The outlet of Lough Neagh is called the lower Bann, and falls into the sea at Coleraine : this is yet unnavi p•able ,a • The Barrow rises in the northern part of the Slieve Bloom Mountains, running eastward to Alonastetetan, where it is crossed by a branch of the Grand Canal ; from thence that canal passes southward, nearly parallel to the river, and joins it at Athy. From Athy 13ridge, in the county of Kildare, the river has been rendered na vigable to the tideway at the rocks, called the scars, be low St. Mallin's, in the county of Carlow, a distance of about 34 Irish or 43 English miles. The total fall is 172 feet ; in 1800, there were 14 old and new locks, the navigation is chiefly in the bed of the river, the total ex tent of the new cuts 5 miles, their breadth 27 feet at bot tom, and 42 at water surface, with 5 feet water. Ten of the locks are 80 feet long and 16 wide ; the others 69 by 14 feet.
This is one of the most valuable communications in Ireland, that is, from Dublin through a fertile country, to the Rivers Nore and Suir, and to the ports of Water ford and Ross. The annual amount of tonnage, about 40,000 tons, tolls 4,250/. from grain, potatoes, lime, ma nure, coal and culm from the Kilkenny collieries, Car low flags, building materials, kc.
The Black•water, a river in the county of Cork, rising on the borders of Kerry and Limerick, and flowing east ward into the Atlantic at Youghall. It admits vessels of 300 tons over the bar. Sloops pass to Dromore, about S miles up the Bridge, within two miles of Tallagh. A navigable canal has been made by. the Duke of Devon shire, from Cappoquin to Lismore, 3 miles. Three miles of canal, and two locks of large dimensions, were made above Mallow, but nothing farther has been effected The Black-water is also the name of a river in the counties of Tyrone and Armagh, forming part of the colliery canal, or Tyrone navigation.
The Boyne. This river rises in the Bog of Allen, in the central plains of Leinster, and flows north-east into the Irish sea, at Drogheda. By the care which has been taken to deepen the mouth of its channel, across the san dy hay of Drogheda, vessels of considerable burthen as cend three miles to that town, where the Boyne 113 iga tion commences, and continues for 9 miles, chicfly in the bed of the river to Slane, thence 6 miles of still water navigation to Navan, and 7 more from Navan to Trim. The chief articles of trade are, coals, slates, timber, iron, salt, Scc. upwards ; and grain, yarn, and linen, down wards. The total ascent from Navan to Trim is 189 feet. Width of cuts from 16 to 25 at bottom, and front
SO to 49 at top water, which is 5 feet deep. The locks 1,•ary from 80 to 100 feet in length; the breadth is 15 feet.
The Foyle river is formed by the union of several streams from the counties of Tyrone and Donnegal, at Strabane ; its course is northwards into the bay, called Lough Foyle, below Londonderry. The river is natu rally navigable for 7 miles, by Londonderry to St. John ston, thence a navigation WaS made by the larquis ol Abercorn for three miles to Strabane.
The Fergus, is an arm of the Shannon into the coun ty of Clare ; it has been rendeted navigable to Ennis, the county town, by hoats which ply on the Shannon.
The Grand Canal and its branches. It commences from the liver Liffey, near its mc,uth, where there is a floating dock, which could contain above 4n0 ships, with 16 feet water ; it has three entrance locks, and three graving docks. From thence the canal proceeds by the south side of the city of Dublin, to James Street harbour, and from thence westward for 6.`It Irish miles through the counties of Dublin, Kildare, and King's county, to the river Shannon, near Banagher, with branches to the Barrow at Athy, and to various reservoirs and towns, in detail as follows: The commodities carried on this canal are, flour, grain, potatoes, turf, Kilkenney coal, manure, building materials, and merchandise. The annual revenue, in 1812, was 79,500/. ; the expense of establishment and maintenance, about 21,920/. In 1813, the revenue was 90,000/. but since the peace it has greatly diminished. The summit level is 240 feet above the sea, and 160 above the Shannon ; the width is 25 feet at bottom, and 40 feet at the water surface ; depth, 5 feet on the lock sills, and 6 feet in the canal. There are 5 double, and 29 single locks, between Dublin and Tullamore ; 10 from thence to the Shannon. Length of locks, 70 feet, width, 14,1 feet, average rise and fall, 9 fcet.
On the I3arrow line, from Lowton to Athy, there are 10 single, and 2 double locks. The portion of this canal adjacent to Dublin, is of great width, laid out in long straight lines, and planted with trees along each side ; the too frequent adherence to these straight lines has frequently involved unnecessary expense, by cuttings and embankings. The only aqueduct of note is about 15 miles from Dublin, whet e the canal crosses the Liffey at Monasterevan, the Barrow line locks down into the river, and crosses the stream to a regulating lock on the opposite side.