Having thus given a general description of this tide-lock, which has a lift or rise eight feet six inches, and is, perhaps, the most extraordinary work upon the whole line of this navigation, or, indeed, in any part of the kingdom ; proceeding eastwards, we come to the second, or Clachnaharry lock, which is con tiguous to the sea-lock, being itself barely within the high water mark. It is close to the small fishing vi!. lage of Clachnaharry, which, prior to the commence. meat of these works, consisted of six or eight fisher men's huts. It has still but a few additional houses, yet when this navigation is fully opened, it may rapidly increase, and in time become the port of Inverness, and a place of considerable trade. Clachnaharry lock has a perpendicular rise of six feet, and forms a division between the sea-lock-basin, and the great basin of Muirton, containing an area of about twenty acres. This great basin is of an oblong, and rather irregular form, but is well suited to the figure of the ground ; it is formed by works of excavation and embankment, and has a wharf wall of considerable extent, which will be convenient for the town of In verness, from which it is distant only about one mile. To defend the projecting mounds upon each side of the sea-lock, ruble stones are laid upon the ex ternal 'slopes with such a gentle declivity to the sea, as to be sufficiently secure against the impression of the waves of the Beauly Firth, while the exterior bank of the Muirton basin is defended from its en croachment, by a dike of considerable extent.
At the southern extremity of"this basin, the road from Inverness to Beauly crosses the line of the canal ; and here a handsome Turn or Swivel Bridge of castAron, on a very light construction, has been erected upon piers of masonry. Canal bridge were formerly constructed of timber, and lifted in two leaves br halves by chains and a large timber framing ; but they are now chiefly framed of cast iron, the roadway only being covered with timber; and by the latest improvements they are raised by a wheel and pinion, as originally projected by Mr Per mnnet for the Neva, at St Petersburgh, and now in troduced on the Forth arid Clyde Canal ; or as here managed, they are made to turn in two pieces, each placed upon an opposite abutment of masonry, sad move upon a centre, similar to those of the West India and London Docks. The compartments which project over the water way of tbe canal, meet and joggle into each other, while the opposite ends, towards the land, are loaded so as to balance and become a counterpoise to the projecting parts. When a vessel is to pass, the two parts of the bridge are disengaged, and turn ed off the line of the canal in a horizontal position, by a person stationed on each side of the canal, who works it with a kind of key-bar with a cross head.
This key is made to fit the pinion, which works e the segment of a wheel several feet in radius, and is thus easily turned out of the way of the rigging of passing vessels.
The Muirton locks are four in number, and have each a rise of eight feet. The foundations of these locks were upon the whole easy, being upon a hot tom of hard whitish clay, mixed -with gravel; by building them in one connected range, it was neces sary to lengthen each a few feet, to give accommo dation to the largest vessels ; but still a considerable saving is introduced by this method, as the head and tail walls, and also one pair of gates, are saved. These locks, when viewed from the bridge below, and espe cially when the gates are open, present a very noble stp and seem to be upon the whole al c ent piece of masonry. The gates or "Valves consist of British oak for the lower and Upper being more liable to accident of ships com ing against them than any of the intermediate ones, which are framed of cast-iron in great bars, covered over with strong oak planks, attached to the cast-iron work by numerous screw bolts with nuts. Lock gates of cast-iron have been for a considerable time in use. Perhaps the first of these were constructed on Carron River, upon a small dock for the repair of .he Carron Company's ships ; but they are very trifling compared with the great dimensions of the Caledo nian Canal-gates, which measure SO feet in height, and each leaf is 22 feet in breadth. Cast-iron gates, however, seem to have been brought into use here, rather as a matter of necessity than of choice, from the difficulty and expence of procuring oak of suffi cient scantling or size. The lock-gates have a very stupendous appearance, yet are moved with compa rative ease, by means of chains with a wheel and pi nion upon the most approved principles. The heel of the gate, or that part which works in the hollow quoins, is placed upon a pivot, and the toe, or out ward extremity, is fitted with a roller connected with • screw-bar, in such a manner that the roller may be raised or lowered to suit the ground-sill of the lock, where a segment of cast-iron is inlaid, on which the roller and gate traverse, in opening and shutting ; so that these stupendous gates, weighing about 40 tons, are opened and shut with great facility, by one man on each side of the lock.
The masonry of the sea lock is executed wholly of freestone or sandstone, from Redcastle quarry ; but the second, or Clachnaliarry lock, and also the four locks at Muirton, and the abutments of the •Muirton and Bught Bridges, are only faced with Redcastle stone, the inward walls or backing being ruble stone, from the more contiguous quarry of •Clachnaharry.