196 best's art op angling. 



descent of the Barometer indicates principally 

 violent wind. 



The Thermometer also which measures the 

 degree of heat in the air near the earth, will con- 

 tribute towards denoting when changes are 

 likely to take place in the lower region's of the 

 atmosphere : The Hygrometer distinguishes the 

 quantity of moisture in the atmosphere and the 

 Electrometer will point out the quantity of Elec- 

 tricity which prevails in it. 



The words generally engraven on the plates 

 of the Barometer, serve rather to mislead than 

 inform; for the changes of the weather depend 

 rather on the rising or the falling of the mercury, 

 than of its standing at any particular height. 



When the mercury, is as high as fair, or at 30 

 degrees, and the surface of it is concave, begin- 

 ning to descend^ it very often rains; and on the 

 contralry when even the mercury is at 29 degrees, 

 opposite to rain, when the surface of it is convex, 

 beginning to rise, fair weather may be expected : 

 these circumstances not being known, or not 

 being duly attended to, is the principal cause, 

 that farmers and others have not a proper confi- 

 dence in this instrument. 



It must be observed that caters paribus, the 

 mercury is higher in cold, than in warm weather, 

 and commonly early in the morning, or late in 

 the evening, than at noon, which seems occa- 

 sioned by the obvious causes of the atmosphere 

 being condensed by the cold of the night, and 

 rarefied by the heat of the day. 

 ^ The follov/ing observations deserve attention 



1. The least alterations in the mercury are to 

 be observed (especially in a showery time), 



2. The rising of the mercury, presages in gene- 

 ral, fair weather^ and its falling foul. 



