Life of Richard Trevithick by F. Trevithick: Volume 1: Chapter 14
CHAPTER XIV. SHIPS OF WOOD AND IRON, AND IRON TANKS.
Trevithick and Dickinson's Specification of 1809.
The first of our said inventions or improvements is, a movable caisson or floating dock, made of wrought-iron plates riveted together, or fastened together by screws, or in any other secure manner for docking a ship or other vessel of considerable size while riding at her moorings in any suitable depth of water, by means of which the said ship may be supported as in a common dock, and the water pumped out so as to leave her keel dry in a few hours, without removing any of her stores, masts, or furniture. The said caisson or floating dock may be made of any convenient size or dimensions, but for the sake of precision in our description thereof, we shall mention certain dimensions fit to receive the largest first-rate, at the same time that we shall describe its form and structure. The internal figure of the said caisson or floating dock resembles that of a boat, and it may be made of wrought iron half an inch thick, and 220 feet long and 54 feet wide and 30 feet deep, with a flanch 6 feet wide extending horizontally outwards from the upper edge for the workmen to stand upon, and also to strengthen the caisson; the weight of such a caisson or floating dock is nearly 400 tons, and it is surrounded by an air-chamber or by air-chambers riveted water-tight to its external surface, which renders it so buoyant that it will draw only 9 feet water when the said air-chamber or air-chambers is or are empty; and the said air-chamber or air-chambers doth or do consist of wrought-iron plates riveted together, so as to form a semi- cylindrical hollow protuberance extending along the sides of the caisson horizontally, and of a figure which in any of the vertical sections thereof would present a semicircle, or outline nearly approaching to a semicircle, which is the best outline, although other outlines may be used; and the said air chamber or chambers contribute much to strengthen the caisson or dock, and support the principal shores from the ship, and the strength of the caisson may be still further augmented, if necessary, by edge bars within. The method of using the said caisson consists in taking it to the ship intended to be docked, and then the water is to be let into the caissons by an opening with a valve at the bottom, and the caisson is to be suffered to sink until the upper part is even with the surface of the water, the air chamber or chambers still keeping it buoyant; a small quantity of air is then to be discharged by opening a plug-hole, or a valve in the air chamber or chambers, until a quantity of water has been let in just sufficient to sink the caisson, which is then to be drawn under the ship's bottom. This being effected, the caisson (of which the residual gravity or preponderancy for sinking is very little) is to be raised to the surface of the water by ropes made fast to the caisson from each quarter of the ship. A pump placed within the caisson is then to be worked by manual labour, or any suitable power but we prefer for this purpose a steam-engine; one of 12-horse power, placed in a barge alongside the caisson, will empty it in three hours, and reduce the draught of a first-rate ship of war 8 feet, namely, from 26 feet to 18 feet, and then she may be carried up into shoal water if required, because the caisson will float with the draught of only 18 feet, while the ship she carries would have required 26 feet. As the ship is to be supported by props or shores as if in a dock, it is manifest that the external pressure of the water against the caisson will support the ship, and she will ride with all the stores on board, and masts standing, nearly as easy as when floating in the water. The advantages of this invention for inspecting the bottoms of ships in an extremely short time, and of docking them in places where that process would else have been impracticable, and of carrying them over bars and shoals, are too obvious to require any detail and if at any time the caisson should, from blowing weather or any other cause, be thought inconvenient, it may be cast off and suffered to sink to the bottom, and may be afterwards weighed with as little inconvenience as raising an anchor.
The second of our said inventions is, to build in the same manner as the floating dock, not small craft fit for canals and inland navigation, such having been long in use, but ships of war, East Indiamen, and other large decked vessels fit to navigate the ocean. In such ships we mean to make the decks as well as the sides of plates of wrought iron, riveted or joined by screws, not only to each other, but to the sides of the ship, and to support the decks with wrought-iron beams. Ships so constructed will possess the following advantages: they can be built at much less expense than wooden ships of equal dimensions, the material is not only a home production but inexhaustible; they will be much lighter and of greater capacity than a vessel of equal outside dimensions built of wood, and will consequently carry a larger cargo, while they will be also much stronger, safe against fire, tight in a gale of wind, require neither caulking nor copper sheathing, will defy all mischief from vermin, will never become unhealthy, and will be extremely durable; they will also have this advantage, in a battle there can be no splinters; a shot will carry away no more of the ship's side than the diameter of the ball, the hole may be instantly plugged, and the damage can be repaired at sea.
The third of our said inventions or improvements doth consist in making masts, bowsprits, yards, and booms, of wrought iron, out of plates riveted or screwed together in hollow or tubular forms. These masts being hollow tubes, the upper mast may be made to slide into the lower mast, as the inner tubes slide into the outer tube of a pocket telescope, or they may be struck exactly in the same manner as the wooden masts are at present, but we refer the former method, because by making the masts in a sufficient number of sliding pieces, the whole may be lowered by means of ropes and pulleys successively, till all be as low as the deck; an arrangement which affords to a ship in the case of a storm that advantage which is endeavoured to be obtained by cutting away masts made of wood. When the storm is over these masts may be raised again to their first situation and original utility with great ease. The bowsprits, when so wanted, may also be made in sliding pieces like the masts.
The fourth of our said inventions or improvements doth consist in the preparation of timber, by seasoning the same most effectually and in a very short time, and also by giving any required curvature during the seasoning process which shall afterwards continue perfect and invariable. For these purposes we place the said timber in iron chambers, disposed over a long horizontal flue which communicates between a fire-place or furnace and an upright or ascending chimney. The heated air and smoke which has passed through the fire, and is incapable of producing or maintaining any combustion in the wood, is admitted into the said chambers by regulated openings with dampers, and so thoroughly heats the said wood that the crude sap and pyrolygnic acid become evaporated and driven out, and may, if required, be collected for use in manufacturing processes; and by this treatment the wood becomes firm, hard, thoroughly dry, and well seasoned throughout its whole substance; and we do construct some of our said chambers with a curved side of such a figure as it may be required to give to the wood by bending; and we do, by means of screws, chains, or bearing pieces suitable to the figure intended to be produced, the form and application of which will be readily apprehended without any further instruction by any competent workmen, gradually compress and bend the said wood against the said curved side, during the time of the said seasoning heat, until the desired flexure is produced therein; and we do suffer the said wood, so bonded and seasoned, to remain, until cold, before we proceed to slacken or relax the actions of the said chains, screws, or bearing pieces; or otherwise, instead of making a curved side to the chamber, we do place or fix within the said chamber such curved pieces or pins or reaction pieces as may be suitable to the effect and figure required to be produced.
The fifth of our said inventions or improvements doth consist in a method of framing or putting together the hulls of ships or vessels. The said method consists in substituting, in the place of those pieces which are disposed between the outer and inner planking, and are called ribs or timbers, a double range of straight-grained pieces of half the substance, more or less, and as long as can be conveniently obtained, the same being bended to the proper figure by the means before described, and placed contiguous to each other between the outer and inner planking, with the joints, as far as possible, from being opposite each other, and the whole is secured by bolts or treenails as usual or otherwise. The said pieces may be disposed, not upright or at right angles to the keelson, but oblique, the inner range of these pieces being inclined forward on the one side and aft on the other side of the ship, as they rise from the keel, and the outer range of these pieces being inclined in the contrary direction to that of the inner range which they cover, by which arrangement the said ranges do act with regard to each other as diagonal spurs.
The sixth of our said inventions or improvements is, buoys made of cast-iron or of wrought-iron plates, screwed, brazed, soldered or riveted together, so as to form a hollow water-tight vessel of any shape or size that may be requisite. The advantage of these buoys is, that they cannot be injured by worms or imbibe water to make them lose any of their buoyancy, and consequently that they will at all times float higher and be better seen than buoys made of wood.
The seventh of our said inventions or improvements consists in a method of working an arm or lever attached to a steam-engine for the purpose of hoisting, pumping, rowing, or other similar works in naval affairs. To effect this the piston-rod of a steam engine is racked on one side, and drives a wheel, or a portion of a wheel, which has a horizontal axis, with an arm of considerable length attached thereto. The whole of the said apparatus, and the steam-engine for working the same, which we usually construct of about the weight of one ton, may be placed on wheels and conveyed to different parts of the ship; and the said arm, which may be varied in its length as well as in the inclination of its positions at the ends of its stroke, may be employed in hoisting a basket of coals successively out of the hold of a ship, and conveying the same by means of a rope of suspension, to the gangway; or goods may in like manner be hoisted and carried over the side, and, in cases where the hoist may prove too long for the circular motion of an arm to carry the goods sufficiently high or with due perpendicularity, we avail ourselves of a runner or rope, one end of which is made fast to the deck, and the other serves to seize the goods, while the bight or bend of the rope passes over a sheave or pulley at the extremity of the arm; and by this contrivance every seaman and mechanic will be aware that the hoist is rendered more direct, and the rise and fall nearly double; and further, we do apply the said arm to pumping ship and other like uses; and when the said arm is passed over the side it may be employed to work a paddle or rowing board of the usual construction, or a rowing trunk of the construction hereinafter described.
The eighth of our said inventions or improvements is, a rowing trunk, tube, or prismatic cavity. When the stroke of an oar or any similar implement is made against water, for the purpose of obtaining a reaction as nearly as may be similar to that of the resistance of an immovable body, part of the force is lost in producing a lateral motion in the water which escapes sideways, and the blade of the oar is far from being stationary. If the oar were to pass in a channel to which it is fitted, and the channel were of such dimensions as to present a great length of water before the oar, which could not otherwise move than by passing out of the channel, it is demonstrable that the said mass of water may be assumed of such a magnitude as to render the actual motion of the oar, by a given force and during a given time, less than any assignable quantity. We have availed ourselves of the foregoing considerations in our rowing trunk or tube. It consists of a tube of considerable length disposed horizontally in the water, and the stroke of rowing is made by means of a piece of the nature of a piston with valves, which is acted upon by the rowing arm and shuts the valves; but in the return of the stroke the valves open, and the said rowing trunk or tube being attached to the vessel, and its contents having too much inertia or resistance to receive much velocity from the piston, the vessel itself and the tube are carried along with much more power and effect that by common rowing. If the tube itself be made movable and attached to the rowing arm, and there be a stop within of the nature of a valve to shut against the stroke, and open with the return, the effect will be the same.
And lastly, the ninth of our said inventions or improvements consists in the adaptation of various particulars or additional parts made of iron, and conducing to the comfort and better subsistence of mariners and others, unto the boiler of the steam-engine that may be used for the forementioned purposes, that is to say, in the upper part of the said boiler we insert or fix a vessel, either single or divided into compartments, for boiling provisions in water, or cooking the same in steam; and in the part of the said boiler opposite the fire-place we insert or fix an oven surrounded by a space communicating with the chimney, so that the walls of the said oven shall be surrounded by heated air, and not in contact with the water; and further, we do adapt and apply to the boiler, or to the place of escape at the steam-cock, any of the apparatus heretofore in common use for condensing steam, in order to procure fresh water and we do apply and use the said last-mentioned addition to the boiler either separately or together as may be required.
In witness whereof, we, the said Richard Trevithick and Robert Dickinson, have hereunto set our hands and seals, twenty-eighth day of October, in the year of our Lord this one thousand eight hundred and nine.
A movable caisson or floating dock, made of wrought iron, of such capacity that the largest first-rate of that day, in fighting trim, might in a few hours be dry-docked, was an undertaking worthy of Trevithick.
The internal figure of the floating dock resembles that of a square-sided boat, made of wrought iron, half an inch thick, 220 feet long, 54 feet wide, and 30 feet deep, with a flange 6 feet wide, extending outwards from the upper edge, giving strength and a convenient platform for workmen to stand on. Large semicircular air-chambers, extending the whole length of the external sides, sufficed to float it when full of water, and gave strength to its sides. It would weigh about 400 tons, and when floated to the ship, valves allowed the dock portion to fill with water, which brought it down to about the top line of air-chambers: the bottom line of air-chambers was then filled until the dock was almost, betwixt sinking and floating, when by the use of chains it was hauled under the bottom of the floating vessel, and again raised as high as convenient, the vessel being inside; the water was then pumped out of the air-chambers, causing the top of the dock to rise above the water-line, after which the dock and vessel might be floated to shallower water. A steam-engine pumped the water out of the dock in three hours, raising its top about 8 feet above the floating water-line of the vessel. One end of the dock might be removed, thus allowing the vessel to be more easily floated into it.
Iron had before been used in constructing small craft for canals and inland navigation but not for ships of war, East Indiamen, or other large vessels fit to navigate the ocean. The reasons why iron should be used in preference to wood were seen clearly by Trevithick at first, as they are now known with sixty years of experience. His last reason of the many good ones was, perhaps, better understood by him then than it is now, and the day may still come when, instead of trying to keep out an enemy's shot, it will be allowed to go through with the least amount of damage, soft tough iron being used in the construction of fighting ships.
The invention of hollow wrought-iron masts and yards and the method of sliding one into another, like a pocket telescope, bringing all down to the deck level, has not been made practical during the sixty years since Trevithick recommended their use but his working model and detail description show that he believed it practicable.
The bending of timbers or planks for ship-building was to be performed in an iron chamber, having screws so placed that from the outside they might be worked to force the timber into the required curve. Hot air and coal smoke or gas, passing through the iron chamber, heated the wood, causing it to bend freely, and at the same time the sap to evaporate.
The doing away with the ribs or bent framing of ships, substituting a double layer of planks, placed diagonally, was a method of ship-building since known as "diagonal planking," and much used in the present day.
The sixth invention, that of wrought-iron buoys, has since come into general use, especially where, as Trevithick points out, buoyancy is required; and non- liability to injury from worms.
The seventh invention was an improvement on the nautical labourer of the year before, and might be called the "steam-arm." The engine and boiler complete, weighing a ton, was moved about the deck on wheels. That part of the piston-rod extending beyond the cylinder was a rack, and worked a toothed wheel, on the axis of which an iron arm or lever was fixed, which could be lengthened or shortened at pleasure, probably by sliding on the axle with tightening screws, making a sort of steam-crane. Suppose coal was being discharged in the ordinary baskets, the basket in the hold would be hooked on to the rope attached to the end of the steam-arm, then about horizontal; turning on the steam caused the toothed wheel to make a portion of a revolution, causing the arm to rise to the required height with the attached load. Should the height to be lifted be greater than the length of the arm, the bight of the whip-rope worked on a pulley in the end of the arm, so that the space moved through by the basket was twice as much as that moved through by the end of the arm. The toothed wheel on the same axis as the arm could also be changed in size, to suit the speed and power required. If the pumps had to be worked, the steam-arm was shortened to suit the stroke of the pump. If the windlass had to be worked for lifting the anchor, warping the vessel, or other purposes, the steam-arm was attached to the ratchet-lever on the windlass if the vessel had to be rowed, the steam-arm moved a paddle or rowing board of other construction.
The eighth invention was devoted to the method of making this rowing arm effective by preventing the slip or escape of the water from the face of the oar or float-board, by causing it to work like a piston in a pipe, the sides of the pipe preventing the slip or dispersion of the water, except in the direction most suitable for propelling the vessel. The pipe was attached to the side of the vessel below the water-line, the steam-arm moving the piston backwards and forwards; the piston was a kind of thin hoop with a large valve, like a pump-bucket, except that the valve was larger. When the piston moved toward the bow of the vessel, the large valve opened, allowing the piston to move on its forward stroke without resistance on the return or back stroke the valve in the piston closed then the solid piston being forced against the water in the pipe, caused the vessel to advance.
The real object and value of these two last inventions was to in his high-pressure portable engine so simple and manageable, that it should do almost any of the ship's work more effectually and at a much less cost than manual labour. Sixty years have sufficed to bring into partial use the present donkey-engines, which are the growing representatives of the original nautical labourer and steam-arm, but they have not yet performed one-half of what Trevithick intended they should do.
The ninth invention in this remarkable patent proves the constant tendency of Trevithick's genius to elevate man, by making matter subservient to his wants.
The boiler of the steam-arm is to "conduce to the comfort and better subsistence of mariners," by inserting in its top an iron vessel having one or more compartments in which provisions are boiled in water cooked in steam, or roasted in an oven, and the ship's company supplied with fresh water, hot, if required, from the steam given off by the salt water in the boiler.
A pamphlet was published, from which the following is extracted:—
Prospectus addressed to the consideration of His Majesty's Ministers, the Right Hon. the Lords of the Admiralty, and others. February 10th, 1809.
A BRIEF DESCRIPTION OF A WROUGHT-IRON MOVABLE CAISSON WITH A RUDDER, FOR DOCKING A SHIP WHILE RIDING AT HER MOORINGS.
This plan may be practised in all countries, and must be particularly advantageous where there are no dry docks or flowing of tide. Ships on many foreign stations when requiring to be docked are now obliged to be sent home, at a great expense of money and waste of time, others being sent to replace them. This may be avoided in future. Docks made in England may be sent out in pieces of five or six tons, with the necessary rivets and bolts, ready to be put together where they may be wanted. Such a dock would last for twenty years without repair. When worn out it may be broken up, and will sell for one-third of its original cost.
By constructing this caisson, adapted to local circumstances, ships of war and merchant ships, with all their stores and cargoes on board, can be carried to wharfs and storehouses up rivers, where the depth of water is not above one-half the ship's draught. For example, in the river Clyde the ships may be carried to Glasgow, instead of being obliged to unload at Port Glasgow, some miles lower down the river.
For a long period the only means employed to effect the bending of ships' planks was by exposing them to the heat of open fires, and in most parts of Europe this is still the practice. As hitherto conducted, it has been found to be a tedious, slovenly process, attended with a great expense of fuel, and unequal in its effects, some parts being only partially heated, while others are burnt. Another system was therefore resorted to, that of employing steam; and it must be allowed that this mode of bending has been found to answer, so far as the interest of the ship-builder is concerned. But ship-owners have suffered from its effects. It is possible by means of steam to give the required degree of flexibility to planks but steam of a degree of temperature high enough to destroy the vegetable sap cannot be confined in vessels of any reasonable strength, so treated has been found liable to a sudden decay. The durability of charred wood is confirmed, by being found in ruins free from decay after several hundred years.
The process now recommended is for heating both planks and timbers without steam, and in such a manner that they may be enveloped and equally surrounded on all sides with hot air and smoke, the coal-tar contained in the latter entering at the same time the pores of the wood, and acting as a feeder.
This process is so conducted as to prevent the wood front being burnt by it; all the air that reaches the timbers while under process being previously obliged to pass through the fire, and being by that means deprived of its oxygen, on that principle which maintains combustion.
The means employed to effect this are horizontal curvilinear flues, made of cast iron, adapted to the forms intended to be given to the wood, and furnished with a powerful but simple apparatus for applying the force requisite to bend the timbers into the required form. The heat can be so managed as to give at the same time the degree of charring requisite for the preservation of the timber against wet and dry rot.
Mrs. Trevithick spoke of a very pretty model at a scale of 1 inch to 8 feet, showing a first-rate ship, fully rigged, enclosed and floated in a dock of thin iron. It was sent to various places to make the plan known, and so was lost. A rudder was fixed to the dock for steering it, or it might be made in pieces, for a foreign country, and be there riveted together. During 1869 a floating dock, with a rudder, was towed to Bermuda and a steamer of 150 tons burthen was constructed in England, in separate pieces, or plates, to be sent to the White Nile, there to be riveted together.
The particular advantages of floating docks in countries not having the rising and falling of tides, arose from vessels in such situations having to be sent great distances in search of a dry dock.
Timber had been bent before the date of Trevithick's patent by exposing it to the heat of an open fire and to steam, the latter plan not destroying the sap, while the open fire was unmanageable in the uniform heating of the wood and in the difficulty of bending, both of which were given in the iron flue while the coal-tar contained in the smoke entered the pores of the wood, preserving it, and may be called the origin of the modern most approved method of creosoting wood by heated coal-tar.
In addition to the pamphlet a long statement of the advantages to flow from the patent was sent to "The Honourable the Commissioners of His Majesty's Navy."
We presume that our plan goes to obviate most of the evils complained of in Lord Melville's letter to Mr. Perceval.
By our process we give a greater degree of curvature than is required for ships' ribs to a piece of oak fourteen inches square and fourteen feet long.
Ships' ribs standing perpendicularly, as they now do, instead of holding by each other, require, absolutely require, to be held together by other and collateral means, namely, the planks and lining. Hence the longitudinal strength of a ship depends on these same planks and lining, and not at all on the ribs, whose disposition of themselves is to diverge and tumble to pieces, instead of leaning against and bracing each other, inch by inch, throughout the whole ship. Ships' ribs, as we purpose to place them, are to be split, and cross each other at all points, the one sett stretching diagonally towards the head, and the other towards the stern, each forming a diagonal stay, not at right angles, but forming the lozenge, diamond, or lattice, or close, if preferred, in which case the starting of a plank would be of no consequence. We have a model and drawings exemplifying these facts, which we desire to be permitted to exhibit.
The winner in the race of homeward-bound clipper tea-ships in 1869 was built on the diagonal principle. The experience therefore of sixty years has proved the correctness of Trevithick's plans.
In 1835 the writer was employed in putting engines on board the 'Diamond,' a new steamboat on the Thames, competing for the traffic below London Bridge, and specially built to excel the others. The outer planking was horizontal, backed by two thicknesses of diagonal planking; thus the whole thickness of the ship's side was but 3.5 inches, while a few iron knees tied the deck timbers to the ship's sides. The vessel was 145 feet long. Engines of 40-horse power have her a speed of 12.3 miles an hour, the greatest that had then been attained on the Thames.
Diagonal planking is now generally adopted in building life-boats; its usefulness is still extending, and the writer believes one of Her Majesty's favourite yachts was so constructed.
A memorandum in Trevithick's writing, without date, but evidently of about the period of the patent of 1809, gives his views of the detail of an iron sailing ship. The necessary calculations for the parts are jumbled up with the writing, as he proceeds with the description. Unfortunately the drawing he refers to has disappeared. The vessel was for a trader, carrying 300 tons, drawing 8 feet 3 inches. The length 70 feet, width 35 feet, depth of hold 10 feet. The keel 1 inch thick, the vessel's bottom 0.75 an inch thick, the sides an inch, the deck 0.375 of an inch, and the gunwale of an inch thick, the whole riveted together and strengthened with iron ribs in the hull. Three iron keels of 2 feet in depth and 2 feet apart have strength to the bottom and helped sailing qualities on the wind, while the great breadth enabled her to carry canvas without taking ballast. The weight of the vessel was 70 tons. The masts and yards were wrought-iron tubes, the shrouds and stays were iron chains each of the two masts was supplied with a square sail 50 feet high by 44 feet wide, its larger half being aft of the mast, as a lug sail. This aft or long end of the fore-yard was connected by a chain with the fore or short end of the yard on the main-mast, thus making the two sails balance one another to save labour in trimming them.
The yards were centred on the masts, and could be lowered down, while the sails fixed to the yards reefed themselves by rolling on the yards as a roller-blind. Studding sails had two-thirds the spread of the square sails, the yards for which slid into the hollow main- yards when not wanted. Such an iron vessel would not disgrace a builder of the present day. The peculiarity of reefing by rolling on the yard has since been tried with some success.
The pamphlet of 1809 thus speaks of the tubular iron mast, and establishes the date of the drawing and memorandum referred to:
Sliding tubular masts, made of iron, and so constructed that the upper ones slide into the lower in a manner somewhat like a pocket telescope.
A model of one for a first-rate ship, on a scale of one-eighth of an inch to a foot, is now ready for inspection.
This tubular mast, being half an inch thick, and the same height and diameter as a wood mast, will be lighter, considerably stronger, much more durable, and less liable to be injured by shot, and will cost less money.
This mast is made to strike nearly as low as the deck, to ease the ship in a heavy sea. Yards and bowsprits may also be made of wrought iron, and chain shrouds and chains will not cost half the expense of rope.
The description in Trevithick's handwriting gives such close detail, that a practical intention of constructing such a ship of iron, with tubular masts and yards, and self-reefing sails, was certainly made public, if not really acted on in 1809, as is evidenced by the workman-like grasp of the whole design, expressed in few words, interspersed with calculations establishing his practical deductions, resulting in the greater speed, carrying power, and economy of management of iron sailing ships as compared with wooden sailing ships.
The figures in his detail description are omitted, as the calculations were frequently broken off, when be mentally saw the approximate result.
A plan, side and cross section of a wrought-iron trading ship. Scale one-sixth of an inch to a foot.
Vessel to be 70 feet long, and 35 feet wide on the deck, and 10 feet deep in the hold, with three iron keels of 2 feet wide, with iron rods for strengthening the hull, the whole riveted together the same as a steam-engine boiler, the keel to be 1 inch thick, the bottom three-quarters thick, the sides half an inch thick, the deck three-eighths thick, and the gunwale one quarter of an inch thick. The mast and yards wrought-iron tubes, and the shrouds and stays iron chains.
Weight of the ship 70 tons, width of the sails 44 feet by 50 feet high, two-fifths before the mast, and three-fifths aft the mast.
Studding sails two-thirds of the width of the large sail. Deep waterline with 300 tons, 8 feet 3 inches, including the keels of 2 feet in depth.
The yards fall down near the deck, and the sails reef themselves without going aloft, and are always drawn tight in a chain frame, that holds the sails close to the wind, and prevents their flopping.
The yards being centred on the masts, and the after-end of the fore-yard chained to the fore-end of the after-yard, balances the sails, that they go about easily.
The iron keels act as ballast; and, together with the extreme width of beam, enable the required canvas to be carried without taking in additional ballast. This vessel would be lighter, sail faster, stow more cargo, be more durable, and worked with a less number of hands than a wood vessel.
The news of the day describes a race between the English yacht ‘Livonia' and the winning American yacht ‘Columbia,' a large centre board schooner, built in 1871, 98 feet long, 26 feet beam, 8.5 feet hold. Trevithick's iron trader of 1809 was 70 feet long, 35 feet beam, 10 feet hold, to which add the sliding keels, described in the following chapter and the two schooners, allowing for the different requirements of racer and trader, exhibit similar general principles, though the vessel of sixty years ago had spars and hull of iron.
From the time of his work on the Dredger in 1803 to his leaving London in 1810 his occupations caused him to be almost daily within sight of the ships and mercantile operations on the Thames — iron buoys, iron tanks, iron docks, iron steamboats, iron sailing vessels, iron fighting ships, designed, patented, and more or less brought into commercial use, were results of those seven years of labour.
Our small and imperfect knowledge of Richard Trevithick has caused him to be regarded merely as the inventor of the high-pressure steam-engine, while in truth that one machine, among his numerous useful discoveries, was but as a foot or hand to a perfect man; just as it took its place of relative usefulness in the improved sailing ship made of plates of iron, giving greater safety and comfort to the sailor, reducing his labour by the use of sliding keel, water ballast, and self-reefing sails the steam-engine giving auxiliary propelling power, discharging cargo, and weighing the anchor, while the steam-boiler gave facilities for cooking food, and the iron tanks a larger supply of more wholesome water.
Many men scheme, take patents, and are no more heard of. Trevithick's working models, made known by his written description, show on what a different basis his schemes were built. Every detail is practically described, as though it was a history of a thing of the past rather than of a thing to come.
After a lapse of sixty years the greater portion of those schemes have become valuable realities a paper of the day, on the great increase of iron steamships, states that "about £11,000,000, worth of shipping is now in course of building;" and this marked branch of national prosperity took its rise from the designs that we have traced in their original working form in 1809; the sliding tubular masts and yards remain to be made practicable.
- See patent, 1808, Propelling Vessels
- Pamphlet, 10tih February, 1809.
- 1 Pamphlet, February 10th, 1809.
- The Western Morning News, October 26th, 1871.