|
IN 1851, having obtained the
appointment of Engineer-in-Chief at Birkenhead, Mr. Abernethy removed from
Aberdeen to reside at 55, Hamilton Square, which he made his head-quarters
for some two years. His appointment was chiefly due to the influence of the
late Mr. John Laird, M.P., who afterwards became one of his most intimate
friends, and to the late Sir Joseph Bailey, Bart., Chairman of the Dock
Company, but both at that time, 1851, knew him only by repute as a hydraulic
engineer. For four years he acted as engineer to the Birkenhead Dock
Trustees, and during that period designed and constructed an extensive range
of Graving Docks and River Wall, near Woodside Ferry, in addition to the
well-known shipbuilding yard of Messrs. Laird. In describing the latter
work, the Liverpool Albion, of October 21st, 1857, says—
“While inspecting the
ship-building yards and works of Messrs. Laird, the First Lord of the
Admiralty, Sir Charles Wood, appeared to be much struck with the
completeness of the arrangements in every department and with the great
engineering skill which had brought the Graving Docks and the numerous
appliances to such perfection. In justice to Mr. Abernethy it should be
stated that he is entitled to the chief credit, his plans in every
particular having been closely and faithfully carried out, and at a
marvellously moderate cost.”
In 1855, however, the
Liverpool Corporation purchased the Birkenhead Company’s property, and Mr.
John B. Hartley was appointed engineer in his place. Later, in 1858, the
property was again transferred to the Liverpool Dock Trustees, under the
newly accorded title of the Mersey Docks and Harbour Board. Before this
purchase of the Birkenhead Company’s property by the Liverpool Corporation,
the Birkenhead Dock Company had requested Mr. Abernethy to design a Dock on
the site of Wallasey Pool, and a rival scheme having been put forward some
years before by one of the most eminent engineers of the day, the late Mr.
James Rendel, he became involved as one of the principals in a memorable
conflict of engineering opinion which occupied the attenti >n of
Parliamentary Committees for a period of twelve years, and although interest
in the prolonged engineering controversy has long since abated much of the
evidence given is of permanent value as bearing upon the construction of
works in the estuary of such a river as the Mersey.
As tar back as 1844 Mr.
Rendel had brought forward his design for the construction of a Great Float
at Birkenhead, and had stated thai the first great object he had in view was
to give to the Port of Liverpool a Low Water Basin, into which vessels might
run as soon as they came up the river from the bar, previous to docking, so
as to take away the necessity for dropping anchor, or beating about a the
liver, to the inconvenience of and danger to one another. The proposed
extended accommodation for the Port of Liverpool on the Birkenhead side, was
different from any hitherto afforded, or that could be afforded, on the
opposite shore as the sills of all the docks at Liverpool were dry at low
water spring tides, and only for about two-and-a-half hours of every vide
was there available depth for the admission of vessels drawing 18 feet,
while at neaps a vessel drawing 16 feet, could not enter any of the docks
even at high water. By the proposed Low Water Basin, at Birkenhead, at low
water spring tides, vessels drawing 10 feet and at low water neap tides
vessels drawing 18 feet would be able to get into dock, while at high water,
at neap tides, vessels drawing 29 feet, and at high water of spring tides,
vessels drawing 36 feet, would be able to enter without delay.
By Mr. Rendel’s scheme, the
inner portion of Wallasey Pool was to be converted into a great reservoir,
from which sufficient back water might be obiained by retaining the water at
the height of the tide of the day by means of an embankment across the Pool,
called the Great Dam, in which were siiuate the tide gates through which
vessels would sail ;nto the Great Float above at high water; the smaller
gates being used for filling the Pool as the tide rose.
The Low Water Basin proposed
to be constructed at the Mersey end of Wallasey Pool was nothing more or
less than a long narrow creek, projecting at right angles from the river
Mersey, and surrounded on three sides by strong and lofty walls of masonry.
The advantage of this proposed basin was, as already stated, that it could
be freely used by steamers at the lowest period of low water, and
accordingly a floating landing stage was recessed along its southern wall.
But the difficulty which militated against the theory was that the silt with
which the water of the Mersey is so largely charged would begin to deposit
itself when within the still water enclosure, as it had done in the basins
on the Liverpool shore, and ultimately render the basin useless by filling
up that which had been excavated at so large a cost. To obviate this a
system of gigantic sluices were suggested, which by communicating with the
Great Float drew off thence sufficient of the superfluous water to scour the
basin, and all other works were made subservient to this object.
Such was the scheme put
forward in favour of treating Wallasey Pool as a Great Float and Low Water
Basin.
In November, 1850, however, a
scheme which found favour with some of the Trustees of the Birkenhead Docks
was brought forward by Mr. Abernethy, who had on three distinct occasions,
dating from 1847, as the Surveying Officer of the Admiralty under the
Preliminary Inquiries Act, inspected and reported upon the advisability of
providing dock works at Wallasey Pool. In December of that year he produced
a plan which was the forerunner of various others projected and recommended
in reports, but abandoned almost as soon as ushered into existence.
At length, in April, 1851, he
furnished a design which the Trustees thought fit to propose to the
Authorities for their sanction, and a letter dated the 26th of April, from
the Secretary of the Trustees, accompanied with plans a^d reports of Messrs.
G. Rennie, Captain Maughan, Duck Master of the London Docks, and Captain
Andrews, Harbour Master at Lowestoft, was forwarded to the Commissioners for
the Conservancy of the Mersey, namely, the First Lord of the Admiralty (Sir
F. Baring), the Chancellor of the Duchy of Lancaster, and the Chief
Commissioner of Woods. Their lordships took the subject into consideration
on the 3rd, 7th, 10th, 14th and 16th of May, and after hearing the
explanations of the authors of the two rival schemes, ordered the whole case
to be referred to Admiral Sir F. Beaufort and Robert Stephenson, Esq., M.P.,
if they would undertake the reference.
These gentlemen held a long
enquiry, and reported on October 17th, 1851, in favour of Mr. Rendel’s
scheme, which after further Parliamentary fights in 1852 and 1855 was
sanctioned in 1856, and the works of the Great Float were shortly afterwards
commenced and finished in 1864.
Passing over the years during
which the work was in progress, the Liverpool Daily Post of January 21st,
1864, contained the following paragraph :—“Yesterday was a day that will
have for the scientific world a peculiar interest. The great sluicing
operations at the Birkenhead Low Water Basin, in connection with the
Cheshire estate of the Mersey Docks and Harbour Board were commenced. The
reputation of a great man, now deceased, was at stake: and the question as
to whether Parliament had compelled the Dock Board to expend £'150,000 on a
worthless scheme was involved.” Some of the sluices were worked that day
without mishap, but the same paper in its issue of the 26th, had to convey
the following tale of disaster.—“ The experiments in connection with the
sluicing operations at the Great Low Water Basin at Birkenhead were resumed
yesterday evening, and we regret to say that a very serious accident
occurred. The works were very much damaged. ... At twenty minutes to five
the two sluices at the river end of the 240 feet lock were opened, and soon
gave evidence from the muddy state of the water that they were doing their
work effectually, viz: clearing away the accumulation of silt at the lock
entrance. A few minutes later Mr. Lyster, the dock engineer, ordered two or
three of the doughs at the head of the basin to be partially opened, and it
having been ascertained that all was in good order, and the machinery under
perfect control, the whole of the doughs were raised and a fierce tide swept
along the basin at the rate of about three miles an hour, carrying with it a
dense body of silt, if one might form a judgment on the subject, from the
colour of the water in the creek. Whilst this operation was proceeding, it
was announced that the two grandest sights in connection with the
experiments were the indraught of water through the flood gates in the Great
Floal into the subterranean chambers below where the spectators were
standing, and the regurgitation of the water, caused by its sadden stoppage
at the outfall of the sluices by the doughs or paddles being suddenly
closed. . . . These gates are opened and closed by hand power, and when
opened are recessed in the walls. It was never intended that they should be
secured by anything else than the strong chains by which they are opened and
closed, because it was anticipated that the entrances to the floodgate locks
being bell-shaped would so direct the water that there would be little, if
any, pressure upon the gates. From the commencement of these experiments,
however, Mr. Lyster, the dock engineer, somewhat doubting the efficacy of
the theory of the engineers who had devised the plans for this portion of
the dock works, caused powerful tackle to be placed around the outer head of
each gate, so that when opened each pair should be firmly held back in its
place. Mr. Lyster was at the southern floodgate lock explaining to Alderman
Woodruff and other gentlemen the reason for adopting this precaution, when a
loud grinding noise was heard, followed by a heavy crash. The southern gate
of the north floodgate lock was seen sliding off the coping of the lockpit,
and a fearful upheaval of water followed. About ioo ladies and gentlemen ran
for their lives, and the greatest consternation was caused by the event. In
a few seconds the other gate was lifted slowly forward, the first part to
yield apparently being the heel at the bottom of the gate, then the gate was
wrenched off the massive upper pivot on which it swung, rose about six feet
above the coping, and with a fearful crash fell into the lock. Both gates
were for a second or two tossed about, and then borne away out of sight by
the swift current—which we likened on Thursday last to a miniature Niagara
above the Falls—into the vast subterranean chambers beneath. . .
“On the 23rd of November the
water was pumped out of the north chamber, and an examination showed that
the masonry therein had sustained considerable damage. The side walls and
upper portions of the interior were uninjured, but a large quantity of the.
floor at the back of the sluices had been torn up, and the concrete and
piles laid bare in several places. No remains of the broken up masonry were
found in the chamber; all had been carried out into the basin except one
sand stone ashlar block, which being too large for the opening, had become
jammed 'n one of the central sluices.” These test operations clearly proved
that the sluicing was attended by a considerable amount of danger. It
threatened to destroy the foundations, and by forming a sub-communication
between the Great Float and the Low Water Basin, to point to the ultimate
destruction of the works. The rapid lowering of the water, too, in the Great
Float was highly objectionable, for the Low Water Basin had to be cleared of
vessels when the sluices were to be run, and delay arose on this account.
Upon the failure of these great works, which had occupied the attention of
Parliament for many sessions, a new era opened for Birkenhead, and in 1866
Mr, Hartley applied to Parliament for powers to abandon the works, though it
was not till after long negotiations with railway companies and other public
bodies that the authority of Parliament for the abandonment of the great
work was obtained.
The preamble of the Act of
1866, after reciting the section of the Act of 1858, authorizing the
construction of the Low Water Basin, proceeds :—
“And whereas the said works
have been completed and opened for public use, but the operation of the
sluices constructed in accordance with the provisions of the said Act has
been found to be dangerous to the stability of the works, and practically
unsuited to the proper and efficient working of the Great Float and Low
Water Basin for dock purposes, and it is therefore necessary that the use of
such basin for the purposes intended by the said Act should be abandoned,
and it is expedient in order to utilize as far as possible the large amount
of money expended upon the works, that the said Low Water Basin should be
converted into a Wet Dock, so as to be used in connection with the Great
Float, by the construction of a sea wall at the eastern end of such basin.”
Mr. Abernethy’s plan as to
the best method of utilising Wallesey Pool was with slight alterations
adopted. Instead of the water being reduced to and retained at as low a
level as possible, as had been planned by Mr. Rendel, it was henceforth to
be reduced as little and retained at as high a level as possible. The Great
Float was to be a dock, not a reservoir. Mr. Rendel, it is true, had after
1848 regarded the Great Float as a dock, but had designed the latter for
maaitaining the Great Low Water Basin. “The difference between one plan and
the other .simply amounted to this: whether the dock is to be designed for
maintaining the Great Low Water Basin or creek of the Mersey, or whether the
creek of the River Mersey is to be curtailed in its proportions and the dock
maintained.” Sluicing was, in the event of silting taking place, to be
superseded by a system of dredging, while as substitutes for the tide gates
as entrances to the Great Float there was to be a system of entrances by
which vessels could be locked up at all times into the Float.
Thus the Low Water Basin,
insisted on by Parliament, was still a prominent feature in the scheme,
although altered in form and considerably reduced in size. Its position on
the foreshore remained nearly the same as at first, and it still lay at
right angles to the river, but the southern fork was lopped off, and it now
tools the form of a single channel 1700 feet in length, 400 feet wide at the
western end, and 300 feet in width at the mouth. Its primary object, too,
was maintained: viz., to serve as an open deep water harbour into which
vessels might run and remain, or be “locked” at once into the Float. With
the completion of these works, the concluding advice of Mr. Abernethy in his
report to the Birkenhead Dock Trustees of May 19th, 1851, in criticism of
the Great Low Water Basin scheme was in effect carried out. “ The simple and
rational course,” said he, “ to be pursued under existing circumstances
appears to me to be to regard the dock as being what it really is—a dock,
and to provide a suitable entrance or entrances into it as early as
possible, and at the smallest possible cost, in order to develop the germ of
traffic already established there at the earliest possible period.” Among
the eminent engineers who appeared as witnesses before the Parliamentary
Committee for the Bill of 1856 were the late Mr. George Rennie, Sir John
Macneill, and Mr. Thomas Hawkesley, in support of the scheme brought forward
by Mr. Hartley, and which was in its main features the same as that
recommended in 1850 and 1851. In opposition Mr. Rendel very ably tendered
the engineering evidence as he had done in furtherance of his own scheme in
previous years, while in the list of the leading Counsel engaged appear the
names of Serjeants Bellasis, Wrangham and Merewether, and Messrs. Hope
Scott, Talbot and T. Webster, father of Sir R. E. Webster, Q.C., the present
Attorney-General. |
