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Though this fcience has been cultivated with much ardour 

 in many parts of Europe ever fince the difcovery of the gravity 

 of the fluid that furrounds us, it muft be owned very little pro- 

 grefs has hitherto been made in it. In every other branch of 

 phyfical fcience from a knowledge of the caufes we are enabled 

 to forefee the efFeds ; but from a knowledge of the actual flate 

 of the above mentioned properties of the atmofphere, who can 

 with certainty forefee what it fhall be the next day ? 



The obftacles which originally obftruded all advances in this 

 fcience were, 



i^. The want of proper inflruments to meafure the proportion 

 or quantities, whether of moifture in the atmofphere, or of its 

 weight, or its temperature, its denfity or its eledricity. 



2"^. The want of general ilandards to which, as to their pro- 

 per units, the fever^l degrees of each property may be referred. 



3**. Interruption of the obfervations of the ftates of the atmof- 

 phere, by reafon of which their connexion muft remain unknown. 



4°. As the adual ftates of the atmofphere are intimately con- 

 neded, not only with the preceding, but with the contemporary 

 ftates in different and moft diftant parts at leaft of the fame he- 

 mifphere, the negled of comparing either of them, as far as 



they 



