Chapter XII: Steam Navigation--The ‘great Eastern’ Steam-Ship. the Launch (1)

A.D. 1857--1858. ÆTATIS 52.

REASONS FOR DETERMINATION THAT THE SHIP SHOULD BE LAUNCHED
BROADSIDE TO THE RIVER--AND THAT THE LAUNCH SHOULD BE
SLOW--EXTRACTS FROM MR. BRUNEL’S REPORT OF FEBRUARY 1855--REASONS
FOR THE ADOPTION OF IRON SLIDING-SURFACES--DESCRIPTION OF THE WAYS
AND CRADLES--AND OF THE MOTIVE POWER PROVIDED FOR LAUNCHING THE
SHIP--MEMORANDUM ON PROPOSED ARRANGEMENTS FOR THE LAUNCH (SEPTEMBER
26, 1857)--LETTER TO CAPTAIN HARRISON ON RIVER TACKLE (SEPTEMBER
30, 1857)--LETTER ON THE NATURE OF THE OPERATIONS (OCTOBER 23,
1857)--MEMORANDUM ON GENERAL ARRANGEMENTS AND INTENDED MODE OF
PROCEEDING (OCTOBER 30, 1857)--HISTORY OF THE LAUNCH, NOVEMBER 3,
1857-JANUARY 31, 1858--LETTER TO THE DIRECTORS, NOVEMBER 26,
1857--REPORT AND MEMORANDUM ON THE LAUNCHING OPERATIONS (DECEMBER
17, 1857)--FLOATING THE SHIP--_NOTE A_: EXPERIMENTS AND
OBSERVATIONS ON FRICTION.--_NOTE B_: LETTER TO W. FROUDE, ESQ.
(FEBRUARY 2, 1858).

The mode in which, the great ship was to be launched had necessarily to be determined before she was commenced. In May 1858, when the contract for her construction was entered into, the question was left open, and the contractor was either to launch her, or to build her in a dock ‘if it be found preferable.’ With Mr. Brunel’s full concurrence, Mr. Russell determined to build the ship on the river-bank, broadside to the river.

The reasons which led to this determination were fully described by Mr. Brunel in his report of February 5, 1855. This report has, with the exception of the parts relating to the launching operations, been printed above, p. 315. The passages there omitted are as follows:--

One of the first points to be decided was the mode of launching the
vessel, which of course would determine the position in which it
was to be built; and I wish to take this opportunity of explaining
my reason for adopting the plan I have decided upon, which, being
unusual, might be supposed to be unnecessary.

Vessels are generally built above the level of high water, and then
allowed to slide down an inclined plane into the water;
occasionally, as in the case of the ‘Great Britain,’ they are built
in a dry dock, into which the water is afterwards admitted, and
they are floated out.

Both plans were well considered in the present case; but the size
of the dock required, the difficulty of finding a proper site for
such a dock, the depth required for floating a ship with her
engines and boilers, which it was most desirable to introduce while
building the hull, and the depth of channel required to communicate
between such a dock and the deep water of the river, all combined
to render the dock plan a very expensive, and, considering the
nature of the soil in which it would have to be formed, a somewhat
hazardous proceeding. Launching seems to offer the fewest
difficulties and the greatest certainty; but the dimensions of the
vessel required some modifications of the usual modes of
proceeding.

Launching is generally effected by building the ship on an inclined
plane, which experience has determined should be at an inclination
of about 1 in 12, to 1 in 15, the keel of the ship being laid at
that angle, and the head consequently raised above the stern, say
one fifteenth of the whole length of the ship. In the present case
this would have involved raising the fore part of the keel, or the
fore-foot, about 40 feet in the air, and the forecastle would have
been nearly 100 feet from the ground; the whole vessel would have
been on an average 22 feet higher than if built on an even keel.

The inconvenience and cost of building at such a great height above
ground may be easily imagined; but another difficulty presented
itself which almost amounted to an impossibility, and which has
been sensibly felt with the larger vessels hitherto launched, and
will probably, ere long, prevent launching longitudinally vessels
of great length. The angle required for the inclined plane to
ensure the vessel moving by gravity being, say 1 in 14, or even if
diminished by improved construction in ways to 1 in 25, is such
that the end first immersed would become water-borne, or would
require a very great depth of water before the forepart of the ship
would even reach the water’s edge. Vessels of 450 or 500 feet in
length would be difficult to launch in the Thames unless kept as
light as possible; but our ship could not be so launched, the heel
of the sternpost being required to be, as I before said, about 40
feet below the level of the fore-foot. Some mitigation of the
difficulty might be obtained by an improved construction of the
ways; but the great length of ways to be carried out into the river
would, under any circumstances, be a serious difficulty.

These considerations led me to examine into the practicability of
launching or lowering the vessel sideways; and I found that such a
mode would be attended with every advantage, and, so far as I can
see, it involves no countervailing disadvantages. This plan has
been accordingly determined upon, and the vessel is building
parallel to the river, and in such a position as to admit of the
easy construction of an inclined plane at the proper angle down to
low-water mark.

In constructing the foundation of the floor on which the ship is
being built, provision is made at two points to ensure sufficient
strength to bear the whole weight of the ship when completed. At
these two points, when the launching has to be effected, two
cradles will be introduced, and the whole will probably be lowered
down gradually to low-water mark; whence, on the ensuing tide, the
vessel will be floated off. The operation may thus be performed as
slowly as may be found convenient; or, if upon further
consideration more rapid launching should be thought preferable, it
may be adopted.

I have entered at some length into an explanation of all the
reasons which led to the adoption of this plan; as I am anxious
that they should be known, and particularly that it should be well
understood by the proprietors and those interested in our success,
that I am not adopting any novelties; unless, so far as those
modifications of the more usual practices which experience points
out as necessary to meet the peculiarities of a particular case may
be deemed such.

I should add that the necessity, arising from the same causes, of
launching transversely has been felt with long vessels of another
description, namely, pontoons, or floating piers; one of 300 feet
in length, which I have built at Plymouth, was so launched, and
previously to this, one of 400 feet in length by Mr. Fowler on the
Humber.[158]

I hope to be able to arrange that the machinery, which is to be
provided by the contractor, for lowering the vessel down the ways
will be also fitted to form a ‘patent slip’ arrangement for hauling
the ship up for repairs; so that, if it should be found desirable
to do so, such apparatus may be purchased for that purpose, and
fitted up at the port which the ship will frequent. With the view
of facilitating such an operation, or the grounding of the ship on
a gridiron for examination at low water, a sufficient extent of the
floor of the ship is formed perfectly flat, and is so strengthened
as to allow the ship when loaded to be grounded without being
unduly strained.

After it was determined that the ship should be built on the river-bank instead of in a dock, and parallel to the river instead of at right angles to it, the next point for consideration was, whether the ship should be lowered gradually to low-water mark, or whether a free launch should be attempted.

In a free launch the ship is allowed by the action of the force of gravity to run down the ways at a considerable velocity. In the case of the ‘Great Eastern’ there were insurmountable objections to this plan. Some of them might have been overcome by mechanical appliances; but these would have introduced complication and additional elements of risk.

In accordance with the opinion which he had from the first entertained, Mr. Brunel determined to move the ship slowly down the ways.

* * * * *

Subsequently to his determination to launch slowly, Mr. Brunel decided to employ sliding-surfaces of iron instead of greased wood.

In ordinary launches the ways are thickly greased, so that there is between the ways and the cradles a thick stratum of grease, which renders the friction very small. The conditions, however, do not remain the same throughout the passage of a ship down the ways; for, when she has moved some distance, the cradle has been rubbing away and squeezing out the grease; and therefore the part of the cradle which supports the middle and bows of the ship meets with increasing resistance from friction. Another and more serious cause of the destruction of the lubrication arises from unevenness in the ways.

The result of the action of the friction between the wooden surfaces after the destruction of the grease is sometimes so great that they become mutually imbedded, the fibres of the wood being rolled up together to such an extent that it has been found difficult afterwards to separate the timbers. The increased friction due to the deterioration of the sliding-surfaces of grease does not often produce failure in ordinary ship launches, because the vessel, while still on the fresh grease, acquires a momentum sufficient to carry it over the lower part of the ways, notwithstanding the retardation resulting from increased friction.

It was from a legitimate fear of the development of a retarding force due to the destruction of the grease, that Mr. Brunel hesitated to employ wooden sliding-surfaces. The ground was far from solid; and the use of piles as a foundation for the ways would not have prevented the possibility of excessive local pressure being brought on parts of the surfaces. The heat produced by undue pressure at any point under the great area covered by the cradles would tend to spread and aggravate the evil; and, had any considerable portion of the sliding-surfaces become wood-bound, the difficulty would have been far less remediable than in the case of an ordinary launch, where the cradles and ways are throughout accessible. But in the case of the ‘Great Eastern’ the space between the ship and the ways, over a considerable portion of the area covered by the cradles, was very confined, and it would have been a most tedious, if not a hopeless, task to get at the injured part so as to repair it properly.

At the end of the year 1856, when the construction of the ways had to be commenced, Mr. Brunel acted upon his views as to the dangers attendant on the use of wooden sliding-surfaces, and adopted iron. By this step, although there might be some fresh difficulties to be encountered, the disastrous consequences were avoided which might have followed from employing wooden surfaces.

* * * * *

Under two places in the length of the ship the ground had been prepared for the reception of the launching ways. These ways or inclined planes were two in number, and reached to low-water mark. They were placed at such positions as best to carry the weight of the ship without straining her. The ways, as originally designed by Mr. Brunel, were each 80 feet wide; but, with the desire of spreading the weight of the ship over a still larger area, he decided to add 20 feet to each side of each way, thus increasing their breadth to 120 feet. The ship’s head pointed down the river; 180 feet of the bow projected beyond the forward way, 110 feet were unsupported between the two ways, and 150 feet of the stern projected beyond the after way. The distance from the starboard side, the side next to the river, down to low-water mark, was about 240 feet; and the actual length of the ways, including the portion under the ship, was about 330 feet.

At the same time that he decided to use iron as the sliding-surface, Mr. Brunel adopted means for ensuring, as far as possible, the even distribution of the weight upon the ways. With this object he did not attempt to make them unyielding, but allowed them to yield slightly, so that, like a cushion, they might adapt themselves to the under surface of all parts of the cradles with a sufficient upward pressure. The ways rested on the river-bank, and piles were used to prevent the earth under the edges of the ways from swelling out at the sides, and yielding more than the ground under the middle portion.

The ground having been prepared to the slope of 1 in 12, a layer of concrete of about two feet in thickness was laid over the area of the ways. On the concrete were placed timbers running at right angles to the ship. These timbers, which were imbedded in the concrete, were 1 foot square, with a space of 2 feet 6 inches between them. Across these timbers, and parallel to the ship, were placed other timbers, with intervals of 2 feet between them; and upon these again were laid rails 18 inches apart, parallel to the ways, and at right angles to the ship. The rails were of the ordinary kind used on the Great Western Railway.

Thus the ways consisted of a network of timber resting on a thin bed of concrete; and on the top of the timber network were placed the rails which formed the actual sliding-surface.

* * * * *

The under side of the cradles consisted of iron bars, which were laid parallel to the ship, and therefore across the rails of the ways. These bars were each 1 inch thick and 7 inches broad, with an interval of 11 inches between the bars. Upon these bars was fixed 6 inches of hard wood planking (see fig. 15, _a_), and on this again came the framing of the cradles. Tapered timbers (_b_) were driven in, so as to fill up the wedge-shaped space between the hard wood over the bars and the flat bottom of the ship. On the side next the river, between these timbers and the rounded part of the under side of the ship, were driven in separate wedge-shaped pieces (_c_), which were secured to the timbers below by long bolts, arranged so as to allow the removal of the wedge-pieces when required. The means of unbolting the wedge-pieces was an essential provision for floating off the ship, as they had to be removed before she could move sideways off the cradles. Resting on the lower timbers of the cradle were stout props (_d_), which pressed against the ship’s side higher up than the wedge-pieces, and took part of the weight, and spread it over the outer part of the cradle. There were similar props (_e_) on the landward side of the cradles.

_Scale of feet._]

There were 80 rails on each of the ways, and nearly 60 transverse bars under each cradle; so that there were 9,000 intersections of the bars and rails. As the ship and the cradles weighed 12,000 tons, each intersection carried on the average a weight of 1⅓ tons.

* * * * *

After the construction of the ways was settled, the amount of power required to move the ship down had to be determined.

The motive power was not simply the chains, tackle, presses, &c.; but there was also the action of gravity. One motive power, then, was not only available, but was inevitably present; and, as the ways were at an inclination of 1 in 12, the motive power of gravity upon the weight of 12,000 tons was 1,000 tons. The question to be decided was, whether the 1,000 tons of motive force was sufficient to overcome the friction; and, if not, then what additional force would be required to do so.

* * * * *

In January 1857, immediately upon the adoption of iron sliding-surfaces, an experiment was arranged on a considerable scale, in order to form some idea on this important point. Two rails were laid at an inclination of 1 in 12, and upon them an experimental cradle was placed, weighing some 8 tons, and representing a small portion of the actual cradle.

The effect of the friction of iron sliding-surfaces may be summed up very simply. It appeared that the motive power need not, at most, be more than would have been given by placing the ways at an inclination of 1 in 8, and that restraining power could not have been safely dispensed with if the ways had been placed at a greater inclination than 1 in 16; as it was observed that, contrary to received notions, the friction became less as the velocity increased, and that, in case any considerable velocity were attained, a great force would be required merely to overcome the motive power of gravity down the incline, independently of that required to destroy the velocity.[159]

The task of getting the ship from the place where she was built to her moorings in the river divided itself naturally into two parts--the moving of the ship down the ways, and the floating her from off her cradles.

This subdivision of the whole undertaking of the launch into two almost distinct operations is of great importance in considering the manner in which Mr. Brunel conducted them; especially when it is borne in mind that one, the moving down the ways, was capable of being, by careful precautions, rendered almost safe; whereas the other, the floating the ship off, was dependent on the successful issue of various minor operations, in the management of which the fallible human element had a greater share, and where small accidents, though, in their primary effects, productive only of delay, might cause irretrievable disaster.

* * * * *

In the operation of lowering the ship, there had to be provided both power to move her and power to check her motion. In floating, but one force was necessary, namely, that required to pull the ship off if she got jammed on the cradles.

* * * * *

With a desire to provide for the possibility of an extreme amount of resistance on the ways, Mr. Brunel designed a complete hydraulic apparatus, which would have been sufficiently powerful to move the ship down without interruption or delay. It is much to be regretted that he did not persist in carrying out his original intention.

In the operation of floating, chains and tackle were the best means of supplying the tractive force that might be required; and Mr. Brunel decided to have a very large amount of available power. If the weather were fine, and the tide at its calculated height, if no part of the cradles got disarranged, if the calculations as to the ship’s draught of water were correct--if everything went right, there would be no necessity for any great hauling power; a few tug-boats would suffice to take the ship to her moorings. But Mr. Brunel determined that in this critical operation of floating he would not trust to good fortune, when the absence of it might produce grave injury. The power which he thought it desirable to provide in chain purchases for the floating was very considerable, being equal to a pull of 500 tons.

As it seemed probable that the ship would not require much force to move her down the ways, it seemed also probable that the river tackle (as the chains and appliances for hauling the ship off were called) would be sufficient for both purposes. This being the case, it at the time appeared right, in the embarrassed state of the Company’s finances, to dispense with the more powerful and costly apparatus which Mr. Brunel had proposed for moving the ship down; there being no fatal consequences to be apprehended from a defect of power.

Influenced by these considerations, Mr. Brunel resolved to trust to the river tackle alone.

He referred to this decision in a letter to the Secretary of the Company written during the launch:--

November 26, 1857.

My original intention, the right one, was to fit up properly such
an hydraulic apparatus as should be fitted to move the ship the
whole length of the ways, and to depend upon the whole river tackle
only in the event of her moving very easily, and for getting her
off the ways at the end. From an unwise attempt to economise I
determined to dispense with the immediate costly apparatus for
pushing, and by sufficient power merely to move the ship at
starting or in the event of sticking,[160] and to depend upon the
same river tackle to keep her moving down the ways.

The experiments made with the trial cradle had shown the necessity of providing a certain amount of restraining force. As will be seen in the description of the launch, it was only used once, but it must not therefore be supposed that there was no necessity for providing it.[161]

The arrangement of the checking gear was the same at each of the ways. Attached to the land side of the cradle, by means of bolts, was a strong iron framework which held two large horizontal wheels or sheaves. At the upper end of the ways another sheave was fixed in a strong timber framing; and opposite the middle of the upper end of the ways was placed a large windlass or drum.

This drum was a cylinder, about 20 feet long and 6½ feet in diameter, of solid timbers, strongly bolted together, and secured at each end in a broad cast-iron disc, 12 feet in diameter.

To a point in the framing was attached one end of a 2⅝-inch chain cable; this chain was passed round one of the sheaves attached to the cradle, then round the sheave attached to the upper end of the ways, then round the second sheave attached to the cradle; and its end was coiled round the drum. Thus, as one end of the chain was secured, it was necessary, before the ship could move down the ways, that the drum should revolve, and slacken the end of the chain coiled round it.

Round the discs of the drum were wrought-iron straps; these, when tightened by levers, formed brakes by which the revolution of the drum could be retarded. Gearing was provided with a train of toothed wheels, so that the drum could be turned round by handles, and the chain wound on to it.

The following paragraph is from the commencement of a memorandum by Mr. Brunel on the launching arrangements, written about five weeks before the launch began:--

September 26, 1857.

It is expected that, with the present construction of the ways, the
friction and the tendency to descend by gravity will be about
balanced; so that when once in motion no very great amount of power
(at least, in proportion to the mass to be moved) will be required
to keep the vessel in motion, or to check it if disposed to move
too quick, or quicker at one end than at the other; still the
forces which may be required either to help it on or to check it,
though relatively small as compared with the mass to be operated
upon, will be very large as compared with forces usually obtained
by the ordinary means of rope or chain purchases, and at the first
start, or after any accidental or intentional stoppage, a still
larger power may be required.

The apparatus which Mr. Brunel prepared for performing the double duty of moving the ship down the ways and hauling her off the cradles was as follows:--At each end of the ship was a powerful chain tackle. One end of a chain cable was secured to a mooring in the river, and it was passed round a large sheave attached to the ship, then round a sheave fixed on a barge about 300 feet from the ship, and the end brought on shore, where it was hauled on by a chain tackle worked by a steam crab. The sheave attached to the ship at the bow was slung by chains about 80 feet from the stem. The sheave at the stern was fixed on the end of the screw shaft. These purchases were intended to be good for 80 and 100 tons respectively, and were to be able to follow up the ship quickly if she moved.

In addition to these purchases, Mr. Brunel desired to have ‘the means of bringing a considerable strain to bear in the event of the ship sticking at starting, or at any subsequent time, and particularly at the last;’ and he considered that ‘nothing under 250 or 300 tons would be of any use for the purpose.’ This power he desired to apply to the centre of the ship between the two cradles by means of double crabs and treble purchase blocks on four barges.

One of the double crabs was mounted on each of the four centre barges, and was placed on a platform, elevated so that the blocks of the chain tackle could pass underneath it. This tackle was made fast to a chain attached to the ship; and the mooring chain extending across the river was hauled on by the tackle.

Each of these four crabs and tackle was to be capable of working up to a strain of 80 tons. The strain which Mr. Brunel intended to be able to put on the ship by the river tackle, in the form of a good continuous pull, was in all 500 tons.

Two hydraulic presses were also provided, one at each of the cradles, to overcome adhesion in first moving the ship. Each of these presses should have been able to exert a strain of 300 tons. Therefore, including the force of gravitation, the power which Mr. Brunel hoped to have to start the ship was 2,100 tons, or more than one-sixth of the weight to be moved; and for a continuous steady pull to keep her moving, 1,500 tons, or one-eighth of the weight.

* * * * *

It was at one time thought possible that the launch might be effected in October. But it was found that it would be impossible to be ready before the spring-tides at the beginning of November; and even then, when the time came, there was considerable hurry, and important matters were, as will be seen, insufficiently attended to.

The cradles were put together and wedged up under the ship, and every effort was made at low water to extend the ways as far as possible; so that, by moving her further down the slope, a greater margin might be obtained, to allow for any falling off in the expected level of the tide, or for any miscalculation in the ship’s draught.

In the memorandum already referred to on the launching arrangements Mr. Brunel instructed Captain Harrison to superintend the moorings for the river tackle, and to satisfy himself of their sufficiency. A few days afterwards he wrote to Captain Harrison on the subject:--

September 30, 1857.

I fancy (I may be wrong) that you hardly estimate sufficiently
highly the forces that we may require to get the ship down if she
sticks at all, or to drag the cradle from under her, or to force
her off the cradle at the last. She _may_ move down pretty easily,
and the cradles _may_ possibly not stick; but if she does stick at
all, it is as likely to require a dead pull of 500 tons as not, and
we must not shut our eyes to the real exact amount of strain which
may and will come upon purchases and moorings, &c., if this force
is required and is exerted; but we must provide for it. The several
moorings must really be good for the 80 and 100 tons respectively
mentioned in the memorandum--and we must not rest satisfied with
the feeling that the moorings are stronger than any generally sold
or than common tackle will effect, but must apply purchases that
will produce the strain, and if necessary we must strain them to
it; and our moorings ought to be beyond a doubt.

We are going to move 11,000 tons, a far greater weight than ever
was moved before, and we must not hesitate at providing a clear
pull of 500 tons; but bear in mind that 500 tons clear pull is
something much beyond what one is accustomed to. The power usually
brought to bear with purchases, chain cables, &c., is never
measured, but is very small; and we must take care and not be
misled by comparison with them. 80 tons is a heavy pull, and
nothing under 2 or 2¼ chain will be safe....

These are great strains we have to deal with, but they must be had,
and therefore we must meet them boldly.

Frequent enquiries were now made relative to the time of launching; and the number of applications which poured in for admission to the yard led Mr. Brunel to write the following letter to the Directors of the Company, and it was published by them in the newspapers. In it he not only removed current misapprehensions as to the nature of the proposed operations, but he also took the opportunity of pointing out that there would be no risk to the ship in the mode of launching adopted, and that, although it might at first be unsuccessful, further power could be applied, and the ship safely launched.

October 23, 1857.

The difficulty of replying to the numerous enquiries made
respecting the period at which the ship will be launched seems to
render it desirable that some means should be taken of giving the
information generally, that it may be uncertain, up to the end of
next week, whether the ship will be launched on the 3rd proximo or
the 2nd of December, and also of correcting the erroneous
impressions which exist as to the nature of the operation, which
can only lead to the disappointment of those who are erroneously
anticipating a display, on an unusually large scale, of that which
is a beautiful spectacle with ships of ordinary dimensions.

As regards the period of the launch I have, for some time past,
calculated upon being ready by the first tides of next month, and
by the unwearied exertions of those on whose assistance I have
depended, with the advantage of unusually fine weather, the
principal works required are so far advanced that there seems every
prospect of success; but a change in the weather is threatening,
the time remaining is short, and comparatively small causes may
create such delay as to render it more prudent, if not unavoidable,
to postpone the operation until the following available tide,
namely, that of December 2. As no mere desire to launch on the day
supposed to have been fixed will induce me to hurry an operation of
such importance, or to omit the precaution of a careful and
deliberate examination of all the parts of the arrangements after
all the principal works of preparation shall have been completed,
should such postponement prove necessary or be adopted from
prudence, everything having been now prepared, the launch would be
on December 2.

As regards the nature of the operation, it has frequently been
stated, but it seems necessary to repeat it, that the ship will not
be ‘launched,’ in the ordinary sense of the term, but merely
lowered or drawn down to low-water mark, to be thence floated off
by a slow and laborious operation, requiring two and possibly three
tides, and very probably effected partly in the night, and at no
one time offering any particularly interesting spectacle, or even
the excitement of risk; as I am happy to feel that, even assuming
accidents to occur or miscalculations to have been made, rendering
the operation unsuccessful--the ship may stop halfway or not move
at all, more power or other remedies may have to be applied--but no
injury to the ship can result from any failure in the course of
proceeding in this mode of launching.

Throughout October an immense amount of work had to be done, and the multiplicity of matters to be attended to pressed heavily on Mr. Brunel and his assistants.

With the check tackle he had reason to be content. The chains, which were the ship’s cables, had been very carefully made; and, in addition to the usual tests, pieces had been taken at hazard, and were found to bear a good breaking-strain.

The river tackle was not so satisfactory. In operations that have to be conducted afloat unexpected delays arise, and all the work may be suspended by bad weather, and it is moreover frequently dependent on tides. In the present case the work to be done was not easy. Heavy chain cables had to be laid out, and moorings picked up and connected to the tackles; one work having often to wait for the completion of another.

Mr. Brunel had determined that each purchase should be tested by being strained to the utmost stress for which it was intended; but, owing to the delays which had occurred in preparing the river tackle, this was not done.

* * * * *

A few days before the launch Mr. Brunel addressed the following memorandum to all who were to take part in the operation:--

_General Arrangements and intended Mode of Proceeding._

October 30, 1857.

It is desirable that all engaged in directing any part of the work
should understand the general course of proceeding which it is
intended to pursue, so far as may be found practicable;
circumstances may modify these pre-arranged plans, and may compel a
total departure from them, but every endeavour will be made to
adhere to them.

GENERAL COURSE OF PROCEEDING.

[Sidenote: To start about noon of Tuesday.]

I propose to commence operations about two hours before high water,
or about noon, and to endeavour to get the ship down as quickly as
I can into the water, and down to within about 36 feet of the
bottom of the ways.

My object in starting at this particular time of tide would be to
get the ship into the water, and waterborne to some extent as soon
as I could.

[Sidenote: Stop short of end of ways.]

I propose to stop short of the end, in order to avoid the necessity
of having to knock away all the shores, and clear the cradle at the
evening tide, when it would be dark, and to float on the morning
tide, when it would be also dark.

I should propose then to stop about 36 feet short of the end.[162]

[Sidenote: _Evening._ Clear away shores of the 20-feet cradles.]

At low water, although dark, I shall endeavour to knock away the
shores of the 20-feet cradles, or as many of them as possible, and
clear all from these cradles except the unbolting of the
filling-pieces.

[Sidenote: Under favourable circumstances clear away also _all_ the
shores on the port side.]

If the operations have proceeded easily, and the ways not sunk
much, I shall also knock away all the long shores on the inshore or
port side of the ship, so as to leave less to do on the following
day.

[Sidenote: Prepare for a further pull at the night’s high water.]

I shall then prepare at leisure to place the barges to get one pull
of 36 feet, or as much more as I can (as I shall not hesitate to
pull the cradles 20 feet off the ways) after high water of that
night.

[Sidenote: Last move at 4 A.M.]

Soon after the high water of that night, and when the water has
fallen sufficiently to prevent any risk of floating, but while the
ship is still waterborne, probably about 4 or half-past 4 A.M., I
shall make the last pull; and although it will be in the dark, yet
having only one pull to make, and plenty of time to prepare, and no
expedition required in the operation, I think it may be easily
done.

[Sidenote: Float on high water, Wednesday afternoon.]

The ship will then be left till low water, when we shall clear away
everything we can from the cradles, and get all ready for floating
at high water on the afternoon of Wednesday.

Provided the mechanical arrangements should prove efficient, the
success of the operation will depend entirely upon the perfect
regularity and absence of all haste or confusion in each stage of
the proceeding and in every department, and to attain this nothing
is more essential than _perfect silence_. I would earnestly
request, therefore, that the most positive orders be given to the
men not to speak a word, and that every endeavour should be made to
prevent a sound being heard, except the simple orders quietly and
deliberately given by those few who will direct.

In a memorandum of ‘Particular Instructions,’ dated the next day, October 31, there is the following passage:--

_Starting_.--A strain being brought upon all the purchases, and the
holding-back purchase being slack, if the ship does not move, the
two presses will then be worked; if she does not then move, or if,
when moved, she stops and each time requires the presses, the
attempt will be postponed, and more moving power applied for the
next time.

If, after being started by the presses, the river purchases are
found sufficient to move her, the operations will proceed.

In another part of these ‘Instructions’ Mr. Brunel again shows that he was not, as has sometimes been supposed, under the impression that the friction would be so small that the only important thing to be thought of was to check the ship from rushing too fast.

On the contrary, he foresaw the possibility of her not moving at all, even with the presses, that is to say, with a force of 1,100 tons over and above the action of gravity. If after moving she stopped, and then required the presses again to move her, this would show that the operation could not be properly carried out, and that the work must be suspended till more motive power was applied. If, again, the river tackle were sufficient to move her, then the work was to proceed, but the friction might even then be so great as to render it desirable to remove all retarding force. He says, in another passage in his ‘Instructions:’--

It is very likely that no checking whatever at the drums will be
found necessary, but that, on the contrary, it will be found
desirable to get rid of any resistance by overhauling the heavy
chains through the sheaves.

The best day on which to begin the launch was Tuesday, November 3, as it left two or three days of the high full moon spring-tides for the operations, should they be prolonged.

On Monday, November 2, the chief work remaining to be done was stowing kentledge or iron ballast on the cradles, to prevent the timbers floating when the ship should be moved off them. All the appliances were ready, and, except the river tackle, had been carefully examined. This, as has been already said, had not been tested.

It was now for Mr. Brunel to consider whether, in consequence of the river tackle not having been properly tested, he should postpone the launch till the following month.

It was most important for the Company that the ship should be afloat as soon as possible; and, as any defects which might exist in the river tackle would almost certainly declare themselves in the earlier part of the operation, when nothing worse than delay could be apprehended, Mr. Brunel, after a careful review of all the circumstances, determined to attempt the launch.

* * * * *

On the morning of November 3, the work of putting kentledge on to the cradles was completed by firelight, and the rails were rubbed over with a mixture of oil and black-lead. All the shores and props which supported the weight of the ship had been removed, and she was now resting entirely on the cradles.

Later on in the morning the brakes of the drums were tightened down, and the dogshores were removed from the ways in front of the cradles. Mr. Brunel, who had been engaged from an early hour in examining all the preparations, superintended this operation, and, having satisfied himself that all was clear and ready, returned to the upper part of the yard.

By this time it was crowded with people. The Directors, contrary to Mr. Brunel’s expressed wish, and without informing him of their intention, had issued a large number of tickets of admission. A few days before, Mr. Brunel had suggested that four policemen should be obtained, thinking that all they would have to do would be to contend with trespassers. The police force actually present were ignorant of the portions of the yard to be kept clear, and Mr. Brunel had himself to go and assist in ordering visitors away from the neighbourhood of the path prepared for the tackle of the stern hauling gear. The crowd soon became so great that it was almost impossible for the men in charge of the hauling-engine at the stern to see the signals given from the middle of the yard, or for those in the middle of the yard to see what was happening at the stern.

At about half-past 12 o’clock the fastenings of the ship at the bow and stern were let go, and Mr. Brunel ordered a small amount of slack to be given off from each drum. This was done by men turning the handles of the gearing which had been provided for winding the chain on to the drums. The order was then given to haul on the bow and stern tackle, and to pump at the hydraulic presses. It is doubtful what amount of strain was put on by the tackle and the presses, but it was probably not very great.

Presently a shout from the forward cradle announced that it was moving, and almost immediately the stern cradle also started with what appeared to be a considerable speed. The men who had been engaged in turning the handles of the gearing had remained leaning against them. As soon as the ship had moved a few inches, she took up all the slack chain. This made the drum revolve, and the handles of the gearing spun round very rapidly, striking the men, and throwing them into the air. The men who were at the brake-handle next to the gearing ran away. Mr. Brunel, who was standing near the drum when the accident happened, shouted to the men to hold on to the brakes, and ran to the spot. The men who had remained at the other brake-handle hauled it down with the tackle. A great restraining force was thereby brought upon the ship, and her progress ceased; the forward cradle having moved 3 feet, and the after cradle 4 feet 3 inches.

Five men were injured. On the death of one of them it was stated at the inquest, by the foreman of the drum, that, after the slack had been paid out, he had ordered the men to stand clear. Be this as it may, it cannot be denied that the handles should not have been used after the securing chains had been let go; and indeed Mr. Brunel said at the inquest, ‘I may blame myself, for I did not anticipate that the handles would have revolved so rapidly.’

After this accident, Mr. Brunel determined to wait till high water before recommencing the operations. In the meantime the gearing was removed from both drums.

A more important change was also made in the arrangements. When the ship moved, the men on the four middle barges became frightened, thinking she was about to overwhelm them; a rush was made, and one man, jumping into a small boat, shoved off, leaving the rest to their fate. A report was at once sent to Mr. Brunel that the men were untrustworthy, and that they would not remain; and that, as the barges would be of no use without the men, the chains had better be dropped and the barges removed. To this Mr. Brunel consented.

It would, however, have been sufficient to take the men off, leaving a tug-boat and a few steady men to keep the barges out of the way of the ship; they would then have been available if required. Mr. Brunel, a short time after he had given the order, ran round the bow with Captain Harrison to countermand it; but it was too late, as it had been already acted upon. As events turned out no harm was done, as the centre barges alone would not have been sufficient to go on with, after the rest of the tackle failed.

The result of these changes was that when the operations were recommenced, the only hauling gear was the bow and stern purchases; the hydraulic presses were also available to start the ship.

At a little after 2 o’clock the signal was given to haul on the bow and stern tackle, the presses being at the same time pumped up. The brakes of the drums were slackened, but kept all ready for tightening.

Not long after the strain had been brought on the tackle, several of the teeth of one of the wheels of the bow steam crab gave way, and the chief anchor at the stern began to drag, so that no efficient strain could be obtained. On this being reported, the operations were discontinued; and, as there was no possibility of getting things ready by the next day, the launching operations were postponed till December 2, the next full moon spring-tides.

* * * * *

As soon as this was known the visitors rushed in on the works, crowding about the cradles and ways; and Mr. Brunel had to postpone those investigations which he wished to make at once.[163] The whole yard was thrown into confusion by a struggling mob, and there was nothing to be done but to see that the ship was properly secured, and to wait till the following morning.[164]

* * * * *

The next day was devoted to an examination of what had gone wrong, and to the consideration of what should be altered before another attempt was made.

At the stern mooring the anchor was bedded into the ground on the further side of the river.

The difficulty with regard to the four centre barges was got over by placing the four crabs with their tackles in the yard, on the landward side of the ship. The four chains attached to the ship, which had before been hauled on directly from the barges, were now passed round sheaves on the barges, and brought back under the ship’s bottom to the tackles in the yard.

The chief alteration, however, was in the arrangement of the hydraulic presses. On November 3, there were, as has been said, two presses. Two additional presses were now provided; each of these consisted of two 7-inch cylinders, and was equivalent to a 10-inch press.

With the object of being able to employ the presses continuously during the descent of the ship, they were arranged to point down the ways at an inclination of 1 in 12. The four presses were placed one on either side of the check tackle at the two ways, and were supported by abutments of timber-work. These abutments each consisted of four rows of piles, one behind the other at intervals of about 8 feet. The press abutted against the row of piles nearest to the ship, which were connected by wooden struts to the piles behind them. Long balks of timber of various lengths were prepared to transmit the pressure to the cradles.[165]

The four presses might be considered equivalent, at their full power, to a force of 800 tons; this was so much in excess of the small force that had moved the ship on November 3, that, even making every allowance for the advantage of the fresh lubrication in the first instance, it seemed reasonable to suppose that with this force the ship could be moved down easily.

* * * * *

As the process of moving the ship with the presses would naturally be a slow one, Mr. Brunel determined to proceed with the operations as soon as everything was ready. On November 19 the work was commenced.[166] The bow tackle was hauled upon first, as the forward cradle was more than a foot behind the after one, and the men at the forward presses were set to work. After a short time the timber backing of the presses began to crack and ‘cry out’; and, without much stress on them, the abutments were forced back some 3 or 4 inches. The mooring chain of the bow tackle also gave way, although there was not any excessive strain on it. On examining the abutments, Mr. Brunel saw the cause of their failure, and ordered the strain to be taken off. The number of piles was sufficient, but the way in which the strain was communicated to them did not enable them to exert the proper amount of resisting power.

This defect was cured by tying the heads of the rearward piles with bolts to the foremost piles. The ship being secured, each press was tested to a full strain, and the adequacy of its abutments ascertained.

It was different, however, with the river tackle. The chain which had parted was an old river mooring-chain of great size. Much delay in replacing it was caused by dense fogs, which made it almost impossible to work on the river. Moreover, there seemed a fatality about every attempt to get a regular trial of any part of the tackle. When, at last, a trial took place, and a strain was put on, a mooring-chain gave way; then this had to be fished up from the bottom of the river, and pieced together, the accident being ascribed to a defective link in the chain. The trials were, therefore, so few that it was only proved by degrees that all the regular moorings were worthless; although they had large chains which ought to have been good for three times the strain put on them.

* * * * *

The stubbornness of the ship on November 19 gave Mr. Brunel great anxiety; not from any fear of being unable to apply sufficient power to move her, but because, on continued consideration of the subject, he apprehended that a serious difficulty might arise, if there should be a prolonged delay at a particular part of the ship’s progress.

It has been explained that Mr. Brunel, with a view of obtaining uniformity of bearing over the surface of the ways, had not attempted to support them rigidly on piles, but had rested them on the river-bank. As, however, the foundation of the building slip was comparatively rigid, he feared lest an unequal subsidence might cause injury to the ship, if she were stopped for any length of time before she had completely left the ground on which she was built. He thought that if the ways sank at this point they would assume a slightly convex form, and tend to force upwards the flat bottom of the ship. The main part of the ship’s bottom, between the longitudinal bulkheads, could bend in slightly under a heavy upward pressure; but this action could not take place at the transverse bulkheads, as they would not yield without injury. Mr. Brunel shrank from proceeding with the launch without having in reserve such an amplitude of power as would prevent the ship’s being stopped at this critical point. This consideration, together with the continued failure of the river tackle under such tests as were applied to it, led him to address the following communication to the Directors:--

November 26, 1857.