Geographical Collections. 367: 
Port between Arequipa and Puno, known by the name of Los Altos 
de Toledo, - - = P - - * - - 15,530 
Do. of Guatillas, foot of the volcano of Tacora, = * = 14,830 
Eastern Chain. 
Port between the town of La Paz and the province of Las Yungas, 
“named E/ Pachete de Pacuani, - < - - : 15,2351 feet. 
Do. on the road of Cochabamba to Oruro, between Tapacari and 
Challa, named E/ Passo de Challa, - - - - - 14,830 
We will not enter here, then, upon the question, whether by other means than 
the comparison of the mean height of the cols or ports, we might not obtain a 
better idea of the mean height of the crest. It is sufficient for us that this is the 
plan adopted by the learned physical geographer Baron de Humboldt, though, as 
that gentleman himself remarks, it is an abstract idea, and indeed rather vague, 
when there is grouping of mountains and not a continuous chain. 
The mean height of the crest of the Western Chain, or 15,195 feet, subtracted: 
from the maximum of crest or culminating point, 22,000 feet, would leave a pro- 
portion of 1 to 1.3, while the eastern chain would give 
Mean height of the ports, - - - 15,030 feet. 
Culminating point (m,) — - = : - 25,200 
Crest (n,). - - - - - - 10,170 
MP BUb 8 Blk eS 
which is nearly the same relation as the one bears to the other in the Alps of 
Switzerland. These results would differ very much from those of De Humboldt, 
who finds n:m::1:1.8, and would augment the progressive relation in which 
the Andes stand with respect to the Himalaya mountains. The sum of the 
two means would give 8537 feet for the height of the crest of the Andes of Peru, 
while for the same chain in Mexico, de Humboldt gives 1850 toises. 
Fiesult of the Levellings carried on across the Isthmus of Panama, to ascertain 
the relative height of the Pacific Ocean at Panama, and of the Atlantic at 
the mouth of the rwer Chagres. 
Mr. Lioyn having received from General Bolivar a special commission to 
survey the isthmus of Panama, with the view of ascertaining the most eligible 
line of communication between the two seas, arrived at Panama in March 1828. 
Here he was joined by Captain Falmarc, a Swedish officer of engineers in the 
Columbian service. Anxious to lose no time in the prosecution of their objects, 
they proceeded on the 5th of May to commence their operations ; resolving not 
to be deterred by the difficulties likely to arise from the rainy season, which had 
just set in, from personal privations, or even from the daugers to which they 
might expose their health. Their line of survey commenced at Panama, and 
was continued along the road to Porto Velo, till it came to the bed of the Cha- 
gres, a river which falls into the Gulf of Mexico. The greatest height passed 
ever in this line was 633.32 feet above the level of high water at Panama. Their 
constitutions were now beginning to suffer from the continued exposure to rain. ; 
and they therefore determined, after building a secure station on the,banks of the 
Chagres, to defer all future operations till the ensuing year, when the dry season 
should commence. On the 7th of February 1829, they resumed their labours, 
earrying on their levels from a point of the river below their former station, and 
152.55 feet above high-water mark at Panama, along the course of the river to a 
_ place distant about twelve miles from its mouth, called La Braja, where the wa- 
ter in dry seasons is very brackish, and from which there is no perceptible current 
to the sea. 
The result of this survey fixes the mean height of the Pacific at Panama at 
