Prof. Dove's Outlines of a general Tlieory of the Winds, 237 



the wind does not veer towards the south. With regard to 

 S. and SW. winds no such definite rules can be given. In 

 genera], the barometer falls when the wind comes from this 

 quarter. If, however, it has continued for some time in this 

 direction, and especially if it has rained for some time, the 

 barometer again rises, although the wind continues to blow 

 from S. and SW. I also found the barometer to fall with a 

 N. and E. wind, if the wind came for some time from this 

 quarter, and the clear weather would change into dull and 

 rainy. 



10. Holland. This subject has been examined by Van 

 Swinden* more completely than by Luz. Horsleyf was the 

 first to demonstrate in a more definite manner the influence 

 already pointed out by Halley and Mariotte, of the direction 

 of the wind upon the state of the barometer, by calculations 

 made from a table showing the heights of the barometer for 

 every prevalent wind. The attention of Van Swinden being 

 excited by this, he proposed to himself the question, How 

 often does the barometer fall with a certain wind, how often 

 does it rise with the same? The results of his calculation are 

 a necessary consequence of the law of rotation. He finds in 

 the year 1779, that the barometer 



With 



In the three preceding years, he had obtained with regard 

 to W., NW., N., and E., SE., S., results coinciding with 

 the above ; but, on the contrary, deviations with regard to 

 NE. and S W. These solstitial points then appear here quite 

 as definite as those of Luz. It does not appear from any ex- 

 pression of Van Swinden that he was acquainted with the law 

 of rotation ; and it is on that account that Saussure, in his 

 Hygrometrie y asks, " Why do the east winds, although cold 

 and dry, generally cause the barometer to fall in England and 



* Memoires sur les Observations Meteorologiquesfaites a FrancJcer en Frise 

 pendant 1779. 



f An abridged state of the weather at London in the year 1774. Phil. 

 Trans, for 1775. 



