and their Causes. * 249 



' . Time is another measure applicable to the acquisition" of 

 beat, as it increases to the greatest pitch which a body is 

 m capable of receiving in proportion to its continuance: the 

 land winds should therefore be cooler when they set in at 

 ten or eleven o'clock, and hottest at their termination in 

 the afternoon ; they should be so at least at noon, when 

 the sun is nearlv vertical, and has the greatest influence oti 

 the substances from which heat is to be attracted. The 

 contrary, however, comes nearest to the truth ; for it is 

 known that these winds set in with their greatest violence* 

 and heat at once, which rather abate than increase, as 

 might be expected. 



We should, on this principle, further suppose the heat 

 v/ould increase gradually with the return of the sun to our 

 latitudes, from its southern declination, and stand always 

 in proportion to its position. We find, however, that ex- 

 perience also contradicts this point of the theory under dis- 

 cussion; for after the sun has passed our zenith*, the land 

 ■winds set in at once with all their intensity, in the manner 

 before described, and they cease as abruptly before its re- 

 turn again f . 



A material change in the temperature of this climate is 

 certainly effected by the approach of the sun from the south ; 

 but the heat which is thus caused, and which increases 

 by imperceptible degrees, is never so great, and is only felt 

 by those who expose themselves to it unprotected; for the 

 air remains proportionally cool, and our houses afford, in 

 this season, a pleasant retreat. We find it far otherwise 

 in a land wind ; for this penetrates our inmost recesses, and 

 renders life miserable every where. 



I have before observed, that winds equally hot with those 

 of periodical duration are felt in all parts of the 'country, 

 and at different seasons; a circumstance alone sufficient, 

 if proved, to overthrow the groundwork of the old theory. 

 For a confirmation of this, I will appeal to the general 

 . observation, that immediately before a long rain the weather 

 fs sultry, and that a single shower is always preceded by a 

 warm disagreeable wind. 



We are very particularly reminded of the approaching 

 great monsoon in October by the oppressive'heat we have in 

 the calm evenings of that month, which, I am persuaded, 

 would equal that of the land winds in May, if the atmo- 



* The sun is in the zenith at Madras about the 2Cth of April, 

 f The sun is again in our zenith on its southern, declination about the- 

 J Oth oi Auguft. 



sphere 



