2qS A TREATISE 



with sufficient confidence, that they did not direct 



or regulate the periodical diurnal fluctuation of the 



Barometer. 



By conceiving the wind, which in the month of 

 April is generally from some point in the south, car- 

 rying constantly along with it, in the different degrees 

 of velocity I have described (VIII.) different pro- 

 portions of light and heavy clouds, we may obtain a 

 tolerably just idea of the appearance of the sky at Cal- 

 cutta during that month. 



To express these different states, we have employed 

 in the record the terms clear, cloudy, and overcast. 

 When few clouds only appear, or none, which is sel- 

 dom the case at this season, the sky is said to be clear, 

 when the sun or stars shine through a number of 

 clouds the sky is said to be cloudy ; and when the sua 

 or stars do not appear at all, the sky is said to be 

 overcast. 



N B. As the record of observations from which these negative 

 propositions (VII. VIII. IX.) respecting the thermometer, the 

 state of the wind, and appearance of the sky are inferred, is volu- 

 minous, and would necessarily exclude from this volume of the 

 Researches matter that is much more interesting, it has been 

 considered sufficient for the object of this paper, to insert only 

 the opposite abstract, or Synopsis, of the observations made on 

 t v e Barometer. 



THE STATEMENT, 



XL 



The sum of my observations respecting the four 

 Periodical Diurnal Revolutions of the Barometer 

 which I have described, appears at one view in the 



preceding 



