August 20, 1885 | 
NATURE 3 
considerable depth the rock takes the form of schists in 
horizontal strata. There is no doubt that it can be cut 
through with rapidity ; it is a matter of perforation, either 
by mining and ordinary explosives, or by shafts with 
larger quantities of some explosive to displace great 
masses. Here 30,000 cubic metres of rock have been 
displaced by an explosion of dynamite ; and unquestion- 
ably this colossal channel connecting two seas may be 
executed by simple methods and with economy. 
At the end of the great cutting of Culebra, 6 kilo- 
metres from Emperador, is the great workshop for the 
dam across the Chagres. This gigantic basin, containing 
about 1,000,000,000 cubic metres of water, the surface of 
which is 60 metres above the water of the canal, has a 
bank, the content of which is 7,000,000 cubic metres. 
The volume of water kept in by this exceeds a hundred- 
fold that of any reservoir in the world. By means of 
this work inundations in the river are prevented, currents 
impeding navigation and introducing rough water into the 
canal are avoided, and there is no fear of the accumulation 
of alluvion in the bed. By regulating the flow of the 
Chagres and of the neighbouring streams, the dam at 
Gamboa assures the regular service of the canal. The 
method of constructing this work of proportions without 
precedent in the annals of public works is a very simple 
one. From the great cutting at Culebra, near Gamboa, 
and the neighbouring cuttings, about 50,000,000 cubic 
metres of rock are removed, while only about 7,000,000 
are required for the Chagres dam, and therefore the work 
is one of transport only—a colossal one, it is true. Even 
the site of the dam is formed naturally by the disposition 
of the bed of the torrent, which is contracted at this place 
between the hills of Obispo and Santa Cruz, which are 
distant about 150 metres from each other, and on which 
will rest the front wall of the great reservoir. Behind this 
first barrier will be thrown, as they are taken from the 
Cordillera, the 7,000,000 metres of rock, and the dam will 
be complete. The originality of the project is that, strictly 
speaking, there is no masonry at all in this enormous mass 
of rock of all sizes and shapes; the accumulation alone 
gives the mass firmness. The plan given here enables 
us to follow the sinuous course of the Chagres River. 
Like all torrents, and especially all torrents in equatorial 
regions, it is subject to considerable variations in its flow, 
and to enormous and violent floods. In winter its flow 
is 1600 cubic metres per second, while in spring it is 
barely 13 metres. Its tributaries, or 7zos, are of the same 
character—the rio Trinidad and the rio Gatuncillo have a 
flow in winter of 400 cubic metres. It would be imposs- 
ible to divert these impetuous masses of water into the 
canal without producing currents and deposits and im- 
peding the navigation. The overflow of exceptional 
floods will be conducted to the sea by secondary water 
courses. These latter, which vary in breadth from 8 to 
12, and even to 40 metres near the Atlantic, are easily 
made by utilising the portions of the bed of the river 
situated on the same bank, and connecting them by 
appropriate trenches. The enormous reserve behind the 
dam will flow regularly in this new bed. Of course, the 
bed of the canal will be completely protected from these 
deviating waters, in the trenches by the slopes of the 
latter, and in the lower parts by banks which will soon be 
covered by a vigorous and indestructible tropical vegeta- 
tion. With the construction of this reservoir, assured by 
the clearings from the cutting, and the water regulated 
and controlled by these courses, the work, like that of the 
cutting at Culebra, is only one of time. One objection 
which was raised when the public became acquainted 
with the almost incredible magnitude of the work, 
in which a reservoir becomes a great lake, was that 
this latter might itself be filled up with the alluvial 
deposits, which it was constructed to keep out of 
the canal. It is true that in its tropical floods the Chagres 
carries along a large quantity of alluvion ; but this, which 
would be an insuperable obstacle in the canal, becomes a 
secondary consideration in the reservoir. It has been 
calculated by the chief engineer to the work that the 
Chagres can bring into the lake in @ thousand years 
30,000,000 cubic metres of alluvion, while the cubic con- 
tent of the lake is 1,000,000,000 cubic metres. 
Culebra and the dam at Gamboa have always been the 
two principal points, the main obstacles to the canal. But 
there are thirty-five other principal working stations, all 
connected with the railway between Colon and Panama. 
As the illustration shows, they are sufficiently near to 
each other to be considered uninterrupted. Fifty exca- 
vators and ten dredges work at the canal. Up to the 
twenty-fifth kilometre we meet with dredges, at first at 
Colon for the port, then at Gatun. As far as the Panama 
Plain there are more than sixty excavators. In the three 
workshops at Culebra are now installed the contractors 
who cut the canal from Amsterdam to the North Sea, At 
Corosal, at the sixtieth kilometre, the great port for access 
to the canal from the Pacific is to be placed, and there the 
great American dredges work in the swampy ground. It 
has been calculated that the work done up to the present 
is half that required to complete the undertaking, and 
that this new maritime route to the East will be opened 
in 1888. 
The work stands at present in this position: it involves 
in all the movement of about 100,000,000 cubic metres of 
rocks of varying consistency. Of this, 70,000,000 are to 
be raised, according to the contracts, in successive instal- 
ments in 1885, 1886, and 1887. The remaining 30,000,000, 
which form the actual canal, will be raised at the expira- 
tion of this time either by the same contractors or by new 
ones. Knowing the amount already raised, the contract 
periods for raising a certain other quantity and the 
amount remaining to be done at the end of the present 
contracts, we can, by a sum in simple proportion, calcu- 
late when the whole should be completed. In 1888 it 
should be ready for traffic. This simple programme 
could only be applied to a work so colossal after a long 
and laborious period of minute study and preparation. 
The period of installation is always the most important 
in all these vast enterprises: the study and command of 
the appropriate material, the reception, testing, arrange- 
ment of the machines, the construction of the workshops, 
accommodation for the workmen, &c.; it is only when 
all these have been completed, when all have been made 
ready for work and tested, that the real work can com- 
mence, and that progress becomes sensible. This period 
of installation lasted, for example, in the case of the 
St. Gothard tunnel, for fifteen months; but the Panama 
canal calls for ten times more capital than the tunnel, 
it is executed in a country which has first to be 
cleared of a luxuriant tropical jungle, thousands of 
miles away from all industrial centres. The preparation 
for this gigantic work under these circumstances was 
a most important fraction of the work, and it is the 
opinion of competent men that what has actually been 
done during the installation period now brought to a close 
is equivalent to half of the work necessary to achieve the 
canal. In the case of the Suez Canal, 70,000,c00 cubic 
metres had to be raised ; of these, 50,000,000 were raised 
in two years after the apparatus had been put in working 
order. Seventy million cubic metres must be raised by 
the drags and excavators of the twenty-one principal con- 
tractors; 18,000,000 are to be raised by August 1 of the 
current year. These 21 contracts represent an outlay of 
about 240,000,000 francs, of which 65,000,000 have been 
tendered by French contractors ; 55,000,000 by Americans ; 
20,000,000 by Italian, Swiss, Swedish, and natives, and 
90,000,000 by an Anglo-Dutch Company. All nations 
are working therefore at the task. The French con- 
tractors are at work at the cutting at Emperador; the 
Anglo-Dutch Company has to remove 13,000,000 cubic 
metres in the great cutting at Culebra. Practically 
