the Great Lakes

GREAT LAKES, THE. The Great Lakes and their connect ing waterways are in general along the boundary between the United States and Canada between 75° and 92° W. of Greenwich. In 1909 the United States and Great Britain signed a treaty known as the "Boundary Waters Treaty," whereby the waters between the United States and Canada were guaranteed free and open to the inhabitants of both countries on equal terms, and principles gov erning the use of boundary waters were laid down. An interna tional joint commission consisting of three members from Canada and three members from the United States was established. Neither the United States nor Canada has found it necessary or desirable to organize any defences on the boundary between the two countries or maintain ships of war in the Great Lakes for over years. The channels in the connecting waterways and the sailing courses in the open lakes cross and recross the interna tional boundary many times.

The Great Lakes and their connecting waterways are the most important unit of inland waterway transportation in the world, and have been of great economic importance in the development of the North American continent. Their drainage basin has an area of about 300,00o sq.m., approximately 6o% lying within the United States. The water surface of the lakes and rivers themselves covers 96,00o square miles. The total distance, measured along the steamer track from Duluth to the outlet of Lake Ontario, is 1,160 miles. Their outlet to the Atlantic ocean is through the St. Lawrence river.

Dimensions, elevations and other descriptive details of each of the lakes and connecting waterways are given in the following table, the data being derived from the bulletin and charts of the U.S. Lake Survey : mainder in vessels of the United States. Traffic through the De troit river in 1926 amounted to 95,003,604 tons, valued at $1,179, 944,762. Package freight has not developed in anything like the same proportions as has bulk freight, the total on the lakes aver aging about 2,500,00o tons per annum.

Connecting Waterways

(see table).—The critical points in the navigation of the lakes are the connecting waterways. The channels in their waterways are exceptionally free from silting. Periodic dredging is necessary at a few localities only. On account of the great volumes of commerce, and of the many miles of Traffic.—During the 1926 navigation season 137,000,000 tons of freight, valued at over $2,000,000,000, moved over the GreatLakes. This commerce consists primarily of bulk freight such as iron ore, wheat, limestone and coal. The cost of transporting freight on the bulk carriers of the Great Lakes is cheaper than that of any other inland transportation for equal haul in the world. Freight rates are from one-seventh to one-tenth of the rates per ton mile for similar transportation on the railroads of the country. The tonnage passing through the locks at Sault Ste. Marie is steadily increasing. The average for the years 1922-26 was 8o,000,000 tons, while for the years 1917 to 1921 it was 74,000,000 tons. In 1926 it amounted to a total of 85,679,087 tons of freight, valued at $1,063,875,987. Of this traffic 10,374,000 tons was down-bound grain, 57,549,700 tons was iron ore down-bound, and tons was coal up-bound. About 5o% of the grain, 1% of the iron ore and 5% of the coal was carried in Canadian vessels, the re channel with a narrow margin between keel and channel bottom, extensive sweeping is done annually to ensure that channels in hard bottom are free from accidental obstructions. The Lake Carriers' Association, a federation including nearly all the owners of freight-carriers on the lakes, have formed an efficient system of communication and supervision which permits them to take ad vantage of water conditions and load their vessels to the greatest possible depth. The deepening and widening of the connecting channels authorized some years ago have practically been com pleted; and at many of the most critical points, such as the Neebish channels below Sault Ste. Marie and the channels between Lakes Huron and Erie, separate up-bound and down-bound pas sageways are maintained. On the upper lakes the minimum width of channels used for two-way traffic is 500f t., whereas 300f t. is the least width of channel now used for one-way traffic. Towards the close of the navigation season, the blockade of one-way chan ? will admit the largest freighters to Lake Ontario and the St. Law rence river above Ogdensburg and open these waters to the highly developed commerce of the upper lakes.

Harbours.

Originally the mouths of rivers were used as har bours on the lakes. It was necessary to dig out the bars which usually formed at the lake entrance, and later piers were con structed at river mouths which contracted the area of flow and tended to keep the channels scoured out. Still later, breakwaters were built in the lakes to protect pier entrances from wave action. As conditions became more congested in the rivers, the break waters were extended to form large outer harbours. These struc tures were originally stone-filled timber cribs, the tops of which, after the timber decayed, were replaced by concrete or stone. The more recently constructed breakwaters are formed of a line of con crete caissons sunk side by side, or of a long rubble mound corn posed of stones varying from half a ton to 1 o and 12 tons in weight, more or less carefully placed. Some of these outer har bours are as much as four and five miles long and afford ample protection to the largest lake vessels. Maintenance dredging must be carried on at all times in most of the harbours of the Great Lakes. About 65 harbours on the upper lakes (excluding Lake On tario) have an authorized project depth of 19ft. or more at low water ; many others have been improved so as to be available for smaller vessels.

Carriers.

The aggregate gross registered tonnage in 1927 of the entire lake fleet, including both United States and Canadian vessels, vessels in the package and automobile trade, barges, etc., but excluding passenger steamers and car ferries, is given in the report of the Lake Carriers' Association as 2,887,427 gross regis tered tons. The number of vessels was 765. During the five year period 1922-26 there were built 3o new bulk freight-carriers with a carrying capacity, on loft. draft, of 395,192 net tons. During the same period 12 steel bulk freighters were lost on the lakes, eight of which had a carrying capacity in excess of 3,00o gross tons each. The standard bulk freight-carrier on the lakes (except Ontario) is a vessel with machinery in the stern, navigating bridge far forward and quarters for crew both forward and aft. The vessel is long, narrow and deep, with maximum possible cargo capacity for its displacement. The cargo is open, without intermediate decks, but is usually divided into three compartments by cross bulkheads. Cargo is handled through large hatches extending nearly full width of the deck spaced uniformly at 12ft. or 24ft. centres. This type of freighter is generally regarded as the most economical bulk freight-carrier yet devised and while admirably suited for the lakes' trade is not suitable for ocean navigation. The standard bulk freighter has no equipment for handling cargo although some self-unloaders, largely used for carrying limestone, have been de veloped. The larger freighters have engines of about 2,50o h.p. and are designed with a cargo-carrying capacity of from 13,000 to 15,00o net tons and for a speed of about 10.5 statute miles per hour. The largest boat on the lakes in 633ft. long, loft. in beam and 29f t. moulded depth. Except for several motor ships with diesel engines there has been no marked change in the type of freighters built in recent years. The highly specialized freight handling equipment at the terminals has resulted in remarkable economies in loading and unloading and quick turn round for ves sels. The record for handling cargo between shore and ship is 16Zmin. for loading 12,508 tons of ore, and 3hr. and 5min. for unloading the same cargo. The package and passenger-carrying steamers are in general of the same design as boats in coastwise service along the Atlantic seaboard. The car ferries are strongly built and maintain service throughout the entire year.

About 3o important passenger lines are in regular operation upon the Upper Great Lakes, exclusive of the companies operating day-excursion boats and passenger ferries. Most of these lines operate only during the navigation season, although in certain in stances, notably in the case of the Pere Marquette Line steamers which operate across Lake Michigan, passenger service is main tained throughout the year. Several of the lines offer especially good passenger accommodations and attractive long-distance s cruises. Other lines operating between important cities, notably those running between Detroit, Cleveland and Buffalo, in overnight construction of this canal was commenced in 1913. It was largely In the past more than 9o% of the freight movement of the Great service, carry a heavy passenger traffic in luxurious boats, some of which are of exceptionally large size. Two of the latest passenger steamers, the "Greater Detroit" and "Greater Buffalo," are said to be the largest inland waterway passenger steamers in the world. They are steel vessels of the side-wheel type, 55oft. length overall; width, over guards, roof t. ; draft, 16f t. ; speed, 21 statute miles per hour. Sleeping accommodations are provided for 1,200 passengers. These boats are in operation between Detroit and Buffalo. Pas senger steamers usually have accommodations for automobiles and for a limited amount of express freight.

Diversions.

The period of low rainfall occurring during the years just prior to 1926 brought down the levels of the lakes and with other factors created new low levels. The minimum recorded monthly mean levels during the navigation season since 186o, tak ing the latter as from May to November inclusive, were as fol lows : For all the lakes except Lake Superior the standard datum planes are two feet below the mean level of these lakes for the period 186o-75. The datum plane for Lake Superior is one foot below the mean level of that lake for the same period. The datum planes were intended to represent low-water conditions, but not the ex treme minimum lake levels during the navigation season. At the time of their adoption the minimum recorded monthly mean levels during the navigation season had been below datum as follows : on Lake Superior o.8ft., Lakes Michigan and Huron o• 5f t., Lake Erie o• 1 f t. and Lake Ontario i • 1 feet.

The effect of the present diversions and outlet changes is esti mated as follows : Upon the opening of the new Welland ship canal the lowering of Lake Erie, due to increased diversion for navigation purposes, will be increased to 0.7 foot. Any additional deepening of channels in St. Clair river will further lower the levels of Lakes Huron and Michigan.

A dike on which sluice gates are installed has been con structed across the St. Mary's river near Sault Ste. Marie. The gates are operated under the supervision of an international board of control in order to maintain water-levels in Lake Superior and to compensate for diversions on both the Canadian and the American sides at Sault Ste. Marie for power purposes.

The construction of compensating works in the Niagara and St. Clair rivers, designed to raise the level of Lake Erie by 0.7 foot and of Lakes Huron and Michigan by one foot, have been recom mended by a joint board of engineers appointed by the Canadian and U.S. Governments. The locks include a series of submerged rock sills in St. Clair river with crests 3 I f t. below datum, and a timber crib dike, stone weir and submerged rock sills in the Niagara river.

The question of diversion of water from Lake Michigan into the Chicago drainage canal for the purpose of sewage disposal has not been settled. The Supreme Court of the United States decided against the Chicago drainage district in a suit instituted to enjoin the district against withdrawing water. However, in order to permit the Chicago sanitary commission to prepare plans and construct works necessary to take the place of the prevailing sys tem of sewage disposal, temporary authority to divert 8,50o cu.ft. of water per second from Lake Michigan was granted by the U.S. War Department for a period of five years under certain condi tions, which, when carried out, will permit the reduction and per haps the eventual discontinuance of the diversion for sewage pur poses. The question is of importance because of the enormous losses claimed by shipping interests on account of lower water levels. The matter is again before the Supreme Court of the United States as a result of an action brought by some of the States to restrain the Chicago drainage district from diverting water from Lake Michigan. The report to the court made by former chief justice, Chas. E. Hughes, who was designated as special master, was to the effect that the permit granted by the War Department is valid and effective according to its terms. Final decision in the matter has not been made.

Outlets to the Sea.

The Chicago drainage canal from Lake Michigan at Chicago to Joliet, Ill., the Illinois and Michigan canal from Joliet to La Salle, Ill., and the improved waterways of the Illinois and Mississippi rivers, give a continuous water route from Lake Michigan to the Gulf of Mexico. This route, however, will accommodate at present only very small, shallow-draft boats, and is but little used. The various Federal, State and other agencies concerned are now engaged in works that will deepen this through waterway to nine feet. The U.S. War Department engineers have surveyed and studied several routes for a canal between Lake Erie and the Ohio river, but these reports have to date been unfavour able. It was found that the benefits would be out of proportion to the cost, which would be in excess of $Ioo,000,000 for 9ft. depths. Unfavourable reports have also been made on a proposed ship canal following in general the line of the New York State barge canal.

The New York State barge canal has replaced the old Erie canal. It connects with the Great Lakes at Tonawanda on Niagara river, and at Oswego on Lake Ontario. The present 12f t. depth of canal is designed for use by barges and boats drawing 'al feet.

The St. Lawrence river from its source at the outlet of Lake Ontario to the Atlantic at Belle Isle strait is 1,184m. in length. For purposes of navigation the river may be considered in three portions: the broad estuary below Father Point, 661 m. in length; the section 34 2m. in length from Father Point to Montreal which has been improved for navigation by ocean vessels; and the sec tion 181 m. in length between Montreal and Lake Ontario, in which there is a fall of approximately 2 2 5 f t., and which has been canalized at all rapids and is available for small vessels of 14ft. draft. The problem of providing a channel through the St. Law rence for ocean shipping is now the subject of negotiation between the Canadian and U.S. Governments. (See ST. LAWRENCE RIVER.) By treaty stipulation the amount of water that may be diverted from the Niagara river for power purposes has been limited to 36,00o cu.ft. per sec. on the Canadian side and 20,000 cu.ft. per sec. on the United States side. Of the Canadian diversion all but about I o,000 cu.ft. per sec. is used by the Hydro-electric Power Commission of Ontario in three plants, the largest of which, near Queenstown, has a gross head of over 3oof t. and develops about 450,00o h.p. from the nine turbo-generators installed. Of the American diversion practically all the water is utilized by one concern with an installation of 56o,000 horse-power. Three of the units of the latter company are rated at 70,00o h.p. each and are the largest hydro-electric units in existence. At all the plants, electricity is generated at 11,00o volts, 25 cycles. Much is used in nearby electro-chemical industries for the manufacture of aluminium, ferro-silicon, carborundum, artificial graphite, liquid chlorine, calcium carbide, cyanamide and other products. The remainder is transmitted to various cities for miscellaneous uses. The maximum distance to which this power is transmitted is somewhat in excess of 200 miles.

BIBLIOGRAPHY.--Annual Report, chief of engineers, U.S. army; Bibliography.--Annual Report, chief of engineers, U.S. army; Charts and Bulletins of the Lake Survey ; Transportation on the Great Lakes, U.S. Government printing office (1926) ; Report of Interna tional Joint Board of Engineers, U.S. Government printing office (1927) ; Document No. 288, 69th U.S. Congress, ist Session; Annual Report, Lake Carriers' Association ; Great Lakes Commerce, by Fay, Spofford and Thorndyke, consulting engineers. (E. JA.)