206 | J. Orton on the Andes and Amazons. 
vations at Guayaquil were taken in July, i: at Para i ~—_ 
January with the same instruments. My barometric 
at Para may therefore be too high; but ides nae month test 
tion is unknown. t Havana the mean barometer in January 
is ‘200 in excess of the yearly mean, and the correction at the 
equator should be still greater ; but Dewey makes the Janu- — 
ary variation at Para ‘011 below the mean. His mean in July 
is 30°020. We need an extended series of observations at 
Guayaquil and Para. If we take Dewey’s annual mean at Pari, 
29-941 and 35 ft. as the altitude, the barometer at the Atlantic 
level would stand 29°977. But ‘this makes the Atlantic full 
40 ft. below the Pacific. Moreover, if Para is 35 ft. above the 
Atlantic, the fall of the river is nearly 41 inches per mile, — ‘ 
is also absurd, The rate cannot be far from two inches. 
would make the fall about fifteen feet and the barometer at the : 
Atlantic 29°932. 
Slope and current of the Amazons. 
: Distance. | Fall. | Ce 
Napo village to the Marafion, 600 miles. 213 inches per mile 
cc “ >. Pigox 2800. « 62 . 
b) 
Tabatinga > 2 2000 “ 16 
“ 
Azevedo and Pinto made the fall from Tabatinga to to Pari, 
0:9; Castlenau made it a little more. LaCondamine assigns” 
the Amazon in general a slope of 6:3 in. per mile, which very 
closely agrees with my calculation. Herndon, who, 
his boiling apparatus, made Ega over 2,000 ft, high, d 
from this the descent of the Amazons “a little more ta : 
foot per oy which would about give it a current of 2} miles 
per hour !”* He remarks that the current increases ¢0 ra 
erably after the junction of the Madeira, He calls ay 
Pebas to Ega in November, and three below Serpa ™ Febr 
cae Bet the Peruvian navigators consider it from 3 to 3} : 
as between M. and Para, or 58 ft. 
teresting to compare the Amazons with other rivers : 
Rhone, fall 24-00 in. per mile; slope, 1' 18" 
Mississippi, “ 19-87 “ 6“ ¥ + 
Thames, ee “ “0757 
N ile, sc 6°5 3 66 0’ 21 
Amazons, “ 6°25 & “« 020" 
Ganges, “ 4° “ “ 0’ 13 
Ohio, - 4° “ « 918 
Herndon’s — are very singular. Compare the one 02 pose 
with one on p. 3 
zi “2 : i Se eee jp ae eet 
Witc cabin echinacea mee i a LE ar lly See pe a Ch i eT oe SP a, in onl SANE Far 
i wae 
r 1,000 miles, 1638 dee 
