108 TRANSACTIONS OF THE ILLINOIS 



she points to the facts written in characters of living light on the earth 

 and on the sky. Who will dare say that we cannot read, decipher and 

 interpret this record, when the fact stares us in the face that even those 

 of humblest acquirements and capacity are constantly and intelligently, 

 too, predicting a change in the weather, assigning as a reason therefor 

 that the wind has changed. Not only so, but they predict the character 

 of the change from the point from which the wind blows. Winds, there- 

 fore, are nature's harbingers, sent forth to announce an approaching 

 change. Tell me how it could be possible for winds to be harbingers of 

 changes, if they resulted from axial rotation of the earth, or from rarifica- 

 tion of air on its surface. It is self-evident that these two ideas are incom- 

 patible ; and as we know the changes of wind indicate changes of 

 weather, we accept this proposition as true and let the artificial theory 

 spun by speculating without facts, "slide" as worthless in our investiga- 

 tions. What, then, is the cause of wind? 



We have an instrument which was first considered a philosophical 

 toy ; but its revelations soon became so extraordinary and startling that 

 it gave rise to problems with many of which the mightiest intellects have 

 grappled but failed in solving. It has not yet exhausted its lore, nor taught 

 us half it is capable of doing ; for year by year it is conducting us to 

 higher and higher scientific standpoints. That instrument is the barome- 

 ter ; invented by Torricelli, of Florence, about two and a third centuries 

 ago. Its name is derived from two Greek words baros, weight, and metron, 

 measure. It therefore means a weight measurer. It is used to ascertain 

 the weight of all gases under pressure ; hence the weight of the atmos- 

 phere. It was soon discovered that the mercurial column at any given 

 place, is subject to great fluctuations as to height, sinking below and rising 

 above the general average of the place. Moreover, when the instrument 

 was taken to a greater elevation, the mercurial column fell ; when to a 

 lower, it rose. 



Hence the inference was drawn that the difference in the height of 

 the mercurial column was due to the difference in atmospheric pressure at 

 different times in the same places. After a while it was discovered that 

 the barometer invariably fell on the approach of a rain, from two to three 

 days in advance ; that it continued falling until the storm had attained 

 its maximum, when it would gradually rise. A cognate discovery was, 

 that whenever there was a fall in the barometer there was a rise in the 

 thermometer, and vice versa. Comparing its movements with physical 

 facts it was discovered that the variations of the barometer had an inti- 

 mate relation with the direction and force of the wind ; hence the bar- 

 ometer came to be called " the weather glass," by the common people. 

 The barometer had now led the way into the vestibule of the great temple 

 of nature, and not only qualified man to comprehend the mysterious 

 secrets of the department of Meteorology, but placed the key in his hand 

 that unlocks them. Then it was seen for the first time that the wind 

 always blew out from an area of high barometer into an area covered by 

 a low barometer. Francis Galton, of England, made not only this impor- 

 tant discovery, but also that the course of the wind is a winding spiral. 



