Up to this time the French missionaries and the fur traders had gained the interior by way of the Ottawa River, or the Toronto, and Georgian Bay. La Salle decided to build a sailing-vessel on the shore of Lake Erie, in which he could transport his men to the stations he intended to establish, and also carry his trading goods to the Indians, and bring back the furs which he obtained in exchange for them. He already had a fortified post at Fort Frontenac on the northeastern shore of Lake Ontario; but he could not build his ship at this point, because the natives told him that formidable cataracts interrupted the navigation between Lakes Ontario and Erie. He sent an advance company to establish a station at the head of Lake Ontario, and to seek a convenient site on Lake Erie for the construction of the ship. With this expedition went Father Hennepin, whose graphic account of what he saw and of what he experienced is one of the most interesting in the annals of American exploration. The voyagers reached the mouth of the Niagara River in safety. When the current became too strong for them to go farther in their canoe, they landed and pushed forward through the snow. As they made their way along the edge of the river, they heard more and more clearly the roar of falling waters; and, at length, there burst upon their sight the falls of Niagara, or the “Thunder of Waters,” as the Indians called it,--that “vast and prodigious cadence of water which falls down after a surprising and astonishing manner, insomuch that the universe does not afford its parallel, those of Italy and Switzerland being but sorry patterns.” Hennepin describes this wonderful cataract as made up of two great cross-streams of water and two falls with an island between, and declares that when this “prodigious quantity” of water comes to fall, there is a din and a noise more deafening than the loudest thunder; the rebound of the waters was so great that a cloud arose from the foam and hung over the abyss, even when the sun was at its height. He could not say enough of this “most beautiful, and at the same time most frightful cascade” which he saw for the first time on this December day in 1678.[1] [1] Lake Ontario is 326 ft. lower than Lake Erie and about 30 miles distant. For 18 miles the Niagara River flows peacefully along, then suddenly the channel narrows and the waters rush down 53 ft. in half a mile, and then drop over a cliff 160 ft. in two separate falls, one 600 and the other 200 ft. wide. Seven thousand tons of water are thus discharged every second into a narrow gorge whose nearly perpendicular walls rise 200 ft. on either side. Down its steep slope the imprisoned waters dash in a succession of boiling rapids, white with foam, forming in one loop of the channel a curious whirlpool. Issuing from this gorge at Lewiston, the river flows tranquilly on to Lake Ontario.