He thought it was formed by the moisture arising from the Falls constantly and slowly filtering between the layers of rock, in whose crevices it deposited its heavier portions, and that the violent agitation which the water had undergone disposed it to part with its earth more easily than it would otherwise do. He adds, "The circumstance of this Spray not being found above the Falls seems to suggest an opinion that that part of the vapor which hangs upon the surrounding rocks is the heaviest, as being most loaded with earthy particles, whilst the remainder which mounts up is the purest and contains little or no earth." Dewit Clinton, when he visited Niagara in 1810--as a Member of the first Board of Commissioners, appointed by the State of New York, to report on the whole subject of the proposed Erie Canal, noted in his diary, "A beautiful white substance is found at the bottom of the Falls; supposed by some to be Gypsum, and by the vulgar, to be a concretion of foam, generated by the forces of the Cataract. But it is unquestionably part of the limestone, dissolved and re-united." Since Clinton's time no attention has been paid to this substance as a curative agent. As a geological substance it is still collected, but with greater ease than formerly, for, besides being found on and below the face of the cliff, its existence in the limestone all over the vicinity of the Falls has been demonstrated by means of the huge excavations that have been made in the development of the various Power Plants at Niagara. CHANGES OF CONTOUR