i6o 



GENERAL SCIENCE 



since the last observation, and determining the direction 

 and velocity of the wind. These results are then tele- 

 graphed twice each day to the chief official in the Weather 

 Bureau office at Washington. From these reports the 



; dotted black licet connect places haying 

 temperature; arrows point in direction wind in bio win 

 O dear; partly cloudy; cloudy; R rain; S 

 HIGH indicates center of anticyclone, or high-pr 



WEATHER MAP 



Isotherms, dotted lines, drawn for every 10 degrees; and isobars, unbroken 

 lines, drawn for every tenth of an inch. Line of arrows indicates the 

 ordinary path across the U. S. of this type of low. Such lows usually 

 advance at the -rate of about 30 miles an hour. 



chief officials predict what the weather is going to be in 

 the near future. In the United States the general move- 

 ment of the winds is from west to east, and if a certain 

 kind of weather prevails anywhere in the west, it is possi- 

 ble that it will advance eastward, but many modifications 

 may occur. So many influences change atmospheric 

 conditions that infallible predictions cannot be made. 

 But the Weather Bureau predictions do prove true often 



