THE BAROMETER AND THE WEATHER. 147 



by a steady and continuous fall after a long period of fine 

 weather. This is usually followed by a decided change of 

 weather, and the greater the fall the more violent the 

 change. If the fall is slow, and continues steadily for a 

 long time, the change is likely to be less sudden but more 

 permanent, i.e., the rain will probably arrive after some 

 time, and then continue steadily for a long period. 



In like manner, a steady, regular rise, going on for some 

 days in the midst of wet weather, may be regarded as a 

 hopeful indication of coming continuous fine weather : the 

 more gradual and steady the rise, the longer is the fine 

 weather likely to last. 



The least reliable of all the barometric changes is a sud- 

 den rise. In winter it may be followed by hard and sud- 

 den frost, in summer by sultry weather and thunder-storms. 

 All that may be safely said of such sudden rise is, that it 

 indicates a change of some sort. 



The barometer is usually high with N.B. winds, and 

 low with S.W. winds. The preceding explanations show 

 the reason of this. In a given place the extreme range of 

 variation is from 2 to 2-j inches. 



It has been proposed that the following rules should 

 be engraved on barometer - plates instead of the usual 

 words : 



1st. Generally, the rising of the mercury indicates the 

 approach of fair weather; the falling of it shows the ap- 

 proach of foul weather. 



2d. In sultry weather, the fall of the barometer indi- 

 cates coming thunder. In winter, the rise of the mercury 

 indicates frost. In frost, its fall indicates thaw, and its 

 rise indicates snow. 



3d. Whatever change in the weather suddenly follows a 

 change in the barometer, may be expected to last but a 

 short time. 



4th. If fair weather continues for several days, during 

 which the mercury continually falls, a long succession of 

 foul weather will probably ensue; and again, if foul 

 weather continues for several days, while the mercury con- 

 tinually rises, a long succession of fair weather will proba- 

 bly follow. 



