Page:Popular Science Monthly Volume 32.djvu/170

158 The connection is so close between the consistency of the strata and the slope of the cutting, that the following as to this point will be of interest. The director-general continued:

Well, these borings, made in large numbers at Culebra, showed us that we had to excavate a rock, semi-bard, schistous in quality, having nearly horizontal strata, and that the earth was dry. The result is, that one could not desire better earth for a work of such an exceptional character. We shall be obliged, manifestly, to be very prudent. Accordingly, at the top we have opened the cutting, as if the slope was to be a gentle one. We remove the clayey part which, under the action of water, can be brought to the consistency of paste or mud. Here we have made a very ample opening. But in proportion as we reach clear rock, we make the prism narrower, so as to comprise the cubic contents strictly necessary, with the purpose to make the slope more gradual should experience require it.

The bringing together by an undertaking such as Panama of contractors of divers nationalities, naturally leads to the use of various machines, and it remains to be seen what advantage is to be derived from the sort of rivalry thus established. Here the Panama work may be said to possess an advantage over Suez. The latter was almost exclusively in the hands of French engineers, and was carried through by French contractors and inventors. A single Englishman, Ayton, contracted for a considerable part of the work, but he became bankrupt owing to the withdrawal of forced labor, and the French were obliged to assume his portion. In the case of Panama, contractors of several nationaltiesnationalities [sic] have been employed—French, English, Dutch, Swedes, Swiss, Italians, Americans, and Colombians. The "Canal Bulletin" for February 1.5, 1885, contains a table of contracts, arranged according to nationality, entered into at the time.

After treating of the American use of the diamond-drill, the director-general proceeded to speak of some of the other machines employed. He said:

The excavation is effected in different ways. We are very eclectic at Panama. We reject no system, no method, and as the earth varies at every step, as the works at one point do not resemble those at another, we can try different ways. At certain places we have mellow earth, which is generally composed, in the valleys, of clay mixed with a feldspathic sand. In such places we can make the attack by mechanical processes. We employ excavators.

There are two sorts of excavators, the French and American. The American excavators are very ingenious, and in mellow soil they give satisfactory results. The French excavators are of a type already tested in many places. In clayey and rather adhesive earth they seem preferable. Accordingly, the American papers, knowing, not that We had declared as much, but that facts had