ON RECENT IMPROVEMENTS IN THE POKT OF DUBLIN. 171 



The tonnage rates for Cork include 3791Z. derived from one half- 

 penny per ton levied on vessels using or entering the harbour as a port 

 of call, but not loading or unloading cargo therein. It represents a 

 tonnage of 1,819,860 tons, and is quite distinct from the 740,201 tons 

 which represents vessels loading or unloading cargo ; but, as it is avail- 

 able for port purposes, it is included in the tonnage rates of Cork 

 harbour, in the second column above. If this were omitted, the income 

 would be reduced to 9d. per ton register. 



This table shows that for every ton entering their respective ports, 

 Liverpool receives more than four and a half times and Glasgow more 

 than twice the revenue that Dublin gets, while Belfast gets two-thirds 

 more, and Cork nearly fifty per cent. more. 



The floating shears and diving bell are useful for many other purposes 

 besides building quay walls. Among others they are well adapted for 

 breakwater construction and laying the foundations of beacons and light- 

 houses in suitable localities. There is at present a lighthouse in process 

 of construction at the extremity of the Bull Wall which forms the north 

 side of the entrance to Dublin Harbour, the foundations of which in such 

 an exposed place would have been very costly if built by any of the ordi- 

 nary methods. The base is formed of two large semicircular blocks, 

 each sixteen feet high, and together forming a circle of thirty feet in 

 diameter and weighing nearly 700 tons. These blocks were built on the 

 block wharf and conveyed about three miles down the harbour, where 

 they were laid at a depth of several feet below equinoctial low waters on 

 the rubble stone forming the extremity of the Bull Wall which had been 

 previously excavated by the diving bell. On top of these blocks is built 

 in heavy granite ashlar with solid rubble hearting the lower part, or what 

 may be called the plinth of the tower, rising some feet over high water, 

 and on top of this again the shaft of the tower is in process of construc- 

 tion, formed of wrought iron lined with timber, the total height from 

 foundation to top of lantern being 79 feet. Opposite this lighthouse, and 

 at the south side of the harbour entrance, stands Poolbeg Lighthouse, 

 erected in the last century at the extremity of the pier beyond the Pigeon 

 House Fort. The foundations of this latter lighthouse were laid at about 

 low water level in the centre of a mound of rubble stone, and it was 

 originally surrounded by a handsome cut stone platform, which was heavy 

 enough to stand ordinary rough weather, but which, with the rubble stone 

 on which it was laid, was constantly washed away by heavy storms from 

 the sea front of the lighthouse, leaving the base of the latter exposed and 

 liable to be undermined, and causing heavy annual expense from hauling 

 the rubble back again, to be again scattered in the next gale. The light- 

 house base and foreshore are now protected by large blocks weighing 

 140 tons each, two of which were carried at a trip by the floating shears 

 and dropped on the irregular foreshore in front of the lighthouse, which 

 they now protect from the violence of the sea which breaks on them before 

 reaching the lighthouse. This work was exposed to the full brunt of the . 

 great storm of January 3rd, 1877, which nearly cut across the east pier 

 of Howth Harbour and did considerable damage to the paved slope of 

 Kingstown West Pier, and to the railways both at Monkstown and at 

 Howth, which, strange to say, were apparently completely covered by 

 their respective piers. The big blocks, however, protected the base of 

 Poolbeg Lighthouse, and no damage whatever occurred to it. Besides 

 excavating, the diving bell has been used for removing portions of wreck 



