ized state, so that the engineer is obliged to make many conjectures as to the quality of the rock, in order to know what slope to give the excavation.Generally one is much puzzled. The Americans have discovered a method of bringing up the rock itself in a shape large enough to admit of our judging as to its hardness. A carrot, as the workmen call it, is fetched up. It is obtained by means of a cylinder armed at its lower extremity with black diamonds. This is given a rapid rotary motion; it descends and penetrates into the rock, and in this way we can bring up a block which furnishes the exact consistency of the strata. We placed, before the eyes of the commission, this morning, a box of specimens taken in Culebra. The result is, that we have a perfect knowledge of the ground, and it is these soundings which enable us to fix our prices.
The following reference to these American soundings occurs in Admiral G. H. Cooper's report to our Government on the progress of the work, dated March 2, 1883. After observing that soundings to ascertain the nature of the soil had been made all along the line, he says:
- The "Commission consultative" of engineers.