5$ - BAROMETRICtJ, CHANGES. 



ever/ view inconfidqrable, and their coincidence on the 

 whole, not a liitle fingular. The variations in Dr. Bal- 

 four's barometer between the neareft maximum and maximum 

 is fometimes about ^^ of an inch, though in general coniider- 

 ably lefs. 

 Whether the 1" ^^i^ abftraft of Dr. Balfour's obfervations referred to 



caafe which pro- above, it is remarked, that it feems not improbable that thefe 

 fta'^wiii" could variations of the barometer are conne6led with the recipro- 

 produce the re- cations of the fea and land winds during the day and night. 

 gu ar change, g^^. ^,|-,afgygj. ^^y ^^^^ h^Qw formerly the probability of this 

 fuppofition, it is entirely deflroyed by the obfervations of the 

 — moft probably French navigators. Thefe obfervations were made too far 

 '*°^* out at fea to leave room for fuppofing that the land winds had 



—neither is it a^y influence on the phenomena to which they refer. It is 

 likely that it at the fame time doubtful, whether thofe phenomena can be 

 tides in the air, afcribed to the atmofpherical tides produced by the fun and 

 as it does not moon, as the ebbing and flowing of the mercury in the baro- 

 foUow the moon. ^ ^, jj xLi-i.- c 



meter appears to have no dependence on the pontion or 



thofe luminaries relatively to one another, but happens, it 

 would feem, conftantly at the fame hour, in all afpeds of 

 the moon and all feafons of the year. The fubje6t is well 

 deferving of a fuller inveftigation. We fliould probably 

 before now have had farther information refpeding it, if 

 happily the able navigator above-named, and his brave aflb- 

 ciates, had been declined to revifit their nativ,e (bores. The 

 cruel fate of an expedition fo well planned, and fo well ap- 

 pointed for the purpofes of fcience, will never ceafe to be 

 matter of fincere regret. 



Jnnotation. — W, N. 



Probability-that I have inferted the foregoing with a view, in fome meafurei- 



the equi-tro- j^ afford a comparilon with Mr. Horlburgh's paper on the fame 



pical change iS- ^ . oir 



caufed byafcend- 'ubjed, at page 1 6. It is not without diffidence that I venture 



ing ar.ddefcend- 1^ propofe a coniedure on this fubieCl, which in fa6l requires 



ihe aimofpherc. '"^''^ conhderatjon than I can, at prefent, beftow on it. Its 



change feems to me to be governed by the afcent of the air 



which would take place immediately beneath the fun, if the 



earth were ftationary, and the furrounding defcent of theTame 



fluid, of which the circuraftances and modifications are fo w^ll 



^ explained 



