18:39.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL 



175 



bended to be defcdive in its origiiial construction, altering tbe deptb, pro- 

 curing tow-vessels, and otlier measures not urgent, bowevcr important." 



I shall adbere to this division as closely as I can, ])rcuiising that tbe two 

 subjects are so connected and so blended with each other, that it will be very 

 difficult to draw the line between them. 



On the 8tli February I also received from Mr. Spearman instructions to 

 report such information as I bad in my recent survey collected on the 

 subject of tbe navigation of the Crinan Canal ; and, in conversations with 

 th.it gentleman, I have been requested not to confine my report strictly to 

 the points above .stated, but to embrace any information respecting tbe 

 Caledonian or Crinan Canal which I might be in possession of, and which 

 1 might think likely to be useful, when the general question of the canal 

 should come to be considered by their Lordships. 



Tbe general history of the Caledonian Canal, with its objects, difficulties 

 and defects, are very ably stated in .Mr. May's report of 1st November 1837, 

 addressed to Mr. Smith, secretary to tbe Commissioners, and in Mr. Smith's 

 letter to the Cbanccllor of the Exchequer, dated '22d December I8o". Tliese 

 are most important and useful documents, the fdcts of wlrjch I found fully 

 confirmed by my survey. The principal defects there referred lo are, how- 

 ever, chiefly in tbe original scheme and construction of the canal, which 

 have therefore, with the danger .ittending them, existed from tlic time of tbe 

 can.il being opened. I name this as a reason against any very sudden alarm ; 

 although 1 fully agree in tbe necessity for prompt measures of secinity, in 

 which tbe canal is certainly defective, probably from the great e.\cess of cost 

 above the estimates, tbe consequent loss of time, and tbe difficulty of obtain- 

 ing funds for the purpose previous to its being opened, all of which are 

 fully stated in Mr. May's report. 



3urvi:y riRsT nivisioN. 



IVesl Eud Culverts Beginning from tbe west end, the first danger arises 



from the culverts made between the Bannavie Locks and Gairlocby, a reach 

 of si.x miles, to carry the mountain floods under (he canal into tbe river 

 Locliy. The masonry of these is certainly very rough, but they are alt(»gether 

 in a better state than I expected from Mr. May's report, the leakage 

 through the work being very small and partial, when, however, the serious 

 eftects of a failure in one of these culverts, which would empty the reach of 

 water, is considered, their perfect security, as the locks at present arc, is most 

 important. 



Gairlmliij J.uck — At the head of the reach is Gairlocby Lock, which hiis 

 the important office of keeping up the waters of Loch Lochy. This lake 

 contains an area of (j,000 acres, the water of which was raised 12 feet above 

 its natural level for the purpose of the canal ; in its ordinary state it is ti to 

 7 feet, and in times of great Hoods 10 to 12 feet, above the present level of 

 the canal in the reach below. If at this time any of the culverts were to 

 give way, so as to empty the reach, an addition of Iti feet would bo added 

 to the pressuie upon the gates of Gaiilochy Lock, making a vertical head of 

 2G to 28 feet, which would, to say the least, place them in danger, and if 

 they should then give way, the contents of th« lake, for a depth of 27 feet, 

 would be discharged upon tbe valley of the Lochy, the general surface of 

 which is much below the level of tbe canal. The destruction of the canal 

 works, and of property, and perhaps life, would be very great, and there- 

 fore the importance of securing the culverts, particularly as the works of the 

 Gairlocby Lock arc by no means in the best state. But my decided opinion, 

 in which Mr. May agrees, is, that the renewal ofthe culverts would be but a 

 paitial remedy, and that complete security cannot be obtained here but by 

 another lock at the entrance of the lock to tbe eastward of the present lock. 

 By this means also the trade of the canal, which, with one lock is liable to 

 be entirely stopped by any accident that would prevent the working of any 

 one of the gates, would be secured. As things now are, a ship or steam- 

 vessel coming up to the lock with any w.iy upon her, and striking tbe gates, 

 might produce this stoppage of the canal for a considerable time, and incur 

 danger, as the d. pendence must then be upon one pair of gates. Con- 

 sidering all circumstances, 1 think it fortunate that this h,as not happened 

 ere this time. I was delayed some time in my passage through the Crinan 

 Canal by a slf;;ni-boat having, in the course of the preceding day, run 

 against and sei iuusly damaged one of the gates; a similar accident to one of 

 the Gaiilochy gates might have very serious consequences. When at Gair- 

 locby, I advisLd Mr. May, as a temporary precaution, to stretch a strong 

 chain across tbe lock at each end ; this has to be lowered to enable vessels to 

 pass, but, when drawn up, stops the vessel before she gets to the gates. The 

 estimate of this lock, with the dams and other works, is 15,9o0/. If 

 executed, the culverts in the reach below may, with a little repair, be left in, 

 as the failure of one of them would then be confined to the discbarge of the 

 water in the reach of six miles. 



Waste Vi'cir for Lovh Okh — A better provision for letting off the flood 

 waters of Loch Oich is the second work required for preventing danger from 

 inundation. In the flood of November 1834, tbe water rose 7 feet i inches 

 above the 20 feet water-mark of the canal, or 15 inches above the gates of 

 Abeichaldcr Lock at the east end of the lake. An extension of the length of 

 the waste weir, and widening the passage for the waters under it, is all that 

 will be required; and then the present weir can be raised, so as to prevent 

 the waste of water through it in droughts. The expense of this will 

 be 1,287/. 



Fo)t Auyiiiliis Locks are next in order. The masonry of the live locks 

 is in general very bad, but only the lower lock comes strictly under the 

 present consideration. To repair it, a dam will be requisite against Loch 

 Ness, tbe sill of tbe lower lock being 15 to 20 feet under the water of the 

 lake, and then (he opportunity should be taken to repair tbe second lock 



also. I calculate on taking down to the bottom and rebuilding the recess 

 walls, renewing the segments and other works, which will amount 

 to 7,690/. 



I think the above are all that come under the head of preventing damage 

 or inundation, without reference to tbe mere stoppage of the canal, which 

 would be the consequence of a failure at any of the Fort Augustus Locks, 

 and from which, owing to the defective masonry having strained and injured 

 tbe gates none of them are by any means secure. 



Tbe collected amount of the tirst division is 24,82"/. 



In tlie-abovc, and in all that follows, I have calcukited upon the avail- 

 able and standard depth of water being only 17 feet, which is less by 3 

 feet than the original design. To obtain 20 feet would be a work of enor- 

 mous magnitude, difficulties and expense, and would much increase danger, 

 without by any means a compensating advantage. A laden vessel of 38 

 feet beam (tbe available width of the locks) does not draw more than 18 

 feet, and 17 feet is sufficient depth for a ship of 400 to 500 tons,* and few, 

 if any ships in the Baltic or American trade exceed this siie. 

 SECOND nivisioN. 



Finis/iinf! Cunal and remedt/iiiff Drfccls With the expenditure of 



24,827/., for averting inundation, and for the repair of Fort Augustus Lock, 

 the canal will still be left in a very unfini.-.hed stale, liable to stoppages, incon- 

 venient for business, portions very leaky, and many of its works much out 

 of repair. All these, however, come more properly under the second head, 

 of " finishing tbe canal, and remedying what is defective in the original 

 construction," which come now to be considered. These, though not urgent 

 as respects security to the country, are most of them essential if tbe canal is 

 lo be kept open, and to prevent still greater expense, which will be the 

 effect if the repairs be delayed. With (be present disadvantages, imperfec- 

 tions and w,-int of convenience, it is raiber to be wondered that there should 

 have been even the ir.ade tliere bii3 been ; and the fact of there having been 

 even a small trade, certainly goes to prove wh.it there would be if the canal 

 were finished, and convenience given. 



In explaining the particulars of tbe works required, it is so very difficult 

 to separate repairing and finishing from improvements, that (he better 

 way may be to state the articles in detail, as I have taken them, with the esti- 

 mate of each ; this will also afford information as to what is the nature and ex- 

 tent of the repairs, and what appear to me to be re<iuired in the way of im- 

 provements, to render the Caledonian Canal complete and convenient for as 

 great a trade as can be carried on upon it. 



The repairs, improveurents and machinery as detailed.f amount to 104,490/, 

 .and with this expenditure I Jconsider that tbe canal will be complete and 

 proper for work as originally proposed, nnd combining additional safety, but 

 with the difference of 17 feet in lieu of 20 feet depth. 



Sliam Tugs As yet I have included nothing for steam-tugs, which, 



although no part of the original plan, appear to me quite indispensable for 

 the proper working ofthe canal, as respects either the ticcommodation to trade, 

 or the probable chance of a return for the great expense incurred in its 

 construction. present DU'FictjLTiEs. 



Lakes.— One ofthe temptations to make a canal at all, and particularly of this 

 great size, from Loch Eil to the Beauly Frith, was the appaient facility 

 afl'orded by the three lakes, which lie in almost a continuous line, and arc for 

 the inost part of ample width and depth ; viz.. Loch Lochy, 10 miles; Loch 

 Oich, 4 miles; and Loch Ness, 23^ miles; together 37A miles; thus leaving 

 of the whole length of C0§ miles only 23 miles of canal to ni.ikc. That 

 the cost of making the canal has been much reduced, probably more than 

 half, by tbe lakes, cannot be doubted; but it is equally apparent, as fully 

 slated in Messrs. May and Smith's reports, that they are now great hindran- 

 ces to the passage of vessels. From lying in the trough or hollow between 

 two ranges of mountains, the wind blows always parallel to the line of the 

 canal, so as necessarily to be a foul wind in one direction. From the rocky 

 nature of the banks, and their crooked irregular shape, tracking through I he 

 lakes is impossible. The width of l/och Lochy and Loch Ness is sulHcicnt 

 for vessels of about 100 tons to work when once fairly in tbe lakes, but there 

 is a great difficulty in warping against a strong head wind to reach this, and 

 great danger also from the rocky .shores in case of a vessel missing stays. 

 Therefore, working or tacking through the lakes is seldom attempted, and 

 the consequence is, that the passage of tiO miles, which, were tracking 

 practicable for the whole length, might be accomplished generally in three 

 to four days, often takes as many weeks; even a monlli is not unusual, and 

 cases of five weeks have been known. The evil is increased by the Hcsterly 

 winds which prevail for eight or nine months of the year, and are opposed to the 

 direction of what ought to be the greatest trade on the canal. To prevent 

 passage of vessels proceeding from the east to the west end, which the is 

 delay, sometimes three or four mouths, of going through the Pcntland 

 Frith and round Cape Wrath during the westerly winds, was one ofthe piin- 

 cipal objects of the canal, which is thus in a great metisure defeated. When 

 1 was upon my survey, several vessels were waiting for a change of wind at 

 (he east end of Loch Oich, and another number at the east end of LoclrNesy, 

 none of thcnr above 13.5 tons burthen. A very few hours of a steam-tug 

 would have set tbe whole at liberty. The approaches to the ctiual from the 

 estuaries at each end are subject to the s,ame inconvenience. 



The iroiit of Drjilh in the canal and portions of the locks is another great 



—-■ 



' The late alter.ition in the measuring for register has (enUed to reduce the depth 

 of British ships built since the passing of the Ilegister Act. 



t The report contains a detailed estimate, which we h.-ive here oniillcd, in cons- 

 (picnce of the great length of the {f port, ljut,« c will endeavour tu give il in the nc.-a 

 Joursal.— Ediioe. 



