THE CLIMATOLOGY OF THE UNITED STATES. 25 



succeeded in sending out veiy correct indications in re- 

 gard to the results likely to follow such given conditions ; 

 and during the last summer western farmers were enabled 

 to go about their work without being needlessly alarmed 

 at the sight of every ordinary thunder shower. 



These storms within the past five or six years, have 

 been spreading over a greater area and becoming more 

 severe. This is in part merely apparent from the spread- 

 ing of the population over hitherto unpopulated districts 

 and the greater number of reports received of these 

 storms ; but aside from this there seems to have been a 

 greater display of this form of atmospheric disturbance 

 than formerly. Besides cyclones and tornadoes, we have 

 thunder showers and local showers which need no special 

 explanation after what has already been said. 



Having now noticed the principles of weather changes 

 in our climate, we will devote a few moments to the 

 consideration of the United States Signal Service and its 

 work in collecting reports of the weather and deducing 

 therefrom the bulletins and indications which are daily 

 sent out to the principal cities of the country. When me- 

 teorologists and scientific men found that storms moved and 

 acted in a somewhat orderly way arid travelled in about the 

 same direction, it became apparent to them that some plan 

 might be adopted whereby vessels about to leave port might 

 be appraised of the approach of severe storms, especially 

 those from the West Indies, and, accordingly, a move- 

 ment was set on foot with this object in view. On Feb- 

 ruary 9, 1870, Congress passed a joint resolution authoriz- 

 ing the Secretary of War to put this scheme into operation 

 and a weather bureau was established in the Signal Ser- 

 vice to collect weather reports and issue warnings and 

 probabilities of weather changes for the benefit of com- 

 merce and agriculture. 



ESSEX INST. BULLETIN, VOL. XVIH. 3 



