Out of Ontario the great river St. Lawrence flows one hundred and seventy-two miles down to Montreal, being for much of the distance the boundary between the United States and Canada. Kingston, with twenty-five thousand people, guarded by picturesque graystone batteries and martello towers--the "Limestone City"--stands at the head of the river where it issues from the lake. To the westward is the entrance of the spacious Bay of Quinté, and on the eastern side the terminus of the Rideau Canal, leading northeastward to the Rideau River and Ottawa, the Canadian capital. This was originally the French Fort Cataraqui, established at the mouth of Cataraqui River in 1672, the name being subsequently changed by Count Frontenac to Frontenac. The Indian word Cataraqui means "Clay bank rising from the water," and after the fort was built the meaning changed to "fort rising from the water." Here the Sieur de La Salle, in 1678, built the first vessel navigating the lake. The British captured the fort in 1762, naming it Kingston, after the American Revolution, and by fortifying the promontories commanding the harbor, made it the strongest military post in Canada after Quebec and Halifax, the chief work being Fort Henry. Its garrisons have been long withdrawn, however, and now the old-time forts are useful chiefly as additions to the attractive scenery of its harbor and approaches. At the outlet of Ontario the course of the St. Lawrence begins with the noted archipelago known as the "Lake of the Thousand Islands," there being actually about seventeen hundred of them. This is a remarkable formation, composed largely of fragments of the range of Laurentian mountains, here coming southward out of Canada to the river, producing an extraordinary region. This Laurentian formation the geologists describe as the oldest land in the world--"the first rough sketch and axis of America." During countless ages this range has been worn down by the effect of rain, frost, snow and rivers, and scratched and broken by rough, resistless glaciers, and we are told that, compared with these fragmentary "Thousand Islands" and the almost worn-out mountains of the lower St. Lawrence basin, the Alps and the Andes are but creations of yesterday.