Commissioners of Public Works (Ireland): twentieth report with appendices

Back to Search Bibliographic Data Print
214, IRELAND:—APPENDIX TO TWENTIETH REPORT Appendix (E.) 
Annual Report of Mr. 
C. 
S. 
Ottley, C.E., 
District Engineer. 

erected, ready for next season's work, which it is expected will finish the excavation of that extensive shoal. 
The "Camroc*' lock has been, completely finished and coped. 
The upper or breast gates have been hung, and the lower gates are on the ground, made, and ready for erectin* also. 

At Movanaghcr lock (the third in succession from Oolcraine) the sluice machinery has been got up, and ihe lock is in full working order. 
The operation of stone (marrying and dressing at Tamlaghf quarry, on this division, has proceeded without intermission, and arrangement^ have been made for boating the stone to Portna lock, passing the boats through Movanagher lock and canal, which is found the most convenient mode of transit. 
During the season of 1851, the underpinning of the Antrim abutment and throe adjoining piers of Kilrea Bridge was accomplished, without, accident, or injury to ihe structure; and at the same time the shoal on which the bridge stands, extending up and down stream to a length of 450 feet, was enclosed and excavated to full navigable depth for a width of 100 feet. 
The depth of underpinning was 7 feet, and the excavation of the shoal was the same. 
A wharf wall, 60 feet in length, has also been built, adjoining the bridge on the north side, where previously no landing place had existed. 
On the 2d division the following work was done in 1851 :— 

Excavation -33,218 cubic yards. 
Stone quarried and dressed --22,126 cubic feet. 
Masonry built -420 cubic yards. 
3d or Portna Division, extending from Kilrea. 
Bridge to Portglenone, 7 miles. 
Tho whole of the works in this division having been linished, as regards excavation, in 1850, except about 12,000 cubic yards, there was not much room for extended operations in that branch. 
However, the portion of the canal below lock site, which had been left undone, is now completed. 
But the shoal of Gortroaghy, 8,000 cubic yards in extent, which is the only excavation on the division yet to be done, has been purposely deferred, as its removal would have let down too great a, body of water this winter on the lower reaches of the river. 
Next season, however, if is intended to complete this excavation. 
On the 6th "November the first stone was laid of the Portna double lock, the foundations having been cleared out, and the necessary machinery erected previously. 
My anticipations as to dispensing with inverts of masonry have been realized, and the floor of both chambers of the lock is of solid rock. 
The building of the side walls and upper sill has rapidly advanced, and the supply of stone by boat from the 2d division is found to be fully sufficient to keep the masons going. 
The lock pit is further favourable, in being unsually free from water. 
Timber has been procured, and other preparations made for constructing the three pair of gates required for Portna lock, which it is expected will be altogether finished next season. 

"Work done in 3d division in 1851. 
Excavation ---35,305 cubic yards. 
Masonry built ---870 „ 

Fourth or Toome Division, Extending from Portglenone to Toome (8 miles). 
On this division of the district a very large amount of work has been done. 
The whole of the piers and abutments of the new bridge at Portglenone have been built up to their springing level, and at the same time the excavation of the river bed between them has been completed by dredging and otherwise to the full intended depth. 
The gangtrec road having been extended the whole way across the river, and two gangtrees erected, the getting up of the centres and the setting of the arches can be readily pro¬ ceeded with. 
For this purpose the whole of the stone has been prepared, and it is expected that the arches will be all turned next season. 

t 

They are three in number, segmental in form, having each a span of 65 feet and a rise of 15 feet, in addition to which a navigation ope of 20 feet has been provided, which is to be spanned by a wrought-iron swivel. 
Much difficulty was experienced in getting the piers founded, owing to the gravelly and porous nature of the substratum, and the rapidity and depth of the current of water outside the dams. 
However, the leakage was successfully overcome by large pumps worked by horse-power, and the masonry was raised above the influence of the water early in the month of November. 
The centres are in progress of construction, and will be erected with as little delay as possible. 

The new wharf wall and alteration in boat-house in Mr. 
Alexander's demesne have been completed, the banks finally formed and soiled, and the general character of the place decidedly much improved.