The New York herald., 1877-09-01
THE DARIEN SHIP CANAL.

coMMANpHR sELrRIDoE's SURVEYS EXPLAINED
BY HiMsELF.
NEWPORT, r. l., August 80, 1877.
To EDlroR THE hERALD:-
Your issue Of August 20 contained long aud inter-
esting article upon the subject of the ship canal be-
tween tho Atlantic aud Pacific oceans, but devoted
chiefly what known the San Bias route. There
several errors however, In the article which bear
80 directly upon me that am constrained TO notice
them. and ask that you will give the correction room
In your valuable columns In the first place, would
impress upon all the important feature OF my
surveys upon tho Daricn Isthmus. That is,
water seeking always It's lowest line; the lowest line
0f depression, wherever 1t may be, will be
found In the water that dram the region be
surveyed. Also another cardinal point is that when
the survey of line after careful examination gave
Indications OF obstacles incompatible with the further
prosecution Of such particular line 1t abandoned
and deemed impracticable. Without such a plan
being followed, striking out Wildly into the impene-
trabo of tropical forest, 1t would require
survey OF ship canal the length and breath of
the Darien lsthmus period not less than generation
Governed by tnese principles challenge the fact that
no party IN the future hnd a point possible for
this canal the line OF the Panama Railroad TO
Qulbdo, 200 miles south the Atrato River, COM
prisng the whole length OF possible ground that has
not been visited and thoroughly reconnoitered by
parties under my command, excepting the Truando
line, which was surveyed by a United States expcdi
ton under Craven and Mchler
NArIPI LINES
The article in question states 'he Truando line
is shorter than the Nappi." This is a mistake The
Nappi is the shorter, which easily be verified by
measuring the surveyed Iinss Of each route. Again
It s stated severa partial surveys were made between
Caledonia Bay and the Gulf oil San Miguel" These
surveys were not partial, but complete, and included
every depression IN that locality which was deemed
desirable explore a stay OF two months In that
vicinity. Finally, the article speaks OF the survey OF
the San Bias route by Mr.. Kelly having been u
plete from ocean TO ocean, while il seeks 10
sirongthen TINS survey of Mr Kelly by belittng .he
work done by tho United States government, whose
survey under my charge is termed guess work. Upon
placed The field works OF his engineers at disposal,
and McDouga, the principal engineer bong dead, had
prominent engineer connected with the Eric Canal
These field books indicate that Mr.. Keliy's engineers
did carry their level ACROSS the divide TO tdcwaer
tho Atlantic as he claims, but stopped short
tance from the summit on the Pacific slope They
small and the Atlantic coast and Indians would not
permit them to proceed further. However, the
character of Mr. KclIy's engineers was sufficient
guarantee of their work for me as far as /. went;
ana knowing too, that the routo thcy took on
the Pacfhc side Nhe Valley OF the harmonD
the only practicable lnc l doomed it only
desirable TO give the Atlantic slope thorough,
partial, survey, then TO the bes, of these
over the divide to a known point Mr. Key's nne
For this purpose separate and dstiuct lines OF
levels also one additional Ia barometrical recon-
nolssance) were run up the four depressons from the
Atlantic shore to the divide and tue most favorable
connected with the Pacific survey of Kelys ut point
known Buffers Greek.
THE ATLANTIC COAST
The position of base line the Atlantic coast
was fixed by thorough observations OF the transit and
zenith telescopes by Assistant Mossman OF the coast
survey beyond a doubt These observations deter
mine. tnat the Atlantic coast line three miles TO
the ward, in other words, the breadth oil tho
sthmus AT San Bias Is three miles greater than as
measured on the chart THIS fact. which Mr. Kelys
engineers could not have been expected TO KNOW may
have caused them to make their report OF tunnel
miles ls fatal objecuon TO a ship canal Is not my
province at tins time 10 discuss The article further
states that Tor some reasons not specified by Com
mandor Selfrdgc he differs from McDougal In the
length of tunnc;'' also, "had the survey been
thoroughly made shoue have mad sonnet thing more
definite TO judge whether McDougals length OF tunnel
Was correct;' also, "We may confidently believe that
McDouga is right as that sefridge did not 60 on the
Pacific slope"
From what has been read IL will bo that my
report Of the San Bias route Is based upon complete
and correct line OF levels Mr. Kellys levels OF the
Pacific slope (which with more courtesy than he has
shown for mel are correct, which l cheerfully be-
lieve Also, that complete and exhaustive survey
OF the route points the divide made, aud
also, that we may not confidently believe hat
McDousa Is right, because his line Of Levers ended
tho middle OF the lsthnus. Furthermore, Commander
Selfdge did not judge the San Bias impractical
but because careful survey Of this line demonstrated
that no line could be found that would require
mel less than ten miles IN length.
The various routes across the 1sthmUs mapped
out and discussed n my report issued by Congress and
to be found ia most public libraries Persons inter-
ested IN the subject VIII find there full details OF the
different routes aud the reasons Tor regarding them
impracticabe.
II has very difficult in this short space to make
survey Of the San Bias route clearly understood
and in closing wish to add that Mr. Kellys praise
worthy energy and zeal his work the Isthmus Is
appreciated by no one more highly than myself.
THOMAS o. SELFRIDGE, Jr.
Commander. United States NAVY.