Page:Popular Science Monthly Volume 88.djvu/773

 Popular Science Monthly

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��Panama's Locks Guarded by Chains

THE huge locks of the Panama Canal are guarded by massive chains stretched across the channel. No vessel can crash into the gates at any of the locks because of these fenders, placed seventy feet from each gate and near the surface of the water. When a boat is allowed to pass, the chains are

���Great chains act as fenders to keep ships from smashing into the locks at Panama

��lowered to the bottom of the canal. If the chains are struck by a boat, they gradually yield to the force, paying out to a certain distance which depends upon the violence of the impact.

The mechanisms which regulate the chain-fenders are installed on either wall. A system of hydraulic cylinders is used for raising and lowering the chains. The action of the fender when struck by a boat is modified in part by the friction pro- duced in the machinery, but mainly by the resistance produced by water flowing through valves.

Satisfactory experiments were conducted last Novem- ber under the direction of Henry Gold mark of New York. The Cristobal, laden with her cargo from New York, was run against a chain at various speeds and was brought to rest without injury. The distance trav- eled after striking the chain agreed, in each case, with the previous calculations.

��Three- Quarters of Humanity Are Deficient in Lung- Capacity

RECORDS show that fully three- . fourths of us are deficient in lung capacity. Regarding six as a normal standard, the average person is able to register only three or four units of pressure. In cases of asthma, the lung capacity is only one-sixth normal.

Bronchial affections such as asthma, hay fever and similar disorders are readily benefited by the therapeutic use of the vacu- um breathing -apparatus. The mechanism is not complex in its operation, the chief end to be at- tained being the gradual increase of the breathing capacity of the patient.

The patient places a rubber hood over his nose and mouth so that all air reaching him must be drawn through the rubber tubing. This tubing is connected with a glass containing water, which is permeated by air ob- tained through another, inde- pendent opening. The patient is to draw the air he breathes

��forced

through the water, or against an ap- proximate pressure of six pounds. This makes him breathe deeply and vigor- ously. Exhalation is made easy by the pull of a vacuum apparatus operated by motor, connected through a second tubing with the breathing hood. The lung energy expended is indicated on a mercurial register.

���A vacuum breathing-apparatus to increase your lung power by drawing air through water

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