TYPHOONS. 
65 
A change of weather also followed the variations of the baro- 
meter, however inconsiderable. Its rise like that of the hygrometer 
usually indicated northerly winds ; a fall of four lines was followed by 
rain ; and a fall of a tenth of an inch, by thunder and lightning. 
The many accounts I had heard of the dreadful effects of Typhoons, 
induced me to collect such particulars respecting them, as I could ob- 
tain from some gentlemen of the East-India Company’s service, who 
had witnessed them. My enquiries were directed to the state of the 
barometer, and of the atmosphere, previous to their approach, and 
during their continuance ; to the influence which the moon might 
exercise over them, during her changes ; to the extent of latitude 
and longitude through which they have been known to occur ; and 
to the seasons of the year in which they were most frequent. I 
gathered the following information from the answers I received. 
The mercury in the barometer falls slowly for several hours before the 
commencement of the Typhoon, descends during its continuance below 
27 inches, and its re-ascension is a sure indication that the storm is 
subsiding. These barometrical movements are not accompanied by 
any constant atmospherical changes. The storms occur more fre- 
quently during the changes of the moon than at her full. They 
seldom prevail below 10° N. Lat. or beyond the tropic of Cancer. 
They are felt as far as 130° E. Lon., and are most violent in the 
China seas during the S. W. monsoon, especially in the month of 
July. It is also stated that the wind is most violent when it blows in 
the direction of the monsoon, but that it also blows strong from all 
points of the compass, through which it is continually shifting ; 
but before the commencement of the gale is generally light. 
The state of the thermometer has been little attended to either 
before or during its continuance, and that of the hygrometer still 
less ; it appears, however, that the air feels very cold during its preva- 
lence, and that it is frequently accompanied by storms of thunder and 
lightning, with heavy fails of rain impelled in a horizontal direction. 
It is much to be regretted that a full account of the phaenomena 
of Typhoons has not yet been given by those who have often expe- 
