Part 35 (1/2)
And lastly, I cannot allow it to be stated, apparently on authority, while I have the whole heavy responsibility of its success resting on my shoulders, that I am a mere pa.s.sive approver of the project of another, which in fact originated solely with me, and has been worked out by me at great cost of labour and thought devoted to it now for not less than three years....
The works had been commenced in the spring of the year 1854, and the progress of the s.h.i.+p towards completion was eagerly watched, both by scientific men and by the general public.
The newspapers and periodicals of the day frequently contained descriptions of the work, and statements of the antic.i.p.ated performances of the s.h.i.+p, often very much exaggerated. The writers seem to have been quite at a loss how to convey to their readers any idea of her size, and they generally attempted to do so by comparing her dimensions with those of some of the well-known streets and squares in London.[152]
In the beginning of the year 1855, the longitudinal and transverse bulkheads, which formed the main framework of the s.h.i.+p, were completed for nearly 400 feet of the centre portion, and the plating was being fixed in place.
As the general design was now settled, it was thought that the time had arrived when it would be desirable for Mr. Brunel to describe at some length the nature of the undertaking, and the manner in which it was being carried out.
_Report to the Directors of the Eastern Steam Navigation Company._
[This Report was published at the time and excited much attention.[153] The paragraphs which describe the arrangements proposed for launching the s.h.i.+p have been omitted, as they will more conveniently be inserted in the following chapter.]
February 5, 1855.
Although the simple description of the present state of the works of the s.h.i.+p and engines, and of what has been done during the last six months, may be summed up in a few words, I shall, in compliance with the request of the Directors, embody in this the substance of the several other reports which I have from time to time made to the Court of Directors during this half year, and take this opportunity of laying before the proprietors the fullest information upon our plans and proceedings. In doing this it may be difficult to avoid some appearance of repet.i.tion of statements previously made; but I have thought it better, even at the risk of this, to refer to the objects we have had in view, and explain fully the nature of the works we have undertaken, and the manner in which we are carrying them out.
The construction of the vessel is the portion of our work which, without being actually novel, involved in all its details the greatest amount of special consideration and contrivance.
The unusual dimensions, the general form and the mode of construction of all the parts involved by these dimensions, the necessity of studying each part in detail, so as to obtain, by judicious mode of construction alone, the greatest amount of strength with the minimum amount of material; all these circ.u.mstances, and particularly the last, have rendered necessary a very large, though unseen, amount of labour in the preliminary plans and stages of the work; and, although I had for nearly two years before the contracts were entered into, devoted a great deal of time and thought to the subject, yet of course until the exact size of the vessel, and the general plans of the Company, had been finally determined upon none of these matters could be entered into in detail. Much time has consequently been required to mature and prepare these plans; and as I have made it a rule from the first that no part of the work should be commenced until it had been specially considered and determined upon, and working drawings in full detail prepared, and, after due deliberation, formally settled and signed, the work did not make at the onset that display of progress which might have been made, if less regard had been paid to establis.h.i.+ng a good system which would prevent delays hereafter, and ensure a more perfect and satisfactory result. I am not prepared to say that the work is in that state of progress which will ensure its completion within the period fixed in the contract; but I am quite certain that if we had proceeded with less system we should have considerably delayed the final completion.
I shall now refer to a few of the princ.i.p.al peculiarities in the construction of the s.h.i.+p.
In the preparation of the detailed plans, I have carried out fully those principles which I originally described as leading features of the construction.
The whole of the vessel is divided transversely into ten separate perfectly water-tight compartments by bulkheads carried up to the upper-deck, and consequently far above the deepest water lines, even if the s.h.i.+p were water-logged, so far as such a s.h.i.+p could be; and these are not nominal divisions, but complete substantial bulkheads, water-tight, and of strength sufficient to bear the pressure of the water, should a compartment be even filled with water; so that if the s.h.i.+p were supposed to be cut in two, the separate portions would float; and no damage, however great, to the s.h.i.+p's bottom, in one or even two of these compartments would endanger the floating of the whole, or even damage the cargo in the rest of the s.h.i.+p, or above the main-decks of the compartment in question, and all damageable cargo would be stowed above that deck.
Besides these princ.i.p.al bulkheads there is in each compartment a second intermediate bulkhead, forming a coal bunker, and carried up to the main-deck, which can, on an emergency, also be closed.
There are no openings under the deep-water line through the princ.i.p.al bulkheads, except one continuous gallery or pipe near the water line, through which the steam pipes pa.s.s, and which will be so constructed as to remain closed, the opening being the exception, and the closing again being easy, and the height being such that, under the most improbable circ.u.mstances of damage to the s.h.i.+p, ample time would be afforded to close it leisurely, and to make it perfectly water-tight. I have also adopted the system, to be followed rigidly and without exception, of making no openings whatever--even by pipes and c.o.c.ks--through the s.h.i.+p's bottom, or through the inner skin below the load water line, and I attach much importance to this system.
In the majority of cases in which steamboats are compelled to put into port from failure of bilge-pumps and other really trifling defects, no such serious consequence would have resulted, but from the difficulty and almost impossibility of remedying at sea any defects in the numerous pipes and openings now carried through the s.h.i.+p's bottom, wherever convenient, and without much regard to the danger of doing so.
I have found no great difficulty in carrying out this system completely, and the advantages, both as regards safety and the facility of remedying defects without delaying the s.h.i.+p on her voyage, must be obvious.
Independently of the security attained by the perfect division of the s.h.i.+p into really water-tight compartments of a sufficient number, so that the entire filling of one or even two of them will not endanger the buoyancy of the whole, the chances of any such damage as can cause the filling of one of them are greatly diminished by the mode adopted in the construction of the s.h.i.+p's bottom. The whole of the vessel (except the extreme stem and stern, the whole buoyancy of which is comparatively unimportant from the fineness of the lines), up to a height considerably above the deepest water line, is formed with a double skin, with an intervening s.p.a.ce of about three feet. This arrangement resulted originally from the system of construction I adopted, in which the bulkheads, placed at intervals of twenty feet, form the main transverse frames or ribs of the s.h.i.+p, and in the intermediate s.p.a.ce the material is disposed longitudinally in webs connecting the two skins, giving to the whole much greater strength with the same amount of material; but one of the most important results has been the great increased security attained, as the outer skin may be torn or rent against a rock without causing the s.h.i.+p to leak.
The s.p.a.ce between these two skins is thus divided, by the longitudinal beams or webs and the princ.i.p.al bulkheads, into some fifty separate water-tight compartments, any one or more of which may be allowed to fill without materially affecting the immersion of the s.h.i.+p.
Besides the main transverse bulkheads, at about 60 feet intervals, there are two longitudinal bulkheads of iron running fore and aft, at about 40 feet in width, adding greatly to the strength of the whole, and forming, with the transverse bulkheads, being all carried up to the upper deck, fire-proof party walls, cutting up the whole into so many separate parts, that any danger from fire may be almost entirely prevented.
The transverse bulkheads being perfect, there being only one door--and that of iron--in each, at one of the upper decks, all currents of air or means of communicating fire may be completely cut off; and with an additional precaution, which I will refer to afterwards, besides the most ample means of supplying water, I believe that all possibility of danger from fire may be completely prevented.
All these principles of construction being kept in view, the details of construction--that is, the arrangement and due apportionment of the strength and sizes of all the plates, and the mode of fastening them--having been determined separately, the plates have been made at once of the required dimensions, and the work has proceeded systematically. This system is the most important, as securing not only good work, but affecting, to a much greater extent than might at first be supposed, the total weight of the s.h.i.+p; which, although the terms of the contract protect the Company against any excess of expenditure beyond a certain fixed sum, is yet of the greatest importance, as will be easily understood when I mention the fact that several merely trifling alterations in the modes of arranging the plates and other details have caused an economy of 20 to 50 tons each, and that the vessel may thus be made capable of carrying 200 to 300 tons more of coal, cargo, or provisions; or iron to the same amount may be usefully applied to strengthen other parts or effect useful additions.
The details of the engines have all been settled; and the princ.i.p.al parts, as already stated, are in an advanced state of completion.
In considering the plans of those engines, the largest that have yet been manufactured, I have endeavoured to ascertain what may be termed the weak points of the best engines. .h.i.therto constructed by the same or by other makers--those points in which experience has pointed out deficiencies--and to provide fully against similar defects in our case.
Before commencing the boilers, I have taken every means in my power of profiting by the experience of others, and have collected all the evidence and opinions as to the precise form and proportions which have been found most efficient; and particularly such as have been found best suited to the combustion of anthracite coal. A very great difference is found to exist in the useful and economical results of boilers, even of good manufacture. Some are noted for the power of producing rapidly abundance of steam, at the cost of great consumption of fuel; others have the opposite qualities, and some combine successfully both those qualities which are desirable.