352

HISTORY OF ENGINEERING.

Book T.

ferry between the two forts it widens considerably. On the side of Fortrose a jetty hasbeen built for the convenience of disembarkation, and a mound has been formed on theother side upon a tongue of land. The pier is raised 18 feet above the level of low water,and is 22 feet thick at top : both sides are faced with squared stone, and filled in withrubble.

Cromarty stands on the inner extremity of the bay, on the banks of the Petter. Twoquays have been recently constructed at Dingwall, where vessels drawing 9 feet water maydischarge their cargoes.

The Bay of Cromarty has several landing-places, lately built for the convenience of thosewho frequent this magnificent coast, as Invergordon, Balinghead, &c. &c.

Mahomac , in the Firth of Dornock, which is separated from that of Murray by aprominent tongue of land, has a pier recently constructed for its protection, 450 feet in

MAHOMAC

length, with an end or jetty of 68 feet, returned at right angles. The wall towards thesea batters, and has a parapet for its defence; that towards the harbour is curved on theface, both built of squared stone and filled in with rubble.

Tain is another harbour in this gulf, which is exceedingly narrow.

}Vick, in the county of Caithness, has a small harbour protected by a jetty at the moutliof a small river; beyond this resort for fishing boats is seen Cape Duncansby, whichterminates the western coast.

Harbour of Pulteney Town. Caithness in Scotland , situated in the latitude of 58° 26'north, and 3° 5' west longitude, has been improved by the British Fisheries Society, partlyunder the late Mr. Telford. A stone bridge connects the improvements with the town ofWick, formed of three arches, having a clear water-way of 156 feet, which was builtin 1805.

The rise of the tide at neaps is 5 feet, and at ordinary springs only 9 feet 6 inches; atextraordinary springs, from the lowest ebb to the highest flow', 13 feet.

The north harbour, only adapted for small vessels, being found very insufficient for thegrowing trade of this improving fishing port, in 1823 the south harbour was undertaken;the quays are built with stone of a hard quality, and vary in length from 3 feet to 20 feet,and 3 feet 8 inches in breadth, and in thickness from 8 to 15 inches. These w’ere set onedge, and the courses placed diagonally in the slope; in the front walls the courses werelaid flat, and perfectly horizontal.

The foundations of the slope were formed of stones weighing from 15 to 20 tons each,which were floated to their place by means of casks made of fir ; each weighed about 25cwt.,and displaced about 445 cubic feet of water, so that two of these casks would lift 34^ towsof stone.

Four of these casks were made use of, and sometimes they were found useful to lift thevessels loaded with stones; when the water was low in the harbour, they exercised a liftequal to 44 tons, by means of chains passed under the keel. These casks, which did notcost more than 8/. each, were found of great service in moving the stone, which cost onlyIs. 6d. per ton, when they were moved three miles, and lowered into their respectivesituations. When the casks were applied to stones under low water, a wooden frame wasmade use of for boring holes in the stone, for the insertion of a Lew’is of rather a novelform: the shank which was inserted was about 2 inches in diameter at the bottom, andtapered upwards, diminishing to ljinch at the top, where, into the eye, welded at the