a quarter of a mile beyond the viaduct: its position is shown in Photog. No. 155, the view in which is taken, looking southwards, some of the revetment walls at the turn of the zigzags of the military road, mounting the hill, beyond the viaduct, being visible at the left of the picture. Near the centre of the view, where the white face of rock is visible, a mass of limestone had been thrown off in a S. W. direction, 69° E. of N., from the face of the cliff, and, shattering in its fall, had carried some thousands of tons of rock, small stone, and fine whitish debris, down into the bed of the river. The talus was heaped up at the base of the cliff, and stretched nearly across the whole breadth of the bed, forming a serious obstruction to the current, which was dammed back a good deal, notwithstanding the rapidity of its slope, and the torrent had already washed away large portions of the fallen mass, and as I watched it, was sorting out the finer material, and as it was removed slight falls of stuff continually occurred at the toe of the slope of debris, into the water rushing past its base.
The Padre informed me, that for four or five days after the 16th December, the volume of water discharged at Pertosa, both by the open channel of the river, and by the cavern of St. Michael, was visibly diminished, he thought by as much as one fourth the former delivery, and both currents ran turbid and foul. The delivery of the cavern, he thought, was even now, less than what it had been before, but the open river had returned to its usual regimen, except in so far as it was much whiter in colour, from the suspended chalky limestone, than he ever remembered it, though always more or less, so discoloured.
I remarked that many other smaller falls of rock had taken
