an extensive country of North America, bounded on the north-east by the gulf of St Lawrence, and St John's river; on the south-west, by the great line of lakes, Erie, Huron, and Superior; on the south, by the province of Nova Scotia, and the territories of the United States; and on the north-west, by Indian nations. Under the name of Canada, the French comprehended a very large territory; taking into their claim part of New Scotland, New England, and New York on the east; and extending it on the west as far as the Pacific ocean. That part, however, which is occupied or claimed by the British at present lies between 61° and 92° of west longitude, and 42° and 52° of north latitude, and is divided into Upper and Lower Canada. The climate is not very different from that of the United States; but as it is much further from the sea, and more to the northward, than most of those provinces, it has a much severer winter, though the air is generally clear; and, like most of those American tracts that do not lie too far to the northward, the summers are very hot, and exceeding pleasant. The soil in general is very good, and in many parts extremely fertile; producing many different sorts of grains, fruits, and vegetables. The meadow grounds, which are well watered, yield excellent grass, and breed vast numbers of great and small cattle. The uncultivated parts are a continued wood, composed of prodigiously large and lofty trees, of which there is such a variety of species, that even of those who have taken most pains to know them, there is not perhaps one that can tell half the number. Canada produces, among others, two sorts of pines, the white and the red; four sorts of firs; two sorts of cedar and oak, the white and the red; the male and female maple; three sorts of ash trees, the free, the mongrel, and the bastard; three sorts of walnut-trees, the hard, the soft, and the smooth; vast numbers of beech-trees and white wood; white and red elms, and poplars. The Indians hollow the red elms into canoes, some of which made out of one piece will contain 20 persons; others are made of the bark; the different pieces of which they sew together with the inner rind, and daub over the seams with pitch, or rather a bituminous matter resembling pitch, to prevent their leaking; the ribs of these canoes are made of boughs of trees. In the hollow elms, the bears and wild cats take up their lodging from November to April. The country produces also a vast variety of other vegetables, particularly tobacco, which thrives well. Near Quebec is a fine lead mine, and many excellent ones of iron have been discovered. It hath also been reported that silver is found in some of the mountains. The rivers are extremely numerous, and many of them very large and deep. The principal are, the Ouattauais, St John's, Seguinay, Despaires, and Trois Rivieres; but all these are swallowed up by the great river St Lawrence. This river issues from Lake Ontario; and, taking its course north-east, washes Montreal, where it receives the Ouattauais, and forms many fertile islands. It continues the same course, and meets the tide upwards of 400 miles from the sea, where it is navigable for large vessels; and below Quebec, 320 miles from the sea, it becomes so broad and so deep, that ships of the line contributed in the last war to reduce that city. After receiving in its progress innumerable streams, it at last falls into the ocean at Cape Rosiers, where it is 90 miles broad, and where the cold is intense and the sea boisterous. The most considerable settlements are upon the river and its smaller branches, and upon Lake Ontario, though a few settlers have fixed themselves also on Lake Erie, and the fur traders have stations far beyond Lake Superior. Here are five lakes, the least of which is of greater extent than the freshwater lakes to be found in any other part of the world: these are Lake Ontario, which is not less than 200 leagues in circumference; Erie, or Oswego, longer, but not so broad, is about the same extent. That of the Huron spreads greatly in width, and is about 300 leagues in circuit; as also is that of Michigan, though, like Lake Erie, it is rather long, and comparatively narrow. But Lake Superior is larger than any of these, being not less than 500 leagues in circumference. All these are navigable by any vessels, and they all communicate with each other; but the passage between Erie and Ontario is interrupted by a most stupendous fall or cataract, called the falls of Niagara*. The river St Lawrence, as already observed, is the outlet of these lakes, by which they discharge themselves into the ocean. The French built forts at these several straits, by which the lakes communicate with one another, and on that where the last of them communicates with the river. By these, while the country was in their possession, they effectually secured to themselves the trade of the lakes, and preserved an influence over all the Indian nations that lie near them.
The most curious and interesting part of the natural history of Canada is the animals there produced. These are stags, elks, deer, bears, foxes, martens, wild cats, ferrets, weasels, large squirrels of a grayish hue, hares and rabbits. The southern parts, in particular, breed great numbers of wild bulls, divers sorts of roebucks, goats, wolves, &c. The marshes, lakes, and pools, with which this country abounds, swarm with otters and beavers, of which the white are highly valued, as well as the right black kind. A vast variety of birds are also to be found in the woods; and the river St Lawrence abounds with such quantities of fish, that it is affirmed by some writers, this would be a more profitable article than even the fur-trade.—There are in Canada a multitude of different Indian tribes; but these are observed to decrease in number where the Europeans are most numerous; owing chiefly to the immoderate use of spirituous liquors, of which they are excessively fond. Their manners and way of living we have already particularly described*. The principal towns are Quebec, Trois Rivieres, Montreal, and York.
The commodities required by the Canadians from Europe are, wine, or rather rum; cloths, chiefly coarse; linens, and wrought iron. The Indian trade requires rum, tobacco, a sort of duffle blankets, guns, powder, balls, and flints, kettles, hatchets, toys, and trinkets of all kinds. While the country was in possession of the French, the Indians supplied them with poultry; and the French had traders, who, like the original inhabitants, traversed the vast lakes and rivers in canoes, with incredible industry and patience, carrying their goods into the remotest parts of America, and among nations entirely unknown to us. These again brought the furs, &c., home to them, as the Indians were thereby habituated to trade with them. For this purpose, people from all parts, even from the distance of 1000 miles, came to the French fair at Montreal, which began in June, and sometimes lasted three months. Since Canada came into the possession of Great Britain, its progress has been extremely rapid. Its population in 1759, when the French lost it, amounted to 70,000. In 1814 the inhabitants of Lower Canada amounted to 335,000, and those of Upper Canada to 95,000; but a part of this increase may be attributed to the great influx of emigrants from Britain. The agriculture and commerce of Canada have also been vastly extended. In 1769 the value of the produce exported amounted to £63,105l., and it employed 72 vessels belonging to Britain and the colonies. But in 1812 the value of the goods imported into Britain, from Canada, Nova Scotia, and Newfoundland, amounted to £909,689l. Since heavy duties were laid on Baltic timber, a vast quantity has been imported from Canada; but its quality is found to be very inferior to what is procured from Norway.
The greatest obstruction to the trade of Canada arises from the rigour of the climate. This is so excessive from December to April, that the broadest rivers are frozen over, and the snow lies commonly from four to six feet deep on the ground, even in those parts of the country which lie three degrees south of London, and in the temperate latitude of Paris. Our communication therefore with Canada, and the immense regions beyond it, will always be interrupted during the winter season, until roads are formed that can be travelled without danger from the Indians. For these savage people often commit hostilities against us without any previous notice; and frequently, without any provocation, they commit the most horrid ravages for a long time with impunity.
Canada was undoubtedly discovered by Sebastian Cabot, the famous Italian adventurer, who sailed under a commission from Henry VII. But though the English monarch did not think proper to make any use of this discovery, the French quickly attempted it; we have an account of their fishing for cod on the banks of Newfoundland, and along the sea-coast of Canada, in the beginning of the 16th century. About the year 1526, one Denys, a Frenchman, drew a map of the gulf of St Lawrence; and two years after, one Aubert, a shipmaster of Dieppe, carried over to France some of the natives of Canada. As the new country, however, did not promise the same amazing quantities of gold and silver produced by Mexico and Peru, the French for some years neglected the discovery. At last, in the year 1523, Francis I., a sensible and enterprising prince, sent four ships, under the command of Verazani, a Florentine, to prosecute discoveries in that country. The particulars of this man's first expedition are not known. All we can learn is, that he returned to France, and next year he undertook a second. As he approached the coast, he met with a violent storm; however, he came so near as to perceive the natives on the shore, making friendly signs to him to land. This being found impracticable by reason of the surf upon the coast, one of the sailors threw himself into the sea; but, endeavouring to swim back to the ship, a surge threw him on shore without signs of life. He was, however, treated by the natives with such care and humanity, that he recovered his strength, and was allowed to swim back to the ship, which immediately returned to France. This is all we know of Verazani's second expedition. He undertook a third, but was no more heard of, and it is thought that he and all his company perished before he could form any colony.
In 1534, one Jacques Cartier of St Malo set sail under a commission from the French king, and on the 10th of May arrived at Cape Bonavista in Newfoundland. He had with him two small ships besides the one in which he sailed. He cruised along the coast of that island, on which he discovered inhabitants, probably the Eskimaux. He landed in several places along the coast of the gulf, and took possession of the country in the king's name. On his return, he was again sent out with a commission, and a pretty large force; he returned in 1535, and passed the winter at St Croix; but the season proved so severe, that he and his companions must have died of the scurvy, had they not, by the advice of the natives, made use of the decoction of the tops and bark of the white pines. As Cartier, however, could produce neither gold nor silver, all that he could say about the utility of the settlement was disregarded; and in 1540, he was obliged to become pilot to one M. Roberval, who was by the French king appointed viceroy of Canada, and who sailed from France with five vessels. Arriving at the gulf of St Lawrence, they built a fort; and Cartier was left to command the garrison in it, while Roberval returned to France for additional recruits to his new settlement. At last, having embarked in 1549, with a great number of adventurers, neither he nor any of his followers were heard of more.
This fatal accident so greatly discouraged the court of France, that for 50 years, no measures were taken for supplying with necessaries the settlers that were left. At last, Henry IV. appointed the marquis de la Roche lieutenant-general of Canada and the neighbouring countries. In 1598, he landed on the isle of Sable, which he absurdly thought to be a proper place for a settlement, though it was without any port, and without product except briars. Here he left about 40 malefactors, the refuse of the French jails. After cruising for some time on the coast of Nova Scotia, without being able to relieve these poor wretches, he returned to France, where he died of a broken heart. His colony must have perished, had not a French ship been wrecked on the island, and a few sheep driven upon it at the same time. With the boards of the ship they erected huts; and while the sheep lasted they lived on them, feeding afterwards on fish. Their clothes wearing out, they made coats of seal-skin; and in this miserable condition they spent seven years, when Henry ordered them to be brought to France. The king had the curiosity to see them in their seal-skin dresses, and was so moved with their appearance, that he forgave them all their offences, and gave each of them 50 crowns to begin the world anew.
In 1600, one Chauvin, a commander in the French navy, attended by a merchant of St Malo, called Pontgrave, made a voyage to Canada, from whence he returned with a very profitable quantity of furs. Next year he repeated the voyage with the same good fortune, but died while he was preparing for a third. The many specimens of profit to be made by the Canadian trade, at last induced the public to think favourably of it. An armament was equipped, and the command of it given to Pontgrave, with powers to extend his discoveries up the river St Lawrence. He sailed in 1603, having in his company Samuel Champlain, who had been a captain in the navy, and was a man of parts and spirit. It was not, however, till the year 1608, that the colony was fully established. This was accomplished by founding the city of Quebec, which from that time commenced the capital of all the settlements in Canada. The colony, however, for many years continued in a low way, and was often in danger of being totally exterminated by the Indians. As the particulars of these wars, however, could neither be entertaining, nor indeed intelligible to many of our readers, we choose to omit them, and in general observe, that the French not only concluded a permanent peace with the Indians, but so much ingratiated themselves with them, that they could with the greatest ease prevail upon them at any time to murder and scalp the English in their settlements. These practices had a considerable share in bringing about the last war with France, when the whole country was conquered by the British in 1761. The most remarkable transaction in this conquest was the siege of Quebec. See Quebec; see also Canada, Supplement. And for the transactions here during the late American war, see America (United States of).
Canal of Communication, an artificial cut in the ground, supplied with water from rivers, springs, &c., in order to make a navigable communication betwixt one place and another.
The particular operations necessary for making artificial navigations depend upon a number of circumstances. The situation of the ground; the vicinity or connection with rivers; the ease or difficulty with which a proper quantity of water can be obtained; these and many other circumstances necessarily produce great variety in the structure of artificial navigations, and augment or diminish the labour and expense of executing them. When the ground is naturally level, and unconnected with rivers, the execution is easy, and the navigation is not liable to be disturbed with floods; but, when the ground rises and falls, and cannot be reduced to a level, artificial methods of raising and lowering vessels must be employed; which likewise vary according to circumstances.
A kind of temporary sluices are sometimes employed for raising boats over falls or shoals in rivers by a very simple operation. Two posts or pillars of mason-work, with grooves, are fixed, one on each bank of the river, at some distance below the shoal. The boat having passed these posts, planks are let down across the river by pulleys into the grooves, by which the water is dammed up to a proper height for allowing the boat to pass up the river over the shoal.
The Dutch and Flemings at this day sometimes, when obstructed by cascades, form an inclined plane or rolling-bridge upon dry land, amongst which their vessels are drawn from the river below the cascade into the river above it. This, it is said, was the only method employed by the ancients, and is still used by the Chinese, who are said to be entirely ignorant of the nature and utility of locks. These rolling-bridges consist of a number of cylindrical rollers which turn easily on pivots, and a mill is commonly built near by, so that the same machinery may serve the double purpose of working the mill and drawing up vessels.
A Lock is a basin placed lengthwise in a river or canal, lined with walls of masonry on each side, and terminated by two gates, placed where there is a cascade or natural fall of the country; and so constructed, that the basin being filled with water by an upper sluice to the level of the waters above, a vessel may ascend through the upper gate; or the water in the lock being reduced to the level of the water at the bottom of the cascade, the vessel may descend through the lower gate; for when the waters are brought to a level on either side, the gate on that side may be easily opened. But, as the lower gate is strained in proportion to the depth of water it supports, when the perpendicular height of the water exceeds 12 or 13 feet, more locks than one become necessary. Thus, if the fall be 17 feet, two locks are required, each having 8½ feet fall; and if the fall be 26 feet, three locks are necessary, each having 8 feet 8 inches fall. The side walls of a lock ought to be very strong. Where the natural foundation is bad, they should be founded on piles and platforms of wood; they should likewise slope outwards, in order to resist the pressure of the earth from behind.
Plate CXXXIV. fig. 1. A perspective view of part of a canal: the vessel L, within the lock AC.—Fig. 2. Section of an open lock; the vessel L about to enter.—Fig. 3. Section of a lock full of water; the vessel L raised to a level with the water in the superior canal.—Fig. 4. Ground section of a lock. L, a vessel in the inferior canal. C, the under gate. A, the upper gate. GH, a subterraneous passage for letting water from the superior canal run into the lock. KP, a subterraneous passage for water from the lock to the inferior canal.
X and Y, (fig. 1.) are the two floodgates, each of which consists of two leaves, resting upon one another, so as to form an obtuse angle, in order the better to resist the pressure of the water. The first (X) prevents the water of the superior canal from falling into the lock; and the second (Y) dams up and sustains stains the water in the lock. These flood-gates ought to be very strong, and to turn freely upon their hinges.
In order to make them open and shut with ease, each leaf is furnished with a long lever A b, A b; C b, C b. They should be made very tight and close, that as little water as possible may be lost.
By the subterraneous passage GH (fig. 2, 3, and 4) which descends obliquely, by opening the sluice G, the water is let down from the superior canal D into the lock, where it is stopped and retained by the gate C when shut, till the water in the lock comes to be on a level with the water in the superior canal D; as represented, fig. 3. When, on the other hand, the water contained by the lock is to be let out, the passage GH must be shut by letting down the sluice G; the gate A must be also shut, and the passage KF opened by raising the sluice K: a free passage being thus given to the water, it descends through KF, into the inferior canal, until the water in the lock is on a level with the water in the inferior canal B; as represented, fig. 2.
Now, let it be required to raise the vessel L (fig. 2) from the inferior canal B to the superior one D; if the lock happens to be full of water, the sluice G must be shut, and also the gate A, and the sluice K opened, so that the water in the lock may run out till it is on a level with the water in the inferior canal B. When the water in the lock comes to be on a level with the water at B, the leaves of the gate C are opened by the levers C b, which is easily performed, the water on each side of the gate being in equilibrium; the vessel then sails into the lock. After this the gate C and the sluice K are shut, and the sluice G opened, in order to fill the lock, till the water in the lock, and consequently the vessel, be upon a level with the water in the superior canal D; as is represented in fig. 3. The gate A is then opened, and the vessel passes into the canal D.
Again let it be required to make a vessel descend from the canal D into the inferior canal B. If the lock is empty, as in fig. 2, the gate C and sluice K must be shut, and the upper sluice G opened, so that the water in the lock may rise to a level with the water in the upper canal D. Then open the gate A, and let the vessel pass through into the lock. Shut the gate A and the sluice G; then open the sluice K, till the water in the lock be on a level with the water in the inferior canal; then the gate C is opened, and the vessel passes along into the canal B, as was required.
Scarcity of water becomes a very serious inconvenience to navigation in those places where locks are necessary, as without a sufficient supply, it must be frequently interrupted. To save water, therefore, has been an important consideration in the construction of locks. Various attempts have been made for this purpose. We shall here give an account of one which has been proposed by Mr Playfair, architect in London. "The nature and principle of this manner of saving water (says the inventor), consists in letting the water which has served to raise or fall a boat or barge from the lock, pass into reservoirs or cisterns, whose apertures of communication with the lock are upon different levels, and which may be placed or constructed at the side or sides of the lock with much they communicate, or in any other contiguous situation that circumstances may render eligible; which apertures may be opened or shut at pleasure, so that the water may pass from the lock to each reservoir of the canal, or from each reservoir to the lock, in the following manner: The water which fills the lock, when a boat is to ascend or descend, instead of being passed immediately into the lower part of the canal, is let pass into these cisterns or reservoirs, upon different levels; then their communications with the lock being shut, they remain full until another vessel is wanted to pass; then, again, the cisterns are emptied into the lock, which is thereby nearly filled, so that only the remainder which is not filled is supplied from the higher part of the canal. Each of these cisterns must have a surface not less than that of the lock, and must contain half as much water as is meant to be expended for the passing of each vessel. The cistern the most elevated is placed twice its own depth (measuring by the aperture, or communicating opening of the cisterns) under the level of the water in the higher part of the canal. The second cistern is placed once its own depth under the first, and so on are the others, to the lowest; which last is placed once its own depth above the level of the water in the lower part of the canal. The apertures of the intermediate cisterns, whatever their number may be, must all be equally divided into different levels; the surface of the water in the one being always on the level of the bottom of the aperture of the cistern which is immediately above. As an example of the manner and rule for constructing these cisterns, suppose that a lock is to be constructed twelve feet deep, that is, that the vessel may ascend or descend twelve feet in passing. Suppose the lock sixty feet long and six feet wide, the quantity of water required to fill the lock, and to pass a boat, is 4320 cubic feet; and suppose that, in calculating the quantity of water that can be procured for supplying the canal, after allowing for waste, it is found (according to the number of boats that may be expected to pass) that there will not be above 800 cubic feet for each; then it will be necessary to save five sixths of the whole quantity that in the common case would be necessary: to do which ten cisterns must be made (the mode of placing which is expressed in the drawing, fig. 5. Plate CXXXIV.), each of which must be one foot deep, or deeper at pleasure, and each must have a surface of 360 feet square, equal to the surface of the lock. The bottom of the aperture of the lowest cistern must be placed one foot above the level of the water in the lower part of the canal, or eleven feet under the level of the high water; the second cistern must be two feet above the level of the low water; the third three feet, and so on of the others; the bottom of the tenth, or uppermost cistern, being ten feet above the low water, and two feet lower than the high water; and, as each cistern must be twelve inches in depth, the surface of the water in the higher cistern will be one foot under the level of the water in the upper part of the canal. The cisterns being thus constructed, when the lock is full, and the boat to be let down, the communications between the lock and the cisterns, which until then have all been shut, are to be opened in the following manner; first, the communication with the higher cistern is opened, which, being at bottom two feet under the level of the water in the lock, lock, is filled to the depth of one foot, the water in the lock descending one foot also at the same time: that communication is then shut, and the communication between the lock and the second cistern is opened; one foot more of the water then passes into that cistern from the lock, and fills it; the opening is then shut: the same is done with the third, fourth, fifth, sixth, seventh, eighth, ninth, and tenth cisterns, one by one, until they are all filled; and, when the tenth, or lowermost cistern, is filled, there remains but two feet depth of water in the lock. The communication between the lock and the lower part of the canal is then opened, and the last two feet depth of water is emptied into the lower part of the canal. By this means, it is evident, that, instead of twelve feet depth of water being let descend into the lower part of the canal, there is only two feet depth that descends, or one-sixth of the whole; therefore, instead of 4320 cubic feet being used, there are only 720 cubic feet used: the remainder of the water in the cisterns being used as follows. When another boat is to mount, the sluices being then shut, and the boat in the lock, the tenth or lowermost cistern is emptied into the lock, which it fills one foot; the communication being then shut, the next lower cistern, or the ninth, is emptied into the lock, which is thereby filled another foot; and so in like manner, all the other cisterns are emptied, one after another, until the higher cistern being emptied, which fills the tenth foot of water in the lock, there remains but two feet of water to fill, which is done from the upper part of the canal, by opening the higher sluice to pass the boat; by that means the same quantity of water descends from the upper part of the canal into the lock, that in the other case descended from the lock into the lower part of the canal; so that, in both cases, the same quantity of water is saved, that is, five-sixths of what would be necessary were there no cisterns. Suppose again that, upon the same canal, and immediately after the twelve feet lock, it would be advantageous to construct one of eighteen feet; then, in order not to use any greater quantity of water, it will be necessary to have sixteen cisterns, upon different levels, communicating with the lock in the same manner. Should, again, a lock of only six feet be wanted, after that of eighteen, then it will only be necessary to have four cisterns on different levels, and so of any other height of lock. The rule is this: for finding the number and size of the cisterns, each cistern being the same in superficies with the lock, its depth must be such as to contain one half the quantity of water meant to be used in the passing of one boat. The depth of the lock, divided by the depth necessary for such a cistern, will give, in all cases, the whole number of cisterns, and two more: deduct the number two, therefore, from the number which you find by dividing the depth of the lock by the depth of one cistern, and you have always the number of cisterns required; which are to be placed upon different levels, according to the rule already given. The above is the principle and manner of using the lock, for saving water in canals, and for enabling engineers to construct locks of different depths upon the same canal, without using more water for the deep locks than for the shallow ones. With regard to the manner of disposing the cisterns, the circumstance of the ground, the declivity, &c. will be the best guide for the engineer.
But even when water is abundant, if the declivity of a country be such as to require numerous locks, navigation suffers great interruption from them. A method by which boats could be raised and lowered with greater facility, or in a shorter time than can be done by means of locks, is still a very desirable object of improvement in inland navigation. For this purpose the inclined plane has been often resorted to, and particularly in China, where water carriage is more generally employed than in any country of Europe. But this method requires very powerful machinery or a great number of hands, which has prevented it from being much practised in this country. Other contrivances to obviate the use of locks have been proposed. Dr Anderson, in his Agricultural Survey of the County of Aberdeen, has described one, of which we shall give an account in his own words. This contrivance, he observes, "in the opinion of very good judges of matters of this sort, to whom the plan has been shewn, has been deemed fully adequate to the purpose of raising and lowering boats of a moderate size, that is, of 20 tons, or downwards; and it is the opinion of most men with whom I have conversed, who are best acquainted with the inland navigations, that a boat of from 10 to 15 tons is better than those of a larger size. When several are wanted to be sent at once, they may be affixed to one another, as many as the towing-horse can conveniently draw. Were boats of this size adopted, and were all the boats on one canal to be of the same dimensions, it would prove a great convenience to a country in a state of beginning improvements; because the expense of such a boat would be so trifling, that every farmer could have one for himself, and might of course make use of it when he pleased, by the aid of his own horse, without being obliged to have any dependence on the time that might suit the convenience of his neighbour; and if two or more boats were going from the same neighbourhood, one horse could serve the whole.
"You are to suppose that fig. 6, Plate CXXXIV., represents a bird's eye view of this simple apparatus, as seen from above. A is supposed to be the upper reach of the canal, and B the lower reach, with the apparatus between the two. This consists of three divisions; the middle one, extending from C to D, is a solid piece of masonry, raised from a firm foundation below the level of the bottom of the second reach; this is again divided into five parts, viz. d d d, where the wall rises only to the height of the water in the upper reach, and e e, two pillars, raised high enough to support the pivots of a wheel or pulley g, placed in the position there marked.
"The second division h consists of a wooden coffer, of the same depth nearly as the water in the upper reach, and of a size exactly fitted to contain one of the boats. This communicates directly with the upper reach, and being upon the same plane with it, and so connected with it as to be water-tight, it is evident, from inspection, that nothing can be more easy than to float a boat into this coffer from the upper reach, the part of the wheel that projects over it being at a sufficient height above it, so as to occasion no sort of interruption." "Third division. At i is represented another coffer, precisely of the same dimensions with the first. But here two sluices, which were open in the former, and only represented by dotted lines, are supposed to be shut, so as to cut off all communication between the water in the canal and that in the coffer. As it was impossible to represent this part of the apparatus on so small a scale, for the sake of illustration it is represented more at large in fig. 9, where A, as before, represents the upper reach of the canal, and h one of the coffers. The sluice k goes into two cheeks of wood, joined to the masonry of the dam of the canal, so as to fit perfectly close; and the sluice f fits, equally close, into cheeks made in the side of the coffer for that purpose; between these two sluices is a small space o. The coffer, and this division o, are to be supposed full of water, and it will be easy to see that these sluices may be let down, or drawn up at pleasure, with much facility.
"Fig. 10. represents a perpendicular section of these parts in the same direction as in fig. 9, and in which the same letters represent the same parts.
"Things being thus arranged, you are to suppose the coffer h to be suspended, by means of a chain passed over the pulley, and balanced by a weight that is sufficient to counterpoise it, suspended at the opposite end of the chain. Suppose, then, that the counterpoise be made somewhat lighter than the coffer with its contents, and that the line mn (fig. 10.) represents a division between the solid sides of the dam of separation, which terminates the upper reach and the wooden coffer, which had been closed only by the pressure of its own weight (being pushed a very little from A towards B, beyond its precise perpendicular swing), and that the joining all round is covered with lists of cloth put upon it for that purpose; it is evident that, so long as the coffer is suspended to this height, the joining must be water-tight; but no sooner is it lowered down a little than this joining opens, the water in the small division o is allowed to run out, and an entire separation is made between the fixed dam and this moveable coffer, which may be lowered down at pleasure without losing any part of the water it contained.
"Suppose the coffer now perfectly detached, turn to fig. 7, which represents a perpendicular section of this apparatus, in the direction of the dotted line pp (fig. 6.). In fig. 7, h represents an end view of the coffer, indicated by the same letter as in fig. 6. suspended by its chain, and now perfectly detached from all other objects, and balanced by a counterpoise i, which is another coffer exactly of the same size, as low down as the level of the lower reach. From inspection only it is evident, that, in proportion as the one of these weights rises, the other must descend. For the present, then, suppose that the coffer h is by some means rendered more weighty than i, it is plain it will descend while the other rises; and they will thus continue till h comes down to the level of the lower reach, and i rises to the level of the higher one.
"Fig. 8. represents a section in the direction AB (fig. 6.), in which the coffer i (seen in both situations) is supposed to have been gradually raised from the level of the lower reach B to that of the higher one where it now remains stationary; while the coffer h (which is concealed behind the masonry) has descended in the mean time to the level of the lower reach, where it closes by means of the juncture rs, fig. 10. (which juncture is covered with lists of cloth, as before explained at mn, and is of course become water-tight), when, by lifting the sluice r, and the corresponding sluice at the end of the canal, a perfect communication by water is established between them. If then, instead of water only, this coffer had contained a boat, floated into it from the upper reach, and then lowered down, it is very plain, that when these sluices were removed, after it had reached the level of the lower reach, that boat might have been floated out of the coffer with as much facility as it was let into it above. Here then we have a boat taken from the higher into the lower canal; and, by reversing this movement, it is very obvious that it might be, with equal ease, raised from the lower into the higher one. It now only remains that I should explain by what means the equilibrium between these counter-balancing weights can be destroyed at pleasure, and the motion, of course, produced.
"It is very evident, that if the two corresponding coffers be precisely of the same dimensions, their weight will be exactly the same when they are both filled to the same depth of water. It is equally plain, that should a boat be floated into either or both of them, whatever its dimensions or weight may be, so that it can be contained afloat in the coffer, the weight of the coffer and its contents will continue precisely the same as when it was filled with water only: hence, then, supposing one boat is to be lowered, or one to be raised at a time, or supposing one to be raised and another lowered at the same time—they remain perfectly in equilibrium in either place, till it is your pleasure to destroy that equilibrium. Suppose, then, for the present, that both coffers are loaded with a boat in each, the double sluices both above and below closed; and suppose also that a stop-cock u, in the under edge of the side of the lower coffer (fig. 8. and 10.), is opened, some of the water which served to float the boat in the coffer will flow out of it, and consequently that coffer will become lighter than the higher one; the upper coffer will of course descend, while the other mounts upwards. When a gentle motion has been thus communicated, it may be prevented from accelerating, merely by turning the stop-cock so as to prevent the loss of more water, and thus one coffer will continue to ascend, and the other to descend, till they have assumed their stations respectively; when, in consequence of a stop below, and another above, they are rendered stationary at the level of the respective canals (A).
"Precisely the same effect will be produced when the coffers are filled entirely with water.
"It is unnecessary to add more to this explanation, except to observe, that the space for the coffer to descend into must be deeper than the bottom of the lower canal,
(A) "It does not seem necessary to adopt any other contrivance than the above for regulating the motions; but if it should be found necessary, it would be easy to put a ratch-wheel on the same axle." canal, in order to allow a free descent for the coffer to the requisite depth; and of course it will be necessary to have a small conduit to allow the water to get out of it. Two or three inches free, below the bottom of the canal, is all that would be necessary.
"Where the height is inconsiderable, there will be no occasion for providing any counterpoise for the chain, as that will give only a small addition to the weight of the undermost coffer, so as to make it preponderate, in circumstances where the two coffers would otherwise be in perfect equilibrium; but, where the height is considerable, there will be a necessity for providing such a counterpoise; as, without it, the chain, by becoming more weighty every foot it descended, would tend to destroy the equilibrium too much, and accelerate the motion to an inconvenient degree. To guard against this inconvenience, let a chain of the same weight per foot, be appended at the bottom of each coffer, of such a length as to reach within a few yards of the ground where the coffer is at its greatest height (see fig. 7.); it will act with its whole weight upon the highest coffer while in this position; but, as that gradually descended, the chain would reach the ground, and, being there supported, its weight would be diminished in proportion to its descent; while the weight of the chain on the opposite side would be augmented in the same proportion, so as to counterpoise each other exactly, in every situation, until the uppermost chain was raised from the ground. After which it would increase its weight no more; and, of course, would then give the under coffer that preponderance which is necessary for preserving the machine steady. The under coffer, when it reached its lowest position, would touch the bottom on its edges, which would then support it, and keep everything in the same position, till it was made lighter for the purpose of ascending.
"What constitutes one particular excellence of the apparatus here proposed is, that it is not only unlimited as to the system of the rise or depression of which it is susceptible (for it would not require the expenditure of one drop more water to lower it 100 feet than one foot); but it would also be easy so to augment the number of pulleys at any one place as to admit of two, three, four, or any greater number of boats being lowered or elevated at the same time; so that let the succession of boats on such a canal be nearly as rapid as that of carriages upon a highway, none of them need be delayed one moment to wait an opportunity of passing: a thing that is totally impracticable where water-locks are employed; for the intercourse, on every canal constructed with water-locks, is necessarily limited to a certain degree, beyond which it is impossible to force it.
"For example: suppose a hundred boats are following each other, in such a rapid succession as to be only half-a-minute behind each other. By the apparatus here proposed, they would all be elevated precisely as they came; in the other, let it be supposed that the lock is so well constructed as that it takes no more than five minutes to close and open it; that is, ten minutes in the whole to each boat (for the lock, being once filled, must be again emptied before it can receive another in the same direction); at this rate, six boats only could be passed in an hour, and of course it would take sixteen hours and forty minutes to pass the whole hundred; and as the last boat would reach the lock in the space of fifty minutes after the first, it would be detained fifteen hours and fifty minutes before its turn would come to be raised. This is an immense detention; but if a succession of boats, at the same rate, were to follow continually, they never could pass at all. In short, in a canal constructed with water-locks, not more than six boats, on an average, can be passed in an hour, so that beyond that extent all commerce must be stopped; but, on the plan here proposed, sixty, or six hundred, might be passed in an hour, if necessary, so as to occasion no sort of interruption whatever. These are advantages of a very important nature, and ought not to be overlooked in a commercial country.
"This apparatus might be employed for innumerable other uses as a moving power, which it would be foreign to our present purpose here to specify. Nor does its power admit of any limitation, but that of the strength of the chain, and of the coffers which are to support the weights. All the other parts admit of being made so immovably firm as to be capable of supporting almost any assignable weight.
"I will not enlarge on the benefits that may be derived from this very simple apparatus: its cheapness, when compared with any other mode of raising and lowering vessels that has ever yet been practised, is very obvious; the waste of water it would occasion is next to nothing; and when it is considered that a boat might be raised or lowered fifty feet nearly with the same ease as five, it is evident that the interruptions which arise from frequent locks would be avoided, and an immense saving be made in the original expense of the canal, and in the annual repairs.
"It is also evident, that an apparatus, on the same principle, might be easily applied for raising coals or metals from a great depth in mines, wherever a very small stream of water could be commanded, and where the mine was level-free."
It is almost needless to spend time in enumerating the many advantages which necessarily result from artificial navigations. Their utility is now so apparent, that most nations in Europe give the highest encouragement to undertakings of this kind wherever they are practicable. The advantages of navigable canals did not escape the observation of the ancients. From the most early accounts of society we read of attempts to cut through large isthmuses, in order to make a communication by water, either between different nations, or distant parts of the same nation, where land-carriage was long and expensive. Herodotus relates, that the Cnidians, a people of Caria in Asia Minor, designed to cut the isthmus which joins that peninsula to the continent; but were superstitious enough to give up the undertaking, because they were interdicted by an oracle. Several kings of Egypt attempted to join the Red sea to the Mediterranean by a canal. It was begun by Necos the son of Psammeticus, and completed by Ptolemy II. After his reign it was neglected, till it was opened in 635 under the caliphate of Omar, but was again allowed to fall into disrepair: so that it is now difficult to discover any traces of it. Both the Greeks and Romans intended to make a canal across the isthmus of Corinth, which joins the Morea and Achaea, in order to make a navigable passage by the Ionian sea into the Archipelago. Demetrius, metrius, Julius Caesar, Caligula, and Nero, made several unsuccessful efforts to open this passage. But, as the ancients were entirely ignorant of the use of water-locks, their whole attention was employed in making level cuts, which is probably the principal reason why they so often failed in their attempts. Charlemagne formed a design of joining the Rhine and the Danube, in order to make a communication between the ocean and the Black sea, by a canal from the river Almutz which discharges itself into the Danube, to the Reditz, which falls into the Main, and this last falls into the Rhine near Mayence; for this purpose he employed a prodigious number of workmen; but he met with so many obstacles from different quarters, that he was obliged to give up the attempt.
The French at present have many fine canals: that of Briare was begun under Henry IV. and finished under the direction of Cardinal Richelieu in the reign of Louis XIII. This canal makes a communication betwixt the Loire and the Seine by the river Loing. It extends 11 French great leagues from Briare to Montargis. It enters the Loire a little above Briare, and terminates in the Loing at Cepoi. There are 42 locks on this canal.
The canal of Orleans, for making another communication between the Seine and the Loire, was begun in 1675, and finished by Philip of Orleans, regent of France, during the minority of Louis XV. and is furnished with 20 locks. It goes by the name of the canal of Orleans; but it begins at the village of Combleux, which is a short French league from the town of Orleans.
But the greatest and most useful work of this kind is the junction of the ocean with the Mediterranean by the canal of Languedoc. It was proposed in the reigns of Francis I. and Henry IV. and was undertaken and finished under Louis XIV. It begins with a large reservoir 4000 paces in circumference, and 24 feet deep, which receives many springs from the mountain Noire. This canal is about 64 leagues in length, is supplied by a number of rivulets, and is furnished with 104 locks, of about eight feet rise each. In some places it passes over bridges of vast height; and in others it cuts through solid rocks for 1000 paces. At one end it joins the river Garonne near Thoulouse, and terminates at the other in the lake Tau, which extends to the port of Cette. It was planned by Francis Riquet in the 1666, and finished before his death, which happened in the 1680.
In the Dutch, Austrian, and French Netherlands, there is a very great number of canals; that from Bruges to Ostend carries vessels of 200 tons.
The Chinese have also a great number of canals; that which runs from Canton to Pekin extends about 825 miles in length, and was executed about 800 years ago.
It would be an endless task to describe the numberless canals in Holland, Russia, Germany, &c. We shall therefore confine ourselves to some of the more important in our own country.
As the promoting of commerce is the principal intention of making canals, it is natural to expect that their frequency in any nation should bear some proportion to the trade carried on in it, providing the situation of the country will admit of them. The present state of England and Scotland confirms this observation. Though the Romans made a canal between the Nynne, a little below Peterborough, and the Witham, three miles below Lincoln, which is now almost entirely filled up, yet it is not long since canals were revived in England. They are now however become very numerous, particularly in the counties of York, Lincoln, and Cheshire. Most of the counties betwixt the mouth of the Thames and the Bristol channel are connected together either by natural or artificial navigation; those upon the Thames and Isis being now connected with those upon the Severn. The duke of Bridgewater's canal in Cheshire runs 27 miles on a perfect level; but at Barton it is carried by a very high aqueduct bridge over the Irwell, a navigable river; so that it is common for vessels to be passing at the same time both under and above the bridge. It is likewise cut some miles into the hills, where the duke's coal-mines are wrought.
A navigable canal betwixt the Forth and Clyde in Scotland, and which divides the kingdom in two parts, was first thought of by Charles II. for transports and small ships of war; the expense of which was to have been 500,000l. a sum far beyond the abilities of his reign. It was again projected in the year 1722, and a survey made; but nothing more done till 1761, when the then Lord Napier, at his own expense, caused a survey, plan, and estimate, on a small scale, to be made. In 1764, the trustees for fisheries, &c. in Scotland, caused another survey, plan, and estimate, of a canal five feet deep, which was to cost 79,000l. In 1766, a subscription was obtained by a number of the most respectable merchants in Glasgow, for making a canal four feet deep and twenty four feet in breadth; but when the bill was nearly obtained in parliament, it was given up on account of the smallness of the scale, and a new subscription set on foot for a canal seven feet deep, estimated at 150,000l. This obtained the sanction of parliament; and the work was begun in 1768 by Mr Smeaton the engineer. The extreme length of the canal from the Forth to the Clyde is 33 miles, beginning at the mouth of the Carron, and ending at Dalmuir Burnfoot on the Clyde, six miles below Glasgow, rising and falling 160 feet by means of 39 locks, 20 on the east side of the summit, and 19 on the west, as the tide does not ebb so low in Clyde as in the Forth by nine feet. Vessels drawing eight feet water, not exceeding nineteen feet beam and seventy-three feet in length, pass with ease, the canal having afterwards been deepened to upwards of eight feet. The whole enterprise displays the art of man in a high degree. The carrying the canal through moss, quicksand, gravel, and rocks, up precipices and over valleys, was attended with inconceivable difficulties. There are eighteen draw-bridges and fifteen aqueduct bridges of note, besides small ones and tunnels. In the first three miles there are only six locks; but in the fourth mile there are no less than ten locks, and a very fine aqueduct bridge over the great road to the west of Falkirk. In the next six miles there are only four locks which carry you to the summit. The canal then runs eighteen miles on a level, and terminates by one branch about a mile from Glasgow. In this course, for a considerable way, the ground is banked about twenty feet high, and the water is sixteen feet deep, Canal, and two miles of it is made through a deep moss. At Kirkintilloch, the canal is carried over the water of Logie on an aqueduct arch of ninety feet broad. This arch was thrown over in three stretches, having only a centre of thirty feet, which was shifted on small rollers from one stretch to another; a thing new, and never attempted before with an arch of this size; yet the joinings are as fairly equal as any other part, and admired as a very fine piece of masonry. On each side there is a very considerable banking over the valley. This work was carried on till it came within six miles of its junction with the Clyde; when the subscription and a subsequent loan being exhausted, the work was stopt in 1775. The city of Glasgow, however, by means of a collateral branch, opened a communication with the Forth, which has produced a revenue of about 600l. annually; and, in order to finish the remaining six miles, the government in 1784 gave 50,000l. out of the forfeited estates, the dividends arising from this sum to be applied to making and repairing roads in the Highlands of Scotland. The work was accordingly resumed; and by contract, under a high penalty, was to be entirely completed in November 1789. The aqueduct bridge over the Kelvin, which is supposed the greatest of the kind in the world, consists of four arches, and carries the canal over a valley 65 feet high, and 420 in length, exhibiting a very singular effort of human ingenuity and labour. To supply the canal with water was of itself a very great work. There is one reservoir of 50 acres 24 feet deep, and another of 70 acres 22 feet deep, in which many rivers and springs terminate, which it is thought will afford a sufficient supply of water at all times. This whole undertaking when finished cost about 200,000l. It is the greatest of the kind in Britain, and of great national utility; though it is to be regretted that it had not been executed on a still larger scale, the locks being too short for transporting large masts.
This canal was completed in July 1790. On the 28th of this month, a tract barge, belonging to the company of proprietors, sailed from the basin, near the city of Glasgow, to Bowling bay, where the canal joins the river Clyde. The committee of management, accompanied by the magistrates of Glasgow, were the first voyagers on the new canal. On the arrival of the vessel at Bowling bay, after descending from the last lock into the Clyde, the ceremony of the junction of the Forth and Clyde was performed by discharging into the river Clyde a hogshead of water taken up from the river Forth, as a symbol of joining the western and eastern seas together.
About the year 1801, a canal was finished between Loch Gilp to Loch Crinan in Argyleshire. The distance is about nine miles. This canal, which is called the Crinan canal, is intended to accommodate the trade of the Western islands and fisheries. The vessels employed in this trade will, by means of this canal, avoid the circuitous and dangerous navigation round the Mull of Cantire.
Another canal was begun in 1803, which is intended to open a communication between the Western sea, and the Murray frith, through Loch Ness. This canal, which is by far the most magnificent work of the kind in Britain, is expected to be finished in 1821. See Caledonian Canal, Supplement.