Page:Popular Science Monthly Volume 89.djvu/825

 Popular Science Monthly

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��A Wonderful New Glass Which Cannot Be Shattered

ANEW glass, transparent, tough and strong, which has all the advantages and none of the defects of "brittle, fragile window glass, has been in- vented b\- Frank Shuman, of Philadelphia, whose earlier inventions in- clude wire glass, a wide- ly used form of con- crete piling, and the sun power plant erect- ed at Maadi, near Cairo, Eg\-pt.

A twent>'-two cali- lier bullet cannot pene- trate the new glass; a brick cannot shatter it; a heaxT,' man thrown against it under all the terrific momentum of a collision would not go through it, but would be thrown back from it, uninjured by flying

���A sharp blow with a hammer may crack the glass but will not shatter it into splinters

���glass, because none would fly. A stone i irown against it will bounce back like a golf ball.

When struck a powerful blow, as with a hammer, for instance, it will crack into hair lines, as shown in the accompa- nying illustration, but there will be no shower of flying glass or splin- ters. Furthermore, these hair-line cracks leave the surface abso- lutely smooth.

The secret of its strength is a sheet of white, transparent cel- luloid, t w e n t y - o n e thousandths of an inch thick, which is placed between two pieces of glass. The glass and celluloid are simply welded together under high temperature and tremendous pressure, the resultant being a solid sheet possessing all the transparency of the best plate glass, combined with the strength of a sheet of metal.

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��A boiler can be blown clean in six minutes. If cleaned once in every six hours it will increase five per cent in efficiency

��Preventing Boiler Troubles by Mechanical Cleaning

THE shortcomings and diffi- culties connected with the hand-cleaning of modern steam- boilers have resulted in the de- velopment of the mechanical steam-blower, the latest and most effective type of which is shown in the illustration. It employs nozzles arranged across the width of the boiler, so that all surfaces are equally accessible and soot cannot be blown from one part of the boiler to another. Two cleaner-elements are mounted on bearings and ro- tated by a chain and sprocket- wheel outside the setting. The jets of steam are directed along diagonal paths, one in one direction and the other in the opposite direction. When the}' are discharged into the passages between the tubes, the cleaner is slowly rotated, back and forth over a wide arc.

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