No. 50.] 
343 
ed by imperfect graphometers ; bases that have not been levelled, or 
the length of vi^hich has been determined by the log ; triangles that give 
an excessively acute angle at the summit of the mountain ; heights of 
the barometer, vv^ithout any notice taken of the temperature of the air 
and of the mercury ; unquestionably are not means calculated to lead 
to accurate results. Of fourteen trigonometrical and barometrical ope- 
rations above indicated, the four following only can be considered as 
true measurements : 
Borda by trigonometry, 
" means of the barometer, 
Lamanon, the same, 
Cordier, do 
1905 toises. 
1976 " 
1902 " 
1920 " 
Humboldt's 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 measurements 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 geome- 
trical result out of 9, and three barometrical ones out of 4, as the most 
suitable to derive his mean from. 
It appears, also, that the range of the differences of the 4 measure- 
ments adopted as true ones, is 74 toises, or 3 . 9 per cent of the whole 
elevation. This justifies a remark made in an early part of this arti- 
cle, that the two barometrical results should be regarded as accordant ; 
since the difference is only 2.4 per cent of. the elevation of the summit 
above the lower station, which is more than one-third less than Hum- 
boldt, considered consistent v/ith reasonable agreement. 
The measurements which I have made, although by no means so 
numerous as could be desired, are suflacient 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 20 
or 25 square miles, is situated near the geographical centre of it, and 
ma}^ be regarded as its summit, particularly of that portion which lies 
west of the Adirondack mountains. The area of this tract is httle, if 
any, less than 10,000 square miles ; embracing nearly the whole of Es- 
