The declivity in the lower channel through the gorge is ninety feet; but on the surface of the upper banks there is a rise of more than one hundred feet in the same direction--that is, down the river. Hence, when the Falls were at Lewiston they were more than two hundred and fifty feet high. Now the greatest descent is one hundred and sixty-eight feet, the diminution being the result of retrocession in the line of the dip--from north-east to south-west--in the bed-rock. It is owing to this dip that the surface of the water on the American side is ten feet higher than it is on the Canadian. The continuous column of water, however, is longest in the center of the Horseshoe, because of the fallen rock and _débris_ lying at the foot of the other portions of the Fall. At this time the upward slope of the bed-rock is such that--if it shall prove to be sufficiently hard--the Falls, after receding four miles farther, will be two hundred and twenty feet high. It is evident from the descriptions of Father Hennepin and of Baron La Hontan, that the upper stratum of rock over which the water falls must have projected beyond the face of the rock below much farther than it now does. The large masses of fallen rock lying at the foot of the American and Horse-shoe Falls are evidence of this fact. Travelers still go behind the sheet on the Canadian side, and into and through the Cave of the Winds, on the American side. But they do not expect to keep dry in so doing, nor to sun themselves on the rocks below, like the "rattlesnakes" of former days. Nevertheless, there is no more exciting nor exhilarating excursion to be made at the Falls than that through the Cave of the Winds. Nowhere else are the prismatic hues exhibited in such wonderful variety, nor in such surpassing brilliancy and beauty. And although a rainbow is not a spraybow, it may be admitted that a spraybow is a rainbow, formed of drops of water, large or small. So here rainbow dust and shattered rainbows are scattered around; rainbow bars and arches, horizontal and perpendicular, are flashing and forming, breaking and reforming, around and above the visitor in the most fantastic and delightful confusion of form and effect. And if his fancy prompts him, he may arrange himself as a portrait, at half or full length, in an annular bow. The enamored Strephon may literally place his charming Delia in a living, sparkling rainbow-frame, flecked all over with diamonds and pearls. CHAPTER III. The name Niagara--The musical dialect of the Hurons--Niagara one of the oldest of Indian names--Description of the river, the Falls, and the surrounding country.