OF THE COMMISSIONERS OF PUBLIC WORKS.
215 In proceeding from Portglenone up towards Toome, the first point where any work is to Appendix (E.)
be done is the northern bar of Lough Beg.
Here the steam-dredger was kept at work from the beginning of the year till the 4th of March, during which time she removed a lift of Annual Report of 2 feet 6 inches in depth off the top of the shoal, which was of a hard material.
It was then ^ c-?•
Ottley, deemed advisable to transfer the dredger to the upstream or southern bar of Lough Beg, ^ J
District on which she would not have had water to float much later in the season.
This bar,
Engineer, composed of sand, dry at very low water, formed a very formidable obstacle to free dis¬ charge, and much perseverance with constant dredging to the end of the year was neces¬ sary to enable us to cut a channel through it.
The sides required to be protected with hurdles, to confine the stream, and prevent the undue widening of the channel, which had the desired effect, and the result now is, that through this sandbank or island a channel has been formed fully to the intended depth of 8 feet under proposed summer water level, and the whole of the waters of the Bann now pass through it in a direct course, instead of being divided into a number of shallow channels, passing on either side of the island which for¬ merly existed, but which have now been entirely closed by embanking.
The excavation removed from this bar alone during the year measured 53,000 cubic yards, and the dredger has been now sent back to the northern end of Lough Beg, to resume the deepening of the bar there.
Toome.
Early in May, excavating operations were commenced above Toome Bridge, and 300 feet in breadth at both sides of the river adjoining the regulating weir wras enclosed by dams; that on the Antrim side, 200 yards in length, which was enclosed and partially exca vatecl in 1850, and that on the Derry side, 400 yards long, at which nothing had previously been done.
The water was pumped out of each of these large enclosures by steam-power, and excavation went on rapidly till the 15th of August, when the Derry side, being all sand, produced so much water that the engine was overpowered, and we were obliged to stop that work; not, however, till a 6-feet lift had been taken off the greater part of it, and the remainder sunk from 2 feet 6 inches to 4 feet, so that there is now sufficient depth of water in the enclosure to float a dredger, which will probably be the cheapest (though not the most expeditious) means of completing it, the material being soft.
The Antrim side we were enabled to keep dry, and that excavation was brought to a finish in October ; since which the land slope has been paved, and in November the dams were opened, and the water allowed to pass through, which might have been sooner done, but that Lough Neagh was already as low as it could be brought without injury to the navigations entering its southern end.
Above the weir site, so as to form a better approach to it for the water, a large quantity of stuff has also been taken out, extending 200 yards out into the lake, and along the back of the weir for half its length, or 200 yards.
The extension of the navigation cut into Lough Neagh has been considerably advanced, and simultaneously with it the parallel protecting mole has been formed.
The canal and mole are now completed for a length of 470 yards, leaving but 300 yards more to be done to finish.
The bottom breadth of this canal is 40 feet, and the side has been paved next the mole for the whole of the length excavated.
The great regulating weir has been importantly advanced during the past year.
It is to be 1,200 feet long, and the principal row of piles composing it had been driven in 1850.
During the season of 1851, 300 feet of the weir next the Antrim side have been braced, hearted with stone, and paved permanently and securely on its^ downstream face, the second row of piles having been previously driven.
That length is therefore completely finished, except the cast-iron capping, and a strong ashlar terminating wall has been built, into which the weir end has been securely bonded.
The 300 feet of weir next Derry side has been levelled off and adjusted ready to receive the capping, and the second row of bracing piles driven.
The back of the weir has been puddled from the bottom to the weir top for 600 feet in length, and it is hoped in the season of 1852 to pefect the remainder.
The foundation of Toome lock, which is in hard indurated clay, is in progress of excava¬ tion, and a quantity of Coal Island fire-clay bricks has been procured, and delivered at the site, for the purpose of building invert and side walls, which work will be proceeded with next season.
The hollow quoins for the lock have been all dressed and delivered, and as a railway has been made up to it, communicating directly with the quarry, rubble stone, lime, &c.
can be cheaply and conveniently supplied.
The western breakwater, referred to in my report for 1850, as being then in an advanced state, has been completed to its full length of 720 yards, and its termination, which is in deep water has been found valuable as a landing-place for coal, brick, stone, and other materials for the works.
A large quantity of good stone has been dressed and delivered at the site of the intended Toome Bridge; and the foundation for the Antrim abutment and swivel-bridge pier has been excavated, with the intention of commencing the masonry the first week in 1852.
The bottom is of the most solid character ; and as the necessary machinery has been erected, and the water unusually low, there is every probability of going on rapidly and uninter¬ ruptedly with the building.
Ee %
