NORTH AMERICA.

United States.

The advantages resulting to the United States from their separation from the mother country, and the great and rapid improvement which has taken place in the condition and circumstances of that republic since the American revolution, are in nothing more strikingly displayed than in the increased facilities of travelling and intercourse between the different parts of the Union, produced by the construction of roads, canals, and railways, and by the improvement of river navigation. But the spirit of enterprise with respect to internal improvement has been chiefly manifested, and has extended more or less to all the states of the Union, since the close of their last war with Britain. For although it is a considerable time since something was first done towards inland navigation in the United States, yet till then comparatively little attention was paid to this by the Americans. Indeed, as long as they were cramped by the narrow policy of the parent country, they had little inducement to undertake any thing of the sort; and from the peace of 1783 till the adoption of the present constitution they had not the means; besides, their peculiar situation and employment during the long wars in Europe rendered internal improvements of this kind less necessary. The experience of the last war between Britain and the United States, and the long peace which succeeded it in Europe, together with the vast expansion of American population, have shown the importance and necessity of such works, as well as others, in that extensive country; and, since the year 1815, the United States have progressed in these improvements with an unexampled rapidity. Most of the canals on the continent of Europe have been constructed at the expense of governments; in England chiefly at the expense of companies or individuals; and in the United States they have been made by the states and by individuals, aided occasionally by the general government. In locating canals in this latter country, two principal objects have been kept in view; one to insure a safe inland communication along the Atlantic border in case of a war with any power possessing a superior maritime force; whilst another and very important object [7:16:24]has been to connect the waters of the western districts with those of the eastern, and thereby facilitate the intercourse between these two distant sections of the country. The vast expansion of population in the western parts, and the great and growing resources of that portion of the Union, have rendered such improvements of great importance, and have created rival interests in the eastern, in order to secure the advantages of this intercourse. The valley of the Mississippi is watered by rivers, some of which, only of the third rate, extend 1000 miles; and it is also indented by lakes the magnitude of which justly entitles them to the appellation of inland seas. Its population is spread over a country unrivalled in the extent and magnitude of its navigable waters, as well as in the fertility of its soil. The navigation of these great rivers, as well as that of many others, which was formerly very difficult, against the stream, has been wonderfully facilitated by the application of steam power, which has enabled the navigator to propel his vessel up the river, and to triumph over the violence of the torrent; and thus the rivers by which great continents are intersected have been rendered doubly valuable in facilitating the inland communications of the country, and in laying open the most remote and formerly sequestered scenes to the inquisitive researches of travellers. With respect to canals, there is no navigable line entirely artificial (for those of China are partly rivers) of such length as the Erie Canal, which is 363 miles, and was formed in about eight years. That of Languedoc, in France, is only 148 miles, and occupied fourteen years in construction, even during the reign of Louis XIV. However, the great canal of Amsterdam, in Holland, though only fifty miles long, contains twice as much water as the Erie Canal.

The aggregate length of canals now finished in the United States exceeds 2000 miles; but some of the states do not admit of their construction, except to a comparatively small extent, whilst others present a vast field and great inducements for prosecuting such works on a magnificent scale. Our limits, however, will only admit of a very brief description of these improvements; and to this we shall now proceed, following the order in which the states are usually arranged, and omitting of course such of them as are not possessed of canals.

The Cumberland and Oxford Canal, twenty miles and a half long, extends from the tideway near Portland to Sebago Pond. It has twenty-six locks, and was completed in 1829. By means of a lock in Songo River, the navigation is continued into Brandy and Long Ponds, making in all fifty miles. Improvements have been projected in the navigation of the river St Croix and the adjacent waters. It has also been proposed to construct a canal from the mouth of the Sebasticok River, near Waterville, on the Kennebeck, to Moosehead Lake.

Several canals have been constructed around falls in the Merrimack. Bow Canal, one third of a mile in length, three miles below Concord; with four locks, passes a fall of twenty-five feet. Hooksett Canal, fifty rods long, with three locks and a lockage of sixteen feet, passes Hooksett Falls. Amoskeag Canal, with nine locks and a lockage of forty-five feet, passes Amoskeag Falls, nine miles below Hooksett Falls. Union Canal, immediately below Amoskeag, overcomes seven falls in the river, and has seven locks in nine miles. A canal is now in progress around SewalΓs Falls, in Concord.

The Middlesex Canal, connecting Boston harbour with the Merrimack at Chelmsford, two miles below Lowell, opens a water communication between Boston and the central parts of New Hampshire, and is twenty-seven miles in length. It has twenty locks, with a lockage of thirty-six feet; and is thirty feet wide at top, twenty at bottom, and three feet deep. It was completed in 1808, and was then the largest in the United States.

Blackstone Canal, extending from Worcester to Providence, in Rhode Island, is forty-five miles long.

The Hampshire and Hampden Canal, extending from the boundary of Connecticut in Suffield, to Northampton, is twenty-two miles long, and, forming a continuation of Farmington Canal, which is fifty-four miles in length, makes the whole line from Newhaven to Northampton seventy-six miles.

Montague Canal, for passing the falls in the town of that name, is three miles in length; and South Hadley Canal, around falls in the town of South Hadley, is two miles in length.

Farmington Canal, fifty-four miles long, commences at Newhaven, passes through the valley of Farmington River, and at the boundary of the state of Massachusetts it unites with the Hampshire and Hampden Canal, which reaches to Northampton, and is twenty-two miles in length. Enfield Canal, five miles and a half long, is constructed around the Enfield Falls in Connecticut River.

The Erie Canal, extending from Albany on the Hudson River to Buffalo on Lake Erie, a total distance of 363 miles, is one of the greatest and most important works of the kind in the world. It was projected by an American patriot, Mr De Witt Clinton; commenced in 1817, and finished in 1825. The water is forty feet wide at the surface, twenty-eight at the bottom, and four feet deep. These are generally the dimensions of the other canals in this state, and therefore they cannot carry very heavy boats; but a less depth will always suffice if the boats are not encumbered with keels, which are utterly useless in a canal. The western section, from Buffalo on Lake Erie to Montezuma on Seneca River, is 157 miles in length, with twenty-one locks for a fall of 186 feet; the middle section, from Montezuma to Utica, is ninety-six miles, with eleven locks for a rise and fall of ninety-five feet; the eastern section, from Utica to Albany, is 110 miles, with fifty-two locks for a fall of 417 feet; total length 363 miles, with eighty-four locks for a total rise and fall of 698 feet. Lake Erie is 565 feet above the Hudson River at Albany. The average rise or fall of eighty-one of the locks is eight feet and a half, the other three are regulating of guard-locks.

This canal forms a channel by which the trade of the great inland waters of Lake Erie, Lake Huron, Lake Michigan, &c. may find access to markets in the populous cities of Eastern America and of Europe. Indeed there is already such a traffic on this canal and its branches, described below, that it has been proposed greatly to increase its dimensions, which must require many times the additional expense necessary to have made it sufficiently large at first. There is, however, nothing very remarkable in this, because the most proper size of a canal can seldom be foreseen by the projectors.

Champlain Canal, sixty-three miles long, commences, at its junction with the Erie Canal, nine miles north of Albany, and terminates at Whitehall, on Lake Champlain, in Washington county, thus connecting the Erie Canal and the Hudson River with Lake Champlain. It has seven locks for a rise of fifty-four feet from the lake to the summit-level, and fourteen locks for a fall of 134 feet from this to the Hudson, in all twenty-one locks; the rise and fall are 188 feet. It has a lateral cut connecting it with the Hudson by three locks at Waterford, eleven miles north of Albany, similar to the cut connecting the Erie Canal with the same river at West Troy by two locks.

The Oswego Canal, of thirty-eight miles, from Salina to Oswego, connects Lake Ontario with the Erie Canal. Half the distance is canal and half slack-water or river navigation. It has fourteen locks, thirteen of stone and one of wood and stone, for a fall of 123 feet from Salina to Lake Ontario.
[7:16:25]

The Cayuga and Seneca Canal commences at the Erie Canal at Montezuma, Cayuga county, and terminates at Geneva, Ontario county, connecting the Erie Canal with Seneca Lake. It has also a lateral branch to East Cayuga village on the Cayuga Lake, being thus connected with that lake. It opens altogether a lake navigation of more than a hundred miles. The length is twenty miles and forty-four chains from Geneva, on the Seneca Lake, to Montezuma on the Erie Canal. It is half canal and half slack-water navigation, and has eleven wooden locks for a fall of seventy-three feet from Seneca Lake to the Erie Canal at Montezuma.

The Chemung Canal extends from the head of the waters of Seneca Lake to Chemung (or Uioga) River, a branch of the Susquehannah, at the village of Elmira, Tioga county. The length is twenty-two miles and a half, with a navigable feeder of thirteen miles and a half from Painted Post, Stuben county, on the Chemung River, to the summit-level; total, thirty-six miles. This canal connects the Erie Canal with the Susquehannah River. It has fifty-two wooden locks, with 516 feet of lockage, and one guardlock.

The Crooked Lake Canal extends from Penn Yan to Dresden, both in Yates county, connecting the Crooked and Seneca Lakes. It is eight miles long, and has 260 feet of lockage, with twenty-seven wooden locks, and one guard-lock.

The Chenago Canal extends from Utica to Binghamp, a distance of ninety-seven miles, with 109 locks. It has sixteen miles of navigable feeders.

The Delaware and Hudson Canal extends from the Hudson River at Kingston, to Port Jervis on the Delaware, fifty-nine miles; thence up the Delaware to the mouth of the Lackawaxen River, twenty-four miles; thence in Pennsylvania to Honesdale, twenty-six miles; total, 109 miles. From Honesdale a railway of sixteen miles and a half, with five inclined planes, rising 800 feet, extends to the coal mines at Carbondale on the Lackawana.

Haerlam Canal, of three miles, intended to connect the Hudson and East Rivers, is begun, but not completed. Chittenango Canal, connecting that place with the Erie Canal, is one mile and a half long, with four locks. Sodus Canal, intended to connect Seneca River with Great Sodus Bay on Lake Ontario, was projected in 1829, and will be twenty-five miles long. Scottsville Canal, intended to connect the, Genesee River with Scottsville, in Monroe county, was projected in 1829. The Oneida Lake Canal, of eight miles and a half, intended to connect Oneida Lake with the Erie Canal, was put under contract in 1833. Auburn and Oswasco Canal, intended to connect Auburn with Oswasco Lake, was projected in 1832, and is to be three miles in length.

It has been proposed to connect by railways or canals the Erie Canal, somewhere about Rome or Herkinner, with the waters flowing into the St Lawrence at Ogdensburg.

The Genesee and Alleghany Canal. The projectors of the Erie Canal contemplated its connection with the river Ohio, by a south-west branch, uniting with the river Alleghany at Olean, in Cattaraugus county. A report of a survey of the line was made to the legislature in 1829. The length from Rochester along the valley of the Genesee to Olean, including navigable feeders, is to be 107 miles, which, with a side-cut to Danville of fifteen miles and a half, make the total length 122½ miles, with 1057 feet of lockage.

The Black River Canal is proposed to extend from the Erie Canal at Rome to the foot of High Falls on Black River, a distance of about thirty-five miles, with improvements in the navigation of Black River from the High Falls to Carthage, a farther distance of forty miles.

A steam-boat canal from Lake Ontario to the Hudson has been proposed, extending from Oswego to Utica, and thence along the Mohawk to the Hudson. A steam-boat or a ship canal has likewise been proposed around the Falls of the Niagara. The longest proposed route would be fifteen miles, with a lockage of 320 feet; a second route would be nine miles, with the same lockage; and a third only seven miles and a half. A ship canal around these falls, on the Canadian side, called the Welland Canal, has been in operation for several years, and will be noticed hereafter.

Delaware and Raritan Canal extends from Bordentown to New Brunswick, forty-three miles. A navigable feeder from Bool’s Island to Trenton is twenty-four miles long. Morris Canal, extending from Jersey city to Easton, is 101 miles long. Salem Canal, from Salem Creek to the Delaware, is four miles long.

During the last eight or nine years, Pennsylvania has engaged in works of internal improvement more extensively than any other state in the union; and the Pennsylvania Canal and Railway, extending from Philadelphia to Pittsburg, a distance of 395 miles, is the most magnificent work of the kind which has yet been completed in any part of the United States. It consists of the following parts:
[table]

1. Columbia Railway commences at Philadelphia, passes Downingstown and Lancaster, and enters Columbia, on the Susquehannah, by an inclined plane 1720 feet in length. It has thirty-one viaducts, seventy-three stone culverts, and eighteen bridges. It attains its greatest height at Mine Ridge, which is 555 feet above tide-water in the Delaware.

2. The central division of the Pennsylvania Canal commences at Columbia; follows the east bank of the Susquehannah, crossing the Union Canal at Middletown; passes Harrisburg; crosses the Susquehannah at the head of Duncan’s Island; and enters the valley of the Juniata, which it follows to Hollidaysburg. It has thirty-three aqueducts, and 111 locks.

3. The Alleghany Portage Railway, connecting the central and western divisions of the Pennsylvania Canal, commences at Hollidaysburg, passes over the range of the Alleghany Mountains, and terminates at Johnstown. It has one tunnel through a mountain ridge, and ten inclined planes, with stationary engines, five on each side of the summit-level, their total length being 4∙37 miles. The total rise and fall is 2570∙29 feet.

4. The western division of the Pennsylvania Canal commences at Johnstown, traversing the valley of the Conemaugh, Kiskiminetas, and Alleghany Rivers, and terminates at Pittsburg. It has sixty-four locks, sixteen aqueducts, sixty-four culverts, 152 bridges, and a remarkable tunnel about 1000 feet long.

The Beaver Canal extends from the town of Beaver, at the entrance of the Beaver River into the Ohio, to Newcastle, and is twenty-five miles long. The Mahoning and Beaver Canal, extending from Newcastle in Pennsylvania to Akron in Ohio, on the Ohio Canal, is now in progress. The Pittsburg and Erie Canal, of which the Beaver Canal is a part, is intended to connect the Pennsylvania Canal at Pittsburg with Lake Erie, and is to be seventy-three [7:16:26]miles and a half long. There are various other canals in this state, besides some which are in progress, and others which are only projected.

The Chesapeake and Delaware Canal, which connects the Delaware River with the head of Chesapeake Bay, is partly in Delaware and partly in Maryland, and commences at Delaware city, about forty-two miles below Philadelphia. The length is 13∙63 miles, the breadth at top sixty-six feet, and the depth ten feet.

The Chesapeake and Ohio Canal, begun in 1828, commences at Georgetown, on the Potomac, in the district of Columbia, and extends to Harper’s Ferry. Its course, as laid out, extends to Cumberland on the Potomac, thence by Will’s Creek, Youghiogeny, and Monongahela Rivers, to Pittsburg. The total length, as proposed, is 341 miles and a half, and the lockage 3215 feet. It requires a tunnel through the Alleghany Mountains of four miles and eighty yards. Port Deposit Canal, ten miles long, is designed to overcome the rapids of the Susquehannah above Port Deposit. The Chesapeake and Delaware Canal has been already noticed.

The Canal of Dismal Swamp commences at Deep Creek, about seven miles above Norfolk, and proceeds southward about thirteen miles to the boundary of this state, beyond which it is continued about nine miles in North Carolina, to Joyce’s Creek, a branch of the Pasquotank. This canal is thirty feet wide at bottom, and eight deep. Very extensive improvements have been projected and partly executed on the river navigation of Virginia, by means of lateral canals or side-cuts. One on James River extends from Richmond for twenty-three miles up the side of that river, and then joins it again. There are various side-cuts on the Roanoke; one extends about twelve miles from Weldon upward, but that is after the river has got into North Carolina.

Dismal Swamp Canal, already mentioned amongst those of Virginia, enters about nine miles into North Carolina; and Lake Drummond Canal, five miles long, is a navigable feeder of it. North-west Canal, six miles long, connects North-west River with Dismal Swamp Canal. Weldon Canal, twelve miles long, forms the commencement of the Roanoke Navigation, extending around the falls of the Roanoke above the towns of Weldon and Blakely. The navigation of the Roanoke from the Weldon Canal to the town of Salem in Virginia, a distance of 232 miles, as likewise the Cape Fear, the Yadkin, the Tar, the Catawba, and New Rivers, have been greatly improved.

Santee Canal, twenty-two miles long, connects the harbour of Charleston with the Santee. By means of this and the Santee and Congaree Rivers, the navigation of which has been improved, a communication is opened between Charleston and Columbia. The navigation of the Catawba has been improved by five small canals of two, one and a quarter, two and a quarter, one and three quarters, and four miles. Saluda Canal, of six miles, extends from the head of Saluda Shoals to Granby on the Congaree. Drehr’s Canal, of one mile and a third, is designed to overcome a fall of 120 feet in the Saluda River. Lorick’s Canal, on Broad River, one mile and a half above Columbia, is a mile long; and Lockhart’s Canal, in Union District, around Lockhart’s Shoals in Broad River, is two miles and three quarters in length.

The Savannah and Ogeechee Canal, sixteen miles long, extends from the city of Savannah to Ogeechee River. An extension of this canal to the Alatamaha, sixty miles, is proposed.

Huntsville Canal, from Triana on the Tennessee, to Huntsville, is sixteen miles long. A canal of thirty-seven miles, from the head of the Muscle Shoals to Florence, is considerably advanced, but not yet completed.

A ship canal, of eight miles, has been projected at New Orleans, to lead from the Mississippi to the ocean. It is to commence about three miles below Fort Jackson, and pass through the prairie on the left bank of the river. Besides, there are in progress the Orleans Bank Canal, of four miles and a quarter, from New Orleans to Lake Pontchartrain; the Carondelet Canal, of two miles, which likewise connects New Orleans with Lake Pontchartrain, through the river or bayou St John, which is four miles, making the whole line six miles; and the Barataria Canal, proceeding from the Mississippi, six miles above New Orleans, to the Lafourche, thence through the lakes to Berwick’s Bay, and thence to the sea by Barataria. It consists of four parts, amounting to twenty-two miles, which connect an extensive river navigation. The whole exceeds ninety miles.

Kentucky River Navigation, in the course of being executed, viz. the part of that river about to be rendered navigable by locks and dams, extends from its mouth up to where it branches into the three forks. For about 250 miles the whole will be slack water, adapted for steamboats of 150 tons burden. The locks are to be 175 feet long by thirty-eight wide in the chamber, ten feet above the dam; the depth of water is to be six feet; the lift of the locks from twelve to sixteen feet; the dams from twenty to twénty-five feet high, and from 400 to 500 long, and about seventy feet at the base. A variety of improvements, some of them of considerable extent, on other river navigations in this state, have also been projected, and are partly in progress.

The Ohio Canal, which extends from Cleveland upon Lake Erie, to Portsmouth on the Ohio River, is 307 miles long; it was begun in 1825, and completed in 1832. The summit-level is 305 feet above Lake Erie, 499 above the Ohio at Portsmouth, and 973 above the Atlantic. It has 152 locks for a lockage of 12,050 feet. The distances along this canal, beginning from Cleveland, are, to Akron thirty-eight miles, New Portage nine, Massillon twenty-one, Bolivar twelve, New Philadelphia fourteen, Gnaden-hutten thirteen, Coshocton twenty-six, Newark forty, Bloomfield fifty-two, Circleville eleven, Chillicothe twenty, Piketon twenty-four, Portsmouth twenty-seven. It has three navigable feeders, amounting to thirty-three miles.

The Miami Canal, which extends from Cincinnati to Dayton, is sixty-nine miles long; it was begun in 1825, and finished in 1830. The summit at Dayton is 175 feet above the Ohio at Cincinnati. It has thirty-two locks for a lockage of 296 feet. This canal is now in the course of being extended along the valleys of the St Mary’s and Au-Glaize Rivers, and is to be united at Defiance with the Wabash and Erie Canal, which extends from Lafayette on the Wabash River in Indiana, to near the entrance of the Maumee into the west end of Lake Erie. It is 187 miles long, and is nearly completed. The whole extent of this united line, from Cincinnati to Lake Erie, is about 265 miles, of which 105 are in Indiana.

The Mahoning and Beaver Canal, now in progress, extends from Newcastle, in Pennsylvania, on the Beaver division of the Pennsylvania Canal, to Akron on the portage summit of the Ohio Canal. It is eighty-five miles in length, but of this eight miles are in Pennsylvania. Sandy Creek and Little Beaver Canal, also in progress, extends from Bolivar on the Ohio Canal, in an easterly direction, to the Ohio River. Various other extensive navigations have been projected in this state, and companies have been formed for carrying them into execution.

Several extensive canals and river navigations have been projected in this state, and are partly in progress. We have already mentioned the Wabash and Erie Canal, of which part is in Ohio.

The Illinois and Michigan Canal, now in progress, ex [7:16:27]tends from Chicago on Lake Michigan, to Ottawa on Illinois River, a distance of about ninety-five miles. It is to be sixty feet wide at the surface, thirty-six at the bottom, and six deep. About twenty-four miles of this line are to be cut from seven to twenty-eight feet deep, through solid rock. Other canals have been projected in this state.

The Washington Branch Canal, of one mile and a quarter, connects the Chesapeake and Ohio Canal with the Potomac at Washington. The Alexandria Canal, of seven miles and a quarter, extends from that town to the extremity of the Chesapeake and Ohio Canal at Georgetown.

It has been proposed to connect the Atlantic Ocean with the Gulf of Mexico by a canal across the northern part of the peninsula of Florida.

Canada-

Some considerable works for promoting inland navigation have likewise been executed in Canada. Of these the following are the principal ones.

The Rideau Canal commences in about long. 75. 35. E., and lat. 45. 20. N., at Entrance Bay, in the Ottawa River, about a mile and a half from where the Rideau River falls into it, 128 miles from Montreal, and 130 from Kingston on Lake Ontario. It is not so properly a canal as an artificial concatenation of natural lakes. The general direction is south-westerly, to its termination at Kingston; and the total length of the navigation is 132 miles, of which about twenty only are artificial cuts connecting Rideau River and Lake, Mud Lake, Cranberry Lake, and Kingston Mill-Stream. The difference of level is 445 feet, with forty-seven locks, which are each 142 feet long, thirty-three broad, and five deep. This canal, it has been fancied, would be of immense importance for the conveyance of military stores; but this seems to proceed on the assumption that the enemy is to be perfectly torpid during the half year in which the canal is useless from being frozen.^[1. Canals, it is true, which are all on one level, as is the case in Holland, may become convenient roads whilst the ice is sufficiently strong; but where locks occur, and are so numerous as on this canal, they form a serious obstruction; and it is besides considered necessary in America to have canals as empty as possible during the frost. ]

The Welland Canal, connecting Lakes Erie and Ontario, communicates with the latter by the Twelve-mile Creek, and thence ascends the barrier of Lake Erie, near the Falls of Niagara, by means of locks, till it meets the Chippawa, which it ascends for some length, and then joins the Ouse at about a mile and a half from its entrance into Lake Erie. The shifting bar at the month of this river has been remedied by extending piers into the deep water. A safe communication between these great lakes is thus effected by this navigation, which is forty-one miles long; the artificial part being fifty-six feet wide, and eight and a half deep. It has thirty-seven wooden locks, each 100 feet long and twenty-two feet wide, overcoming a height of 330 feet. A much shorter canal for passing round the Falls of Niagara has been proposed on the American side.

Grenville Canal consists of three detached parts, of the nature of side-cuts, or lateral canals; one at the Long Sault on the Ottawa, another at the fall called Chûte à Blondeau, and the third at the Carillon Rapids. This canal renders the navigation of the Ottawa between the Rideau and Montreal complete; but unfortunately some of the earlier constructed locks are only twenty feet wide.

La Chine Canal is a cut of seven miles across the southeast corner of the island of Montreal, to avoid some difficult parts of the St Lawrence, particularly the rapid of St Louis. It is forty-eight feet wide at top, twenty-eight, at bottom, and five feet deep, with a fall of forty-two feet; but the locks only admit boats twenty feet wide.

By means of these great and useful works, a large extent of country is opened up to the industry of settlers. There is a continuous steam-boat communication in Upper Canada of about 460 miles, from the Grenville Canal, on the Ottawa, to Niagara. Many other canals are now in contemplation, such as that projected between the bay of Quinte and Lake Huron. A great deal of information regarding the inland navigation of Canada will be found in the Parliamentary Reports, and a more compendious account of it in Martin’s History of the British Colonies.

The navigable rivers and lakes of North America are numerous and important, several of them being of vast extent. But a very general feature in such of its rivers as fall into the Atlantic, is a bar obstructing their mouths. That of the principal month of the Mississippi had, in 1722, about twenty-five feet of water upon it; Ulloa, in 1767, found twenty feet at the highest flood; and in 1826 the depth was only sixteen feet. Above these obstructions the rivers are generally much deeper, the Mississippi at New Orleans being above 100 feet deep, which depth it preserves to the mouth of the Missouri. Mobile Bay is crossed by a bar having only ten feet of water; and the bar of the Altamabo of Georgia has fourteen feet, which is perhaps about the’average depth to be found at the entrance of most of the southern rivers of the Atlantic coast. Lake Superior, in the great central plain of this continent, is the largest body of fresh water on the globe. The outlet of this, and of the other great lakes of Canada, forms the river St Lawrence, which is of vast dimensions, the tide flowing up it for 400 miles, and affording navigation for the largest vessels the whole of this distance; but above this the current is extremely rapid. Several of the most difficult parts have already been avoided by means of sidecuts and locks, particularly the rapid of St Louis; and others may be disposed of in a similar manner. Vessels of 600 tons ascend to Montreal, and boats all the way to Lake Ontario, and thence to Lake Erie through the Welland Canal. The Connecticut is a large navigable stream entering the sea near the north-eastern extremity of Long Island. The Hudson has enabled New York to extend its commerce by the Erie Canal to the lakes, being navigable to 160 miles above its mouth for large steam-vessels. The Delaware and its tributaries afford a navigation over an extent of 300 miles in length and breadth. The Susquehannah, the Potomac, and others falling into the Chesapeake Bay, together with canals, afford navigation for vessels of one sort or other into the remotest valleys and recesses of the eastern country. The Roanoke, which falls into Albemarle Sound, together with the Pamlico, afford a medium of commerce for North Carolina; whilst the Pedec, Santee, Savannah, Ogeechee, Alatamaha, &c. are so many canals intersecting South Carolina and Georgia in all directions. The St John, again, affords a similar convenience for East Florida. But although the eastern rivers have been by much the longest employed for the purposes of navigation, they are in many respects inferior to the immense streams which intersect the western and inland states, particularly the Mississippi and its tributaries, which have no parallel in any other country possessed by a people sufficiently intelligent to turn the commercial facilities of its inland waters to .proper advantage. The Mississippi is navigable for 3000 miles up from its mouth to the Falls of St Anthony, and extends over fifteen degrees of latitude. At St Louis it receives the Missouri, which above that junction is greater than the other branch, which still bears the name of Mississippi. The principal tributaries of the Missouri are the Osage, Grand River, Kanses, Platte, [7:16:28]White River, Chien, Yellow Stone Rivers, each of which on an average adds 1000 miles to the navigation; and there are many others of less note. Above the junction of the Missouri the Mississippi receives, from the east, in latitude 37°, the Ohio, which is of great importance, as affording a direct communication with the eastern states, and being, besides, the channel of a great inland commerce. About 1200 miles from its mouth the Ohio receives, near Pittsburg, the Monongahela and the Alleghany Rivers. It is connected with Lake Erie by means of the Ohio Canal, and has fifteen large navigable tributaries. The other principal tributaries of the Mississippi more to the north, and each navigable 400 or 500 miles, are the Illinois, Des Moines, Rock River, and St Peter’s, between some of which and the great northern lakes there are only short portages. Besides all these, North America contains a vast number of other navigable rivers, which our limits will not admit of our describing.

SOUTH AMERICA.

The vast region of South America, though it has hitherto been kept in a sadly degraded state, by priestcraft, ignorance, slavery, and incessant wars, possesses a conformation peculiarly favourable to an extensive inland navigation. The Andes skirt its western shore, and, though ascending to a great height, are yet so small in breadth as to leave between them and the eastern coast a vast extent of comparatively flat country, divided into the basins of the Orinoco, Amazon, and Paraguay, none of which is much elevated above the sea; and even the dividing ranges between them are generally of very trifling altitude. Thus the Orinoco is navigable, without difficulty, for 260 leagues, to the falls or rather rapids of Atures, where, according to Humboldt, its mean height above the sea does not exceed 350 feet; and thence, after two short portages, it is navigable for above 100 leagues more, to the point near Esmeralda, where the celebated bifurcation of this river takes place, and a portion of its waters descends along the natural canal of Casiquiari, to join the Rio Negro and the Amazon. On both sides, along its course, the Orinoco receives many tributaries; of which three in particular, the Apure, Meta, and Guaviore, flowing from the westward, have also long navigable courses. The Amazon, again, is navigable to a little above Urarina, near the confluence of the Guallaga, a distance of 750 leagues from its mouth, flowing uniformly along the whole extent, in a direction from west to east, and receiving many tributaries on both sides. By the Napo, Putamayo, and Japura it is connected with the higher districts of Columbia; its own upper navigation, which is uninterrupted above Santiago, connects it with Upper Peru; and the Guallaga and Ucayale descend to it from the south-west, along the eastern face of the Andes, from distances, as it is said, of from 300 to 500 leagues. By the Rio Negro, as already noticed, its waters communicate with those of the basin of the Orinoco; the Rio Branco ascends from this also to within a short and nearly level distance of the sources of the rivers Essequibo and Demerara; and its southern tributaries, rising in the Campos Pareceis (the mean level of which west of Villa Boa, and in about 16° south latitude, where the waters divide, is not probably above 2500 feet), approach so closely to the sources of the Paraguay and its feeders, that near Villa Bella, in Matto-Grosso, only a short portage of three miles divides the course of the Aguapehy, falling into the Jaura and Paraguay, from that of the Guapore, joining the Madeira and Amazon; and, lastly, the Paraguay itself is navigable through nineteen degrees of latitude, from the confluence of the Jaura in 16° 20' south, to its mouth in the Rio de la Plata, near Buenos Ayres, in 35° south lat., and receives also many tributaries along its course, of which four only need be cited, viz. the Parana and Uruguay from the eastward, rivers each nearly equal to the main trunk in value and importance; and from the west the Pilcomayo, said to be navigable with very little interruption as far as Chuquisaca; and the Vermejo, in which there are three fathoms as high as the junction of the Rio Grande, and large boats ascend beyond it as far as Tariga.

From these facts, then, it appears that, with the exception of one short portage of three miles, water flows, and is for the most part navigable, between Buenos Ayres, in 35° south, to the mouth of the Orinoco, in nearly 9° north la-tude. The distance across the continent from east to west, through which the same convenience exists, varies greatly in different lines; but in the basin of the Orinoco it is not under 400 leagues, in that of the Amazons it is nearly 1000, and in that of the Paraguay it varies probably from 200 to 500. That all the interior provinces of South America would be prodigiously benefited by advantage being taken of these facilities for internal communication, cannot admit of a doubt; but the districts which are at present the most secluded, and which would be most strikingly improved by it, are those of Moxos, Chiquitos, and Santa Cruz de la Sierra, which contain about 43,000 square leagues, and produce a great variety of valuable articles, which are unavailable on account of there being no method of transporting them. .The only seaport with which they have any communication is Lamar (Cobija), on the Pacific, although the junction of the Jaura with the Paraguay, where the latter becomes navigable, is only seventy leagues from Santa Anna, the capital of Chiquitos, a hundred from Santa Cruz de la Sierra, and seventy-three from Villabella in Matto-Grosso.

It has long been proposed to form a communication between the Atlantic and Pacific Oceans, by means of a canal across the Isthmus of Panama. A very interesting account of a survey of a line across the isthmus, which was made a few years ago by Mr J. A. Loyd, will be found in the Philosophical Transactions for 1830; and some account of a different line by the Lake of Nicaragua is given by Captain Philips in the Journal of the Royal Geographical Society (vol. iii. 275). There can be no question that a ship canal, if practicable, would be greatly preferable to any other equally slow communication; and a railway, again, better than a small canal. A line partaking of both is also talked of.

CONSTRUCTION OF CANALS, TUNNELS, LOCKS, &c.

Canals formed for navigation are generally upon a dead level from lock to lock, except when they are also intended for conveying water, whether to other parts of the navigation, or for some different purpose. Feeders or conductors of water to canals should always have a certain declivity; but even in these it is not customary to give the bottom a greater descent than four inches in the mile. The simplest mode of constructing a canal over level ground, is to form it partly by excavation and partly by embankment; that is, to proportion the depth of digging such, that the stuff thrown out shall exactly embank or raise the sides sufficiently to make the canal of the required dimensions. This is called level cutting. But when a canal runs along the side of a declivity, the one bank will require more raising than the other; or the cutting may be all at one side, and the embankment only at the other. If, again, the surface of the ground is undulating, the case becomes more complicated; but it is always a desideratum in the formation of canals, that the stuff excavated from one part may, with the least labour [7:16:29]or shortest carriage, exactly supply or form the embankments that are to be raised in another; so that, at the t completion of the work, as few spoil-banks or mounds of useless soil as possible may remain, and as little ground as possible be rendered useless by excavations or pits. However, the great expense of rock-cuttings, and other difficulties, often occasion a wide departure from this rule. For, in conducting a canal across a hilly and rugged country, there are many difficulties to be overcome, much levelling, and many works of art to be executed. Some of these, perhaps, cannot be foreseen till the operations have been commenced or are far advanced. The slopes of the banks are regulated by the quality and difference in the tenacity of the soil; but they are seldom made greater than two feet of perpendicular to three of horizontal measurement, particularly where the embankments are heavy. The inside slope soon becomes chafed and indented at its upper edges by the motion of the water, which is occasioned by the passing of boats; and this abrasion often penetrates so much as to diminish irregularly the width of the towing-path. This may be remedied in a good measure by planting the sides with aquatic shrubs, and also by driving stakes into the bank at short intervals along the water line, so as to form a rude wicker-work, in places where the soil is loose and porous. The Caledonian Canal is provided with a break in the slope for this purpose, as was mentioned in the description of it. But the most effectual protection against the action of the water is attained by walling or paving the sides of the canal for some breadth both above and below the water line. This, however, from its being expensive, has not yet been extensively resorted to; but when it is recollected that the washing of the banks of a canal not only destroys its security, but diminishes its depth and the facility with which it is navigated, this reason loses its weight. By facing the sides with a substantial wall, which might be made nearly vertical at the top, the surface of the water need not be much more than two thirds the usual width, and consequently the canal need not occupy much more than three fourths the extent of ground; so that in situations where the ground is valuable, the wall would conduce to economy. The canal, too, having less earth crumbling into.it, would need less cleaning; and where water is scarce, the smaller waste by evaporation, from the contracted breadth of the surface, would be of importance. To prevent as much as possible the wash, as it is termed, the speed of the canal-boats is variously restricted, and steamboats have generally been excluded.

It frequently happens that canals have to be formed more or less by artificial embankments of loose materials, or that they are excavated in earth, sand, rock, &c. so very porous as to allow the water to escape by filtration. To remedy this, the usual method is to make the excavation much wider and deeper than the intended dimensions, and to line it to the thickness of two or three feet with a tenacious clay mixed with gravel, which is to be thoroughly puddled, and then, according to some, exposed for a long while to the weather, though others condemn exposing it at all. A trench four feet in width is also dug out in the middle of each side-bank, to at least three feet below the bottom of the canal, and this in like manner is -to be filled up with puddle. The puddle trench is made principally with the view of preventing rats and other vermin from perforating the banks, and occasioning breaches, as they often do. When once the water has obtained a very small egress, it gradually washes it wider; so that sometimes in a few hours a breach may be formed sufficient to empty the canal, and require weeks or even months ere it can be repaired. But besides beingable to resist the penetration or gradual escape of the water, an embankment must always be composed of materials capable of withstanding, by their weight, the ten dency of the hydraulic pressure to overturn them in a mass, and also of resisting, by their lateral adhesion, the force tending to thrust them out horizontally. When the side of a canal gives way, it is of great consequence to prevent as much as possible the escape of the water. For this purpose, it is usual to have doors or valves in various parts of the canal, so attached by joints or hinges to the bottom, that when the water is at rest they lie nearly flat at the bottom, but when it begins to flow rapidly over them, they ‘rise by its force, and arrest its farther progress. However, when such gates have lain long in the bottom, and have become coated with slime and imbedded in the mud, their spontaneous rising at the proper time is not much to be depended on, and therefore they should be provided with chains or rods, by which they may be drawn up when required.

Tunnels.

The first thing to be attended to in constructing a tunnel is to execute a correct survey of the ground through which it is intended to pass. This is done by tracing over the surface of the ground a line which shall be all in a vertical plane parallel to the direction of the tunnel, and which, when transferred upon a reduced scale to paper, shall accurately represent a vertical section of the ground. To obtain a section of this sort with accuracy for an extensive tunnel, the relative levels of the principal points along the line upon the surface are to be ascertained; and it is generally necessary to use an instrument similar to a transit telescope, and perhaps to fit up one or more temporary observatories upon the most elevated spots along the line, from which may be determined the position of any pits or shafts which it may be necessary to sink, whether for the sake of free ventilation, or for commencing and carrying on the excavation of the tunnel at several different places at the same time. Through these openings the stuff is to be hoisted up, and the water pumped out should any occur. The shafts being sunk to the requisite depth, which is ascertained from the levels which have been taken at the surface, a heading or small tunnel, at least sufficiently high and wide to allow the men to move freely in the work of excavation, is to be commenced just below the crown of the intended large one. Such smaller excavation is generally made very unshapely in the sides and roof, but ought to be nearly flat in the bottom. It is to be carried forward from one working shaft to another, as nearly as may be in a straight line, till a connection be formed between all the shafts and the ends of the tunnel. If, in the progress of the heading from one shaft to another, the air become so bad as to oblige the workmen to desist, an air shaft is to be immediately commenced from above, about five or six feet in diameter, and sunk vertically to the point at which the heading was left off. In excavating the tunnel of the Thames and Medway Canal, there were twelve working shafts; and, on account of the foulness of the air, it was besides necessary to sink eleven air-shafts. After the heading has been driven from one working-shaft to another, or a complete perforation obtained throughout the whole of the intended line, the roof of the tunnel is commenced, by an excavation in the form of a circular, an elliptic, or a parabolic arch. At this stage of the work the strength and quality of the roof are easily ascertained; and where weak and crumbling portions occur, a brick or stone arch must be formed for their support The stuff is generally carried out by means of a railway. Some tunnels are formed in strata of such a texture as to require no building whatever, unless, perhaps, in fitting up a towing-path; whilst others are so very insecure that the construction of a complete lining of building must keep pace with the work of excavation. Some tunnels, again, are naturally water-tight, whilst others [7:16:30] require a substantial lining of clay, and must be excavated of so much the larger dimensions as to have room for it.

Inclined Planes.

It is probable that the earliest mode of passing a boat from one level to another consisted in simply dragging it over the intervening space, whether that might be a natural rapid in a river, an obstructing rock, or a dam built across on purpose; and this last was generally in the form of a ridge, or double inclined plane. In a rapidly descending current it was necessary to have many such dams at short intervals, in order to obtain the requisite depth of water. In China these inclined planes have been long in use, especially in their smaller canals. Between the upper and lower levels of the water a double glacis of hewn stone is built, the principal slope of which extends from the bottom of the lower canal to the surface of the water in the upper canal, ora little above it, and there terminates in a large cross beam of wood, rounded off, and very smooth. From this beam another but shorter and steeper plane of stone descends to the bottom of the upper canal; and over these the boats are dragged, sometimes by simple manual power, and sometimes by the aid of capstans. It is not uncommon in China for a hundred men to be employed in drawing up a large vessel from the lower to the higher canal. Their strength is usually applied by means of levers turning capstans, which are placed on the abutments on each side of the glacis. A rope being passed round the stern of the vessel, has its ends attached to and wound round the capstans. In this way a vessel is more speedily raised into the upper canal than if locks had been employed; but it is effected by a prodigions exertion of human force, which, however, in China is always to be had at little cost, and is there preferred to any other. When a vessel is to be transferred from the upper to the lower canal, she is, as before, lifted over the cross beam, and then glides safely down by her own weight. To insure this, the head of the vessel is provided with a railing, which being covered with a strong matting at the time of the descent, not only breaks the fall, but prevents any water from flushing*up over the deck. We here see human power sadly lavished away where a very different one might suffice. Horses, oxen, water-wheels, &c. are in some countries applied to turn machinery for the same purpose. To lessen the friction, long rollers are sometimes placed across the inclined planes, at short intervals from each other; but it is evident that, whether with or without rollers, boats which will bear to be dragged over any such structure must be excessively strong for their size. The long feeble boats which usually navigate canals would undoubtedly break into several lengths were they to be passed over the ridge. Sometimes the boats are placed upon a sort of cradle or hurdle, with or without wheels, and the whole dragged over; and sometimes the boats themselves are furnished with wheels, which only come into play in passing such planes.

There have been numerous other contrivances for transferring boats from one level to another, without any expenditure of water; and descriptions of the most of them will be found in some of the scientific journals, particularly in the Repertory of Arts, Nicholson’s Journal, the Philosophical Magazine, and the Repertory of Patent Inventions. But these have generally been very unsuccessful, although for not a few of them patents have been obtained. One of the most recent patents i π ∙ that of Mr Thomas Grahame, of which the specification is published in the Repertory of Patent Inventions for March 1837. By far the greater number of the schemes now alluded to would require an exertion of mechanical force which would either be more than sufficient to raise water to fill a common lock, or would be attended with greater expense. Some of them, it is true, might save a little time, but in general the case would be otherwise.

Lochs.

Amongst the many approximations to the gates of a lock, the following rude one may be mentioned, especially as it is still used in various parts of England. A beam or sill is fixed across the bottom of the stream or canal; and directly over this, but at the water’s surface, is placed a second but moveable beam. Against and behind these parallel beams a set of loose boards are placed upright and close together like a door, so as to obstruct the progress of the stream. When a boat is to pass, the boards are either removed singly, or, if they can be prevented from floating away, the upper beam is lifted or moved round, so as suddenly to let go the whole system, and thus afford a temporary increase of depth, to enable the boat to pass or repass the otherwise too shallow water. In China it is common to have a similar set of loose boards or planks, but placed horizontally across the stream; these being dropped one by one into grooves formed in the side walls, or in upright posts, from which the boards are to be singly removed in a similar manner. Such are the sluices or gates used on the Imperial Canal of China; for the emperor’s boats or barges are far too large to be dragged over inclined planes. Machines of the same sort have also been used on the river navigations in Flanders. Since both the kinds of gates now described are supposed to be placed at the upper end of the fall or shoal over which they are temporarily to increase the depth of water, and since the boat is to pass through the gate, while the accumulated water rushes out with great force, it is evident that this must render it difficult for a boat to ascend the stream, and must accelerate it too much in descending. However, a method, similar to this, at least in letting go a flash of water, has long been used in floating down rafts of timber over shallows and rapids in rivers, and is perhaps the best that could be contrived for the purpose. But for the navigation of boats there is a greatly preferable mode of using the same sorts of gates, so as to be free from the inconveniences above mentioned; which is to place the gate in moderately deep water at the lower end of the fall or shoal, and such that a boat may pass up through the gate before the water has been raised by it at all. The gate is then shut till the water rise sufficiently to enable the boat to ascend the fall or shoal, which it does in almost still water. These sorts of gates Lalande calls half-locks; and indeed it is supposed, with considerable probability, that the casual position of two of them near each other had given rise to the invention of the lock. For in that case it would soon be seen, that when the lower of these two gates was closed, and the water above it had risen to a sufficient height, such water would be nearly stagnant at the upper gate, and would afford an easy passage through it. If, therefore, the boat was ascending, the upper gate being next shut, the water above it would rise, and enable the boat to proceed a stage farther in its ascent.

However the real origin and early history of the modern lock, like those of many other valuable inventions, are involved in obscurity, yet its nature and mode of operating will be readily understood by a reference to figs. 1 and 2, Plate CCCLXXV1II. where A AAA are the walls of the lock chamber, which can be closed by the two single gates G,G. The water in the part or reach of the canal which lies to the right of the lock is supposed to be higher than in that to the left. When, therefore, it is wished to pass a vessel upwards through the lock, she is first floated in at the lower gate, previously opened, as shown in fig. 1, and which is next to be shut. Water is then admitted through a valve from the upper canal into the lock-chamber, till it has filled it up to the same level, and has of course raised the [7:16:31]vessel along with it. The upper gate being next opened, the vessel quits the lock, and passes immediately into the higher part of the canal. This process is called locking up ; and the reverse of it, or locking down, will obviously conduct a vessel down through the lock, which is to be emptied by another valve into the lower reach of the canal. For when the water in a lock is reduced to the lower level, it is usually said to be empty, although it has still the same depth of water as the lower canal.

In navigations where great differences of level are to be overcome, it is not unusual to have two or more locks following in such close succession that the lower gate, or pair of gates when they are double, of one lock, forms also the upper gate or upper pair of the next lock below it. This obviously tends greatly to lessen the cost of constructing them, and also requires fewer lock-keepers. It tends, besides, to lessen the time spent in the repeated stoppages and startings in the trackage of the boats; though it is rather beamed for expending somewhat more water than if the locks were scattered separately over a considerable extent.

It was not until artificial canalshad become very general, that locks were brought to any thing like their present state of perfection; for the difficulty of procuring water had been but partially felt, as long as inland navigation was confined to a few rivers. But when the value of water for canals came to be properly appreciated, it was necessary to be careful of every resource, and to use it with the strictest economy. With this view the chamber, or the space between the upper and lower gates, instead of being made of an oval, a circular, or an octagonal figure, as in the locks on the earlier canals, was so much contracted as only to afford room for the vessels to pass through; to effect which, the sides were made vertical planes formed of wood, brick, or stone, instead of the sloping banks of earth or turf used in the older locks, and which required such a length of time to fill or empty them, and consumed a vast quantity of water besides. The lift of the lock, or the difference of level which it is made to overcome, is regulated by circumstances. It varies from one foot or less, up to sixteen or eighteen feet. Where the levels of the parts of a canal, or of the several reaches as they are sometimes called, differ greatly, and where water is plentiful, the locks are generally made with a greater lift than where the ground is more flat and the water scanty. For a given difference of level, locks generally consume more water as the lift of each is greater; but, on the other hand, they tend to save time. The chambers of narrow locks are generally from seventy to eighty feet long, and from seven to eight feet wide. Those of the Caledonian Canal are from 170 to 180 feet long, forty wide, and thirty deep; and still larger ones are used on the great ship canal from the Texel to Amsterdam; but locks are also made of every intermediate dimension.

A naturally hard bottom is the best foundation for the walls of locks; but where that does not occur, they are frequently built on a system of piles well driven and bound together; for the mode of preparing the foundation must be regulated by the nature of the ground. The sides are carried up sometimes in straight, sometimes in curved lines, and often reclining or battering outwards from the bottom. In this last case, too, the beds of the stone or brick-work are generally formed at right angles to the face of the wall, inclining from half an inch to an inch in the foot. Such battering, however, should only be used near the bottom; because, caeterisparibus, a lock the opposite sides of which are perfectly vertical and parallel planes, and which is of no greater width throughout than to admit the boats, must obviously consume the least water, and spend least time in passing a boat; a circumstance which ought always to outweigh any little saving of materials or expense which might be expected from a different form of construction. Curving the sides longitudinally, like crescents, can add nothing to the strength on the principle of the arch; because such a figure is at best an arch having nothing to abut against. The like may be said of dishing-carriage wheels, and of all curved structures which either have no abutments, or which are not equally pressed against all their abutments. At Agde, on the Languedoc Canal, a circular basin which unites three canals of different levels is used as a lock, and has long been extolled as the very perfection of lock-making; whereas it requires a needless length of time, and wastes an enormous quantity of water in passing a boat. If the foundation be clay or gravel, a wooden bottom is sometimes formed of cross sleepers planked longitudinally, upon which the side-walls are built with or without buttresses at the back, according to the quality of the side-banks. A flat segment or inverted arch of stone or brick is sometimes laid upon the wooden bottom, in order to distribute the weight more equably, and to prevent any partial settling or subsiding of the work; and the same method is observed between the buttresses along the outside of the chamber walls. In each wall, behind the hollow quoins, a recess is left sufficient for the gates to open back into, out of the way of the vessels. In the recesses belonging to the upper gates, a weir or over-fall for the water is provided, four or five feet long, having a coping or sill of stone or brick, just the height at which the water is intended to stand in the upper reach of the canal; these are called the paddle-weirs or lock-weirs. A large flat stone is usually laid as a lintel over this opening, to complete the wall upon, and leaving a space of three or four inches in height for the egress of the surplus water. This cavity is conducted downward, diminishing in width and enlarging in depth, behind the walls of the lock, into the paddle-hole or culvert for filling the lock, if such be in use there. This water having got into the lock, makes its escape from it by a similar opening at the other end into the lower canal. In other cases a culvert is purposely continued behind the wall, so as to carry this surplus water quite past the lock to the lower canal. Sometimes an open channel, properly lined with stones or bricks, is made for it. But in many cases, where the surplus water would be of no use in the lower canal, it is allowed to escape over a waste weir, built on purpose in the side of the canal, into some river or brook which may be near. In order that any considerable quantity of water may be readily withdrawn from a canal when required, it is generally provided in various places with waste-gates or sluices in its sides, which can be drawn up either with a rack and pinion, a chain and roller, or a crow-bar, as circumstances may render most eligible. Sometimes pipes furnished with valves are placed in the bottom of the canal for withdrawing the water.

The frame of a lock-gate usually consists of two strong upright posts, connected by horizontal ribs; and the latter are closely covered with boards or planks caulked like a ship. The gate, again, generally turns horizontally on one of these uprights, which is called the ÄeeZ-post or com-post, whilst the opposite one is named the ∕zeat∕-post or niitre- post. Large gates are frequently curved, so as, for greater strength, to present an arched or convex surface to the pressure of the water; and on this point there is an interesting article by Mr Barlow in the Transactions of Civil Engineers (vol. i.). It was usual to make all such gates of timber; but, on account of the difficulty of getting it at the time of sufficient size for those of the Caledonian Canal, the most of the gate-frames for it were made of cast iron, boards being still used for covering the ribs. Other locks have since been similarly constructed; and iron gates cast in one piece have been used on the Ellesmere Canal. But wooden gates are by some engineers preferred to those of [7:16:32]cast iron, which are apt to corrode and get out of order, especially if exposed to the action of salt water. In England the cost of gates for large lock-chambers is nearly the same, whether they are made of wood or of iron. Some canal gates are made to rise and fall vertically, like those of ancient castles and temples, or, like our common windows, counterpoised by weights, which slide in grooves. The locks on the Shrewsbury Canal are not only closed by two gates of this sort, but can also be divided by others, so as to admit or contain one, three, or four boats at a time, without the loss of any more water than is just necessary to regulate the ascent or descent of the boat or boats that are then in the locks.

As it would on several accounts be inconvenient, and often impracticable, to open lock-gates against a strong pressure, they are either provided with smaller apertures furnished with valves, through which the locks are emptied or filled before opening the large gates themselves; or, instead of apertures in the gates, the water is passed through one or more culverts or pipes formed in the walls of the lock, these being in'like manner furnished with sliding valves or paddles. The valves of lock-gates are generally opened and shut by a rack and pinion attached to the lever beams of the gates, and moving in vertical guides spiked fast to the lining of the gates. They are formed of wood, and' placed near the middle of the gate at the bottom. A rack and pinion are likewise generally employed to open and shut the valves of culverts.

Sometimes the valve in a lock-gate is formed into a large lever, shaped like a rudder, which extends from near the bottom of the gate, and passes through a guide fixed on the side of the beam. One edge is hinged on a pivot about four feet above the bottom of the opening, the sideworks against the lining of the gate, and the top is drawn backward and forward by means of a rack and pinion fixed on the lever beam. This is in some respects a convenient contrivance, being easily worked by the boatmen, without the awkward necessity of standing upon the lever beam.

Another method of constructing the valves, especially for large tide-locks, where the gates have no lever beams, but move upon rollers by means of a drag-chain, is to form two apertures above one another, each about one foot high by two feet wide, and to connect the two valvecovers by links at the same distance apart; so that a motion of one foot perpendicular, given by a coarsely threaded screw, fixed upon the head of a connecting rod, will open and shut four superficial feet of aperture through the gate.

But since all sliding valves are necessarily attended with much friction and wear, and it is likewise inconvenient to have any valve in the gates, we should think a greatly preferable method would be, to use a culvert departing perpendicularly in the bottom of the canal or of the lock-chamber, and to close it there with a horizontal lid or valve, hinged at one edge, and having a long arm or lever projecting from its opposite edge. In this simple construction, it is obvious that a mere rod or chain attached to the lever might have any required degree of power to raise the valve; which, on being let go, would readily, of its own accord, shut down out of the way. This method would scarcely either be attended with friction, or be subject to wear.

Many of the canals of England which have succeeded best are both narrow and shallow;^[2. There is little room to doubt that such would have been still more successful had they been of lärger dimensions. However, the contrary error seems to have been committed in the too large dimensions of the Grand and Royal Canals of Ireland, and in the Caledonian Canal. ] and consequently their lock-chambers are narrow and long, particularly those of the Grand Trunk and Birmingham Canals. Fig. 1 and 2, Plate CCCLXXVIII. show one of these, which is seventy-five feet long and eight wide, with vertical and parallel sides AAAA, built of brick, four feet thick, and coped with stone. The gates G, G are single, hung in a stone quoin or coin, and they shut against a rebate of stone, which is lined on the corners with a cast-iron plate two inches thick and six broad, screwed fast to the coins. The gates are framed simply with square ribs, and a single lining of plank; they contain no valves, as the chambers are filled by side culverts c t υ, formed through the wall, and entering in the recess left for the gate to fold back into. The valve v of these culverts is opened or shut by turning the handle w i which works a pinion and rack attached to a post about eight inches square. The gate is opened or shut by pushing round the long lever beam B, which is fixed along the top of the gate, and is purposely made very heavy to act as a counterpoise to the weight of the gate. The lower end of the coin-post, or principal upright post of the gate-frame, has a pivot which turns in a socket at the bottom; and near its upper end, at P, it is embraced by and turns in a collar held by the clamp α, which has two long diverging arms made fast in the top of the building.

The lock-chambers built by Brindley upon the Duke of Bridgewater’s Canal at Runcorn, upwards of sixty-five years ago, are still in good order. They are formed with vertical sides of brick, coped with heavy stone clamped into the heart of the wall, and are sixty feet long by thirteen wide. The gates are double, and form, in meeting, a very acute-angled mitre. The valves or paddles are opened perpendicularly by a rack and pinion on the beam. There are two of these apertures in each gate, about twenty inches square. The hollow coins or grooves in contact with the gates are of timber, bolted and clamped into the brickwork.

Fig. 3, 4, and 5, Plate CCCLXXVIII. represent one of the tide-locks of the Thames and Medway Canal. Its walls AAAA are of brick built upon piles with a wooden bottom, upon which is laid an inverted arch, the sides battering into the bottom curve from the water line. The gates G, G are double, and curved so as to form nearly a circular arch in meeting. Their frames are made of cast iron, and their coin and mitre posts are formed hollow like a pipe, with oblong openings in the sides for the workman to put in his hand with the bolts which are to fix the horizontal ribs. Formerly, when such posts had no openings in their sides, it was necessary that a boy should go inside with the bolts, like a sweep into a chimney. The ribs are about eighteen inches apart, an inch and a half thick, curved in plan, with a flange on each end, which is bolted into the coin and mitre posts. The ribs are covered with planks two inches thick, bolted to the ribs, and caulked in the joints like those of a ship. These gates are very heavy, but rest in a great measure upon rollers, which run on the curved tracks r, r, r, r when the gates are moved by the capstans C, C, C, C, and drag-chains winding round them, as seen in fig. 5, and denoted by the long, cross, dotted lines in fig. 3.^[3. In some locks, instead of the drag-chain, a pinion is formed on the axle of the capstan, and works into a' toothed rack attached by a joint to the gate. As the pinion and rack can work both ways, only one capstan is required for each gate; whereas the chains always need one capstan to open the gate and another to shut it. ] These chains pass through holes in the walls Ο, O, as seen in fig. 5, where also the curve I denotes the inverted arch. This lock is filled and emptied through culverts, as described in the account of the single lock of the Birmingham Canal.

As the tide-water flows and rises above that within, it [7:16:33]pushes open the gates G, G, and passes into the basin and canal; but this can also be stopped or prevented by shutting the gates g∙, g, which, opening outward, cannot give way to external pressure. The lock-chamber is 130 feet long within the outer gates, and thirty wide. It is about ten feet deeper than the canal, and eight wider than the tunnel, which is only twenty-two feet; so that much larger vessels may come into the basin, whose bottom is even with that of the lock, than those which can get through the canal. By these means, too, boats drawing almost eight feet, the ordinary depth of water in the canal, may pass through the lock when the tide-water without is ten feet lower than in the canal.

This lock exhibits one feature which, though common a century ago, we should not have expected in a first-rate lock made in the nineteenth century; we mean the curvature of the side walls, which contributes rather to weaken the structure, because, instead of these curved sides acting as arches having something immoveable to abut against, their only tendency in the circumstances is to transfer the lateral pressure from the middle of the walls, where the stress is least, to the very parts on which the gates are hung, and which, of course, already sustain the greatest strain, and therefore have more need of being relieved or assisted, than thus burdened with any such unnecessary or additional strain.

When a boat is to be raised through a given height, there is not necessarily any difference in the expense of water, whether the ascent be gained by one previously empty lock, embracing the whole lift, or by ever so many sharing it √ for since the boat on ascending leaves all the locks full, there must at least be as much water used as would fill up one deep lock from the lower to the higher level, and which ought just to fill ever so many shallow ones. However, when the locks have been previously full, the water of one only need be expended, and therefore the less the lift of each, the less will be the expense of water. On the other hand, it is obvious that many small lifts unavoidably put off much time. Again, when a boat is to have a given descent, this may be effected with as much less expense of water as the number of locks, if previously empty, is greater; because, whatever water suffices for one of a series of equal locks, may successively serve each of the rest during the descent. When the locks have been previously full, the whole of them are emptied by the descent of a boat, whether they are many or few. However, there is this difference between an ascent and a descent: A boat in ascending lets down or consumes twice the weight in water of itself and cargo more than it does in descending; because, on entering the empty lock, the boat which is about to ascend expels as much water into the lower reach of the canal as equals the weight of itself and cargo, whereas a boat about to descend expels from the full lock an equal weight of water into the upper reach of the canal. The former is therefore lost, whilst the latter is saved.

The failure of the schemes hitherto projected for remedying the defects of the common lock are ascribed by Μ. Girard to the impossibility of resolving the problem completely, without an unnecessary expenditure of mechanical force; and he therefore reduces the maximum effect of the common lock to questions of the comparative time and economy required by boats in passing insulated locks, and in passing connected systems of locks. But he does not, says Mr Rennie,^[4. Reports of the British Association for 1834, p. 459. ] consider the stoppage and the loss of time attending the repeated changes in the force of trackage required by the isolated system. The value of the water lost can only be contrasted with the value of time under certain circumstances; but the question had already been discussed by Gauthy and others with reference to the locks of the Canals of Briare and Languedoc.

Economy of Water.

There have been numerous expedients for more effectually economising the water of canals. By making the locks double, that is, placing two equal locks on the same level in the breadth of the canal, a much smaller quantity of water will generally suffice. For since a boat on descending must enter a full lock and leave it empty, whereas an ascending boat must enter an empty lock and leave it full, it would obviously be a saving of water could the full lock, by which a boat had ascended, be reserved for the next boat which should descend, and vice versa with the empty one; though it is evident, that when several boats pass together in the same direction, this can only be partially done. But when the one lock is full and the other already empty, and we wish to let down a boat through the former one, half the water might always be let through a sluice into the empty lock, instead of letting the whole go to waste in the lower canal; and in like manner, when we wish to raise a boat through the empty lock, half the water may be obtained from the full one. By putting more than two locks in the breadth of the canal, still less water would sometimes suffice; but the increased cost puts this out of the question.

A different method of saving water is by means of side-pojids i into which the water is partly withdrawn from a full lock, and reserved for farther use. Sometimes a single side-pond is employed, and sometimes two or more, being all upon different levels. A single pond, no matter how extensive, cannot, in the usual way in which it is employed, save quite half the lockful of water, two ponds cannot save quite two thirds, nor can three save three fourths, &c. But it is most common to employ two ponds, each having the same horizontal area as the lock has, and being made to receive one fourth its fill of water. The one of these ponds has its bottom at half the height or lift of the lock, so that when a valve is opened into it from the full lock, this pond receives one fourth of its contents. This valve is now shut, and another valve opened between the lock and the second pond, which, in its turn, receives another fourth of the water, because its bottom is at one fourth the height or lift of the lock. The second valve is now shut; and the remaining half-full of water in the lock is let go into the lower canal in the usual way. When the lock is to be filled again, the lower pond is first run into it and closed, and then the higher one, which together make up one half of what will fill the lock, and which has been saved by means of the ponds.

A great improvement on side-ponds has been proposed by Mr Field (Transactions of Civil Engineers, vol. i. p∙ 61), which is to apply to them the principle of the pendulum, or rather of water vibrating in an inverted syphon, viz. that it would rise to the same height in the one leg as that from which it has fallen in the other, were it not for friction or other resistance. Mr Field’s method is to connect a lock with a side-pond by means of a long pipe or culvert, in such a manner, that when the water in the lock is allowed suddenly to run into the empty pond, it may rise in the latter nearly to the level from which it had fallen in the former; and at the moment this occurs, the valve or sluice in the culvert is to be shut. The same thing should obviously take place when the water is to be restored to the empty lock, excepting that, whatever may have been [7:16:34] the loss of water in the former case, the total loss will now be doubled; but this additional loss would be avoided by using a second lock alongside of the other, instead of a pond, as no restoration would be required.

On one point we beg to differ materially from Mr Field. In all the five different forms in which he has illustrated his method, he assumes it as absolutely necessary that the long culvert should always have two valves, one at each end; and in order to get these two valves near each other, he proposes to bend round the culvert in a spiral or circular form. Now, with all deference, we presume, that if the culvert be kept as low down as it ought to be on several accounts, any more than one valve will not only be troublesome and expensive, but occasion a needless obstruction to the free motion of the water. Indeed, to avoid giving a great and sudden lateral shock to any boat or vessel whilst in the lock, it would be proper that the water should enter or depart perpendicularly in the middle of the bottom of the lock. In that case it would not be very material in what part of the culvert the valve was situated, except for the greatest convenience. It would perhaps be an improvement to give the culvert very wide spreading mouths or ends. If, however, Mr Field’s ingenious scheme should save nine tenths of the water, as he expects it to do, it would have the farther advantage, that the gates of such locks could generally be opened without their needing to have any valves or paddles to be previously opened, either in them or in the walls. Mr Field makes his method to depend on the principle of Montgolfier’s ram, a principle, we beg to observe, which had been discovered, applied, and published by Whitehurst, long before Montgolfier’s time; but it is much more elementary and simple, we presume, to refer, as we have done, so much of Mr Field’s scheme as has now been described, to the undulations of water in a syphon.

Where canals are all on one level, and have either no locks at all, or at their extremities only, there is seldom much difficulty in supplying them with water; though in certain cases canals of this sort may communicate with some very muddy river, whose waters, if admitted, would soon silt them up with mud. In such cases it has been recommended to exclude the muddy water, and, if nothing better could be done, to supply the canals with clean water, raised by a steam-engine. This method has been followed in the case of the West India docks on the Thames, where the foul water of that river, after having stood in a basin till it has deposited its mud, is pumped up into the docks by a steam-engine. But where a canal is to form a communication between separate valleys or basins of a country, and where a double lockage is unavoidable, the summitlevel which divides the rise and fall is generally too elevated to permit a regular supply of water being drawn directly from the streams on either side. In such cases it becomes necessary to collect the flood waters of the adjacent higher grounds into proper reservoirs, to be used as circumstances may require. Some canals are provided with very large receptacles for the flood-waters. That of Languedoc has one of 595 acres; and one belonging to the Trent and Mersey Canal covers 160 acres. But cases occur in which no such supply can be obtained, and where, of course, it is necessary either to raise water by steam-engines, or to employ inclined planes or machinery to pass the vessels, or at least their cargoes, from one level to another.

RIVERS.

Engineers are generally agreed that side artificial canals are eventually more judicious than the attempts to dredge or to deepen channels in the beds of the streams themselves; and that, for the purposes of navigation, rapid rivers are only useful to supply canals with water. On this account, locks are rarely constructed in the beds of rapid rivers. It is more usual to apply them to side-cuts or to a lateral canal, formed for the purposes of the navigation, and to leave the river course for the passage of the floods or other surplus water. A quick bend of the river is generally chosen for being crossed by a side-cut; and to keep up the water to a sufficient height for navigation in the upper part of the river, a dam or weir is thrown across the old river course, at or rather a little below the upper point at which the artificial cut joins it. The lock is then built at the most convenient part of the cut, generally near the upper end; and its fall or lift is made equal to the difference in the levels of the water at the top of the dam or weir, and in that at the lower end of the cut. But it may happen, that, owing to some rock or other natural obstruction in the river, no artificial dam will be required; and, on the other hand, it is probable that the fall of the river may be so great that several locks will be required in the same cut.

Of the impropriety of placing locks in a rapid current, a remarkable instance may be mentioned in the case of the locks which Polhem, a Swedish engineer, fearlessly attempted, in 1755, to place in the cataracts of Tröllhaetta, in the river Gotha, but which were wholly swept away by a flood, after they had been considerably advanced, and vast sums expended upon them.

In estimating the propriety of deepening shallows in any river, it must be of importance to take into consideration the nature of the shoals. If they have been created by deposits collected by the action of the current, it may be inferred that the same process will continually tend to the same results, and that any efforts to preserve the channel clear will require to be perpetual and laborious; but if the obstructions have been artificially made, or consist of a natural and solid substratum, it may be reasonable to presume that the excavations once made will either be permanent, or, at all events, be easily maintained.

Regarding the main question, whether the free and natural flow of the floods is to be arrested by locks, dams, and other works, the principles which have guided the operations of different engineers have been various and contradictory; but, in general, the practice has been to confine the freshes by artificial works, as in the Clyde, Witham, and other rivers, and to preserve the basins, or other receptacles for tidal waters, to their full extent. A contrary proceeding has tended to ruin many rivers and estuaries, and consequently to impede the drainage and navigation in a great degree, and to occasion the destruction of several harbours, such as those of the Dee and Rye. The effects of embankments in Plymouth and Portsmouth harbours, and particularly in the estuary of the Mersey, one third of the ancient capacity of which has been filled up by encroachments, have materially diminished the depths of the sea-channels, and a consequent deterioration of the harbours has been the result

Where the navigation of a river is impeded by its waters being too much spread, or occupying too wide a channel, this may be remedied by contracting it by embankments, which will have the effect of increasing the depth of the stream, whether it scour out the bottom so as to lower it or not. Such is the usual mode of forming inland navigations in China. It has the advantage of being more speedy than passing through locks, and, indeed, rather too speedy to be safe for vessels in descending. A great power is, in some such cases, required to make a vessel ascend through the contraction. This is accomplished in a variety of ways; often by men aided by capstans; in other cases by machinery, such as a mill being at hand, which may be employed for towing up the vessel, while its weir [7:16:35]or dam may, besides, be useful in prolonging the navigation of the river considerably farther up.

A splendid example of some of the more recent operations in the management of rivers is to be found in those of Μ. de Fontaine on the Rhine.^[5. Fontaine, Des Travaux du Fleuve du Rhin, 1833; and Mr Bennie’s Report on Hydraulics. ] Near Emmerik the . Waal branches off from the Rhine, so as to form two nearly equal rivers, each of which has its bed almost as large as that of the whole river; and when the waters rise, they are at an equal height in both. The Rhine divides itself again towards Arnheim to form the Issel, which has nearly the same section as the Rhine. The first division of all .the waters of this river was begun under the Roman generals Drusus and Corbulo; and many subdivisions were made in subsequent ages. But such a multiplicity of channels, although productive of advantages to Holland, led to many fatal consequences. The waters being so much subdivided, lost the rapidity and strength necessary to push forward the alluvial matter, which being therefore deposited, occasioned a continual rising of the bottom, rendered the drainage of the adjacent lands more difficult, increased the expense of the embankments, and augmented the damages over the extensive lands when the dikes happened to break. The irregularity of the course of the Rhine, and the ravages which it constantly committed on its shores, particularly those of Alsace, one of the most fertile provinces of France, rendered the construction of defensive works imperative; and in 1820 Μ. de Fontaine was selected to perform this important task. The part of the Rhine to which he principally directed his attention is comprised between Basle and Neuburg, that being the political limit between France and the German states. In this part, the bed of the river is situated in the alluvium which forms the bottom of the valley; and through this the Rhine forces its way by many channels, forming, in its passage, islands and sand-banks, which render its motions very irregular both in times of high and low water. Amongst the different streams there is generally one more considerable than the others, and which forms the navigable channel. These branches are annually diminished by artificial works, and probably in a few years the whole of the waters of the Rhine will be forced into one channel, which may then be expected to become so much deeper, and freer from obstructions, as to be far more fit for navigation.

To enable vessels to ascend a rapid in a river, a powerful though rather tedious method, called warping, has been long in use. This consists in attaching or making fast one end of a rope somewhere up the rapid, and then winding up the other by means of a windlass or capstan on board, till the vessel ascends against the stream. Sometimes a tug-boat in constant attendance at the rapid is provided with two paddle-wheels, one on each side, which, turning by the force of the stream, wind up the rope on their axle, and enable the tug itself not only to ascend the torrent, but also to draw up other vessels after it. This method is probably at least a century old, being described in the Machines Approuvées par l’ Academie des Sciences; but within the last twenty years it has been repeatedly announced as a wonderful discovery just made, sometimes here and sometimes in America. This shows the importance of diffusing knowledge, to save ingenious men from uselessly wasting their time in re-inventing what is already well known. Sometimes a paddle-wheel stationed somewhere up the rapid winds up the rope, and draws the vessel to it, which we should think by much the better method. Where the navigation of a river is incommoded by shifting mud or sand, the force of the current is sometimes employed, particularly in France, to urge forward a plank held on edge across the stream, so as to make it clear the way like a snow-plough for a fleet of boats, &c. which are to follow. But it is more systematic to have a boat provided with flaps or wings for cleaning a river.

BRIDGES.

Where canals or rivers are navigated only by such boats as have neither masts nor rigging, the bridges over these waters are, for the most part, fixed, and have scarcely any thing peculiar in them on account of the navigation, except that the arch may rise a little higher, and have a towing-path under it, as shown at B, fig. 8, Plate CCCLXXIX. But a moveable bridge is always employed where a fixed one would occasion too great a rise in a road, or where the arch cannot be elevated sufficiently to clear the masts of vessels. There are several sorts of moveable bridges.

The draw or lift-bridge AA, fig. 8, is one which is fastened with ajoint or hinges at one end, so that the other end may be lifted or let down by some easy artifice. Formerly this sort of bridge was lifted and suspended by chains and levers working in a huge wooden frame, which was often of great height, and usually painted in gaudy colours, to the great terror of such horses and other animals as were unaccustomed thereto. Some of these were long to be seen on the Forth and Clyde Canal. But such bridges are now generally lifted, without chains or levers, by turning a pinion which works into a toothed∙rack fixed upon the bridge; or, if the bridge is large, it has two of these racks and pinions. This simplification of drawbridges is said to have originated with Μ. Perronet in France. For small canals a drawbridge consists of one leaf or frame only; but for entrances to docks and harbours, and for large canals, such as that of the Forth and Clyde, it is made in two halves, which meet in the middle when they are shut or let down. Such bridges, however, have been found inconvenient in practice, from their being apt to catch the yards and rigging of vessels in passing through them.

This inconvenience has given rise to a different form of moveable bridge, which, instead of lifting, like the former, round a horizontal axis, swings or turns horizontally, as it were, round a vertical axis; but the weight of this bridge is not supported on the centre or axis, but rests and is poised upon a circular series of balls or rollers surrounding the centre of motion. Some of the earliest of these bridges were principally made of wood, and for small canals consisted of a single leaf only; but they are now commonly made of cast iron, and, when large, are double. Fig. 1 shows an elevation, and fig. 2 a plan, of a double bridge of this sort, by the late Mr Ralph Walker, where AA is the line of the roadway, RR the rollers and lower ring, shown separately in fig. 6, with the outer ring to which they are attached. The upper ring is seen in fig. 4. Fig. 5 is a vertical section of the bridge through the centre of the rings, supposing the bridge and building to be laid on their side, and the section to be made across the roadway. In fig. 7, F is a vertical section of the abutment, while E is the upper side of the cross for the pivot, round which either half of the bridge turns. Fig. 3 shows a section of the part of the bridge to which is attached the pinion, which, by working in the fixed segment by means of the handle H, turns either half of the bridge quite out of the way of vessels passing along the river or canal, and also brings it back or shuts it again. GG are holes for putting in pins for locking the bridge. When the bridge is shut, three of the five ribs bear at right angles on the abutments; the other two are secured upon the upper circles, and at GG. We should think that a far [7:16:36]more simple bridge of the moveable sort might be formed, so as to move backwards and forwards in a straight line, like a waggon on a railway. Some rude bridges upon this principle are said to have been long in use in China.

BOATS.

Boats formed exclusively for canals are much longer and narrower than those which are also intended for rivers, or for river navigation alone. It is found, that when made of this shape, they are tracked with more ease or speed than when of a wider and shorter form; and they likewise occasion less injury to the sides of the canal. Indeed the proportions of the boats must always be regulated by the dimensions of the locks and bridges; and these have often been made of very reduced width, from considerations of economy in the construction. In the central districts of England, the boats are without masts. They are generally sharp at both ends, having no projecting stern, but being guarded by three rows of wrought-iron’bands, which extend round the bows to the distance of twenty feet on each side, above and below the water line. The bottom is nearly flat, but they are generally encumbered with a keel, which is of no use in a canal but to require a greater depth of water. Keels sufficiently heavy, it is true, may act as ballast, but that would not compensate for the other inconvenience. Where very long boats would not have room to turn, several short ones are linked together in a string; one horse drawing these more easily tb an a single boat of great breadth, which, besides, might not have room to pass through the locks. The boats of the Mersey and Irwell Navigation Company are provided with masts and sails, such that they can coast round the whole island; and they are capable, too, of contending with the most boisterous weather. Their masts are made to strike by means of a forestay attached to two double-sheaved blocks, one of which is firmly fixed to the top of the stem; and the stay is heaved down by a windlass on the forepart of the deck. The boom extends no farther out than the after extremity of the rudder, and the stern is made nearly vertical. Vessels similar to these, especially in having a falling mast to pass under bridges, are much employed on the Thames and other rivers.

Oars, no doubt, in some shape or other, formed at an early period a means of propelling vessels on inland waters, and are still in use for that purpose. Sails, too, are employed on lakes and in the wider parts of rivers, if the current is moderate, with sufficient room for tacking; and during a favourable wind almost all vessels which may, on any account, be provided with sails, are in the habit of hoisting them when on a narrow river or canal. But in the latter cases the most usual method is to track or draw the vessels along by the power of men or horses travelling on the banks. The practice of men tracking boats is probably very ancient, and is still the mode in China and other barbarous or obscure places, where vast numbers of men continue to be thus employed. Nay, to come nearer home, it was even continued on the Thames and the Severn till near the end of last century, when proper towing paths and horses were, for the first time, introduced on these rivers, as they had been long before on canals.

But the most efficient power hitherto employed for propelling vessels, either in still water or against a moderate current in a large river, is that of steam, which has now come into general use for that purpose; though it certainly acts at a prodigious disadvantage, by re-acting against water which it is either leaving or which is moving from it,— a disadvantage, too, which augments with the rate of sailing. For this reason, and on account of the force which is wasted by the paddle-boards in entering and quitting the water with great velocity, and which waste also increases with the velocity of the paddles, it follows that the force of the steam-engine must be greatly increased, to occasion such an increase in the re-action of the paddles as shall urge the vessel with any considerably greater rapidity. Such seem to be some of the reasons why we often hear of a vessel being propelled by a power equal to that of 500 or 600 horses, while there is not the least probability that it is encountering a resistance of one fifth so much.

Of late years a great many experiments have been made on the trackage and resistance of canal-boats, particularly by Mr Palmer, Mr Macniell, and Mr Russell; but their results, though interesting, are very discordant. Mr Palmer makes the resistance as the cube of the velocity, which would be fatal altogether to any thing in the shape of swift boats. Mr Macniell, again, makes the most advantageous velocity about nine or ten miles per hour, which is nearly what has been in use, and found to answer so well for several years with light boats carrying passengers on different canals, as we shall presently notice more particularly. But Mr Russell carries the most advantageous velocity so very high, if indeed he gives it a limit, that, even granting his experiments to be perfectly correct, we have great doubts whether such velocities can ever be applicable to any practical purpose, at least of the nature of a long navigation.

Light boats for conveying passengers with a speed formerly unknown upon canals, were first introduced by Mr Houston, in June 1831, on the Glasgow and Paisley Canal.^[6. A small boat closely covered in is by no means free from danger on a deep canal; for if by accident or mismanagement it were allowed to sink, it would be very apt to confine the inmates under water till they were drowned, especially as those who become frantic would prevent the more sober from escaping. ] The following account of its success, after a two years’ trial, is given by Mr Thomas Grahame, civil engineer, in his Letter to Canal Proprietors and Traders. “The ordinary speed for the conveyance of passengers on the Ardrossan Canal has, for nearly two years, been from nine to ten miles an hour; and although there are fourteen journeys along the canal per day at this rapid speed, its banks have sustained no injury. The boats are seventy feet in length, about five feet and a half broad, and, but for the extreme narrowness of the canal, might be made broader. They carry easily from seventy to eighty passengers; and, when required, can and have carried upwards of 110 passengers. The entire cost of a boat and fittings up is about L.125. The hulls are formed of light iron plate and ribs, and the covering is of wood and light oiled cloth. They are more airy, light, and comfortable; than any coach. They permit the passengers to move about from the outer to the inner cabin; and the fares per mile are one penny in the first, and three farthings in the second cabin. The passengers are all carried under cover, having the privilege also of an uncovered space. These boats are drawn by two horses, the prices of which may be from L.50 to L.60 per pair, in stages of four miles in length, which are done in from twenty· two to twenty-five minutes, including stoppages to let out and take in passengers, each set of horses doing three or four stages alternately each day. In fact, the boats are drawn through this narrow and shallow canal at a velocity which many celebrated engineers had demonstrated, and which the public believed, to be impossible.”

Swift boats have likewise been for several years in use on the Forth and Clyde Canal, the Edinburgh and Glasgow[7:16:37] Union Canal, the Lancaster Canal, and on various others, with equal success, at least between locks, or wherever they are free from locks. There is, however, little reason to expect, as some seem to do, that any material increase of swiftness above that now described is likely ever to be effected with advantage on ordinary canals. Horses have already been pushed to their utmost speed; and were steam introduced, with all its machinery and apparatus, the weight would be so enormously augmented as to require a prodigious increase of moving power. But, on several other accounts, the ordinary canals, and almost every thing connected with them, are totally unfit for a much greater velocity. Swifter boats would require canals to be interrupted by no locks, to have no contractions at tunnels and bridges, and to be incommoded by no barges or other slow and heavy craft, which cannot instantly be cleared out of the way. Drawbridges would be attended with a similar inconvenience. The slightest covering, even of broken ice, would occasion a serious resistance; whilst intense frost, which has no effect upon railways, arrests boats altogether. The Americans, it is true, pretend to have greatly outstripped us in swiftness; but it is fully as easy to read some of their statements on this head as to give them entire credit. There can be no question that it is easier to propel a boat more speedily along a great river like the Hudson, than in our narrow and shallow canals, where much time is lost in passing through the locks, or great inconvenience is experienced in conveying the cargo from one boat to another, past the locks.

The swiftest boat would take almost the same time to pass through a lock as the most tardy and unwieldy barge; and it would be difficult, and even hazardous, from the risk of striking against the ends of the building, to force it swiftly through, and especially to make it enter a narrow tunnel, or the narrow contractions at bridges or aqueducts. On these accounts, and the perpetual risk of running foul of other craft, the pilotage of a very swift boat is a task with which few could be intrusted, or rather for which no one is competent. These, however, are difficulties and dangers with which railways have not necessarily any thing to do; because the railway itself acts as the most perfect pilot. In short, to think, as some do, that, at this age of the world, canals can ever be brought to compete with railways in point of swiftness, is a project which cannot be listened to by any disinterested person who is sufficiently informed on such subjects.

On the other hand, although the kind of traffic on which canals have hitherto depended principally for their support is not likely to be withdrawn from them by the competition of railways, as appears from the canal business between Liverpool and Manchester having increased since the railway came into operation, yet it is not so easy to quiet the fears of those who are more immediately concerned; and those who do give way to such fears put themselves in the way of being ridiculously imposed upon. Accordingly, a few years ago, a pamphlet was most industriously circulated throughout England, with the view of setting forth the great superiority of canals over railways, and also of showing what a most ruinous speculation the Liverpool and Manchester Railway had been. Such assertions, however, met with a speedy refutation; and, in some discussion which arose on the subject, the author of the pamphlet let out that he had been hired on purpose, and also, what is curious, that his reward was not simply derived from proprietors of coaches and canals, but that one of our great seminaries of religion and learning had liberally afforded him its share of support.

The following is a list of works to which we have either been indebted in drawing up the preceding pages, or at least from which much farther information may still be obtained; though these, after all, form but a small proportion of the works which treat more or less on subjects relating to inland navigation:—Belidor, Architecture Hydraulique; Lalande, Traité des Canaux de Navigation; Frisi, de Canali Navigabili; Phillips’ History of Inland Navigation; Fulton on Canal Navigation; Chapman’s Observations on Canals, &c.; Leach on Inland Navigation; Anderson’s Recreations; Smeaton’s Reports on Civil Engineering; Nicholson’s Philosophical Journal; Telford’s Reports on the Caledonian Canal; Strickland’s Reports on Canals, Railways, &c.; Coxe’s Travels in the North of Europe; Barrow’s Travels in the North of Europe; Transactions of the Society of Civil Engineers; Transactions of Statistical Society; M‘Culloch’s Commercial Dictionary; M‘Culloch’s Statistics of the British Empire; Martin’s History of the British Colonies; Journal of the Royal Geographical Society; Dupin’s Commercial Power of Great Britain; Rennie on Hydraulics, in the Reports of the British Association; Fairbairn on Canal and Steam Navigation; Macniell on the Resistance of Water, &c.; Priestley’s Account of Canals, &c. in Britain; Hamilton’s East India Gazetteer; Girard, Mémoires sur les Canaux, &c.; Huerne, Des Canaux Navigables; Dutens, Histoire de la Navigation Intérieure de la France; Dutens sur les Travaux Publics d’Angleterre; Warden’s Account of the United States of America; Pitkin’s Statistics of the United States; Flint’s Geography of the Western States; the American Almanac; the Franklin Journal; Mechanics’ Magazine; Railway Journal; Edinburgh Philosophical Journal; Edinburgh Review; Balbi, Abrégé de la Géographie; Tableau des Etats Danois, &c. (e.e.e.)