The Grand Canal was begun in 1765 by a body of subscribers; but they could not have completed the work without very large advances from Government. The canal commences at Dublin and stretches in a westerly direction, inclining a little to the south, to the Shannon, with which it unites near Banagher, a distance of 85 statute miles, and thence on the west side of the river to Ballinasloe, 4 miles distant. But, exclusive of the main trunk, there is a branch to Athy, where it joins the Barrow, a distance of about 27 miles, and there are branches to Portarlington, Mount Mellich, and some other places. There is also a westerly branch, more recently constructed, from the Shannon to Ballinasloe, about 14 miles in length. The total length of the canal, with its various branches, is about 164 English miles. Its summit elevation is 230 feet above the level of the sea at Dublin. It is 40 feet wide at the surface, from 24 to 20 feet at the bottom, has 6 feet depth of water, and cost, in all, about 2,000,000_l._ The tonnage on this canal for the eight years ending with 1837 varied from 215,000 to 237,000 tons, while the tolls varied from 33,000_l._ to 38,000_l._ The highest part of the canal rises 298 feet above sea level. Two errors are said to have been committed in the formation of the Grand Canal; it was framed on too large a scale for that time, and it was carried too far north. Had it been 4 or 4½ feet, instead of 6 feet deep, its utility would have been but little impaired, while its expense would have been very materially diminished. But the greatest error was in the direction of the canal. Instead of joining the Shannon about 15 miles above Lough Derg, it should have joined it below Limerick, and conversely would have avoided the difficult and dangerous navigation of the upper Shannon. The canal would then have passed through a comparatively fertile country, and it would not have been necessary to carry it across the bog of Allen, in which, says Mr. Wakefield, “the company have buried more money than would cut a spacious canal from Dublin to Limerick.” The main line of the Grand Canal is 89 miles long, but there are branches to Naas, Mount Mellick, Portarlington, and other places. On the main line there are six locks, each 70 feet by 14½ feet. THE ROYAL CANAL. The Royal Canal was undertaken in 1789. It stretches westwards from Dublin to the Shannon, which it joins near Tormanbury. Its entire length is about 92 miles, exclusive of a branch of 5 miles, from Kilashee to Longford; its highest elevation is 307 feet above the level of the sea. At the bottom it is 24 feet wide, and it has 6 feet depth of water. It had cost, exclusive of interest on stock, loans, &c., advanced by Government, in February 1823, 1,421,954_l._ The tolls produced in 1826 25,148_l._, the expenses of the canal for the same year being 11,912_l._, leaving only 13,236_l._ net. The canal has paid dividends over a number of years, although not on a high scale.