60 



GENERAL SCIENCE 



eter reads 28.92 inches. At C, Lowell, Neb., 2000 feet above sea 

 level, it reads 27.88 inches. At D, Spica, Kansas, 3000 feet above 



sea level, it reads 26.87 inches. At E, Kana- 

 rado, Kansas, 4000 feet above sea level, it 

 reads 25.9 inches. At F, Kanfield, Colo., 

 5000 feet above sea level, the barometer 

 reads 24.97 inches. 



The pressure at sea level is not station- 

 ary. The barometer has been known to vary 

 from 31.7 inches to 26.96 inches, but its 

 average movement is from 28.4 inches to 

 30.3 inches. The United States Weather 

 Bureau requires that all barometers be cor- 

 rected for sea level; for example, if the 

 barometer is reading 30 inches at sea level, 



the corresponding reading at Kanfield, Colo., would be 24.97 inches, 

 but the Chief Forecaster at Washington must have the reading of the 

 barometer which would represent the reading if Kanfield, Colo., were 

 at sea level; consequently each reading is reduced to sea level. 



Instead of telegraphing to Washington 24.97 inches for Kanfield, 

 or 26.87 inches for Spica, the local forecaster of each place would 

 send 30 inches as the reading of his barometer. 



Corrections for Elevations above Sea Level. If altitude is 



250 feet add . 29 inches to barometer reading. 



FIG. 52. An aneroid 

 barometer. 



500 

 750 

 1000 

 1250 

 1500 

 1750 

 2000 

 2500 

 3000 

 3500 

 4000 

 4500 

 5000 



0.57 

 0.85 

 1.12 

 1.39 

 1.66 

 1.93 

 2.20 

 2.72 

 3.24 

 3.74 

 4.24 

 4.72 



5.20 



