486 Meteorology. 
level of the sea is nearly 180 feet ; it is about 
100 feet above the level of the Duke of 
Bridgewater’s canal, and that is nearly 80 
feet above the sea. This elevation is rather 
greater than would be deduced from the ob- 
servations of the barometer for the last period 
of 15 years, in which the annual average 
height of the instrument is about 29.91. 
On the supposition that the average height of 
the barometer on a level with the sea is 30 
inches, my barometer would be inferred to 
be about 90 feet above the sea; but I con- 
ceive the real average height of the baro- 
meter on a-level with the sea has never been 
accurately determined. Possibly there may 
be some difference in the specific gravity of 
the mercury used for this instrument. 
~ During so long a period of years, there 
must have occurred interruptions to the ob- 
servations, but I never delegated any person 
to supply for me; these interruptions, how- 
ever, scarcely happened except in the month 
of July, when they have been very frequent 
for half of the month. These blanks, how- 
ever, have been filled up partly from the ob- 
servations: of Mr. Thomas Hanson “of this 
town, who has kept a meteorological journal 
with great attention, for several years, and 
partly from the observations of the Royal 
