The sun., 1901-12-30
TIE PANAMA SIDE or Ir.
Gen. II. l.. Abbot's Summary OF Conds-
tions on the Darien Route.
From Me Engineering Magazine.

rUuCIOfl o n iildil WI o'ifo'
possible route between tho oceans. Here
only three formidable difficulties were TO
be apprehended; the cut at the continental
divide. regulation Of the Chagres River,
and the tropical climate. Each will be
considered In turn
The deep cut at the Culebra has now quite
lost the ancient terrors which hung over
II in the closing days of the old company
The cutting at that date was in disinte-
grated materials near the surface, and
serious caving and sliding had occurred,
partly from natural causes and partly
from neglect to secure proper drainage.
The old company had made numerous
borings, and they have been multiplied
by the new company. with deep pits per-
mitting the material to be inspected to
the full depth adopted for the bottom Of
the canal; six million cubic yards have
actually been removed since the resumption
Of the work, so placed as 10 secure depth
rather than width. and thus To throw light
on future conditions; and lastly a tunnel
2iOo feet long and 2oxi3 feet in cross sec
ton has been driven at low level without
difficulty. at the point whore the worst slid
ing has occurred All the evidence thus
secured concurs in establishing the fact
that the dangerous material has already
been passed, and that future deep cutting
will lie chiefly in an indurated argillaceous
schist which stands we'll even on steep
slopes and in which caving Is not 10 be
feared.
II may be added that the remaining hea Wy
excavation is exaggerated in popular esti-
nation, and the fact is often ignored that
very large volume has already been taken
out. For example. the height OF the con-
tinental divide on this route il constantly
stated at its original figure. which on the
line of the axis of the canal was really 345
feet above tide. The bottom OF the cut
there has now attained a level Of i4s feet;
and this. rather than the historic height,
should be used in comparing the Panama
with the other routes. Moreover. the
length Of the deep cutting including the
Emperador and Culebra sections extends
over about only five miles. and the really
formidable cut over less than a mile. In
fine the old phantom Of sliding mountain
and an impossible continental divide has
been definitely laid at rest by the operations
Of the new company.
The problem Of the regulation Of the
Chagres River demended Investigations Of
the most elaborate character. 1t is a
stream having basin above Bohio Of about
700 square miles in surface. From this
point the canal and river follow different
routes to the sea, and at Ganboa, thirteen
miles above. they again separate. One
problem, therefore. was to provide for the
joint occupancy OF thirteen miles Of val
ley without allowing interference with the
canal in times Of river floods: another was
to determine with certainty whether the
river could lie made to supply sufficient
water for canal purposes under the demands
Of any probable prospective traffic.
The Chagres River Is characterized by
two distinct regimens. one corresponding
to the season Of heavy rains, from May
to December both included, and the other
to the dry season covering three OF tho
four remaining months Of the year. Dur
ing the former. the average discharge Is
about :. 900 cubic feet per second at Gamboa
and s 400 at Bohio, but 1t In subject 20 fire.
quent freshets in which the volume may
rise TO rs 600 or even 80 900 cubic feet, last
ing however only for an hour or two. Dur
the past quarter OF century, and so far
as can be determined by the records OF the
Panama Railroad during the past half of
only FIVE great floods have occurred.
In by far the largest Of them. that OF Sovem-
Der, 1879 the river carried a maximum
volume literally estimated at ii2 600 cubic
feet per second az Bohio. and at 5000 cubic
Get at Gamboa, but only during the period
Of two or three hours, The plans OF the
for regulating the floods are
based on the figures Of this year, which
are known TO be far in excess Of any other.
During the dry season the Chagree IL a
quiet peaceable strea'n with at Gamboa an
average discharge Of about 100 cubic feet
per second, and In years Of greatest drought
a minimum average Of $50 cubic fest Al
Bohio the latter IL about $50 cubic feet
tn. company has been careful to make its
rood estimates err. II at all, In e,oe-s. and
It's low-water estimates err. II AZ all, 10y
under valuation The provisions for river
regulation contemplate two great artificial
lake. one formed by a dam at Bohlo, ere
Atiug a lake having 80 square miles Of
.urfane and which Tor thlTteen miles will
form a br.d ~ the canal the other above.
on the. upT"f nv"i, fof storage ~ water water
any excessive food water 10 ho held hack.
60 h. discharged gradually aud thus r"n-
dar,-i harmless 60 ua aNigailun.
such a system 10 superior a. one immsuse
natural lake. l-slhtIss. un the American
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