430 Mr. Six’s Experiments to inveftigate 
At the time of taking thefe thermometrical obfervations, I 
likewife noted the different difpofitions of the atmofphere in 
other refpeéts: fuch as the preflure, moifture, and drynefs of 
the air; force and direction of the winds; quantity of rain ; 
whether the appearances of the fky were clear or cloudy, &e.. 
as I apprehended the local variation of the thermometers might, 
in a certain degree, correfpond with fome particular change in: 
the ftate of the atmofphere. 
The event anfwered my expectation in a fingular manner 
in refpect to the nocturnal variation ; for it generally happened, 
that when the {ky was dark and cloudy, whatever was the con- 
dition of the atmofphere with relation to the other particulars 
above enumerated, the thermometers agreed pretty nearly with 
each other; but, on the contrary, whenever the fky became 
clear, the cold of the night at the loweft {tation im the garden 
con{tantly exceeded the cold at the top of the Cathedral tower, 
where the inftrument was placed 220 feet from the ground, 
entirely expofed to the open air, wind,.dews, and rain, in 
a fhady northern afpect. 
The local variations in the day-time feemed to be regulated 
by the general degree of heat only, without being affected by 
any other particular difpofition of the atmofphere, or the clear- 
nets or cCloudynefs of the fky, as the nocturnal variations were. 
In the month of September, when the glafles rofe from 60° to 
-a°, the heat at the lower ftation conftantly exceeded the heat 
at the upper ftation; and in fome meafure proportionally, as 
the weather was hotter *. In December and January. when 
* Asthe heat at the lower ftation exceeded the heat at the upper ones, when 
the weather was hot; and equally fo, whenever the fky was cloudy, as well as 
when it was clear; it appears, that the glafs at the lower ftation was not mate- 
rially affected by the reflection of the fun’s rays from the earth, as at firit F 
apprehended % would be, 
from 

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