93 



what are commonly called "changes of 

 weather," when we will again revert to the use 

 of the barometer. 



The use of the telegraph in connection with 

 the establishment of a weather bureau having 

 stations for observation at convenient points 

 throughout the country has contributed much 

 to the science of meteorology. It is found 

 that there are areas of high and low pressure 

 existing at the same time in different parts of 

 the country. These usually have their origin 

 in the far northwest, and follow each other, 

 sweeping down the eastern side of the Rocky 

 Mountains and gradually bending easterly and 

 from that to northeasterly by the time they 

 reach the Atlantic coast. The areas of low 

 pressure are called cyclones, while the areas of 

 high pressure are called anti-cyclones. (By 

 cyclone we do not mean those cloud funnels 

 commonly called by that name that form at 

 certain times of the year in certain sections of 

 the country and produce such destruction of 

 life and property. These storms are usually 

 confined to a narrow strip and are short-lived. 

 They arise undoubtedly from local conditions. 

 A description of these tornadoes for such is 

 their true name will be given in some future 

 chapter.) 



These centers of high and low pressure may 

 be several hundred miles apart. In the area 

 of high pressure, if it is in the winter season, 



