The summit loch of the whole is Loch Oich, the surface of which is exactly a hundred feet above high water-mark, both at Inverness and Fort William; and to this sheet of water the navigation climbs up by a series of locks from both the eastern and western seas. The whole number of these is twenty-eight: the entrance-lock at Clachnaharry, constructed on piles, at the end of huge embankments, forced out into deep water, at Loch Beady; another at the entrance to the capacious artificial harbour above mentioned, at Muirtown; four connected locks at the southern end of this basin; a regulating lock a little to the north of Loch Dochfour; five contiguous locks at Fort Augustus, at the south end of Loch Ness; another, called the Kytra Lock, about midway between Fort Angustus and Loch Oich; a regulating lock at the north-east end of Loch Oich; two contiguous locks between Lochs Oich and Lochy; a regulating lock at the south-west end of Loch Lochy; next, the grand series of locks, eight in number, called "Neptune's Staircase," at Bannavie, within a mile and a quarter of the sea; two locks, descending to Corpach basin; and lastly, the great entrance or sea-lock at Corpach. The northern entrance-lock from the sea at Loch Beauly is at Clachnaharry, near Inverness. The works here were not accomplished without much difficulty as well as labour, partly from the very gradual declivity of the shore, and partly from the necessity of placing the sea-lock on absolute mud, which afforded no foundation other than what was created by compression and pile-driving. The mud was forced down by throwing upon it an immense load of earth and stones, which was left during twelve months to settle; after which a shaft was sunk to a solid foundation, and the masonry of the sea-lock was then founded and built therein. In the 'Sixteenth Report of the Commissioners of the Caledonian Canal,' the following reference is made to this important work, which was finished in 1812:-- "The depth of the mud on which it may be said to be artificially seated is not less than 60 feet; so that it cannot be deemed superfluous, at the end of seven years, to state that no subsidence is discoverable; and we presume that the entire lock, as well as every part of it, may now be deemed as immovable, and as little liable to destruction, as any other large mass of masonry. This was the most remarkable work performed under the immediate care of Mr. Matthew Davidson, our superintendent at Clachnaharry, from 1804 till the time of his decease. He was a man perfectly qualified for the employment by inflexible integrity, unwearied industry, and zeal to a degree of anxiety, in all the operations committed to his care."*[1]