1849.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL 



135 



facilities were afforded. For instance, at Hartlepool, he had 

 counted fifty-five vessels leavinfj in a tide, and he had heard of 

 seventy vessels leavinc: in the same time. The forms of widened 

 entrances, shown by Mr. Redman, approximated to the system JMr. 

 JVlurray liad recommended; lie would present to the Institution a 

 description and plans of the dock at Sunderland, as soon as the 

 workswere completed. 



Mr. Redman remarked, that in the case of the Ipswich Docks, 

 the particular direction was obviously entailed by the peculiarities 

 of the site. The entrance was from an artificial cut, which was so 

 narrow as not to afford space for swinjj-ing; and the entrance was, 

 as Mr. M'alker liad e.xplained, away from the channel, in an arti- 

 ficial recess or fore-bay, which created dead or slack water, and 

 neutralised to some extent the effect entailed by an obtuse angle 

 with the line of flood. 



Fig. 1". — Duke's Dock, Liverpool. 



Mr. CuBiTT, V.P., quite agreed, that ho%vever desirable it might 

 be to place the entrance pointing upwards, as had been suggested, 

 and had been so frequently and successfully practised, still locality 

 must in general govern the engineer inlaying out his plans, and he 

 must exhibit his skill, not only in the construction of the work, 

 but, if possible, in the selection of a spot where an eddy of the 

 tide or slack water could be obtained, and which at the same time 

 possessed tiie other requisite qualities for a dock. Mr. Cubitt had 

 recently put in practice at the Duke's Dock at Liverpool (shown 

 in fig. 17), the system as proposed by Mr. iMurray for the 

 Sunderland Dock. A pair of gates had been adapted to the 

 entrance of the outer dock, which had thus been converted into a 

 tidal basin, whence the "trows" and other vessels could be passed 

 into the dock with great facility, thus materially adding to its ad- 

 vantages. He believed that principle was generally found to 

 answer, and he would advise its adoption wherever there was an 

 e.\tensive trade. 



Mr. Murray exhibited a plan and enlarged diagram of the 

 docks in progress of construction at Sunderland, of which he pro- 

 mised to give a detailed account on their completion. The original 

 intention liad been to leave a portion of the old pier, in order to 

 form two entrances; but it was subsequently decided to remove all 

 the old work, in order to afford as large a space as possible for the 

 ^■essels to bring up and swing by their anchors, or to be towed by 

 steamers into the tidal basin, whence thirty at a time would enter 

 the half-tide basin and thence into the dock. By these means a 

 very extensive trade could be accommodated, as was indeed neces- 

 sary, when as many as 150 to 100 vessels required to leave on a 

 tide. 



At Hartlepool the lock was not used for passing the vessels; the 



gates were left open for an hour and a half at the top of the tide, 

 and the vessels were towed by steamers directly into the dock. 



Mr. Rendel, V.P., agreed with the commendations bestowed 

 upon the industry and talent displayed in the paper; but he did 

 not accord with the opinion, that any general rule could be laid 

 down to suit all cases. Many points required careful considera- 

 tion; the velocity and rise of the tide, the local currents, an eddy 

 caused by a bend of the ri\'er, the width of the channel, the nature 

 of the trade and tlie size of the vessels, would all influence the 

 plans of an engineer, whose skill and talent should be displayed 

 by his meeting and combating successfully, the natural difliculties. 

 For this reason few entrances were similar, and it was evident 

 that in practice it had been found impossible to establish any 

 definite angle. If that were possible, one set of drawings would 

 suflice for all cases, and the exercise of skill and judgment would 

 no longer be required. 



Mr. ScoTT Russell confirmed Mr. Rendel's views; the science 

 of engineering had not yet arrived at such definite conclusions, as 

 to enable given rules to be laid down for a subject embracing so 

 many considerations. It was evident from tlie examples brought 

 before the meeting, and from many others which were familiar to 

 all engineers, that it was not possible to lay down any undeviating 

 principle; but in comparing the examples, and considering local 

 peculiarities, he thought it might be assumed that a step towards 

 it had been arrived at. If, as was stated, facilities for docking a 

 loaded ship upon the flow of the tide were given, by having the 

 entrance pointing upwards at an angle of 60°, and for vindocking a 

 loaded vessel on the turn of the tide, by an entrance pointing at 

 the same angle down the stream, it must be evident that the wide 

 entrance, with the piers at opposite angles, as proposed in (fig. 16), 

 would be advantageous wherever sufficient ground could be ob- 

 tained; and if a deep fore-bay could be constructed so that it 

 would not silt up, it would afford additional facility, as a vessel 

 in entering would swing and come in without interfering with a 

 vessel going out. This was only the first step to a tidal basin, 

 which appeared to be a great convenience for an extensive trade. 

 This however presumed that the docks were upon a wide river, and 

 where land was not of very great value; but in a narrow channel, 

 where the stream or the tide set heavily across the entrance, and 

 where the value of the land on the banks was as great as in London, 

 even that rule could not be observed, and the engineer must be 

 guided by local considerations, in order to afford the greatest 

 amount of facility at the least cost. 



Mr. Red.man expressed his regret, that Jlr. Rendel had not 

 been present when the paper was read, and that he had only par- 

 tially heard the discussion upon it. It had certainly not been his 

 intention to assume that there were certain angles for dock 

 entrances applicable to all sites; on the contrary, he had distinctly 

 stated, that all the circumstances of position, set of tide, &c., 

 must be carefully attended to. The examples he had given for 

 proposed enti-ances, were intended as examples of combinations of 

 the good qualities of the different entrances on the Thames, and 

 were laid down in accordance with the opinions generally enter- 

 tained in the port of London, among ship-builders, pilots, and 

 dock-masters, whose practical opinions upon such a subject were, 

 he conceived, well worth attention. These examples, therefore, 

 were only recommended where the site and the set of the tide 

 would admit of such constructions. Neither did he understand 

 the tone of the discussion to lead to the conclusion that one 

 angle was suitable for all situations; for, on the contrary, the dif- 

 ferent attendant circumstances appeared to have been considered 

 by the various speakers. 



He could not agree with Mr. Scott Russell, that possessing a 

 well formed fore-bay, the direction of the lock, or inner portion of 

 the entrance, became of minor or secondary importance. It was 

 necessary, having the upper wing pointing upwards at the angle 

 shown, that the lock should be in the same line, in order that the 

 vessel might be easily drawn in. Mr. Russell had also fallen into 

 error in assuming that a vessel was iindocked upon the ebb; if 

 that were the case, the direction of the lower wing would be un- 

 important, as immediately the vessel's bow met the tide she would 

 swing round into the desired position; such however, was not the 

 case, as vessels were undocked upon the flood, and it was necessary 

 to form the lower wing in such a manner, that by means of the 

 warps attached to her larboard bow, as she left the entrance, she 

 would be brought head upon tide, and swing in the requisite di- 

 rection. If the lower wall pointed considerably up the stream, 

 the labour in counteracting the tendency of the tide, and hauling 

 her bow down stream, would be much increased. It might like- 

 wise be oljserved, as Mr. Russell had instanced, that a position 

 where the tide set very strongly across the entrance, was the exact 



