In the spring of 1852 a triangular mass, the vertex of which was just beyond or south of the Terrapin Tower, while its altitude of more than forty feet lay along the shore of the south corner of Goat Island, fell in the night with the usual grinding crash. And with it fell some isolated rocks which lay on the brink of the precipice in front of the tower, and from which the tower derived its name. Before the tower was built, some person looking at the rocks from the shore suggested that they looked like huge terrapins sunning themselves on the edge of the Fall. A few days after the fall of the triangular mass, a huge column of rock a hundred feet high, about fourteen feet by twelve, and flat on the top, became separated from the bank and settled down perpendicularly until its top was about ten feet below the surface rock. It stood thus about four years, when it began gradually to settle, as the shale and stone were disintegrated beneath it, and finally it tumbled over upon the rocks below, furnishing an illustration of the manner in which we suppose the rocks which once accumulated below the Whirlpool must have been broken down. In the spring of 1871 a portion of the west side of the sharp angle of the Horseshoe, apparently about ten by thirty feet, went down, producing a decided change in the curve. On the 7th day of February, 1877, about eleven o'clock of a cold, cloudy day, there occurred the most extensive abrasion of the Horseshoe Fall ever noted. It extended from near the water's edge at Table Rock, more than half the distance round the curve, some fifteen hundred feet, and at the most salient angle the mass that fell was from fifty to one hundred feet wide. By this downfall the contour of the Horseshoe was decidedly changed, the reëntering angle being made acute and very ragged. Less than three months afterward the abrasion was continued some two hundred feet toward Goat Island. The trembling earth and muffled thunder gave evidence of the immensity of the mass of fallen rock, but no one saw it go down. For several months after the fall, until the mass of rock got thoroughly settled in the bed of the Falls, the exhibition of water-rockets, sent up a hundred feet above the top of the precipice, was unique and beautiful. The greatest angle of retrocession, which had previously been wearing toward Goat Island, is again turning toward the center of the stream.