868 KEPOitT — 1887. 



almost dii-ectly opposite to it is that part of the Irish Sea where there is no 

 perceptible current, owing to the meeting of the branches of the Atlantic tidal wa^'e 

 which have passed round the north and south of Ireland. 



Admitting the disadvantage of the absence of a transporting current, the author 

 considers the great volume of the local tidal flow sufficient, if properly directed, to 

 maintain a navigable chaonel at the bar, which would greatly reduce the delay and 

 risk to shipping caused by the present want of depth over it. and thus materially 

 benefit the trade of the Mersey. 



The fact that the same tidal flow where directed by natural sandbanks does 

 now maintain a channel about 6,000 feet wide at low water springs, and from 24 

 to 48 feet deep for over nine miles from New Brighton, is adduced as a proof that 

 the quantity of tidal water is suflicieut to maintain such a channel. 



That it faUs to do so now where the bar occurs ( i.e., from 9|^ to 11 miles from 

 New Brighton) is sufficiently explained by the increase of the eflective width of the 

 channel at the bar from 6,000 to 23,000 feet. 



The author finds that tbe sectional area of the low-water channel from New 

 Brighton to the bar is tolerably constant, as might be expected from its being 

 formed and maintained by a constant flow of water through yielding materials. 



He accounts for the increase of 30 per cent, in the eflective area at the bar 

 itself by the eddies and irregularities in the flow which attend so great an increase 

 of width, and by the tendency of the flood tide to break through the south side of 

 the horseshoe ridge of the bar. 



The author considers that a channel formed tlirough the bar by dredging 

 would not be self-maintaining on account of this tendency of the flood tide to 

 break through the sides, and so to keep open subsidiary channels which would rob 

 the main channel of the full scouring power of the ebb. 



In order to enable a perm.anent channel to be made, or at least maintained by 

 natural scour, the author would restrict the width of the low-water channel over 

 the bar by extending the natural sandbanks seaward. 



To do this he would deposit mounds of rough stone, protected where necessary 

 by larger blocks. 



The proper direction in which the channel should be fixed by the works, and 

 their height and distance apart, can only be determined by a minute examination of 

 the present channel and tidal currents, but the present direction of the bar cha)inel 

 appears particularly favourable, and it is not antici])ated that the works need be 

 carried to a greater height than four feet abo^e low water of spring tides. 



They would leave undisturbed the present navigation of the Rock and Formby 

 Channels, and they would not involve a disturbance of the natural regimen of the 

 bay. 



The communication is illustrated by a model of the bay, extending from 

 Liverpool to the deep water outside the bar, which shows clearly the advantage 

 of the present line of the channel as an access to deep water, and the prevalence of 

 shallows and shifting sands on the south side of the Burbo banks which render 

 extremely undesirable the opening of a new channel in that direction. 



The possibility of such an occurrence lias long been recognised, and in the 

 author's oi^inion is a danger to be carefully guarded against in the interests of the 

 Mersey ports. 



3. The Manchester Ship Canal. Bj E. Leader Williams. 



The author mentioned that, iifter uusuccessfiil attempts in the years 1883 and 

 1884, Acts of Parliament have been obtained in the sessions of 1885, 1886, and 

 1887, which give the Manchester Ship Canal Co. power to construct a large ship 

 canal from the deep water at Eastham, near Liverpool, to Manchester. 



The Board of Trade having certified that the conditions in the Acts relating to 

 capital have been complied with, the contract for the whole of the works has 

 been let to Mr. T. A. Walker, of Westminster, and the construction of the canal 

 will be commenced as soon as the arrangements, now in progress, for the purchase 

 of the lands required are completed. 



