The other scientific question--which the future will answer--is, How fast does this Niagara concrete form? With that 400 feet length of cliff on the Canadian shore--which was formerly covered by the end of the Horse-shoe Fall--exposed to the air and to observation (the outer end of those crevices in its face being now free from any such deposit); with the extensive excavations on the debris slope for the Power House below the bank, exposing new surfaces, where little such deposit now appears; with other probable excavations in connection with the power development, exposing similar surfaces at other points along the Gorge; it will be possible to approximately determine the yearly amount of accumulation and deposit of this ancient Niagara product. For that deposit will go on as ceaselessly as it has been going on, ever since the time--possibly many thousands of years ago--when the waters of a great lake (which was formed by the melting of the ice sheet) covered all this region; finally breaking over its northern barrier at the Lewiston escarpment, where, seven miles from its present location, Niagara was born. STILL A TRADE CENTER Le Sieur Gendron, of whom we know nothing more than is contained in the printed letters, noted before, passed away many a year ago; but at this late date, some two and a half centuries after his death, a lover of Niagara, in his search for and his collecting of early books that in any way refer to its famous Cataract, secured a copy of De Rocoles' "America, the Third Part of the World," 1660, which contains the first publication of Docteur Gendron's interesting letters from, and about, the Huron Country, in Canada. Therein he found this remarkable reference to the Waterfall,--which was quoted verbatim from the good Docteur's "hasty letter," by the State Historian of King Louis of France,--and is thereby enabled to add an hitherto unknown link (which turns out to be the second) in the chain of the earliest references to Niagara Falls; and so, both in History and in Medicine, to assign to good Docteur Gendron, a place (next alongside of the great Founder of Quebec) in Niagara's Temple of Fame. For the Sieur Gendron probably wrote from actual knowledge; he had probably, through some Huron emissary, secured some of those "Erie Stones," that "Petrified Spray of the Falls" in trade, at Niagara; he had doubtless tried the healing qualities thereof on some of his Savage Patients--and let us hope that this Niagara Remedy proved efficacious, and justified its wide-spread reputation. At any rate, in recording its uses, and its distribution by "Trade," and by probably himself using it in his Practice--limited then to the Huron Indians; and the few Frenchmen (perhaps a score or more) who then made their headquarters at the Home of the Jesuit Mission to the Hurons,--he showed, even as many a good Physician of later days has done, that he was a believer in, and user of, every one of Nature's