cution. Huddart was the constant coadjutor of civil engineers: he assisted the late Mr. Rennie in many of his surveys of harbours, and on those occasions had always the command of the vessel, even if he did not participate in the actual operations of the survey. Whether Huddart was viewed as a sailor, boldly striking out for himself a new track to his destination; as a shipbuilder, constructing a vessel in order to avoid the defects which he observed in the ordinary class of ships; as a hydrographer, displaying in his chart of the St. George's Channel those powers of observation and of reasoning which made him an astronomer; as a constructor of the equatorial instrument, which had been so justly commended; or as a mechanic, designing and constructing one of the most beautiful pieces of machinery on record, he appeared equally great.

The Institution was much indebted to Mr. Cotton for this memoir of Captain Huddart, whose name would be always venerated by every member of the profession of civil engineering.

Mr. Thornthwaite must in justice correct a misapprehension relative to the laying machine for cables; the idea of that machine originated with the Reverend Edmund Cartwright, who had projected more improvements in cotton machinery than any person, except Arkwright. The machine was materially modified by Captain Huddart, and to him must be given all the credit for the perfection of its proportions, and its careful construction, which had enabled a machine weighing twenty tons, and revolving rapidly upon one vertical spindle, to work a number of years without costing £5 for repairs. The register, which preceded the laying machine several years, was entirely Huddart's invention, and was the origin of his improvements in rope machinery.

February 8, 1842.

"Description of the Port of London, and of the Works at the London Docks." By Robert Richardson, Grad. Inst. C. E. In this communication the author examines the state of the Port of London, when the accommodation for landing and bonding foreign produce was almost entirely limited to a single spot, called the "Legal Quay," which was only about 1,400 feet in length, extending downwards from London Bridge, affording no greater facilities for commerce in the beginning of the nineteenth century than in the year 1660, when the quay was appointed. This state of things continued until the year 1773, when Mr. J. Sharp suggested the formation of floating docks. In the year 1800, the West India Docks were commenced; in the year following the

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London Docks were projected, and in the year 1805 the East India Docks were commenced. For all these undertakings Mr. Ralph Walker was appointed engineer, having Mr. William Jessop associated with him for the West India Docks. The paper enters fully into the bad state of the navigation of the river, owing to defective management and other causes; gives a table showing the progressive increase of tonnage and number of ships from the beginning to the close of the last century; mentions the various plans of Dodd, Spence, Revely, and others, for diverting the channel of the river for the formation of more extensive docks, near the Isle of Dogs; and then proceeds to detail minutely the origin and progress of the London Docks, giving the dimensions and mode of construction of the principal works connecting the Eastern Docks with the Thames, which were constructed under the superintendence of Mr. H. R. Palmer, to whom the author has been indebted for much of the information contained in the paper.

The communication is accompanied by fifteen drawings, showing the details of construction of the locks and gates, bridges, quays, embankments, &c.

February 8, 1842.

"Description of the Ponte della Madelena, over the River Serchio, near Lucca." By Bichard Townshend, Assoc. Inst. C. E.

The bridge described in this communication, is situated about half-way between the town and the baths of Lucca, in the Grand Duchy of Tuscany; it was built by Castracani, in the year 1317, on the site of one which had been constructed by order of the Countess Matilda, early in the twelfth century, and subsequently destroyed; it is believed that a Roman bridge formerly existed on the same spot.

The

The present bridge is of grey limestone of the country. The large arch of 126 feet 6 inches span, is of a semicircular form, and springs directly from the bed of the river, without any prepared foundation. smaller arches are of various spans, 46 feet 10 inches, 33 feet, 28 feet, and 7 feet 6 inches. The style of construction is somewhat similar to that of the Pont-y-prydd, over the Taff, in South Wales.

An engraving of the bridge accompanied the paper.

"Description of the Mill, Forge, and Furnaces of a Welsh Iron Work." By Thomas Girdwood Hardie, Assoc. Inst. C. E.

The author commences by describing the

general plan of an iron work, consisting of six blast furnaces, four double-fire refineries, and a forge and mill, capable of converting into bar-iron the produce of the six blast furnaces.

He then enters very fully into certain alterations of the interior shape of the blast furnaces introduced by him at the Blaenavon works, from which have resulted an economy of fuel, regularity of work, and an improved quality of iron. The principal alterations appear to be, making the interior diameter greater above that at the boshes, and establishing a proper ratio between the diameter of the boshes and that of the charging place, and proportioning both to the height of the furnace. The opinions are supported by calculations of the quantity of blast used in smelting given quantities of ore, and the effect which the form of the furnaces must have in directing the current of the blast through the materials, by which also the point of fusion would be necessarily effected, and the chemical combinations varied. The particulars are then given of the construction of the furnaces at Blaenavon, and the details of the blowing engines, blast mains, regulators, valves, &c., with calculations of the quantity of blast used in the various processes of the manufacture. The construction of the casting houses, with the mode of ventilating by the iron roof, is detailed. The general arrangement of the balance pits, coke yards, mine kilns, and bridge houses are shown, and the author proceeds to describe the forge and mill, which have thirty-five puddling furnaces, with hammers, shears, rolls, and heating furnaces in proportion. He then condemns the usual practice of leaving the coupling boxes loose upon the spindles, as liable to break the rolls, shafts, or machinery, and gives theoretical and practical reasonings for preferring fixed couplings.

The communication is illustrated by three drawings, showing the general distribution and the details of an iron work.

Mr. Lowe believed that there was an incorrectness in the statement of the iron after being freed from its oxygen by the heat of the furnace, taking up a dose of carbon from the coke, thus becoming a carburet of iron, which is a fusible compound, and as such, fell melted into the hearth. On the contrary, he thought that the iron was combined with carbon in the ore, and that there was not any necessity for the medium of the fuel to charge it with carbon.

In reply to "Why the ore required, or why the iron carried away, any of the carbon of the fuel?" Dr. Faraday stated, that the ore being essentially a carbonate of iron, the first action of heat, either in the mine kilns

or in the furnace, was to draw off the car. bonic acid and leave an oxyde of iron, and then the further action of the fuel (besides sustaining a high temperature) was to abs. tract the oxygen of the oxyde, and so to reduce the iron to the metallic state, after which a still further portion of the carbon of the fuel combined with the iron, bringing it into the state of easily fusible, or pig. iron.

As carbon may be communicated to the iron in two ways, distinct in their nature, either by contact with solid carbon, as in the process of cementation, (that by which steel is commonly converted,) or from the carbonated gases, either carburetted hydrogen, or carbonic acid, which occupy nearly every part of the air-way of the furnace, it would be desirable to distinguish, as far as may be in any furnace having a particular form or action, what proportion of the whole effect is due to the one mode of carbonization or the other.

Mr. Wallace stated that the ore was a carbonate of iron, or a protoxyde of iron and carbonic acid united, and not a carburet of iron, (or iron and carbon simply,) as was generally believed. In smelting, the car. bonic acid was driven off, the simple oxyde remaining; the oxygen of which, being carried off by the heat, left the pure iron, which, combining with the carbon of the coke, formed a fusible carburet of iron, or the pig-iron of commerce.

Mr. John Taylor observed that his brother, Mr. Philip Taylor, being sensible of the advantages to be expected from the use of anthracite in smelting iron, made a series of experiments several years ago, from which he derived the opinion that the carbon absorbed by the metal, and which is necessary to produce it in the shape of pig-iron, must be presented in a gaseous state to the mass in fusion; and as anthracite did not afford a sufficient supply of coal-gas during combustion to produce the proper effect, he proposed to adopt a very ingenious method, by which this gas would have been thrown into the furnace in such proportions as might be found necessary, mixed with the common air employed as the blast.

Circumstances interrupted the course of these experiments, or it is possible that the use of anthracite for this important application might have taken place at a much earlier period than it has happened to do.

February 15, 1842.

"Description of Chelson Meadow Sluice." By Theodore Budd, Grad. Inst. C. E.

The sluice which is described in this communication was erected from the designs of Mr. Rendel for the Chelson Marshes in

Devonshire, which, being very low, had previously suffered much from floods, but now are entirely relieved. The novelty in the construction consists in hanging each of the doors respectively by two hinged flat bars of iron, of 18 feet 6 inches, and 15 feet 3 inches in length, and thus, by placing the centre of motion so high above the centre of gravity of the doors, to give greater freedom of action than by the modes usually adopted in similar works.

The dimensions of all the parts, and the method of construction, are given in great detail, and are illustrated by a drawing.

Mr. Rendel explained that the sluicedoors which had been superseded by those described by Mr. Budd, were of the ordinary description, placed side by side. They were frequently hinge-bound and clogged up, which caused the land to be flooded sometimes for three months during the year; the hinges were attached in the usual manner to the frames, close at the head of the doors, and they required a pressure of at least 6 inches of water to act upon them either way. He considered the principal advantages of these doors to consist in the freedom of action

given by the length of the bar-hinges by which they were suspended, their giving the full extent of opening, and the pressure of 1 inch head of water sufficing either to open or close them.

Mr. Prior inquired whether there was any similarity between these sluice-doors and that erected by the President near Blackfriars Bridge, at the bottom of Fleet Ditch. That door was so well hung as to be even acted upon by the wind; and the slightest pressure of water sufficed to open or to close it.

The President explained that the principle was not the same; at the Fleet Ditch sluice double hinges were used, or rather hinges with a link between the part attached to the frame, and that which was screwed to the door-that form of hinge always acted freely, and allowed the doors to open with a slight pressure.

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a more matured and perfect state, than hydraulics. But although we can, perhaps, boast of as much in the way of performance in this line as most nations, it is but too certain that we must look elsewhere than to English books for nearly all the science belonging to it. Our Smeatons, Telfords, and Rennies, have at best but turned to good practical account, in the embankments, drainages, docks, &c., for which they are celebrated, the principles of construction which they found developed to their hands in the writings of the Italian, Dutch, and French engineers and philosophers, particularly Guglielmi, Frisi, Mariotte, Belidor, Bossut, and De Buat. Of our men of abstract science, the only names which occur to us as connected with contributions to hydraulics, worthy of mention, are, Robinson, Hutton, Leslie, and Young; and these contributions, besides being scanty, are all more of an elucidatory than original character. Of making a study of this branch of engineering knowledge, more than any other, to qualify a man for professional eminence in England, few, if any, of our engineers, have ever thought. In this, as in but too many other matters, it has been al ways too much the fashion, with us, to find the occasion for the knowledge first, and to let the knowledge come after, as it may. When the at-all in the story was asked, "Can you play on the fiddle ?" his answer was, 64 I don't know, but I'll try;" and so with our engineering aspi rants, the rule has been, first to get a dock or harbour to do, and afterwards to find out how it is to be done. And though now and then, some egregious blunder will occur, to furnish its instructive commentary on this inversion of the proper order of things, it must be confessed that, in general, its worst effects are to be traced in that excess of expenditure over estimate, for which English engineers have become almost quite as

Hydraulics, in its common acceptation, includes every thing mechanical having any relation to water, from the huge breakwater erected to oppose the inroads of the ocean, down to the garden watering pan; but strictly speaking, it relates only to the motion of water in pipes, being compounded from vcwp, water, and avλog, a pipe. Would not Hydratics be a better term, and square well with Pneumatics? Hydraulics might then be restricted to its original signification-reduced to its proper rank, which is that of a General of Division, while Hydratics would become, by right of suffrage, the true Generalissimo.

famous as for the excellence of their constructions.

We are accustomed to hear all sorts of reasons assigned for such excesses-unfavourable seasons, "accidents by flood and field," extra works, &c.-but the reason which is more potent than allthe trying to play on the fiddle before learning is but rarely glanced at, or if occasionally urged by some obstinate malcontent, only to be drowned by a flourish of trumpets from the successful engineer and his friends. It would not, perhaps, be straying far from the truth, were the item which now stands as

contingencies" in most estimates for public works, expunged, and the following inserted in its place-" To education of the engineer," 100,000l. or 1,000,000l. as the case may be.

It is but one of the natural results, or rather types of this state of things, that there should be such a paucity of works, in our language, on hydraulic engineering. Where there are so few learners there cannot be many teachers. То even the most rudimental and essential parts of the art or science, there are either no guides, or none that are trustworthy. The making of soundings, sections and borings, tidal and hydrometrical observations, are, for example, things of the first necessity; but how to make them, none of our authors have been at the pains to show, explicitly and fully. A desire to supply-so far-the great existing deficiency in this branch of our scientific literature, has led to the production of the work before us.

The author, Mr. Stevenson, is already favourably known to the public by his clever and instructive "Sketch of the Civil Engineering of North America." In his present work we have some of the fruits of his own engineering practice. "The observations," he says, "contained in the following chapters, have been thrown together at intervals of leisure from more urgent duties, and are chiefly the result of a pretty extensive experience obtained in the course of surveys, which were either at an early period conducted by myself, or have latterly been made under my directions." It would be well for the world, were all learned leisure employed to as good purpose. A work of more extensive practical utility, more certain to bring honour to its author and confer lasting benefit on his profession, has seldom come under our notice.

As the series of operations necessary in the survey of a river, embrace almost every point of consequence in the general application of surveying and hydrometry, to the practice of hydraulic engineering, Mr. Stevenson judiciously makes them the principal object of his attention; supplying, as he proceeds, those further explanations, which are occasionally necessary with respect to the surveys of harbours or lines of coast. The subjects treated of in succession, and each with great particularity of detail, are Triangulation-The Base Line-Tidal Observations-Soundings-Low Water Surveys-High Water Margin SurveysCross Sections and Borings-Hydrometrical Observations (on the Discharge and Velocity of Rivers, Qualities of Water, &c.)-Protraction of the Triangulation, Base Line, and Traverse Survey-and Protraction of Low Water Survey and Soundings. The work is not of a nature to afford much quotable matter, nor is it easy, by any quotation, to exemplify the value of the information which it contains; but the following extracts will at least serve to show that it is not deficient either in originality or novelty.

Local Variation of the Magnetic Needle, a frequent but neglected source of Error in Surveys.

"The magnetic needle, independently of those changes which are ascertained to be constantly going on in its direction and dip, to which the term "variation" has been applied, is subject to other variations occasioned by local attraction, in consequence of which, it has, under certain cir. cumstances, been found, that, in surveys even of limited extent, the magnetic north, as indicated by the needle, varies in its direction to a very appreciable amount at different stations. The causes of these variations are in some cases very apparent, but in others they are not so easily discovered, and therefore cannot be so well guarded against. I have met with many instances of errors in observations produced by local variation, some of which have given rise to considerable trouble, before the cause from which they proceeded could be detected. On the river Tay, for example, I found the variation on one occasion to amount to 2° 30' in a distance of about a quarter of a mile. The first of the series of observations by which this local variation of the needle was discovered, was made on the top of a high bank, about 50 feet above the level of

the water, and the second on a low tide covered sandbank in the middle of the river; but the attracting influence could not, in this case, be satisfactorily ascertained. On another occasion, an error, amounting to no less than 70, was introduced into the bearings of a survey, in consequence of certain observations which had been referred to the magnetic north having been made in the vicinity of a large steam boiler, which lay concealed from view in a warehouse, close to which the instrument had been set, and the influence of this mass of iron on the data of the survey, could not, at the time the observations were made, be avoided. In another instance an error of 2° was in like manner introduced into a harbour survey, owing to the instrument having been inadvertently set too near a cast iron mooring pall which was fixed on one of the quays.

The Datum Line for Soundings.

"It is evident that all soundings must be reduced or referred to one datum line, before a correct notion can be formed of the depths of water at the places where they were taken. Different opinions have been advanced as to the most convenient datum to be used for this purpose. When the whole rise of the tide can be observed, which is the case in harbour surveys situated on the coast, the half tide mark,' or that central point from which the high and low water levels of every

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tide are very nearly equidistant, is a convenient point for referring to. The existence of such a point equidistant from the high and low water of any one tide and on the same level, or coinciding with the points half way between high and low water of every other tide,' has been determined by observations made in several situations. It is believed to have been first detected in 1830 by my father, while surveying the Dornoch Frith in reference to a salmon fishing question, and is particularly alluded to in his report to the Court of Session on that subject, dated 31st January, 1831. In 1833 it was found to exist in the Frith of Forth, in making the tide observations for a harbour survey; and in 1834, in surveying the Skerryvore Rocks on the west coast of Scotland, with a view to the erection of the Skerryvore Lighthouse. In 1835, I obtained the same results at the Isle of Man ; and in the same year Captain Denham brought a similar result, obtained from extensive observations made at Liverpool, before the meeting of the British Association, held at Dublin. The agreement of these different series of observations, made at points so far distant from each other, seems to prove the universality of the phenomenon, at least on the shores of this country."

Instrument for Measuring the Velocity of Water.

"The instrument employed for this purpose is a modification of the tachometer of Woltmann, which is in general use in France and Germany, both as an anemometer and a hydrometer, being made of the degree of delicacy suited to the purpose to which it is applied.

"The construction of this beautiful instrument and the manner in which it acts, will be best described by reference to the accompanying cut, which is taken from a

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