540 Progress in Science. [October, 



500 feet, making its total length 7860 feet from the shore. These extensions 

 considerably more than doubled the capacity of the harbour for refuge pur- 

 poses, for they sheltered a roadstead of 400 acres of deep water, in addition 

 to the 267 acres of water space. The breakwater consists of a sub-structure, 

 or rubble mound, of stone, upon which is erected a substantial stone super- 

 structure, the end of the breakwater being terminated by a head, on which is 

 erected a lighthouse. The rubble mound is of great size, the average depth of 

 water at low-water spring tides being 40 feet, and the greatest depth 55 feet, 

 the rise of tide being 18 feet. The inclination given to the foreshore, or the 

 slope from low water to the superstructure, is nowhere steeper than 7 to 1, and 

 this inclination continues to about 10 feet below low-water mark, when the 

 mound assumes a slope of 2 to 1, to about 25 feet below low-water mark, and 

 somewhat flatter than 1 to 1 from that point to the bottom. On the harbour 

 side the slope of the mound is about 1 to 1. At the level of low water the 

 mound is nowhere less in width than 250 feet, and in 50 feet depth of water 

 it is 400 feet wide at the base. It contains altogether about seven millions of 

 tons of stone. The superstructure consists of a solid central wall of massive 

 masonry, built principally of stone from the "Holyhead mountain 'quarries. 

 The foundations of this wall are laid at the level of low water, and it is 

 carried up to a height of 38 feet g inches above low water, upon which is a 

 handsome promenade, surmounted on the sea side by a massive parapet. At 

 a lower level, or at 27 feet above low water, there is on the harbour side of the 

 central wall a lower terrace or quay, 40 feet wide, formed by an inner wall 

 built at a distance from the central wall, the intermediate space being filled in 

 with suitable material. The head at the end of the breakwater is a massive 

 structure, 150 feet long and 50 feet wide. The first contract for these works 

 was made on the 24th of December, 1847. The late Mr. Rendel was Engineer- 

 in-Chief from the commencement of the work until his death, at the end of 

 1856, when Mr. John Hawkshaw was appointed to that post, and the works 

 have since been carried on under his superintendence. The cost of the whole 

 of the works has been £"1.479,538, which includes not only the outlay on the 

 north breakwater, but also the provision of the accommodation for the Irish 

 Postal Service in the old harbour, the construction of a beaching ground, and 

 other miscellaneous works. 



Kurrachec Harbour. — These important harbour works in India having re- 

 cently been brought to a completion, a brief notice of them will be interesting. 

 Kurrachee is situated near the north-western extremity of Sindh, and is the 

 only seaport of that province available for vessels drawing more than to feet 

 of water. Its position is one of very great importance, whether regarded 

 from a commercial, political, or military point of view. In 1848 a lighthouse 

 was erected on Manora Point, on the western entrance to the harbour; and, 

 in 1855, in consequence of the increasing importance of the place, two 

 dredging vessels were constructed for the improvement of the harbour, and a 

 light-draught steamer was provided for the purpose of towing vessels in and 

 out. In 1856 a committee was formed on the spot for the purpose of consi- 

 dering the best means of effectually improving the harbour, and their report 

 was referred for the opinion of the late Mr. James Walker, C.E., who, in 

 October, 1858, submitted his report, in which he recommended the construction 

 of a breakwater from Manora Point, on the west side of the entrance ; of a 

 groyne from Keamari, at the eastern side ; the closing of Chinna Creek, so as 

 to force the ebb and flow tides to pass up and down the entrance channel, 

 and the construction of new docks and basins, and of a graving dock. In 

 i860 orders were issued for the commencement of the works, which, with 

 certain interruptions, have been carried on up to the present time, — first under 

 the direction of the late Mr. Walker, and at his death by Mr. W. Parkes. 

 Keamari Groyne is 7400 feet long, constructed of stone upon the Keamari 

 sand-spit, having its top 2 feet 6 inches above monsoon high-water. This 

 work was commenced in December, 1861, and completed in April, 1863. The 

 extension of the groyne for 1500 feet (known as the East Pier) was commenced 

 in May, 1864, and completed in October, 1865. Other works within the chan- 

 nel were also carried out which had the effect of considerably improving the 



