922
��Popular Science Monthly
��Comic Photographs Made With Film Negatives
SOME very interesting and simple comic pictures can be made with old films and film negatives in the following manner.
���The film
��pen and ink picture and the finished cc
��drawn on plain >mic photograph
The pen and ink part of the picture is drawn upon an old film that has been thor- oughly cleaned. This comic part may be drawn in free hand with India ink.
The head and shoulder part of a portrait film is cut out on the outlines of the figures and pasted on the comic film. These are printed in the same manner as other negatives. — C. Bush.
��Testing the Strength of Norway Iron While Hot and Cold
IRON made in Norway owes its fine qualities to the exceptional purity of the ores from which it is made, and the care taken in its manufacture. The smelt- ing is done with charcoal. The metal has a purity of 99.8 per cent of iron, the remainder being sulphur, slag, carbon, silicon, manganese and phosphorus. This iron is very low in sulphur and phosphorus, the two ingredients which modern manu- facturers strive to keep as low as possible in their product.
Sulphur makes iron brittle when hot, thus causing it to break in the rolls. Phos- phorus, on the other hand, makes iron brittle when colcf and interferes with its strength and ductility' in bending. Norway iron, on account of its exceptional purity, has come to be recognized as the world's standard, to which the quality of all other irons is comparea.
A round bar of Norway iron will stand the severest cold bending test. You can bend and hammer it back on itself, and
��then bend and hammer it at a right angle to its previous position so that one part is touching another. The iron will show no signs of cracking at the bends. One bar of this metal was tied into a knot while hot, and showed no signs of cracking at the bends. Cracking at the bends when the iron is hot is due to sulphur. When pulled apart in a testing machine, this iron showed a very fibrous fracture. Steel made from Norway iron by the crucible process makes the finest kinds of razors, tools, etc., which keep their edges sharp for a long time. It is a metal that can be depended upon in every respect. — W. S. Standiford.
��A Protection Curtain for a Mechanic's Work Bench
IN a large railway shop heavy cloth screens are provided on the work benches around devices which are used by metal workers, especially in cases where babbitt or other soft metal is removed from arma- tures. This protects passing workmen or bystanders from flying pieces of metal. The curtain also tends to confine the chips to the bench and keep them from littering the surrounding floor space.
The curtain is extended on a frame made from two upright round iron bars, con- nected by another iron bar. From this connecting bar rods extend which are of
���Protecting passing workmen or bystanders from flying pieces of chipped metal
sufficient length to carry the curtain across the bench.
This is an inexpensive but effective arrangement for the purpose and could easily be adopted for other uses of a similar nature. — Ralph O. McGraw.
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