Royal Naval Biography/Brown, Samuel
SAMUEL BROWN, Esq.
[Commander.]
Obtained the rank of lieutenant in Oct. 1801; and served as third of the Phoenix frigate. Captain Thomas Baker, at the capture of la Didon, French national ship, of very superior force, Aug. 10th, 1805[1]. He was subsequently appointed to the Ulysses 44, Captain the Hon. Warwick Lake ; and on the 1st of Aug. 1811, promoted to the rank of commander[2].
This officer is the inventor and manufacturer of the twisted iron cables, respecting which the following observations appeared in the Philosophical Magazine for October, 1814:
“The great importance of safe cables for ships is known to every one in the slightest degree acquainted with maritime affairs. In circumstances of danger, the preservation of the cargo is often a matter of great magnitude; but that of the lives of the seamen is infinitely greater. Like almost every thing connected with navigation, the means resorted to have, till lately, been confined to improvements in the manufacture of cordage, and some of these have been great; but, either from prejudice or wont of consideration, a change of the material for one of greater strength, and less liable to be ruptured by strain, or worn away by friction, seems never to have been even thought of.
“The first, we believe, who made any attempt to introduce a stronger and better material for anchor cables and moorings, was Captain Samuel Brown, of the royal navy. He had the merit of at once adopting the best that could possibly be thought of, both in point of strength and oeconomy. We mean good tough wrought iron; and had he not fallen into an error in principle in the construction, his invention, as applicable to naval purposes, would have almost defied the possibility of any further improvement.
“This gentleman was so confident of the correctness of his ideas respecting the superior strength, and consequent safety to be derived from iron chains in place of ropes, that he equipped a vessel of 400 tons, the Penelope, with iron rigging, stays, cables, &c. in which he proceeded on a voyage to Martinique and Guadaloupe, and in four months returned to London in perfect order, after experiencing every severity necessary to demonstrate the efficacy of iron in place of hemp. But the introduction of iron ground tackle, we consider as of much greater importance than any thing connected with the rigging.
“Since that time, iron cables have been introduced, not only into different ships in the royal navy, but in the merchant service, and with great success; for though some did give way in severe weather, especially of those first made, it is but justice to state, that even in these cases the hempen cables of the surrounding ships had all given way hours before, and that in most instances the ships so furnished have kept their anchors, when other ships parted and drove. This important fact has been so clearly established by reports from the different captains who have tried iron cables, that we confidently anticipate the day as not very distant, when hemp will be entirely discarded from the ground tackle of every British ship.
“We have said, that but for an error in his principle of construction, Captain Brown’s substitution of chain for hemp cables would have been perfect. This error arose from a prejudice natural to persons who are not thorough mechanicians, or who overlook those mathematical dicta which ought to guide every mechanical arrangement – an idea that a certain portion of elasticity should be given to the chain. To attain this ideal advantage, a certain degree of twist, equal to nearly one-fourth of a revolution, was given to each link; so that, when a strain comes upon the chain, it never finds any part of any portion of it in that situation which would present the greatest resistance to a change of figure. In such a chain, every strain makes an effort to bring every link into that form which it ought to have had in its first construction: and in proportion as the strain effects this, 80 far the links have been weakened, by having the particles of which they are respectively composed placed in a new order, at the expence of the corpuscular attraction exerted by these particles individually for those to which they are most contiguous.
“That this derangement of particles, and consequent diminution of strength, does take place in twisted links, is plain from what happens in proving the chains composed of such links: ‘a cable for a ship of 400 tons will stretch, during this operation, in a whole cable, nearly thirty feet! and will recover about ten[3], when the strain is taken off.’ What a derangement is here! When we look at this, and contemplate the injury hereby inflicted on the materials, we confess that we are not surprised that some of these chains have given way. That any of them should stand after sustaining such an injury, furnishes, perhaps, the strongest evidence that could be adduced, of the superiority of iron over hemp for the purposes of a cable.
“It is the more surprising that Captain Brown should have fallen into this mistake respecting elasticity, having himself detected and exposed its fallacy as to hemp: ‘There cannot, says he, ever be any certain advantage deduced from the portion of elasticity which cordage is known to possess; for the force which caused its extension may be extended for a considerable time after the cable has been stretched to its utmost limits:’ – of course, under a further strain it must break. He might have added, that every lengthening of a rope by strain is accompanied with the rupture of a certain number of its fibres: every repetition of the force ruptures more of them, and thus in time it becomes unserviceable. There is no stretching without this partial rupturing; and it is equally true, that no change in the relative position of the particles of matter in the link of a chain can be induced without a proportionate rupturing, injurious to its strength, taking place, though not perceptible to the eye.
“Were it even true that the giving of a hempen cable was in its favour, the iron cable, from its superior gravity and the consequent weight of its curve, (an advantage justly appreciated by Captain Brown,) possesses more capability of giving (i.e. of lengthening the distance between the points of resistance) by the first effect of every strain, namely, an effort to straighten the chain, than any cable can by stretching. The elasticity, therefore, which Captain Brown gives to his chain, presents no one benefit to compensate in the slightest degree for the injury done to the iron, by giving it a form unfavourable to the resistance of violence
“The defect, and it is a most serious one, which attaches to the construction of Captain Brown’s chain, has been most happily obviated in another mode of construction, for which the inventor, Mr. Thomas Brunton, of the Commercial Road, has likewise obtained a patent. In Mr. Brunton’s chain cable, that arrangement which can most effectually resist every solicitation to change the form of any of the links – or, in other words, that form of link which shall present the substance of the iron in the best possible position for bringing the whole mass into equal action when assailed by an external force – has been most successfully adopted. * * * * * *
“The public, we think, have been laid under great obligations both to Captain Brown and Mr. Brunton – to the former, for introducing the iron cable, and combating the prejudices of the public in favour of hemp – to the latter, for perfecting the cable chain. It is impossible to anticipate the advantages which will accrue from the general adoption of iron cables. Many, many lives will be saved by this invention; not to speak of the saving of property, which, though of great importance in a national point of view, is but of secondary consideration. Such is our opinion of the safety to be derived from the use of iron in place of hemp, that we have no doubt whatever, that, were ships generally furnished with a good scope of chain, of proper weight, and of the best construction, net one instance out a hundred that now occur, of ships being lost on a lee shore, would take place. In rocky anchorage, hemp is cut to pieces in a short time in rough weather; but chain receives no other injury than that of a little rubbing or polishing, and the weight of the bight of the latter gives amazing ease to the tossing vessel – giving way to the swelling wave that elevates the ship, and then acting by its gravity to keep her as stationary as circumstances will permit.”
In July, 1817, Commander Brown obtained a patent for the manufacture of iron bridges of suspension, which are composed of straight wrought-iron bolts or bars, united at their ends by side-plates, with bolts passing through them, so that each line becomes, in effect, an entire bar, which extends over its respective piers, and is secured in the rock or ground. A bridge of this description was erected by Commander Brown, in 1813, on his premises in the Isle of Dogs: it was originally intended for foot-passengers, and weighs only 38 cwt., but its strength is such, that carts and carriages pass safely over it. The span is 100 feet.
In July, 1820, Commander Brown’s suspension-bridge across the Tweed, near Tweed-hill, was opened, and its stability proved to the satisfaction of every spectator. The following description thereof is taken from the Monthly Magazine, Aug. 1st, 1822:
“The Union bridge across the river Tweed, at Norham Ford, is about five miles from Berwick. It was begun in Aug. 1819, and opened in July 1820, while a stone bridge would have been the work of about three years. The road-way is made of timber, on which iron cart-tracks are laid for the carriage wheels. It is 18 feet in width, and 361 feet in length. The main beams or joisting, measures fifteen inches in depth and seven inches in thickness. The timber cleading or planks are twelve inches in breadth and three inches in thickness. This great platform is suspended at the height of twenty-seven feet above the surface of the summer water of the river. It is also made to me about two feet in the centre, and is finished on each side with a cornice of fifteen inches in depth.
“The roadway is suspended from the catenarian or main chains by circular rods of iron, which measure one inch in diameter. These perpendicular rods are wedged into caps or pieces of cast-iron, called saddles, which are placed at the distance of five feet apart, and are made to rest upon the shackles or joints of the chains. The attachment of the lower ends of these rods to the beams of the platform which they pass through, is by their embracing a bar of iron which runs along the whole extent of the bridge under the beams of the roadway on each aide. These bars measure three inches in depth, and they are connected with the suspending rods by a spear or bolt, which, in a very simple manner, completes the connection of the roadway with the perpendicular suspending rods, and chains.
“The chains of this bridge are twelve in number, ranged in pairs; the one pair being placed over the other, between the points of suspension on each side of the bridge. These chains, and indeed the whole of the ironwork, is made of the best Welsh iron. The chains are worked into a circular form, and measure about two inches in diameter. The links, as they may be termed, consist of rods of fifteen feet in length, and have bolt-holes, which are strongly welded, and neatly finished at each end. These links or rods are connected together by strong shackles, and a bolt is passed through them, which is of an oval form, measuring 2¼ by 2½ inches. At each joint of the three tiers of the catenarian chains respectively, one of the saddle pieces of cast-iron is introduced. The first saddle-piece, with its suspending rod, for example, on either side of the bridge, may be conceived as resting on the upper pair of chains; the next saddle-piece in the longitudinal direction of the roadway, rests upon the middle pair of chains, and the third upon the lower pair, and so on alternately, throughout the whole extent of the bridge. By this means all the chains bear an equal strain, and the joints are arranged in so precise and orderly a manner, that a saddle-piece and perpendicular suspending-rod occurs at every five feet, so that the distance between each pair of suspending-rods forms a space of five feet. The spaces of five feet between the suspending rods are formed into meshes of six inches square, to the height of five feet on each side of the bridge, and answer the purposes of a parapet wall for the safety of passengers.
“Though the timber roadway is only about 361 feet in length, yet the chord-line of the main-chains measures no less than 482 feet between the points of suspension, with which they make an angle of about 12°, and in forming the catenarian curve-drop, at the rate of one perpendicular to about seven feet in the length of chain, the versed sine of the middle pair of chains being about twenty-six feet. The twelve main-chains, with their apparatus, weigh about five tons each, and the weight of the whole bridge, between the points of suspension, has been estimated at 100 tons.
“On the Scotch side of the river, the catenarian chains pass over a pillar of aisler masonry, which measures sixty feet in height, is about thirty-six feet in its medium width, and seventeen and a half feet in thickness. The sides of the lower ten feet of the walls of this pillar are square, but at this height the walls begin to slope at the rate of one perpendicular to twelve horizontal. The archway in the masonry of this pillar, which forms the immediate approach to the roadway, measures twelve feet in width, and seventeen feet in height. Each pair of main chains, being suspended horizontally, pass through corresponding apertures in the masonry, at the distance of about two feet above one another, and go over rollers connected with the building. The links of the main chains at these points are made as short as the strength or thickness of the iron will permit of their being welded, in order that they may pass over the rollers, without distorting or unduly straining the iron. After going through the masonry of the pillar, the chains are continued in a sloping direction to the ground. Here they are sunk to the depth of twenty-four feet, where they pass through great ballast-plates of cast-iron, into which they are stopped by a strong iron spear or bolt, of an oval form, measuring three inches by three and a half inches in thickness. The cast-iron ballast plates measure six feet in length, five feet in breadth, and five inches in thickness in the central parts; but towards the edge, they diminish in thickness to two and a half inches. The ends of the chain thus fixed, are loaded with mound-stones and earthy matters, to the level of the roadway of the bridge.
“On the south side of the Tweed, the pillar or tower of masonry forming the abutment or point of suspension, is built upon a bench or foundation, excavated in the face of a precipitous sandstone rock, and is only about twenty feet in height; but its other dimensions correspond with the upper part of the masonry on the Scotch side. The chains on the English side are made to rest upon plates of cast-iron, included in the masonry, instead of rollers, as on the opposite side. Here the ballast-plates are of the same dimensions as those already described; but, instead of being sunk into the ground, as on the Scotch side, their position is rather above the foundation of the pillar, where they are set nearly perpendicular, but are placed so as to correspond with the direction of the strain or weight of the bridge. For the greater security of the position of these ballast-plates on the English side, they are connected with a horizontal arch of masonry, which is dovetailed into the rock.
“The whole works of the Union-bridge, for masonry, carpentry, and smithery, were undertaken by Captain Brown for the sum of about £5000, whilst the execution of a bridge of stone must have cost at least four times that sum. The object of its projector, says Mr. Stevenson, (from whose paper we abridge this article,) was not the realization even of the cost of this bridge, but chiefly with a view to shew the application of chain-cables to his favourite object of bridge-building. The trustees for this bridge have, however, presented Captain Brown with 1000 guineas since the completion of the work, over and above his estimated price.”
In a succeeding number of the same periodical we find the following paragraph:–
“About two years since, he (Commander Brown) erected a pier on this principle in Leith roads; while at the same time a solid stone pier, on the old principle, was erected near the same spot. The situation is a rough one, and in the course of the past winter (1821–2) the stone pier was so much shaken by the heavy gales, as to render it necessary to take it down; while the suspension pier of Captain Brown remained as firm as at its first erection.”
Commander Brown’s iron pier of suspension at Newhaven enables passengers to step on the deck of the steam-vessel, at all times of the tide, even at the lowest ebb, without having recourse to a small boat to go through the surf. It extends seven hundred feet into the ocean, from high water mark, and is a curious and remarkable object[4].
That elegant structure, the chain-pier at Brighton, was also projected and executed by Commander Brown; its foundation consists of four clumps of piles, two hundred and fifty-eight feet distant, driven nearly ten feet in the rock, and rising thirteen feet above high water. The first three clumps contain twenty piles each; the fourth, which is in the form of a T, contains one hundred and fifty perpendicular and diagonal piles, strongly braced, the cross part of which is paved with about two hundred tons of Purbeck stone, and beneath which galleries and flights of steps are constructed for the convenience of embarkation. The pier, which is one thousand one hundred and thirty-four feet long, and thirteen feet wide, with a neat cast-iron railing on each side, is supported by eight chains, each containing one hundred and seventeen links, ten feet long, six and a quarter in circumference, and weighing one hundred and twelve pounds, which are made fast in the cliff. From the cliff, the chains, four on each side, pass over a tower of cast-iron, one on each clump of piles, with a dip of eighteen feet, secured at the outer clump of piles, and from which are suspended three hundred and sixty-two rods, connected by an iron bar, on which the platform rests. The length of the esplanade, along which carriages pass, from the Steyne to the beginning of the pier, is one thousand two hundred and fifty feet.
Commander Brown married, Aug. 14th, 1822, Mary, daughter of Mr. John Home, Writer to the Signet, Edinburgh.
- ↑ See Vol. I. Part II. p. 830.
- ↑ Erratum in James’s Naval History, 2d edit. vol. IV. p. 248, line 8; for Samuel Brown read Joseph Oliver; and dele the remainder of the paragraph after Phoenix.
- ↑ Observations on the Patent Iron Cables invented by Captain Samuel Brown.
- ↑ See Hants Tel. 13th Aug. 1824.