The intent of the navigation comprehended in the asidtUe district is about twelve miffs. The whole height, from the Beady Firth or the east sea to Loch Oich, the summit level of the canal, is stated at about 941 feet ; and as 58 feet of this has been overcome in rising to Lech Ness, it appears that about 41 feet will form the rise of the lockage of the middle district ; while the fall on the western side to Loch Eil is only 90 feet. This is to be overcome by a chain of four locks at Fort-Augustus, and one at Callachie, near three miles westward, independe of the Regulating-lock within half a mile of Loch 'Oiab. The foundation of the chain of locks at Fort Augustus has been long a matter of uncertainty; and when the writer of this article visited the works, in the month of August 1816, though preparations bad been made by changing a part of the course of the river Oich, and a steanpengine of 96 horses! power was then erected for clearing the lock-pits of water ; the foundation of the lowest beck was ne vertheless looked forward to with anxiety, from the loose nature of the gravel, and the quantity of water which continued to low into the excavated pert.. But the official gentlemen of thisastablishment are an much accustomed to encounter difficulties, that they other expedients in reserve, in CM of any failure attending the plan -then- in hand. The lock at Callachie is curiously situate, being founded and built upon a dike or stratum of rock called Grey Wade by Mineralogists, which runs across the moor, and is indeed the only piece of rock on thispart of the line of the canal. It is just large enough for the site of the lock, and was preferred to gravel as a foundation. This rock being found very compact, it rendered an inverted arch for the lock unnecessary.
Considerable progress has been made upon the middle district in excavation, which, with little ex caption, is in graveL The greater part of the ca nal is now formed, and 'cut -to the requisite depth. For the purpose of deepening Loch Oich on which is situated the famous castle of Glengary, the seat of the Macdonnels), a dredging machine of great power is to be employed, which is to have four pants or lighters attached to it. This will form a difficult. part of the works of the middle district; but the ex perience and practice acquired upon Loch Dough. four will prove of much advantage to the operations upon Loch Oich.
The track of the canal is here so close upon the river Oich, that the course of that river requires to be altered in two or three instances. Nor is this river quite so manageable as the Ness ; ow ing to the smaller capacity of Loch Oich, and its connection with Loch Gary, it forms the drain age of a great extent of mountainous country, with out having any very considerable space for con. taming its flood waters, like that of Loch Ness ; for the waters of the river Ness cannot be swelled till the whole surface of Loch Ness is raised. We are
thereibse to look upon the river Oich, in so far as it iaterferes with the track of the canal, as much more troublesome, and requiring a different management.
The western or Corpach district of.the Caledonian Canal, may, in a great measure, be supposed to re semble the eastern or Clachnaharry district in its ge neral outline and operations, making a due allowance for the difference of situation and local circumstances.
On the Clachnaharry or eastern division of the canal, we have endeavoured to give some account of the principal works as they occur. To go ,again in to detail, would only be to repeat, in some measure, what is already sufficiently noticed for the general reader. Those who wish to be more critically in formed, would do well to look into the Parliamentary Reports ; and we think a visit to this -great national work, quite as necessary to the traveller, as the Lan guedock Canal is considered by many who visit France; while the mountainous tract through which this navigation passes, is likely to be far more in teresting to the Mineralogist, and to those who seek after and admire the bold scenery of a country, al most completely in a state of nature.
The first great work upon the western district is the raising the surface of Loch Lochy about twelve feet perpendicular ; which is effected by shutting up the present course, and excavating a new channel for the neer Lochy, the ouly stream that flows from the loch, raising the level of its new alveus or bed, and thereby rendering the works of the summit level more easy than by works of excavation. By this meson, the new course of the river Lucby, about , .
half a mile in length, cut through a piece iSf 'flat ground, called Mucomer, forms its confluence with the river Speen, nearly half a mile further up that river. The joint waters of the Lochy and the Spam BOOR afterwards skirt the eastern bank of the canal, where it becomes necessary to make a strong defence against their joint effects, by arming and fortifying it with ruble stone.
From Loch Loch to Loch ED, the'distance is about eight.miles, on which the canal works may now be considered as very nearly finished, having kept pace with those of the eastern district; so that there is little doubt that this end will also be opened for the purpeses of the work in the course of the year 1817. The works of this compartment, both in regard to masonry, excavation, and embankment, have been more expensive than •those of the eastern division ; in particular, the cutting at Moy, Strone, and Muirtheiglich, and excavating the sites of the locks and basin for shipping at Corpach in rock. But, per haps, if all the expence of the foundations and earth , work on the Beauly Firth are taken into account, they may be found to have been as expensive, if not more so, than the blasting of rocks on the Cor Rich district.