Page:Popular Science Monthly Volume 91.djvu/539

 Popular Science Monthly A Crutch Built on the Principle of the Rocking Chair

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��ANEW crutch has made its appear- ance in England, where crutches just now are as numerous as walking sticks. Its principal feature is a rocker at the base, like that of a rocking chair. This is said to make walking easier. Instead of two sticks coming together to form a round stump the sticks of the new crutch are continued parallel from the shoul- der-rest to the rocker. The rest that fits under the armpit is a curved piece of hollow rubber tubing, like a motor-car tire, and the handle is adjustable to the height.

���The crutch has a rocker like a rocking chair, which makes walking easier

��Steam Jets Which Save Thousands of Dollars in Large Power Plants

IN large power plants even little "losses," if allowed to continue, will produce an annual loss of thousands of dollars. Of all such losses, that caused by soot is one of the most persistent. Collecting as it does in layers perhaps an inch thick about the water tubes in the boilers, it serves to in-

��sulate the water from the heat of the fires. A method employed by a Chicago firm for doing away with the soot evil, first allows the soot to col- lect. Then, through rows of nozzles mounted at short in- tervals at the top of the water tubes, live steam is passed at high velocity. At first, the steam jets are directed downward on the lower rows of tubes. No speck of dust can hold its perch. By slowly rotating the nozzles, the turning jet is di- rected upon the middle rows of tubes, and lastly upon the very top ones. The battery of steam jets strike at an angle. The steam glances off, carrying the soot with it with- out wearing away the pipes.

At no point do the nozzles direct the steam directly upon the pipes. By blow- ing diagonally upon them the force ex- erted is used in carrying away the soot rather than in beating upon the pipes. In this way a boiler can be rendered one hundred per cent more efficient. Less coal or fuel will be required to get up a given amount of steam and the pipes and metal parts of the boiler will last longer.

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��Layers of soot on the water tubes of a boiler insulate the heat from the fi-es. Such a condition is avoided by blowing the soot off with high-velocity steam through sets of rotating nozzles

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