PROGNOSTICS CONTINUE*. J05 



PROGNOSTICS CONTINUr.D. 



1. " A d<irk, thick sky, lasting for some time- 

 without either sun or rain, always become first 

 fair, then foul, i. e." Changes to a fair, clear sky, 

 before it turns to rain. Tirsthe Kev. .'r. Clarke, 

 who kept a register of thj weather for thirty 

 yt-ars, since put into Mr. Derham's hands, hy his 

 grandson, the learned Dr. Samuel Clarke : this r 

 he says, he scarce ever know to fiil ; at least 

 when the wind was in any of the easterly points : 

 but Mr. Dei ham has observed the rule to hold 

 good, he the wind where it will. And the cause 

 is obvious : the atmosphere is replete with va-? 

 pours, which, though sufficient to reflect and in- 

 tercept the sun's rays from us, yet want density 

 to descend ; and while the v ..pours continue in 

 the same state, the weather will do so to. 



Accordingly, such weather is generally attend- 

 ed with moderate warmth, aiid with little or no 

 wind to disturb the vapours, and an heavy at- 

 mosphere to sustain them, the barometer being 

 commonly high. But v hen the rold approaches, 

 and by condensing, drives the vapours into 

 clouds or drops then way is made for the sun- 

 beams; till the same vapours being, by further 

 condensation, formed into rain, fail down into 

 drops. 



2. " A change irr the warmth of the weather, 

 is geneally followed by a change in the 

 wind." Thus, the northerly and southerly 

 winds, commonly esteemed the causesofcolduiut 

 warm weather, are really the e-lecis of the cold 

 or warmth of the atuvosphe'e : of which Mr. Der- 

 haiu assures us he has had so many contimia- 



