Onondaga Lake is comparatively small, being six miles long and about a mile broad, and it is noted for its salt wells, which have made the prosperity of the city of Syracuse, the largest in Central New York, built along Onondaga Creek south of the lake, and upon the slopes of the higher hills to the eastward. An Indian trader started the town in the eighteenth century, and soon afterwards Asa Danforth began making salt at Salt Point on the lake, calling his village Salina. When the Erie Canal came along the place grew rapidly, and it is now a great canal and railroad centre, with lines radiating in various directions, and from it the Oswego Canal goes northward to Lake Ontario. The city has a population approximating a hundred thousand. The salt springs come out of the rocks of the Upper Silurian period, and are located chiefly in the marshes bordering Onondaga Lake. The brine wells are bored in the lowlands surrounding the lake to a depth of two hundred to over three hundred feet. The State of New York controls the wells and pumps the brine to supply the evaporating works, which are private establishments, a royalty of one cent per bushel being charged. The main impurity that has to be driven out of the brine is sulphate of lime, and the finer product has a high reputation, the "Onondaga Factory-Filled Salt" being greatly esteemed. The salt wells were known to the Indians, and the French Jesuit missionaries found them as early as 1650, taking salt back to Canada. In 1789 they yielded five hundred bushels, and they have since produced as high as nine millions of bushels a year, the annual product now being about three millions. The brine is first pumped into small shallow vats, where it remains until the carbonic acid gas escapes and the iron is deposited as an oxide. It is then led to the evaporating vats, all processes being used, solar as well as boiling. The land bordering the marshy shores of Onondaga Lake is framed around by rows of factories and heating furnaces, while out on the marshes are clusters of little brown houses, each covering a well and pump. From there the brine is led through conduits made of bored logs, called the "salt logs," to the evaporating vats and factories, some going long distances. Everything throughout the whole district is profusely saturated with salt.