116 Mr. Colebrooke’s Meteorological Observations 
tances to be discarded, in seeking causes, which are in perpe- 
tual activity, for effects which are unceasingly manifested. The 
questions are comparatively simple: but, being well determined, 
they may assist wider researches, where subjects of inquiry are 
more complex. 
On this account, meteorological observations, taken in the 
middle Atlantic, where the trade-winds constantly blow, may 
be considered useful, as tending to ascertain, not only the 
reason of their constancy, but likewise mediately the cause of 
periodical and variable winds elsewhere. 
In like manner the marked prevalence of fair weather within 
the limits of the trade-winds, and the contrasted frequency of 
rain in the tract which intervenes between their range, lead 
to remarks which may go to elucidate the theory of rain and 
of clouds, and lay grounds for general inferences in promotion 
of meteorological science. 
With such views, I was desirous of using the occasion, 
which a voyage afforded to me, for making observations ; and 
among the divers objects to which my attention was directed, 
the topic, which has chiefly engaged me, has been the hygro- 
metric state of the atmosphere above the sea: a subject not 
much pre-occupied. The result is here given in a tabular form 
of diary ; to which a few remarks will be prefixed. 
The main observation for each day was taken about sun-rise, 
which is considered to be a favourable time, giving nearly or 
precisely the temperature of the night, yet unaltered. Another 
observation was commonly set down for noon, being taken at 
that time, or soon after it. Divers observations, at different 
hours of the day, are noted according to circumstances. They 
were in general frequently repeated; but, for brevity’s sake, 
have been passed over, when no notable change nor deviation 
was remarked. . 
Equal diligence was not always applied to note the variations 
of the thermometer and hygrometer throughout. _ The subject 
of hygrometry was not taken up till the voyage was somewhat 
advanced: and I did not satisfy myself, until further progress 
