PHILOSOPHICAL 
T RANSACTIONS. 
IX. Abstract of Observations on a diurnal V ariation of the 
Barometer between the Tropics. By J. Horsburgh, Esq. In a 
Letter to Henry Cavendish, Esq. F. R. S. 
Read March 14, 1805. 
SIR, Bombay, April 20, 1804. 
W hen I was in London at the conclusion of the year 1801, 
I had the pleasure of being introduced to you by my friend 
Mr. Dalrymple, at which time he presented you with some 
sheets of meteorological observations, with barometer and 
thermometer, made by me in India, and during a passage 
from India to England. 
Being of opinion that few registers of the barometer are 
kept at sea, especially in low latitudes, I have been induced to 
continue my observations since I left England, judging that, 
even if they were found to be of no utility, they might at least 
be entertaining to you or other gentlemen, who have been 
making observations of a similar nature. 
During my last voyage I have employed two marine 
mdcccv. A a 
