BAROMETRICAL MEASUREMENTS. 
209 
In view of these measurements, Humboldt makes the following remarks : 
These measures, taken at different periods, vary from 1,700 to 2,600 toises; and, what is remarkable 
enough, the results obtained by geometrical operations differ more from each other, than those which 
were found by the barometer. It has, nevertheless, been extremely wrong to cite this want of harmony 
as a proof of the uncertainty of all measurements of mountains. Angles, the value of which is deter¬ 
mined by imperfect graphometers; bases that have not been levelled, or the length of which has been 
determined by the log; triangles that give an excessively acute angle at the summit of the mountain; 
heights of the barometer, without any notice taken of the temperature of the air and of the mercury; un¬ 
questionably are not means calculated to lead to accurate results. Of fourteen trigonometrical and 
barometrical operations above indicated, the four following only can be considered as true measurements: 
Borda, by trigonometry,_ 1905 toises. 
do by means of the barometer,- 1976 “ 
Lamanon, the same,_ 1902 “ 
Cordier, do _ 1920 “ 
HimboldVs Personal Narrative^ Vol. 1 and 2, in one. 
It is worthy of remark, that the mean of the five geometrical measurements made on land 
differs from the extremes by 422 and 493 toises, while the mean of the barometrical measure¬ 
ments differs from the extremes by less than 53 and 59 toises. It is remarkable, also, that 
Humboldt, after elaborate discussion with the details of the operations before him, should 
select but one geometrical result out of nine, and three barometrical ones out of four, as the 
most suitable to derive his mean from. It appears, also, that the range of the differences of 
the four measurements adopted as true ones, is 74 toises, or 3‘9 per cent of the whole eleva¬ 
tion. This justifies a remark made in an early part of this article, that the two barometrical 
results should be regarded as accordant; since the difference is only 2*4 per cent of the ele¬ 
vation of the summit above the lower station, which is more than one-third less than Humboldt 
considered consistent with reasonable agreement. 
The measurements which I have made, although by no means so numerous as could be 
desired, are sufficient to fix with considerable accuracy the position of that extensive tract of 
table land interposed between Lakes Ontario and Champlain. Racket lake, a beautiful sheet 
of water in Hamilton county, embracing a surface of probably twenty or twenty-five square 
miles, is situated near the geographical centre of it, and may be regarded as its summit, par¬ 
ticularly of that portion which lies west of the Adirondack mountains. The area of this tract 
is little, if any, less than 10,000 square miles ; embracing nearly the whole of Essex, Hamil¬ 
ton and Warren counties, the southern and western parts of Clinton, the southern half of 
Franklin, the southeastern angle of St. Lawrence and northern half of Herkimer counties. 
These estimates are founded partly upon my own observations, and partly upon information 
derived from other sources, and should therefore be regarded as vague approximations only to 
topographical accuracy. 
The natural features of this tract are prominent, and in some respects singularly interesting. 
The eastern division, commencing within a few miles of Lake Champlain, forms the base 
Geol. 2d Dist. 27 
