It deserves to be noticed, in this place, that the whole of the face-walls of the masonry here were only specified and paid for as common ruble work, instead of which, with few exceptions, the work is executed of a superior quality, in regular courses, technically called coursed ruble. This certainly does much credit to the spirit in which the contractors for this great un dertaking seem to have conducted their operations ; and it is but justice here to notice the name of a per son who, for many years, was eminent as a contractor for masonry, especially for canal works, harbours, and bridges, throughout the kingdom—we mean the late Mr Simpson of Shrewsbury, principal contractor upon the Caledonian Canal,—a native of Scotland; and who, it has superintended and exe cuted more work of this kind than perhaps any other individual in the line of his profession.
It is not always poasiblp to apportion the expence of the several compartments of a large work, so as to show the neat cost of each, but it seems probable that these locks, upon an average, exclusively of the sea lock, will have cost, when entirely finished, not • less than L.8000. This sum, compared with other works also of considerable magnitude, appears to be very moderately stated, although it is somewhat higher than the estimates of 1804, and considerably more than had been originally calculated upon in 1802. Besides the difference of time between the estimates and the execution of the work, the unexampled rise in the price of labour, and indeed of every commodity. The estimate of 1802 applied to locks of a very dif ferent construction from those actually executed. The locks originally proposed by Mr Telford would, no doubt, have been considerably less expensive, pro bably not exceeding L. 5000, as they were only meant to have had masonry at the gates, while the space between was to be embanked, like the other parts of the canal. But as this would have made the na vigation much more tedious, it was determined to line the lock-chambers with masonry, in the usual way, when the locks were then estimated, each, at L. 7500 ; so that this part of the work may fairly be considered as not greatly exceeding the estimate.
On the Reach of the canal between Muirton locks and Loch Ness, the distance is about five miles. The works of excavation here are chiefly in gravel, some parts of a loose and others of a more compact nature ; and containing various proportions of earthy matters. But, upon the whole, the soil is exceeding ly bad for canal work ; which renders it necessary to trust a great deal to the puddle-walls of the banks and bottom, against the pressure of the great depth of water in this canal. On this reach there is some deep cutting, in passing the singular hillock of Tomnahurich ; and the road on the eastern side of Torvaine bill, has been carried by a new line on the western side. A considerable embankment also became necessary to the westward of the lands of Bught, where the eastern bank of the canal is actually formed on the bed of the river Ness, under the hill of Torvaine. Here the course of the river has to be altered and widened by cutting away part of its eastern bank, for the apace of about half a mile. A similar operation, but of smaller ex tent, became necessary under the hill of Toremore, where the canal banks again trench upon the river, Ness; after which, the only work of expence on this reach, is the construction of. a regulating-lock
and weir for the waters of Loch Ness.
It was, no doubt, a bold attempt, to place the bank of a canal upon the verge of a considerable river, but after a trial of several years, it has sus tained no material injury. This arises entirely from the waters being, in a good measure, regulated and apportioned by -the great receptacle of Loch Ness, which so regulates the stream of that river, and checks its velocity, as to prevent this injurious ef fects that would, under other circumstances, attend the exposed state of the canal banks at this place, however well armed and secured by a facing of boul der or ruble stones, upon the slope of the outward bank. • The Regulating-kick for Lochs Doughfour and Ness has a rise of six feet six inches, and is situated about half a mile northward from the former, which connects with Loch Ness by the narrow channel of Bona Ferry. This lock was intended to have been placed somewhat nearer the loch, and was proposed to be carried minas the stream of the river Ness; but a proper foundation could not be found for it there. The close connection of its site with the river, has aecessarny increased the difficulties of this part of the canal, while the operations were unavoidably re tarded by the land-carriage of the Redcastle stone, for the outward walls, brought over land from Cinch naharry, a distance of about six miles. Great labour and perseverance were exerted here, in clearing the lock-pit of water, to the depth of about 20 feet under the level of the bed of the river. This work commenced in July 1812, and the masonry was completed in about two years, without the occurrence of any material acci dent. The name of Regulat in g-Locksufficiently implies its use. Connected as the canal is at this end with Lochs Doughfour and Ness, which extend about twenty-four miles to the south-westward, through a range of mountains, and, consequently, forming the drainage of a great extent of country, it is obvious that these extensive lochs must receive vast quanti ties of water during wet and rainy seasons, but es pecially in time of thaw, when there is much snow upon the ground. The effact must be, to raise the surface of the water of Loch Ness, which has been known, on such occasions, to rise from six to eight feet above its ordinary summer level. Indeed, the remarkable regularity of the gravel beach round its margin,--the present position of many aged alder trees, even within the summer water-mark along the shores, sufficiently indicate this, and lead us to sup pose, that the surface waters of the loch are, upon the whole, in a state of increase. At all events, we are certain, that the water of these lochs must have a tendency to- rise, from the great quantity of debris which is constantly falling in and silting up the bot tom, while the surface to be drained, and the quan tity of water 'lowing into it, remains nearly a con stant quantity. This process is, therefore, likely to keep pace with the wearing away of the bed or chan nel of the river, by which the flood or spent waters are let off; considerations which, of course, form the limits of the regulating lock and weir across the River Ness, connected with this chain of lochs.