SYNOPSIS OF PROCEEDINGS. 289 



April 25, i8go. — Regular Meeting. 



President McCowen in the chair; eleven members and several vis- 

 itors present. 



Additions to the Museum were reported as follows : A specimen of 

 fungus, together with some flint implements, from Crawford county, 

 Iowa, and a specimen of topaz from Mexico, presented by M. E. Reid; 

 also, some minerals from the salt-mines of Germany. 



Mr. Warren Watson of Kansas City and Dr. W. R. Sedbury of De- 

 troit were elected corresponding members. 



Mr. F. J. Walz, local Signal Service observer, then delivered an 

 instructive lecture on "Meteorology," explaining the methods and 

 instruments used in the Government service, also the more prominent 

 atmospheric changes the concerted observation of which makes possi- 

 ble fairly accurate prognostications. Factors entering largely into 

 the calculations of the bureau are the direction and force of the wind, 

 and these are influenced by three things — unequal atmospheric press- 

 ure, the specific gravity of the air, and the rotation of the earth. The 

 lecturer explained the workings of the barometer, showed that a high 

 barometer indicated heavy atmospheric pressure, and a low barometer 

 the opposite. He then cited the self evident fact that the air in an 

 area of heavy pressure had a natural tendency to rush into an area of 

 light pressure, and invariably did so. Thus, owing to the weather 

 bureau having reduced its barometrical observations and comparisons 

 to an exact science, it is enabled to locate storm centres with exacti- 

 tude. It has barometers placed all over the country. Their results 

 are corrected for variations in the instrument, for altitude, and for 

 temperature ; and every day these figures are placed upon a chart or 

 map of the United States in all of the signal service stations. Lines 

 are then drawn from stations showing a certain atmospheric pressure 

 to other stations showing the same pressure. These lines naturally 

 resolve themselves, especially in times preceding a storm, into a com- 

 paratively regular series of concentric circles, the center being the area 

 of lowest pressure. The natural conclusion is that the winds are going 

 to tend from the outside area of denser atmosphere to the inner area of 

 less pressure. The charts drawn on the 2 7th of last month, just before the 

 heavy storm which occurred on the evening of the 28th, showed a very 

 pronounced storm center in the central region of the country. The 

 chart for the 28th showed the storm center moved several states to the 

 east, while on the 29th the storm was located on the Atlantic coast 



