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PORT AND DOCKS OF LONDON, ETC.

301 cution. Huddart was the constant coadjutor London Docks were projected, and in the of civil engineers : he assisted the late Mr. year 1805 the East India Docks were comRennie in many of his surveys of harbours, menced. For all these undertakings Mr. and on those occasions had always the com Ralph Walker was appointed engineer, mand of the vessel, even if he did not parti having Mr. William Jessop associated with cipate in the actual operations of the survey. him for the West India Docks. The paper Whether Huddart was viewed as a sailor, enters fully into the bad state of the navigaboldly striking out for himself a new track tion of the river, owing to defective manageto his destination; as a shipbuilder, con ment and other causes ; gives a table showing structing a vessel in order to avoid the de. the progressive increase of tonnage and num. fects which he observed in the ordinary class ber of ships from the beginning to the close of ships; as a hydrographer, displaying in of the list century; mentions the various his chart of the St. George's Channel those plans of Dodd, Spence, Revely, and others, powers of observation and of reasoning for diverting the channel of the river for the which made him an astronomer; as a con formation of more extensive docks, near the structor of the equatorial instrument, which Isle of Dogs ; and then proceeds to detail had been so justly commended; or as a me minutely the origin and progress of the chanic, designing and constructing one of London Docks, giving the dimensions and the most beautiful pieces of machinery on mode of construction of the principal works record, he appeared equally great.

connecting the Eastern Docks with the The Institution was much indebted to Thames, which were constructed under the Mr. Cotton for this memoir of Captain superintendence of Mr. H. R. Palmer, to Huddart, whose name would be always vene whom the author has been indebted for rated by every member of the profession of much of the information contained in the civil engineering.

paper. Mr. Thornthwaite must in justice correct The communication is accompanied by a misapprehension relative to the laying fifteen drawings, showing the details of conmachine for cables ; the idea of that machine struction of the locks and gates, bridges, originated with the Reverend Edmund Cart. quays, embankments, &c. wright, who had projected more improvements in cotton machinery than any person, except Arkwright. The machine was mate

February 8, 1842. rially modified by Captain Huddart, and to

· Description of the Ponte della Madehim must be given all the credit for the per

lena, over the River Serchio, near Lucca." fection of its proportions, and its careful

By Bichard Townshend, Assoc. Inst. construction, which had enabled a machine

C. E. weighing twenty tons, and revolving rapidly The bridge described in this communica. upon one vertical spindle, to work a number tion, is situated about half-way between the of years without costing £5 for repairs. town and the baths of Lucca, in the Grand The register, which preceded the laying ma Duchy of Tuscany ; it was built by Castra. chine several years, was entirely Huddart's cani, in the year 1317, on the site of one invention, and was the origin of his improve which had been constructed by order of the ments in rope machinery.

Countess Matilda, early in the twelfth century, and subsequently destroyed ; it is be

lieved that a Roman bridge formerly existed February 8, 1842.

on the same spot. " Description of the Port of London, and

The present bridge is of grey limestone of of the Works at the London Docks." By

the country. The large arch of 126 feet 6 Robert Richardson, Grad. Inst. C. E.

inches span, is of a semicircular form, and In this communication the author examines springs directly from the bed of the river, the state of the Port of London, when the without any prepared foundation. The accommodation for landing and bonding smaller arches are of various spans, 46 feet foreign produce was almost entirely limited 10 inches, 33 feet, 28 feet, and 7 feet 6 to a single spot, called the “ Legal Quay," inches. The style of construction is somewhich was only about 1,400 feet in length, what similar to that of the Pont-y-prydd, extending downwards from London Bridge, over the Taff, in South Wales. affording no greater facilities for commerce An engraving of the bridge accompanied in the beginning of the nineteenth century than in the year 1660, when the quay was appointed. This state of things continued Description of the Mill, Forge, and Furuntil the year 1773, when Mr. J. Sharp naces of a Welsh Iron Work." Ву suggested the formation of floating docks. Thomas Girdwood Hardie, Assoc. Inst. In the year 1800, the West India Docks C. E. were commenced ; in the year following the The author commences by describing the

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general plan of an iron work, consisting of or in the furnace, was to draw off the car. six blast furnaces, four double-fire refineries, bonic acid and leave an oxyde of iron, and and a forge and mill, capable of converting then the further action of the fuel (besides into bar-iron the produce of the six blast sustaining a high temperature) was to abs. furnaces.

tract the oxygen of the oxyde, and so to He then enters very fully into certain reduce the iron to the metallic state, after alterations of the interior shape of the blast which a still further portion of the carbon furnaces introduced by him at the Blaenavon of the fuel combined with the iron, bringing works, from which have resulted an economy it into the state of easily fusible, or pig. of fuel, regularity of work, and an improved iron. quality of iron. The principal alterations As carbon may be communicated to the appear to be, making the interior diameter iron in two ways, distinct in their nature, greater above that at the boshes, and estab. either by contact with solid carbon, as in the lishing a proper ratio between the diameter

process of cementation, (that by which steel of the boshes and that of the charging place, is commonly converted,) or from the carbonand proportioning both to the height of the ated gases, either carburetted hydrogen, or furnace. The opinions are supported by carbonic acid, which occupy nearly every calculations of the quantity of blast used in part of the air-way of the furnace, it would smelting given quantities of ore, and the ef be desirable to distinguish, as far as may be fect which the form of the furnaces must in any furnace having a particular form or have in directing the current of the blast action, what proportion of the whole effect through the materials, by which also the is due to the one mode of carbonization or point of fusion would be necessarily effected, the other and the chemical combinations varied. The Mr. Wallace stated that the ore was a particulars are then given of the construction carbonate of iron, or a protoxyde of iron of the furnaces at Blaenavon, and the de and carbonic acid united, and not a carburet tails of the blowing engines, blast mains, of iron, (or iron and carbon simply,) as as regulators, valves, &c., with calculations of generally believed. In smelting, the car. the quantity of blast used in the various bonic acid was driven off, the simple oxyde processes of the manufacture. The con remaining; the oxygen of which, being car. struction of the casting houses, with the ried off by the heat, left the pure iron, which, mode of ventilating by the iron roof, is de combining with the carbon of the coke, tailed. The general arrangement of the formed a fusible carburet of iron, or the balance pits, coke yards, mine kilns, and pig-iron of commerce. bridge houses are shown, and the author Mr. John Taylor observed that his brother, proceeds to describe the forge and mill, Mr. Philip Taylor, being sensible of the ad. which have thirty-five puddling furnaces, vantages to be expected from the use of anwith hammers, shears, rolls, and heating thracite in smelting iron, made a series of furnaces in proportion. He then condemns experiments several years ago, from which he the usual practice of leaving the coupling derived the opinion that the carbon absorbed boxes loose upon the spindles, as liable to by the metal, and which is necessary to probreak the rolls, shafts, or machinery, and duce it in the shape of pig-iron, must be gives theoretical and practical reasonings for presented in a gaseous state to the mass in preferring fixed couplings.

fusion; and as anthracite did not afford a The communication is illustrated by three sufficient supply of coal-gas during combus. drawings, showing the general distribution tion to produce the proper effect, he proand the details of an iron work.

posed to adopt a very ingenious method, by

which this gas would have been thrown into Mr. Lowe believed that there was an in the furnace in such proportions as might be correctness in the statement of the iron

found necessary, mixed with the common after being freed from its oxygen by the heat air employed as the blast. of the furnace, taking up a dose of carbon Circumstances interrupted the course of from the coke, thus becoming a carburet of these experiments, or it is possible that the iron, which is a fusible compound, and as use of anthracite for this important applicasuch, fell melted into the hearth. On the tion might have taken place at a much earlier contrary, he thought that the iron was com. period than it has happened to do. bined with carbon in the ore, and that there was not any necessity for the medium of the fuel to charge it with carbon.

February 15, 1842. In reply to " · Why the ore required, or

" Description of Chelson Meadow Sluice." why the iron carried away, any of the carbon By Theodore Budd, Grad. Inst. C. B. of the fuel ?” Dr. Faraday stated, that the The sluice which is described in this con. ore being essentially a carbonate of iron, the munication was erected from the designs of first action of heat, either in the mine kilns Mr, Rendel for the Chelson Marshes in

STEVENSON'S HYDRAULIC ENGINEERING.

303 Devonshire, which, being very low, had pre a more matured and perfect state, than riously suffered much from floods, but now hydraulics.* But although we can, perare entirely relieved. The novelty in the haps, boast of as much in the way of construction consists in hanging each of the

performance in this line as most nations, doors respectively by two hinged flat bars of it is but too certain that we must look iron, of 18 feet 6 inches, and 15 feet 3 inches in length, and thus, by placing the centre of nearly all the science belonging to it.

elsewhere than to English books for motion so high above the centre of gravity of the doors, to give greater freedom of

Our Smeatons, Telfords, and Rennies, action than by the modes usually adopted

have at best but turned to good practical in similar works.

account, in the embankments, drainages, The dimensions of all the parts, and the

docks, &c., for which they are celebrated, method of construction, are given in great

the principles of construction which they detail, and are illustrated by a drawing. found developed to their hands in the

writings of the Italian, Dutch, and Mr. Rendel explained that the sluice French engineers and philosophers, pardoors which had been superseded by those ticularly Guglielmi, Frisi, Mariotte, Bedescribed by Mr. Budd, were of the ordinary lidor, Bossut, and De Buat. Of our men description, placed side by side. They were of abstract science, the only names which frequently hinge-bound and clogged up, occur to us as connected with contribu. which caused the land to be flooded some

tions to hydraulics, worthy of men. times for three months during the year ; the

tion, are, Robinson, Hutton, Leslie, and hinges were attached in the usual manner to the frames, close at the head of the doors; being scanty, are all more of an elucida

Young; and these contributions, besides and they required a pressure of at least 6 inches of water to act upon them either way.

tory than original character. Of making He considered the principal advantages of

a study of this branch of engineering these doors to consist in the freedom of action knowledge, more than any other, to given by the length of the bar-hinges by qualify a man for professional eminence which they were suspended, their giving the in England, few, if any, of our engineers, full extent of opening, and the pressure of have ever thought. In this, as in but 1 inch head of water sufficing either to open too many other matters, it has been alor close them.

ways too much the fashion, with us, to Mr. Prior inquired whether there was any find the occasion for the knowledge first, similarity between these sluice-doors and and to let the knowledge come after, as it that erected by the President near Blackfriars

may. When the at-all in the story was Bridge, at the bottom of Fleet Ditch. That

asked, “Can you play on the fiddle ?” door was so well hung as to be even acted

his answer was, “ I don't know, but I'll upon by the wind; and the slightest pressure

try;" and so with our engineering aspi. of water sufficed to open or to close it. The President explained that the principle

rants, the rule has been, first to get a was not the same ; at the Fleet Ditch sluice

dock or harbour to do, and afterwards double hinges were used, or rather hinges

to find out how it is to be done. And with a link between the part attached to the though now and then, some egregious frame, and that which was screwed to the blunder will occur, to furnish its instrucdoor ; - that form of hinge always acted tive commentary on this inversion of the freely, and allowed the doors to open with a proper order of things, it must be conslight pressure.

fessed that, in general, its worst effects are to be traced in that excess of expen

diture over estimate, for which English STEVENSON'S APPLICATION OF MARINE engineers have become almost quite as

SURVEYING AND HYDROMETRY TO
THE PRACTICE OF CIVIL ENGINEER-

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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 vowp, water, and avdos, a pipe. Would not Hydraties be a better term, and square well with Pneumalics? Hydraulics might then be restricted to its original signification-reduced to its proper rank, which is that of a General of Division, while Hy dralics would become, by right of suffrage, the true Generalissimo.

famous as for the excellence of their As the series of operations necessary in constructions.

the survey of a river, embrace almoet We are accustomed to hear all sorts of every point of consequence in the general reasons assigned for such excesses—un application of surveying and hydrometry, favourable seasons, “accidents by flood to the practice of hydraulic engineering, and field,” extra works, &c.—but the Mr. Stevenson judiciously makes them reason which is more potent than all the principal object of his attention; supthe trying to play on the fiddle before plying, as he proceeds, those further es. learning-—is but rarely glanced at, or if planations, which are occasionally necesoccasionally urged by some obstinate sary with respect to the surveys of harmalcontent, only to be drowned by a bours or lines of coast. The subjects flourish of trumpets from the successful treated of in succession, and each with engineer and his friends. It would not, great particularity of detail, are Trianperhaps, be straying far from the truth, gulation—The Base Line-Tidal Obser. were the item which now stands as vations-Soundings-Low Water Sur. “contingencies" in most estimates for veys—High Water Margin Surveys public works, expunged, and the follow Cross Sections and Borings-Hydro. ing inserted in its place—To education metrical Observations on the Discharge of the engineer," 100,0001. or 1,000,0001. and Velocity of Rivers, Qualities of as the case may be.

Water, &c.)-Protraction of the Trian. It is but one of the natural results, or gulation, Base Line, and Traverse Sur. rather types of this state of things, that vey—and Protraction of Low Water there should be such a paucity of works, Survey and Soundings. The work is in our language, on hydraulic engineer.. not of a nature to afford much quotable ing. Where there are só few learners matter, nor is it easy, by any quotation, there cannot be many teachers.

To

to exemplify the value of the information even the most rudimental and essential which it contains ; but the following ex. parts of the art or science, there are tracts will at least serve to show that is either no guides, or none that are trust is not deficient either in originality or worthy. The making of soundings, sec novelty. tions and borings, tidal and hydrometrical observations, are, for example, things of

Local Variation of the Magnetic Needle

, the first necessity ; but how to make

a frequent but neglected source of Error them, none of our authors have been at

in Surveys. the pains to show, explicitly and fully.

“ The magnetic needle, independently of A desire to supply—so far—the great

those changes which are ascertained to be existing deficiency in this branch of our

constantly going on in its direction and scientific literature, has led to the pro

dip, to which the term “ variation" has duction of the work before us.

been applied, is subject to other variation

occasioned by local attraction, in conseThe author, Mr. Stevenson, is already

quence of which, it has, under certain cir. favourably known to the public by his

cumstances, been found, that, in survey clever and instructive “ Sketch of the

even of limited extent, the magnetic north, Civil Engineering of North America." as indicated by the needle, varies in its In his present work we have some of the direction to a very appreciable amount a fruits of his own engineering practice, different stations. The causes of these TI. “The observations," he says, "contained riations are in some cases very apparent, but in the following chapters, have been in others they are not so easily discovered thrown together at intervals of leisure and therefore cannot be so well guarded from more urgent duties, and are chiefly against. I have met with many instances of the result of a pretty extensive experience

errors in observations produced by local obtained in the course of surveys, which

variation, some of wbich have given rise to were either at an early period conducted

considerable trouble, before the cause from by myself, or have latterly been made

which they proceeded could be detected. under my directions.” It would be well

On the river Tay, for example, I found the

variation on one occasion to amount to for the world, were all learned leisure

2° 30' in a distance of about a quarter of a employed to as good purpose. A work mile. The first of the series of observations of more extensive practical utility, more by which this local variation of the needle certain to bring honour to its author and was discovered, was made on the top of a confer lasting benefit on his profession, high bank, about 50 feet above the level of has seldom coine under our notice.

STEVENSON'S HYDRAULIC ENGINEERING.

305 the water, and the second on a low tide tide are very nearly equidistant, is a concovered sandbank in the middle of the venient point for referring to. The exist. river ; but the attracting influence could ence of such a point equidistant from the not, in this case, be satisfactorily ascer high and low water of any one tide and on tained. On another occasion, an error, the same level, or coinciding with the points Amounting to no less than 7°, was intro half way between high and low water of duced into the bearings of a survey, in con every other tide,' has been determined by sequence of certain observations which had observations made in several situations. It been referred to the magnetic north having is believed to have been first detected in been made in the vicinity of a large steam 1830 by my father, while surveying the boiler, which lay concealed from view in a Dornoch Frith reference to a salmon Warehouse, close to which the instrument fishing question, and is particularly alluded had been set, and the influence of this mass to in his report to the Court of Session on of iron on the data of the survey, could not, that subject, dated 31st January, 1831. In at the time the observations were made, be 1833 it was found to exist in the Frith of avoided. In another instance an error of 2° Forth, in making the tide observations for a was in like manner introduced into a har harbour survey, and in 1834, in surveying bour survey, owing to the instrument having the Skerryvore Rocks on the west coast of been inadvertently set too near a cast iron Scotland, with a view to the erection of the mooring pall which was fixed on one of the Skerryvore Lighthouse. In 1835, I obquays.

tained the same results at the Isle of Man ; The Datum Line for Soundings. and in the same year Captain Denham " It is evident that all soundings must be

brought a similar result, obtained from ex.

tensive observations made at Liverpool, reduced or referred to one datum line, before

before the meeting of the British Associaa correct notion can be formed of the depths

tion, held at Dublin. The agreement of of water at the places where they were taken.

these different series of observations, made Different opinions have been advanced as to the most convenient datum to be used for

at points so far distant from each other, this purpose. When the whole rise of the seems to prove the universality of the phe

nomenon, at least on the shores of this fide can be observed, which is the case in harbour surveys situated on the coast, the

country." half tide mark,' or that central point from

Instrument for Measuring the Velocity of which the high and low water levels of every

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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VOL IXXVI,

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