Popular Science Monthly 



745 



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 



