134 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[May, 



rived, by calculation, at certain results, and had determined 

 that an angle of tS^ pointing upwards was tlie best for a dock 

 entrance. 



Mr. Sidney Yoivg felt that it would be ungracious on his part 

 were he to withhold, on the part of those whose avocations, like 

 his own, would make them practically the recipients of the bene- 

 fits to be derived from such a discussion as the present, his best 

 acknowledgments to his friend Mr. Redman, for the careful in- 

 vestigation he liad undertaken, and to tlie meeting for the atten- 

 tion tliat had now been given to the subject. 



To all tlie remarks and suggestions he had heard from Mr. 

 Redman, in reference to the most convenient "angle to the flow of 

 the tide" for placing dry docks, he gave his unqualified concur- 

 rence; nor did he think that any one who had op))(U-tunities of 

 forming a practical opinion on the subject, would for a moment 

 (piestion their correctnesss. No better evidence of the important 

 service now rendered could, he thouglit, be afforded than the great 

 variety of the angles formed by docks in the Thames, as so ably ex- 

 emplified in Mr. Redman's diagrams — proving, as it appeared to 

 him, tliat this question, important as it was, had hitherto engrossed 

 very little attention. The constructors of these entrances were, 

 in many instances, probably too much restricted by local circum- 

 stances to allow of their placing them at so acute an angle as 

 was now proposed; still, in the instance of dry docks, they might 

 in almost every instance at least have adopted the same direction, 

 with an angle so small as not perceptibly to affect the general dis- 

 tribution of the property. This would frequently increase the 

 facility of moving vessels into and out of dock, especially in those 

 wide situations which were exposed to a particularly strong set of 

 tide, to an extent that could scarcely be appreciated by those who 

 were not in the constant habit of superintending such operations. 



With respect to the entrances of wet docks, the opinion of an 

 experienced pilot should be held of more value than any other; 

 but he was led to believe, from the remarks made by some gentle- 

 men present, that the subject had been too much regarded as 

 though vessels had only to be docked, and not just as often un- 

 docked whilst loaded. For the first purpose he was still of opinicui 

 that Mr. Redman's plan was equally applicable as to dry docks; 

 but as undocking had also to be considered, he thought practi- 

 cally a right angle might be found sufficient, with a lower wing 

 boldly splayed out, as in fig. 16, which frequently afforded the 

 pilot an opportunity of setting sail before meeting the tide. 

 »\'ithout such a provision the vessel's head would be carried up the 

 stream, and the necessity of swinging her round would be involved. 

 This would at all times be attended with great inconvenience, and, 

 in comparatively contracted navigation, with much risk. In all 

 cases, Mr. Redman's proposed dolphin on the upper side would 

 undoubtedly be most advantageous. In reference to H.M. steam- 

 frigate Termagant, now in their establishment, it was true that, 

 from her great length and the slight acuteness in the direction 

 of the dock, the action of the flood presented great impediments 

 to placing her in position, and afforded therefore a powerful illus- 

 tration of the advantages that might have been dei-ived from Mr. 

 Redman's ])roposed conditions for the directions of docks, and the 

 addition of the dol|)hin, which would have prevented her being 

 carried up "fore and aft." 



Mr. T. R. Spence confirmed the statement relative to IMessrs. 

 Tebbutt's establishment, Limekiln Dock, and the general views of 

 the i)aper. In their yard, a dock pointed up in nearly the direc- 

 tion proposed by Mr. Redman for dry docks, and it was found that 

 ships were easily docked in it, with a moderate number of men; 

 certainly with more ease than if it were at right angles to the 

 stream. It was ])robable that the direction of this particular dock 

 had been more influenced by the conditions of the property, than 

 the fact that such a direction was the best for docking; and he 

 explained, as the reasons for the direction, that it had been for- 

 merly a building slip, and the position of another dock had induced 

 this ]iarticular direction to get greater length. Pilots had always 

 f(uind tliat when ships were launched from it, they had been easily 

 brmight head upon tide. Since it had been deepened and altered 

 into a dock, it had been found that ships entered easily, and in 

 going out canu> almost directly head upon tide. Where the form 

 and position of the yard would admit of it, a direction pointing 

 up the stream increased the facility of docking, and was there- 

 fore to be rocommcuded for a dry 'dock. The coiulitions of the 

 property would not, however, always admit of this; but the intro- 

 duction of steam-power had lessened the inconveniences attendant 

 upon docks at right angles to the stream, more so, however, in 

 some cases than in others. 



As regarded wet docks, Mr. Spence stated, that a direction 

 pointing upwards likewise facilitated the introduction of loaded 



vessels, but that he considered a pilot the best authority on this 

 suliject; that, for undocking, it was necessary that the lower pier 

 should point down, as was provided for in fig. lU; as, unlike ships 

 coming out of dry dock stern foremost, and therefore readily 

 swinging head upon tide, ships came out of all wet docks head 

 foremost; conseipiently, unless the lower wing pointed downwards, 

 the ship's head, in coming out on the flood, would have a tendency 

 to drift upwards, instead of coming round head upon tide. 



The dock in their yard which had been referred to, was rather 

 embayed, as a reference to a map of the river would show; this 

 increased the facility; but still he was strongly of opinion, that 

 the convenience attached to it was chiefly due to its direction in 

 reference to the stream. One great object in forming the entrance 

 to a wet dock was to have it sufficiently wide, with diverging 

 piers, so that when the ship was sheered to, her midship part 

 might come against the u])per pier, wliilst her bow was at the 

 lower side; she would thus enter readily. For this reason the di- 

 rection of the lock did not appear to him so important as the form 

 of the outer entrance. The Shadwell entrance of the London 

 Docks, since the addition of the timber jetty on the upper side 

 (pointing upwards), had acted admirably. Viewing fig. IG, a prac- 

 tical difficulty might present itself — viz., of entering one ship 

 while another departed; but this was seldom, if ever, attempted. 

 The outward-bound vessels generally left as soon as there was 

 water for them, and homeward ships did not generally get up until 

 towards high water. If a loaded ship came up whilst another 

 was going out, she was obliged to keep out of the way of the 

 entrance until the outward-bound vessel was clear. 



i\Ir. CuBiTT, V.P., said, the object was to get as many vessels as 

 possible in and out at high water, in order to take advantage of 

 the depth of water and the slack tide, which rendered less power 

 necessary. For the purpose of obtaining still water, a deep and 

 capacious fore-bay was sometimes made, as it was found materially 

 to facilitate the entrance of the vessels; and whenever the locality 

 permitted the formation, and means could be adopted for prevent- 

 ing it from silting up, it should be adopted. The examples which 

 had been brought forward by Mr. Redman were useful, showing 

 as they did, that although the trade of the ptu-t was carried on, 

 practically, with efficiency at all the docks, still from the par- 

 ticular direction and conformation of some entrances, ships 

 were docked and undocked much more readily at some than 

 at others. 



Jlr. jMay drew attention to the entrance of the Ipswich Docks, 

 constructed from the design of the late Mr. H. R. Palmer, and 

 where he had free scope to do as he pleased ; yet he had designed 

 it at an angle pointing down the stream, like the Shadwell entrance 

 of the London Docks. This appeared contrary to the received 

 opinion, and yet the work was very successful and answered the 

 purpose perfectly. The entire width of the river, at high-water, 

 was about 1 50 feet, and the entrance was so placed, that a vessel 

 coming up with the tide went directly into the dock without 

 swinging. 



Mr. AValker said, it must be evident there were practical diffi- 

 culties occasioned by a downward direction being given to an en- 

 trance; they were, however, in some degree compensated for, by 

 the formation of a deep recess or fore-bay, in which a vessel would 

 be out of the run of the tide. This gave great facility for dock- 

 ing a vessel, which under all circumstances was a somewhat 

 hazardous operation. In the case of Ipswich, it appeared that 

 there was a certain difficulty to contend with, and, like a skilful 

 engineer, Mr. Palmer had chosen the simplest method of overcom- 

 ing it. In so narrow a river, it would have been difficult for the 

 vessels to have swung, and therefore he preferred their entering 

 directly into the fore-bay, in doing which they would be aided by 

 the tide. 



Mr. Murray said he had discussed this matter at some length 

 with Mr. AValker, when examining the plan for the proposed docks 

 at Sunderland, and being guided, in a great degree, by the opinion 

 of the shipowners aiul pilots, it was settled that the entrance 

 should be placed acutely up the stream, and that the exit should 

 be the reverse. It was a great object at Sunderland to enable as 

 many vessels as possible to enter and to leave the i)ort on the tide; 

 for which i)uri)ose a tidal basin of three acres in extent, with tide- 

 gates, was intended to be constructed, for the vessels to enter and 

 bring up in; from thence they entered through wide gates into the 

 main dock. The tidal basin became in fact a great lock. The 

 object was to get from three hours to three hours and a half for 

 docking vessels on each tide. In the Thames, from ten to fifteen 

 minutes were occupied by each vessel in passing a lock, so that 

 the amount of acconnnodatiou was in fact restricted; but in other 

 places, where the system he had described was followed, greater 



