MICHLER’S ROUTE.
To Lieut. N. Michler, Corps of Topographical Engineers, (now Brevet Brigadier-General,) the execution of the topographical survey was assigned. The operations of this officer were published in the form of a diary, with special scientific reports and observations, accompanied by maps and profiles. The special reports embrace observations upon geology, botany, hipsometrical and astronomical determinations, climatology, and field notes.
The itinerary is full and interesting, supplying information valuable to future explorers. The reader is never asked to accept a statement upon the ipse dixit of the writer. The observation of a corps of intelligent surveyors is laid before the reader.
The line adopted by General Michler may be described as follows: To avoid the bar at the mouth of the Atrato, a canal, about two and one-half miles, is to be cut through the channel of the caño coquito. The mouth of this caño is protected by nature from the prevailing winds. The Atrato affords navigation for the largest ships. The remaining part of the line is described in General Michler’s words: “Let the first section follow the projected line referred to above, across the Lagunas to its intersection with the Truando; the second section connects this last point by a straight line with the head of the Palizadas; the third extends in a direct line to the foot of the Saltos; the fourth in a curved line to the head of the Saltos, including a tunnel of 800 feet through the Sierra de los Saltos; the fifth leads directly to the mouth of the river Grundó, a tributary of the Nercua; the sixth leaves the valley of the Nercua at the point by a straight line, perpendicular to the axis of the Cordilleras de los Andes, and, after piercing the mountains with a tunnel 12,500 feet in length, continues on to the mouth of the Chuparador; the seventh follows for some distance down the valley of the river Paracuchichí; and, lastly, the eighth strikes in a direct line for the Bahia Ensenadá, or Estero de Paracuchichí.
“The line proposed by Mr. Kennish differs very materially from the one just described. It leaves the Atrato at the mouth of the Truando, and follows the meanderings of the stream to its junction with the Nercua; it then ascends the valleys of the latter and of the Hingador, and strikes across the mountains to the Pacific. The length of the cut by his plan is stated in his report to be 56.08 miles.
“In order to complete the line of canal communication between the Atrato and the Pacific, it is necessary to connect the Estero de Paracuchichí with Humboldt’s Bay. It is proposed to do this by a cut from the former across the peninsula, and then by building out in its prolongation, from the shores of the latter, jetties to form a passage through the surf into deep water of the ocean. The depth of the cut between them will have to be sufficient to allow for the swells of the latter, at least from thirty-five to forty feet below low tide.”
To connect the Atrato with the Pacific by a canal without locks, there would be 95 miles of river navigation, and 52⅔ miles of canal, making an aggregate length of 147⅔ miles.
The following table gives the different items and the total cost of the work:
Interoceanic Ship Canal.
| OBJECT OF EXPENDITURE. | ESTIMATE BY GEN. MICHLER FOR EXCAVATION AND TUNNELING. |
|---|---|
| Works at the mouth of the Atrato | $500,000 |
| Excavation of earth | 24,835,173 |
| Rock cuttings | 64,774,950 |
| Tunneling | 13,995,000 |
| Pacific harbor improvements | 1,150,000 |
| Light-house | 35,000 |
| Piers | 25,000 |
| Depots on Pacific | 50,000 |
| Depots on line, and hospital | 35,000 |
| Depot at junction | 15,000 |
| Executive department | 120,000 |
| Engineer department | 375,000 |
| Medical department | 80,000 |
| Pay department | 90,000 |
| Commissary department | 120,000 |
| Quartermaster’s department | 135,000 |
| Dredging machinery | 350,000 |
| Hoisting and pumping engines’ machinery | 875,000 |
| $ 107,560,123 | |
| Add 25 per cent. for contingencies | 26,890,031 |
| $ 134,450,154 | |
This estimate supposes the dimensions of the canal to be 100 feet wide and 30 feet deep. This rate ($2.50) per cubic yard is evidently too small. Estimating this tunnel at the contract price being employed ($5.40), the cost will be $30,229,200; and should the price reach the not improbable limit of $10 per cubic yard, the cost will be increased to $55,970,000. Substituting these sums in place of the cost of tunneling as given in the above estimate, and the total cost of the canal along this route will, in the first case, be $150,684,354, and, in the second case, $176,625,154, which is not excessive, if the tunnel is to be lined throughout.
The Penaebach tunnel is the only one in England that is self-supporting. It is driven through solid basalt. The Penmaenwhr tunnel, pierced through hard green-stone, had to be lined throughout; and the Bangor tunnel, supposed to be sufficiently firm, was afterward cased with brick. It has been found necessary to line some of the tunnels of the Washington aqueduct, which are driven through very hard gneiss.
Before taking leave of this instructive report, we have selected some interesting portions of the narrative and scientific statements for quotation:
“The great falls of the Hingador are grand and exceedingly romantic, and equal in height and beauty to many of those in other countries which elicit so much admiration from all lovers of magnificent scenery. The valley itself is pleasant to gaze upon; many bright streams gush into it, and impart additional charms to the already picturesque landscape of falls and rapids, and rich tropical vegetation. Several thermal springs were discovered at the foot of the great falls.
“As the party had to wade through the water, over smooth and slippery rocks, and clamber up steep precipices, it took four days to accomplish this section of the survey. Several fragments of rocks were broken off at the head of the falls for subsequent analysis. According to the report of the geologist, of which the following is an extract, ‘the rocky falls were found to be overcoated with a light, shaly conglomerate of a cemented texture, and containing, imbedded in a calcareous matrix, coarse sand and gravel. Higher up, in one of the western head branches of this stream, a more consolidated semi-rock was noticed, containing copiously interspersed fragments of little shells. This rock seems also to be impregnated with carbonate of lime.’”
The character of the natives may be gathered from the extract: “January 30th, 1858—Whilst seated on the rocks overlooking the falls, and listening to the music of the roaring waters, as they rushed fiercely past, with an occasional anxious glance at the curve of the river above, in expectancy of the momentary appearance of the long-expected canoe, the attention was suddenly drawn toward a long line of Indians, men, women, and children, emerging from the trail over the Sierra. As they filed by, several familiar faces were seen, and a kindly nod of recognition given and returned. Each bore a pack, from the largest to the smallest; these rested upon the back, and were supported by bands, composed of the bark of trees, which passed in front of the forehead. Most of their effects were packed away in baskets, made of bark of certain trees, and very neatly manufactured. They proved to be old friends from Tocame, and were en route to make a visit to one of their Tambos, on the Nercua. All fear as to moving ahead was dispelled at sight of them. After depositing their loads on the rocks, near the small haven, just above the falls, they all left again as quietly as they had come, in order to bring up their canoes over the Saltos.
“Whilst the members of the engineer corps were extremely anxious to discharge their duties accurately and faithfully, and to prosecute, in the most thorough manner, every conceivable examination which could, in the remotest degree, furnish additional information in reference to the great work upon which they were engaged; still, circumstances over which they had no control, such as their want of provisions, and the scarcity of money wherewith to purchase and renew even necessary supplies, compelled them to turn back from the Pacific, and leave unaccomplished the reconnoissance of both the Paracuchichí and Jurador rivers. To have rendered their labors complete these examinations should have been made in connection with their other most interesting duties. The future survey of these streams, and more especially of the former, together with that of the country, between its head-waters and those of the Pavarador, a tributary of the Nercua, and also between some of the tributaries of the Truando and the coast, at some more southern point of Humboldt Bay, may throw a flood of light upon the feasibility of the work in contemplation.”
He again expresses his regret that he was unable to extend his examination:
“It is to be greatly regretted that circumstances prevented the party from gaining more minute information concerning the valley of the Paracuchichí, and of the transversal passes leading from it through the mountains into the valley of a large tributary of the Truando, which flows in only a few miles above its mouth. As this river has more than twice the quantity of water possessed by the Nercua, it is highly probable that a still more favorable route can be found leading out from its valley above the junction.”
The following table of comparison between altitudes, determined by the level and by barometric observations, shows how much has been gained in accuracy, since the time of Humboldt, in the use of the barometer:
| STATIONS. | MEAN READING OF BAROMETER. | MEAN TEMP. | BAROMETRIC HEIGHT. | HEIGHT BY LEVEL. | DIFFERENCE. | ||
|---|---|---|---|---|---|---|---|
| INCHES. | DEG. | FEET. | FEET. | FEET. | |||
| Sea coast | 29.874 | 80. | ... | ... | ... | ||
| First camp on Truando | 29.817 | 75.4 | 58.39 | 44.57 | + 13.82 | ||
| Tocame | 29.805 | 76.8 | 69.6 | 57.39 | 12.21 | ||
| Foot of Saltos | 29.759 | 76.1 | 122.65 | 97.5 | 25.15 | ||
| Observatory Hill | 29.663 | 76.6 | 207.45 | 204.95 | 2.5 | ||
| Head Salto Grande | 29.741 | 75.9 | 132.3 | 138.79 | - 6.49 | ||
| Head of Saltos | 29.737 | 75.9 | 138.1 | 183.47 | 45.37 | ||
| Junction of Rivers Nercua and Truando | 29.674 | 77. | 192.5 | 192.6 | + 0.44 | ||
| Tambo | 29.607 | 77. | 260.92 | 264.4 | - 3.48 | ||
| First Ridge west of Rio Nercua | 28.815 | 75.2 | 1,046.45 | ... | ... | ||
| [9] Log Crossing on |  | No. 1362 | 29.053 | 75.2 | 809.42 | 791.23 | + 18.19 |
| Rio Hingador | ... | ... | Mean 879.9 | ... | ... | ||
| No. 1363 | 28.912 | 75.2 | 949.94 | ... | ... | ||
| Camp on Hingador | 29.074 | 75.2 | 788.6 | 814.32 | - 25.72 | ||
| Dividing Ridge | 28.913 | 75.2 | 948.5 | 947.44 | + 1.06 | ||
| Rio Chupepe | 29.631 | 75.2 | 240.24 | 241.35 | - 1.11 | ||
| Rio Totumia, below Dos Bocas | 29.837 | 75.2 | 40.6 | 45.3 | 5.24 | ||
These hypsometric determinations differ from the true levels at the points of observation from two to forty-five feet. These figures fall considerably within the limit of error considered as probable by Baron Humboldt. This distinguished observer states that the barometer may be trusted to determine heights to within from seventy-five or ninety feet of the truth.