$28 . Mr. Bowditch’s estimate of the height of White Tiils. 
The mean of the 26 observations made at Adams, on the 28th of 
July, gives Barometer 29°11 inches, Thermometer 76°3. The mean 
of Dr. Hoiyoke’s observations in the same day is, Barometer 30°15 
inches, Thermometer 76’3. The observations of Mr. Emerson, who 
was probably situated a little higher above the level of the sea, than Dr. 
Holyoke, did not differ sensibly from these. Computing from these 
observations the elevation of Adams above Salem (by the rule given 
in Dr. Maskelyne’s introduction to ‘Vayior’s logarithms) it becomes 
980 feet. The observation of July 27, calculated in the same way, 
gave 965 feet. As there were 26 observations on the 28th of July, 
and but one on the 27th July, the mean of all will be nearly 979 fect. 
To thisadd 34 feet, the height of Dr. Holyoke’s barometer above the 
level of the sea, the sum 1013 feet, is the elevation of Mr. Messervey’s 
house in Adams, above the level of the sea. Dr, Belknap estimates 
this height to be Spee 3000 feet, which is about three times its real 
value. 
By comparing the observations made at the top of Mount Wash- 
ington, viz. Barometer 23°39 inches, and Thermometer 54 degrees ; ; 
with the mean of the observations at Adams at the same time; Barom- 
eter 29°13, Thermometer 84°8; the result is 6149 feet for the differ- 
ence of elevation of these two places. To this add 1013 feet, the 
height of Adams above the level of the sea, and we have the height of 
Mount. Washington above the level 7162 feet. This estimate may 
also be made by comparing the observations at Mount Washingto™ 
with those made at Salem at the same time, viz. Barometer 30° “115 
“inches, and Thermometer 82 degrees, which give 7021 feet, to whic 
add 34 feet (the elevation of Dr, Holyoke’ s barometer) and we have 
7055 feet, for the height of the mountain. The mean of this and the 
former estimate is 7108 feet, which may be assumed as the elevation 
of the summit of Mount Washington, above the level of the sea- 
