Wireless Stations

��AMATEUR and l commercial sta- tions alike have been ordered closed. The Government cannot af- ford to take any chances of military in- formation leaking through to the enemy. All aerials have been dismantled, and the in- struments stored away. In the very powerful wireless stations, the further precaution has been taken of sealing the apparatus electrically.

The manner of seal- ing such a station is well illustrated in the accompanying photo- graph of New York city's most powerful commercial plant. The transformer shown in the foreground was used to convert the low-potential alternating current, that is ordinarily used for light and power pur- poses, into a current of millions of volts in pressure, such as would be required for sending wireless signals.

The Government's agents have simply wrapped a heavy copper wire around the trans- former terminals, and have se- cured the wire ends with sealing wax on which is stamped the great seal of the United States of America. It is impossible to remove this wire without break- ing the seal — and taking the consequences in imprisonment.

���A heavy wire short-circuits the high-po- tential sending transformer. If an at- tempt should be made to operate the station, the transformer would burn up

��lines are spaced by virtue of an evenly notched rack which allows the tablet to be moved away from the elbow rest by the distance of one notch.

An improvement on this tablet has been developed by Arthur E. Tremaine, of Boston. By using a straight edge and a brass wire placed three-quarters of an inch above it across the paper, the sightless writer is able to keep the size of his letters uniform. Moreover, by eliminat- ing the elbow-pivot principle, each line will be straight and not curved in the arc of a circle. Ink as well as pencil can be used since neither the beveled straight-edge nor the wire quite touches the paper surface. The straight-edge can be lowered line by line down the paper and evenly spaced by means of notches at the side. In this way a perfectly neat appearance is given to the written

��rii^h-tension

wt reless t ranstor me

�� � �■

� � � �-r

�%J»

� � �\

� � �•■tA

�LI

��Teaching the Blind How to Write on Straight Lines

THE December issue of the Popular Science Monthly contained an article on an instrument invented to aid the blind in writing. This was the writing tablet invented by the French scientist Dr. Emile Ja'-al, His tablet consists of a fixed elbow rest in which the writing arm swings across the paper. The line of writing is thus made comparatively straight, while the

���As the blind man writes, his letters are kept uniform in size by the straight-edge below the pencil-point and the wire above it

�� �