MACKENZIE RIVER Mackenzie, who had been already outlawed, issued a proclamation offering $100 and 300 acres of land to volunteers. Here he was joined by many American sympathizers; but owing to the exertions of Gen. Scott, the camp was broken up, and Mackenzie was taken pris- oner and sentenced to 12 months' confinement in Rochester jail. On being set at liberty he found employment on the press of the United States, and was for five or six years a contrib- utor to the New York "Tribune." During that period he published some political pam- phlets, one of which was compiled from papers found in the custom house, where he held a clerkship for a short time. On the proclama- tion of amnesty in 1849 he returned to Canada, and was again speedily elected to parliament, where he sat till 1858. From his retirement almost up to the time of his death he publish- ed in Toronto " Mackenzie's Message," a week- ly journal. Toward the close of his life his friends raised a sufficient sum to purchase for him an annuity and a homestead near the city. MACKENZIE RIVER, a river of British North America, in the Northwest territories of Can- ada, which has its head in Great .Slave lake, and, after a N.' course of about 1,200 m., emp- ties through several mouths into the Arctic ocean, in about lat. 69 N., Ion. 135 W. It flows through beds of coal and lignite, and is navigable by steamers throughout, though the rapids below Great Bear river in times of low water might prove an obstacle. Its width, which is irregular, sometimes extends to two miles. The ice breaks up at Fort Simpson, one of the Hudson Bay company's posts, in lat. 61 61', about the beginning or middle of May, and the river is open to its mouth about the end of that month. Floating ice generally prevents navigation even in the upper part of its course before the beginning of June. The chief trib- utaries of the Mackenzie are Mountain river or Riviere aux Liards from the west, and Great Bear river, the outlet of Great Bear lake, from the east. Mountain river rises beyond the Rocky mountains near the- sources of the Yukon, and empties into the Mackenzie at Fort Simpson ; it has a rapid current, and its navigation is dangerous. The Mackenzie is but a part of a stream 2,500 m. in length, the upper portions of which bear different names. It rises as the Athabasca in the Rocky moun- tains, near the source of the Columbia, and, after an extremely rapid descent through a fertile and well wooded country, receiving the waters of Lesser Slave lake from the west, and a little further down successively those of Lac La Biche and the Clearwater or Little Athabasca river from the east, enters the S. W. extremity of Lake Athabasca. The por- tion between the affluent from Lac La Biche and the Clearwater river is called riviere d la Biche or Red Deer river. After leaving Lake Athabasca it is called first the Rock and then the Slave river, until it loses itself in Great Slave lake. The Hudson Bay company's boats MACKEREL 791 ascend with only two interruptions to Jasper House, more than 2,000 m. from the Arctic ocean. These interruptions are a group of rapids in rivi&re & la Biche, and another in Slave river. Just below Lake Athabasca the Peace river enters from the west. This stream, which is considered by some the source of the Mackenzie, rises in the Rocky mountains near the source of Fraser river, and flows through a beautiful and fertile valley ; it is navigable by the Hudson Bay company's boats through- out nearly its entire course. The Mackenzie river was discovered and first navigated in 1789 by Alexander Mackenzie, from whom it derives its name. MACKEREL, a well known acanthopterygian fish of the scomberoid family, and one of great utility to man, from its countless numbers and excellence as food. This family includes also the bonito and its allied forms, the tunny, the pilot fish, and the sword fish. The scales are small, delicate, and smooth, the bones light, the tail slender, and gill covers unarmed ; the first dorsal fin continuous, the rays of the sec- ond and of the anal detached, forming finlets, and with a large interval between the dorsals ; the body is fusiform, the caudal fin powerful, the tail usually with a slight keel on the side, the vertical fins without scales ; a row of small conical teeth in each jaw ; branchiostegal rays seven ; most of the species have no air blad- der. The common European mackerel (scomber scombrus, Cuv.), so well known for the beauty and brilliancy of its colors and the elegance of its form, has a pointed nose, the under jaw the longer, the gill covers large and smooth, the pectorals and ventrals in advance of the dor- sal, the former the most anterior, five finlets above and below the tail, vertically over each other, and the tail crescent-shaped ; the color above the lateral line is fine green varied with blue, and marked with broad, descending, un- dulating, dark lines; the lower parts are sil- very with golden tints. According to Ander- son, the mackerel performs migrations almost as extensive as the herring; it probably in- habits almost every part of the European seas, and comes into shallow water at particular sea- sons to breed; were it not for these periodi- cal visits, no effective fishery could be carried on, as it would be impracticable to follow the shoals over the ocean ; great as is the number caught, it is very small compared with those which escape. It is caught on the shores of Great Britain from March to June, spawning in the latter month ; the young, called shiners, are 6 in. long by the end of August ; in win- ter they retire to deep water, though a few are taken on the Cornish coast all the year round ; as many as 500,000 eggs have been counted in a single female. The mackerel is very voracious, feeding principally on the fry of other fish ; it grows rapidly, and attains an average length of 15 in., and a weight of 2 Ibs., though some considerably exceed this. It is considered bet- ter in May or June than earlier or later in the