Now! Then! Civil engineers John Smeaton and John Wooler explain how to use the River Hull to flush the dock which has replaced the northwest section of the city walls

17 August 1778: Civil engineers John Smeaton and John Wooler explain how to use the River Hull to flush the dock which has replaced the northwest section of the city walls

Wenceslaus Hollar’s 17th century map of Hull, the 1770s dock works extending from the Hull (left) to the Beverley gate (bottom), whence drainage was to be canalised to the Humber (right) (Hollar 1670ish).

John Smeaton. 1812. Reports of the Late John Smeaton, F.R.S., Made on Various Occasions, in the Course of His Employment as a Civil Engineer, Vol. 3/3. London: Longman, Hurst, Rees, Orme, and Brown. Get it:

Excerpt

The dock in its present state is wanting in some essential matters, the principal of which is the means of scouring it from the silt that will undoubtedly gather therein by taking in the muddy tides from the Humber. Had the lock been made with gates pointed both ways – towards the river as well as to the land, so as to shut out all such spring tides as would rise above the gauge height of the constant water in the dock – much of this would have been excluded. Also, the depth of the dock being such as to retain four feet at low water, and being in breadth 255 feet, we are of opinion that no scours from any practical reservoirs can take place so as to clear the silt into the Hull. It therefore remains, that by introducing the current of the river Hull at low water (and particularly when there happens a fresh in the river at spring tides in the summer), to pass through the dock by means of a canal down towards the Humber, this clearance with the aid of men may be effected, which canal must be dug to a depth at least equal, or indeed rather of superior depth to that of the dock, with suitable sluices or locks thereon. The four drawgates now formed in the cross wall at Beverley Gates, amounting together to a breadth of fifteen feet only, we look upon as insufficient to let all the current from the river Hull pass through, that may be introduced to advantage, unless such a pen and fall be brought on at that place as would materially injure the declivity of the current in its passage through the length of the dock, and in consequence the strength of the scour. There being therefore a necessity for the removal of this wall, we would advise a sluice to be erected of equal depth with the present great lock, or indeed somewhat deeper, with a single pair of gates pointed towards the dock, and a draw bridge over it, for the Beverley roads.

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To facilitate reading, the spelling and punctuation of elderly excerpts have generally been modernised, and distracting excision scars concealed. My selections, translations, and editions are copyright.

Abbreviations

Comment

Smeaton’s scheme did not prosper. John Timperley:

Various schemes had been suggested for cleansing the dock of the mud brought in by the tide; one was by making reservoirs in the fortifications or old town ditches, with the requisite sluices, by means of which the mud was to be scoured out at low water; another by cutting a canal to the Humber, from the west end of the dock, where sluices had been provided, and put down for the purpose, when it was proposed to divert the ebb tide from the river Hull along the dock, and through the sluices and canal into the Humber, and so produce a current sufficient, with a little manual assistance, to carry away the mud. Both of these schemes were however abandoned, and the plan of a horse dredging machine adopted; this work began about four years after the Old dock was completed, and continued until after the opening of the Junction dock. The machine was contained in a square and flat bottomed vessel 61 feet 6 inches long, 22 feet 6 inches wide, and drawing 4 feet water: it at first had only eleven buckets, calculated to work in 14 feet water, in which state it remained till 1814, when two buckets were added so as to work in 17 feet water, and in 1827 a further addition of four buckets was made, giving seventeen altogether, which enabled it to work in the highest spring tides. The machine was attended by three men, and worked by two horses, which did it at first with ease, but since the addition of the last four buckets, the work has been exceedingly hard.

There were generally six mud boats employed in this dock before the Humber dock was made; since which there have been only four, containing, when fully laden, about 180 tons, and usually filled in about six or seven hours; they are then taken down the old harbour and discharged in the Humber at about a hundred fathoms beyond low water mark, after which they are brought back into the dock, sometimes in three or four hours, but generally more. The mud engine has been usually employed seven or eight months in the year, commencing work in April or May.

The quantity of mud raised prior to the opening of the Junction dock, varied from 12,000 to 29,000 tons, and averaged 19,000 tons per annum; except for a few years before the rebuilding of the Old lock, when, from the bad and leaky state of the gates, a greater supply of water was required for the dock, and the average yearly quantity was about 25,000 tons. As the Junction dock, and in part also the Humber dock, are now supplied from this source, a greater quantity of water flows through the Old dock, and the mud removed has of late been about 23,000 tons a year.

It may be observed, that the greatest quantity of mud is brought into the dock during spring tides, and particularly in dry seasons, when there is not much fresh water in the Hull; in neap tides, and during freshes in the river, very little mud comes in (Timperley 1842).

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Original

In answer to the fourth, regarding what is further to be done for the completion of the plan, we apprehend that the dock in its present state is wanting in some essential matters, the principal of which is the means of scouring it from the silt that will undoubtedly gather therein, by taking in the muddy tides from the Humber. Had the lock been made with gates pointed both ways, that is, towards the river as well as to the land, so as to shut out all such spring tides as would rise above the gage height of the constant water in the dock, much of this would have been excluded; also the depth of the dock being such as to retain four feet at low water, and being in breadth 255 feet, we are of opinion that no scowers from any practical reservoirs can take place, so as to clear the silt into the Hull, it therefore remains, that by introducing the current of the river Hull at low water, (and particularly when there happens a fresh in the river at spring tides in the summer), to pass through the dock by means of a canal down towards the Humber, this clearance with the aid of men may be effected, which canal must be dug to a depth at least equal, or indeed rather of superior depth to that of the dock, with suitable sluices or locks thereon.

The four draw-gates now formed in the cross wall at Beverly Gates, amounting together to a breadth of fifteen feet only, we look upon as insufficient to let all the current from the river Hull pass through, that may be introduced to advantage, unless such a pen and fall be brought on at that place as would materially injure the declivity of the current in its passage through the length of the dock, and in consequence the strength of the scower. There being therefore a necessity for the removal of this wall, we would advise a sluice to be erected of equal depth with the present great lock, or indeed somewhat deeper, with a single pair of gates pointed towards the dock, and a draw bridge over it, for the Beverly roads.

At Myton Gate it will be sufficient to construct a bridge only of sufficient passage for the water, and at Hazel Gate a sluice of some kind, also of sufficient water passage, with a bridge over it. If this be made a navigable passage even for small vessels, some of them, such as the large keels from Thorn, &c. that cannot strike their masts, will render it proper that the bridges at Hazel and Myton Gates, should also be draw or moveable bridges, and we would recommend that the sluice at Hazel Gates, if made a navigable sluice or lock, should be constructed with double pairs of gates, pointed both to landwards and seawards; and we look upon it that a navigable sluice at Hazel Gates would be found very convenient for the following reasons:

When a considerable trade comes to be established upon the bason, we apprehend it will be found very troublesome to open the great lock for the passage of keels, lighters, and small vessels, as well as reduce the water of the bason in neap tides. This defect may in some measure be supplied by constructing a proper lock for such vessels to pass in and out at the Hazel Gate, which if laid one foot deeper than low water at the Humber, will afford a sufficient passage for the scower water, if made eighteen feet wide, but may be made as much wider as shall be thought necessary for the convenience of trade.

Now, as there will be but about five feet of descent of the surface of the water from the entry of the dock at the river Hull, to its passage out into the Humber opposite Hazel Gate, we look upon it that its velocity through the dock will of itself be too feeble to drive out the silt, it will therefore require to be aided by setting in a large number of men with col-rakes and other instruments to raise the mud and silt, as many tides, once or more in a year, as shall be found sufficient for the purpose of getting rid of the intermediate accumulation; beginning in the middle, and going as near the sides as shall be judged convenient to the security of the walls, for the middle being cleared to a sufficient extent, the grounding of vessels near the sides will continually be pressing down the mud from the sides towards the middle.

It is to be noted, that nothing but the present dock bason will require the aid of men to raise the mud; the external passage from the lock to the river Hull, as also from the proposed sluice at Beverly Gates to the Humber, may be kept clean by scowers from the great bason.

We must conclude with remarking, that, with regard to the keeping the great bason clear of mud, there is doubtless a possibility of doing this by machines worked by men and horses, properly contrived for the purpose; and though doubtless this labour will be very great, and at the same time an almost continual incumbrance to the bason, yet as on the other hand the charge will be very great for the additional works above proposed, it might be wished to bring the matter to a computation; but as it would take up a considerable length of time to enter into a detail of this business, which would be necessary for the purpose of an estimate, we must beg leave to postpone the consideration of this matter to some future opportunity; and indeed till the trial that we have already mentioned to be made of the dock shall shew for a certainty what works it will be most needful for the company to take in hand.

Hull, 17th August 1778.

J. SMEATON.
JOHN WOOLER

1022 words.