Page:Popular Science Monthly Volume 91.djvu/529

 Popular Science Monthly

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���In this holder the baby sits when awake or lies when asleep on the trip

��Can the Baby When You Take a Journey

THE good news is true. We have been hoping for years that some in- telligent inventor would come along with a device to can obstreperous infants during the late hours of the night. We sug- gested a hermeti- cally-sealed can wrapped in sound-proof ma- terial, but Caleb M. Prather, of Evanston, 1 1 1 i - nois, who is the inventor of the can illustrated, sidestepped our

instructions at several important points. He intends to use the can to rock babies to sleep. It is, in fact, a baby holder. Our can was to be a baby holder and silencer combined. Mr. Prather has provided sev- eral holes in his can through which air can reach the baby. We don't object to the baby getting air but as long as there are holes in the can the baby's yells will be as nerve-wracking as ever. That was our reason for the hermetically-sealed can. A cover of the can is fastened by a button, and a seat is provided upon which the baby can sit and suck his thumb when the top and cover have been re- moved. The can is of steel and it can be fastened to the rail of a porch, the back of a chair, or the seat of a rail- road car. If the inventor will make his can air-tight and sound-proof — features which we originally suggested — we know of a bachelor who will buy a half dozen right away.

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��Shells filled witn water are subjected to a strong water pressure test for thirty seconds

��Will the Shell Burst When It Is Fired? A Water Test Tells

A PROJECTILE fired from a gun is subjected to enormous strains which it must be strong enough to with- stand; otherwise it might be as dangerous to the gun crew as to the enemy. To assure safety as well as destruc- tiveness, the steel from which the shells are made is subjected to different tests. Not only this but further examination is customarily made on what are known as test shells. Some of these test shslls are actually fired in the testing grounds; others are cut up and the pieces subjected to various strains which must be successfully resisted.

Since this can't be done to every shell, the shells used are picked at random, it being assumed that they typify the lot. The probabilities are that this would be so, but. it is better to supply a simple pressure test required for some of the French shells.

This French pres- sure test consists simply of fillingeach shell with water and then subjecting it to a strong water pressure for about thirty seconds. If the shells are weak, they will either burst under the strain or a per- manent expansion will take place. On the other hand, if the shells do not collapse and no per- manent expansion takes place, the shells must be satis- factory so far as their strength is concerned. This is conclusive evidence which can be se- cured for each shell with little trouble.

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