Page:Popular Science Monthly Volume 92.djvu/712

 NEW uses are constantly being found for the blue glass electric light in-

��G96 Popular bcience MontliLy

Euclid Never Thought of This Way New Uses Have Been Discovered for of Studying Geometry Blue Glass Electric Lights

I^HE study of geometry, especially of the more advanced branches of spher- ical and de- scriptive geom- etry makes demands upon the imagina- tive power of the students. Perspective drawings upon the blackboard are grasped on- ly by the more gifted students.

Mr.J.O'Hara Carson, who is connected with a manual training school in'.New Orleans, found that the students had no great difficulty in learning the various theorems, etc., so as to pass their examinations, but he noted that many were unable to make a practical application of geometrical principles accurately and con- structively. A careful study of the subject convinced Mr. Carson that many of the students could not perfectly visualize geometric figures drawn on a plane surface and that it was this fact which made it impossible for them to apply geometry practically. So he invented several models.

The illustrations accompanying this article clearly demonstrate the construction of these models. The planes may be made of wood, paste- board or any other suit- able material, the lines of wire or strings. To differentiate between lines to be proved, con- struction lines and im- aginary lines, different color- ing or different material may be employed. These models will also be useful in teaching geometry to the blind.

���Our illustrations contrast the two methods of teaching geometry

��can descents which already have a wide range of uses. A big laundry in the South has installed blue bulb lights for the reason that this light makes the yel- low stains in cloth show up plainly, and therefore enables the workers to do better laundry work. In the West a large mining company uses blue glass lamps over concentration tables as this light assists in bringing out the line between the zinc and iron ore.

��A Picture Frame and Easel for the "Girl I Left Behind Me"

THIS photograph frame is for the soldier boys. The triangular flaps are folded back, and the loop ribbon pro- vided is slipped around the corner of one of the flaps. The oval opening is large enough to accommodate a pic- ture 1^8 x23.^ in. The photo- graph is slipped between the frame and its back through a slit at the top.

����The first illustration shows the simple principle of the frame, the second its appearance with a photograph

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