THE BAROMETER AND ITS USES. 



91 



THE BAROMETER. 



THE PRACTICAL USE OF THE BAROMETER TO FARMERS AND OTHERS, WITH RULES 

 FOR PREDICTING THE WEATHER. 



The proper use of the Barometer as a 

 means of judging of the weatlier is not gen- 

 erally known, or its great practical value 

 would be more extensively appreciated, more 

 especially by fanners. It is only necessary 

 to be well acquainted with the nature of its 

 indications to form a tolerably good, and most- 

 ly a correct, estimate of the impending wea- 

 ther. For this purpose, it is here proposed 

 to embody the most approved rules relative 

 to the Barometer ; and it may be remarked 

 that if all persons, aftected in any way by 

 changes in the weather, will but considt their 

 Barometer daily, they will soon be sensible 

 of the great advantages derivable from such 

 practice. 



It should be first be well understood that the 

 principal critei-ion of the kind of weatlier to 

 be expected is the relative motion of the 

 mercury in the tube, and that its absolute 

 hight is only of secondary importance, when 

 atmospherical changes are to be anticipated. 

 Tlie words engraved on the register-plate 

 should not be much regaided, as they cannot 

 always be relied upon to correspond wath 

 the state of the weather, and in i'act, would 

 show different indications at the top and bot- 

 tom of a lofty iiouse ; but much greater de- 

 pendence may be placed in the lising and 

 falling of the mercury. For this reason the 

 words are more deserving of notice when the 

 mercury has just moved from " Changeable " 

 upward or downward. 



The absolute hight of the mercury is a 

 safe prognostic when it is unusually high or 

 low, and the following observations upon it 

 may frequently be fouud to be extremely ser- 

 viceable : 



1. All appearances being the same, the 

 higher the Barometer i.s, the more likely is 

 the weather to be f;nr. \Vhen the Barome- 

 ter is high, it will be found that very dark 

 and dense clouds pass completely over, and 

 that there is very little probability of imme- 

 diate rain. 



2. When the Barometer is low, it some- 

 times rains almost without any appearance of 

 clouds ; and though the sky may seem to 

 promise fair weather, it may be depended 

 upon that the appearance will not continue 

 long : the face of the sky changes very sud- 

 denly on such occasions. 



Also, when the Barometer continues low, 

 there is seldom much rain, though a fair day 

 is very rare ; the general character of the 



(187) 



weather at such times is short, heavy, and sud- 

 den showers, with squalls of wind from the 

 W., N. VV. or S. \V. 



3. The Barometer is highest of all during a 

 longfi-ost, with a N. E. wind; and it is low- 

 est of all during a thaw following a long frost 

 and accompanied by a S. W. wind. 



4. In all places nearly on a level with the 

 sea, rain may be expected when the mercury 

 falls below 30 inches. 



To judge rightly of the changes to be ex- 

 pected in the weather, we should especially 

 ascertain whether the mercury is actually 

 rising or falling. This will be always seen 

 by regularly adjusting the index of the Ba- 

 rometer; or, we may observe^l. If the sur- 

 face of the mercuiy Jdo convex, standing high- 

 er in the middle of the tube than at the sides, 

 it indicates the rising ; if the surface be con- 

 cave, it is falling; and if it appear level, the 

 mercuiy is stationary. 2. If, on shakmg or 

 ra])piiig the Barometer, the mercury ascenda 

 higher than it stood before, it indicates the 

 rising; but if it descends, it indicates the 

 falling. 



The following rales have been laid down 

 and amply confirmed by long-continued ex- 

 perience, and may be generally relied upon : 



1. Tlie risuig of the quicksilver generally 

 presages fair weather ; the fallhig generally 

 indicates rain, snow, and if the iilll be great, 

 high winds and stonns. 



2. \Vlien bad weather quickly succeeds the 

 falling of the mercuiy, it will not be of long 

 continuance. Similarly, when fair weather 

 soo7i follows the rise of the quicksilver, we 

 must not calculate on its continuance for any 

 length of time. 



3. On the contrary, if in bad weather, the 

 mercury rises considerably, a^id continues in 

 an advancing stiite for two or three days be- 

 fore the fair weather sets in, we may expect 

 a continuance of fiiir weather. And if, iu 

 clear weather, the mercury fall remarkably 

 for two or three days together before the raiii 

 sets in, it is then highly probable that it will 

 be succeeded by much raui, and perhaps liigh 

 winds. 



4. In winter, the ri.sing bid icates frost ; and 

 in frosty weather, if the mercuiy falls three 

 or four divisions, there will certainly follow 

 a tliaw ; but if it rises in a continued frost, it 

 will always be accompanied with snow. 



."J. In hot weather, the sudden falling of the 

 mercuiy portends thunder. 



