VOL. LXX.] PHILOSOPHICAL TRANSACTIONS, 713 



selves; every thing is silent, and the aspect of the sky, whence the tornado 

 approaches, is most dreadful. A violent storm comes on all at once, which is so 

 cold as to occasion the thermometer to fall 7 or 8 degrees in a few minutes, and 

 is strong enough to overset negro huts and vessels, or drive the latter from their 

 anchors, and throw them on shore. The storm abates, and heavy rain follows, 

 accompanied with much lightning and strong claps of thunder. Sometimes 

 tornados happen without rain, or at least with very little; but then the storm is 

 more violent, and lasts longer. It has been imagined by some, that this kind 

 of storm brings some pestiferous quality with it, because they had observed, that 

 out of a number of people several fell sick in one night after a tornado. 



This Dr. S. in some degree experienced himself; for in September 1776, feel- 

 ing himself very well, and having dined as usual, the storm of a tornado sud- 

 denly tore down the window shutters, and blew into the room where he was: 

 about an hour after he had rigors, and in the evening he had a high fever, which 

 turned out to be a very severe bilious one; but notwithstanding this, it has, in 

 his opinion, no such ill quality, and the above phenomenon may be attributed 

 to the change it produces on the air, and of consequence on the body; it may 

 therefore be considered as the occasional cause of a disorder to which the body 

 was pre-disposed long before. 



The dampness of the atmosphere during this season is so great, that it is more 

 or less perceptible in every thing. Leather, wearing apparel, and books, become 

 mouldy; and polished metals rusty. Sea salt, sugar, and other saline substances, 

 which were perfectly dry before, melt; and the meat of cattle killed in the even- 

 ing is spoiled the next morning, so as not to be fit for use. Calms are very fre- 

 quent, and disagreeable on account of the musquetoes and other insects, which 

 then quit their retreats from among the mangroves and marshes, and spread over 

 the face of the country. 



The dry or healthy season begins commonly about the middle of October, and 

 lasts to the middle of July. It is called dry, because then it hardly ever rains, 

 or at least but very seldom; and healthy, in opposition to the sickly one; for 

 though pleurisies and peripneumonies will happen in the months of December 

 and January, and fluxes in the months of April, May, and June, few people 

 die; which, when compared with the numbers that die in the other season, jus- 

 tifies the denomination. When the rains cease, the wind shifts its quarter, and 

 is for the most part east or north-east in the morning; but as the sunrises on the 

 horizon, the wind changes more and more towards the north, till about noon, 

 sooner or later, it gets to the west of north, which is called sea-breeze, and is 

 very refreshing, though it happens sometimes, that as the sun falls again on the 

 horizon, the wind will return towards the east, and continue there all night. 

 This wind blows sometimes very strong, and is always excessively hot, ilrying up 



VOL. XIV. 4 Y 



