180 MARINE BAROMETER, 



Observations believe this extends to both hemispheres, and all climates. The 



and inferences wind from SE then, which combines something more than half 



correspondent the power, both of the south and of the east wind, will raise 



changes of the mercury higher than any other on the south side of the 



^'g"'^ J"'J,J^^_" equator, and the wind from NW permit it to fall lower, inde- 



pected after pendantly oftheir effects as sea and land winds; and this al- 



change in the Jo^ance requires to be first made upon them : the south-west 

 marine baro- , , ' , , , , , , , ■ , , 



meter. aud north-east quarters should be equal where there is no land 



in question, and of a medium strength between the power of 



the south-east, and the deficiency of the north-west wind. 



I leave it wholly undetermined, whether ihe efTectsof sea and 

 land winds upon the barometer, as above described, extend 

 beyond the shores of the country where these observations wer« 

 made, and to about one hundred leagues of distance from them ; 

 but it seems not improbable, that they may be found to take 

 place near the shores of all countries similarly circumstanced; 

 that is, upon those which are' wholly, or for the most part,, 

 surrounding by the sea, and situated within the fortieth degree 

 of latitude. In colder climates, where snow lies upon the, 

 ground during a part ofthe year, the wind from off the land may 

 perhaps be so cold, and the air so much condensed, as to pro- 

 duce a contrary effect ; but this, and the prosecution of the 

 subject to other important consequences, I leave to the philo- 

 aopber ; my aim being only to supply my small contribution of 

 raw materials to the hands ofthe manufacturer, happy if he can 

 make them subservient to the promotion of meteorogical 

 science. 



I will conclude with stating a few general remarks upoa 

 the barometer, such as may be useful to seamen. 



It is not so much the absolute, as the relative height of the 

 mercury, and its state of rising and falling, that is to be attended 

 to in forming a judgment of the weather that will succeed ; 

 for it appears to stand at different heights, with the same wind 

 and weather, in different latitudes. ' • 



In the open sea, it seems to be the changes in the weather, 

 and in the strength of the wind, that principally affect the. 

 barometer ; but near the shore, a change in the direction of 

 the wind seems to affect it full as much, or more, than either 

 of those causes taken singly. 



It is upon the south and east coasts of any country in the 

 southern, or the north and east coasts in the northern hemi- 

 sphere 



