Further light on the difficulties in the way of the enterprise was thrown upon it in a report made by Lieut. Kemball, in 1887, to the United States Government. He found on the Pacific slope, a short distance west of the summit, that the route of the canal was here crossed and recrossed by the Rio Grande, which had been trained in a straight line down the north side of the valley, at a considerable height above the level of the canal.[198] It was found, however, when the rainy season had set in, that in different places the hillside began to slide into the cutting made for the deflection of the river, and that one bank moved almost intact across the cut, with the top surface unbroken, and without any disturbance of the vegetation. The existence of a substratum of a greasy clay bank was the cause of this trouble. Such a foundation is, of course, not to be relied on. It is ready, as has been pointed out, to “swell upwards, or glide sideways, on the slightest provocation, and it may easily develop into a difficulty of the most formidable character, requiring the river to be carried round the back of the hills away from the canal.”[199] In the summer of 1887, Lieut. Rogers, of the United States Navy, visited the canal works, and made a report on them. He declared that in 1886, 11,727,000 cubic metres of excavation had been done, bringing the total quantity completed up to that date at 30 millions of cubic metres. This had, however, been done in the face of tremendous odds. An American dredger of greater power was steadily engaged on the same spot for weeks, the pressure of the material laid on the bank forcing up the soft spongy bed of the cut so rapidly that the machine could do little more than merely hold its own. The canal bed had here and there been destroyed by floods. Lines and trucks had been buried under two metres of silt. In the Culebra cut, the mountain to the left hand of the cut was found to be moving towards the canal, at the rate of 11 to 12 inches per annum. Seeing that this was the case when not one-third of the excavation had been completed, the query is naturally suggested, What will be the rate of movement when the bed of the canal is 250 feet or more under the level of the surrounding country? [Illustration: AMERICAN DREDGER ON THE PANAMA CANAL.] Nor have English writers been slow to condemn the project both from its economic and from its engineering points of view. The following quotation is given as typical of much that has been written elsewhere:—