struction 25 feet long. This anomalous result led to further inquiry, and this being far from satisfactory, the late experiments were fortunately undertaken. Mr. FAIRBAIRN has not only performed the experiments with his accustomed care and judgment, but has also deduced from them practical improvements of very great importance. His results, though by no means singular, or adverse to what might have been anticipated by a scientific mind, will render a change in the construction of boiler flues inevitable. They prove that the resistance to collapse of such tubes from a uniform external pressure, varies inversely as their lengths in all ordinary cases-say, for lengths not exceeding fifteen diameters. They further show that in boilers of ordinary construction, the external shell is three or four times more capable of resisting the forces which tend to burst it than the flues are to resist the forces which tend to collapse them. This amply explains the causes of the many disastrous accidents that have been occasioned by the collapse of internal flues. The maximum strength of the structure, as a whole, is, of course, that of its weakest part only, and consequently the excessive strength of the outer case is valueless. The strength of the flues may, however, it is found, be increased nearly threefold, by the mere addition of a couple of strong angle-iron ribs to each of them. By further forming such flues with double-riveted butt-joints, and longitudinal covering plates over the joints, their circular form may be preserved, and another great source of weakness thus got rid of. These improvements, though extremely simple, are of immense value, and their general adoption will add much to our security in the use of steam boilers. NAVAL ARCHITECTURE. OUR ship-building readers must not be disappointed when they observe how small a portion of our present number is addressed primarily to themselves. In the article on "Naval Warfare with Steam," they will find a few questions of special interest discussed; but on the whole they may with fairness be disposed to complain of the meagreness of the information afforded them this week on subjects of a professional nature. Without entering into the causes of the deficiency, we may state that they are of a transient character, and the defect will not again exist. We have already completed arrangements for a series of articles upon the theory and practice of ship-building, and are also making provision for frequent papers on the actual works in progress in the various Dockyards of the kingdom. To the contemplated articles on the theory and practice of ship-building-in which we include the Laying Off of Ships-we attach very great importance. We shall mis-represent no one when we say that a great and pressing want of comprehensive treatises upon these subjects unquestionably exists. In the Royal Dockyards there are hundreds of shipwright apprentices in training, and in the private yards thousands. And beside these, there are many thousands of other young men, who have completed their apprenticeship, but who are, nevertheless, earnestly desirous of gaining a sound knowledge of their profession. But to all these young men "serving their time," and young men "out of their time"-how little sound and useful professional literature is accessible! Now, we propose to supply precisely what they need. Apart from such information as we may from time to time furnish respecting the mechanical building, or putting together of the parts of the ship, we intend publishing two distinct classes of papers, in which we hope to combine sound science with good practical instruction. The first of these will treat of all that relates | regard to the project for the new Foreign to the calculations which require to be made by Offices. No official announcement that a sea scientific constructor of ships; and our aim lection of the plans of any one architect has will be to give numerous and useful illustrations been arrived at has yet been made, but, while of the several problems which he has to solve. there may exist a disposition to confer the For example, instead of confining our investiga- honour upon some especial one of the competitions to one particular water-line as is always tors, the enlightened portion of the public are the case in books, but hardly ever the case in first to be probed to see how far it would stand practice-we shall give a ship several water-lines, so flagrant a breach of the proprieties. If the and discover what qualities she possesses when pseudo-announcement which fairly stunned the immersed to each of them. It is not possible profession, properly so called, had been quietly to treat the whole, or even many, of these pro- accepted as a fact, then the official order would, blems without assuming some knowledge of the perhaps, have followed as a matter of course; higher mathematics on the part of the student. but no such thing up to the present moment But we shall carefully demonstrate them in has taken place. the most elementary manner possible, and afterwards give the rules deduced from the demonstrations; so that even those whose mathematical attainments are but slight, may still be able to solve the problems practicallyin the same manner as questions in Practical Geometry are solved without a knowledge of Euclid's Elements. We would, nevertheless, earnestly recommend those of our young readers who aspire to become naval architects, to extend their mathematical knowledge as fully as possible, by which means alone they can attain to a proper understanding, and a true enjoyment of their art. There are a few invaluable works on Naval Architecture, which it is next to impossible for the general reader to obtain; and upon these we shall fall back as occasion may require, in order that we may omit nothing of importance to the Naval Architect from our papers. We shall also give several entirely new forms for conducting the necessary calculations, together with the solutions of many questions which arise in the investigation of a ship's qualities, and of which solutions have never yet been published for the guidance of those who have to make the calculations, but who are unable to solve the problems on which they depend. The aim of our second class of papers-on Laying Off-will be no less ambitious than that of our first class. We propose to adopt an entirely new and, we believe, a highly-improved method of teaching this somewhat difficult and repulsive subject. While the only treatises that have hitherto taught Laying Off are of a purely technical character, and dissociated from those geometrical principles upon which the draughtsman's art is based, we shall make those principles our starting points, and proceed from them to the actual operations of the mould-loft floor. This is unquestionably the only truly scientific method of teaching Laying Off, and we are persuaded that it will tend, more than any existing system, to thoroughly instruct the student who gives his attention to the subject. We hope to commence the publication of one, at least, of our series of articles on Naval Architecture next week, and to continue the same, with little or no intermission, until they are completed. THE NEW FOREIGN OFFICES. THERE was a time in England's history when the ministers made laws, and either trusted to, or cared not for, the approval of the community. But of late years, the wisest proposition gets no sanction or open patronage from those in office until it has been well agitated and ventilated out of doors. The law is then granted as a graceful concession to the wishes of the majority; and, should it prove less operative for good than was expected, the minister stands beyond the reach of censure, and the country patiently submits to its operations as the parent submits to a wayward child. Some such operation is now going on in We are aware that in taking this view of the affair we go beyond the inferences drawn from the announcement by many able and far-seeing men, who will not accept even so much as would imply that there ever existed one tittle of authority for the announcement at all. With these gentlemen the announcement assumes simply the nature of a "canard." They say, that professional capital is to be made out of it, whether the affair is true or false; and, indeed, they go farther than this, and affect to see in the apparently hostile letters in the Times and other journals, the artful jobber firing his pellets to provoke a war of words which cannot do other than render popular the individual who is the cause of it. We should not call attention to this phase of the case, did we not feel that there is much to justify such a conclusion. We have no proof, however, that such is the fact ; but its existence would not surprise us after what has occurred, upon similar occasions of public competition. Under any circumstances it is now high time that Lord JOHN MANNERS should take some notice of the rumour. Let that nobleman confirm it if it be true; let him deny it if it be false. If, however, he should be made to continue silent by the requirements of official dignity, what could be easier than for some one of the competitors to ask the question of his lordship? Surely they are most interested in the decision, and it would need no very great space in their note to be devoted to apologies for so suggestive a course. Whatever may be the result, the public are indebted to the "announcement" for awakening a large amount of dormant feeling for Art amongst a class of intellectual men which is becoming every day more and more conversant with the elegancies and requirements of an enlightened society. These men possess a cool judgment, allied to an independent and logical mode of thought. They are, moreover, lovers of a rational and vigorous progress, and from them we may hope that at no distant time we may be able to "announce" the advent of a movement which will at once and for ever place the whole phalanx of copyists and pattern manufacturers in the position they naturally and necessarily occupy in every profession, excepting the great and noble one of architecture. Then may arise some great genius, modestly impressed with the importance of his mission, and endowed with power to advance the art upon which ages and nations almost wholly rest the glory and perpetuation of their worldly fame. In a commercial point of view, we unfortunately at this moment permit our money to be squandered on the whim or fancy of any wellconnected mortal, who may be in his dotage, and never have the opportunity of seeing the coming generation look with sovereign contempt upon the works held in terrorem over suffering "Taste." The system of filching from old German and Flanders examples may be all very well for a little while, but the constant borrowers of ideas, like the fitful customers of THE SMITHFIELD CLUB SHOW. EVERY year adds to the importance of our great agricultural gatherings, not the least of which are the exhibitions of cattle and implements at the Baker-street Bazaar, which are looked forward to by some hundred thousand persons with almost the same interest as the good old Christmas pantomime, without which London at this season would no longer be itself. Notwithstanding the additions which have from time to time been made to the area devoted to the Christmas show at the Baker-street bazaar, it has grown less and less compared with the number and variety of things exhibited, until upon the last occasion the "standings" only measured two feet nine inches in width instead of ten feet, which was their extent about eight years ago. This diminution of space, for which, by the way, the same charge is made as formerly, has arisen from the increased number of applications made year by year; the principle adopted being that of dividing the area into as many standings as are applied for, so that if the same building be used, a few years will suffice to reduce each standing to as many inches as it formerly reckoned feet. This has necessarily greatly increased the cost of exhibiting implements, and no doubt presses severely upon small makers, a few of whom, we noticed, had contented themselves with just room enough for a man to stand upright in, and whose occupation was simply that of distributing catalogues or hand-bills, necessarily borrowing from his next door neigh bours the elbow room required in the discharge of his duties, or when he desired to put his hands in his pockets. Those exhibitors, on the other hand, to whom a few pounds are no object monopolise as many as ten, twenty, thirty, or in one case as many as forty standings, and were consequently enabled to make a considerable display. All this will doubtless be shortly remedied, as it is scarcely possible that the premises hitherto used for the purposes of the show, can very much longer suffice, considering the increased accommodation now so imperatively called for. We understand that so great were the inconveniences acknowledged to be on the last occasion, for want of space, that a committee has actually been appointed to inquire into the possibility of finding more suitable quarters. The Crystal Palace has not been overlooked by those who have given any thought to the subject, but its distance from town is a very serious objection, especially as in order to retain the popularity of the Christmas show, it must be open in the evening as well as in the day time. Another plan has been suggested of holding the shows in some accessible spot under some temporary erection which could be contracted for in the same way as the canvas sheds adopted by the Royal Agricultural Society; but to this, there is some considerable objection on account of the season of the year, which requires the cattle to be well protected from the weather. Perhaps this objection might be overcome by artificially heating the cattle department; a few thousand feet of iron hot-water piping accomplishes wonders in the way of warming long ranges of buildings, or those which are separated by considerable distances. We have no doubt that many of our hot-water apparatus makers would readily undertake to maintain a uniform temperature in a length of canvas-covered and timber-sided shedding, amply Aufficient to hold all the bullocks, sheep, and pigs space in our columns. which the breeders and rearers of England could desire should be brought together. The real difficulty is, doubtless, to find the ground space, but this it is possible the committee referred to may succeed in doing, if they heartily set to work, as we trust they may do. Before concluding these introductory remarks, we should, perhaps, notice of the Smithfield Club Show, which is offer some apology for the late appearance of our simply this: That, until our present number (the first of the enlarged series) and only with difficulty even now, has it been possible to afford it A careful record of the great improvements in agricultural machinery continually being made, and yet to be made, can, however, be hardly better inaugurated than by a short, yet systematic account of what we noticed at the late show; and this consideration, added to the fact that no detail statement has as yet been published, has determined us, even thus late, to draw the attention of our readers to those matters which most interested us in our ramble through the implement department. In our notices of machines or implements exhibited, it must be carefully borne in mind that we profess to do little more than refer to such as were exhibited for the first time at any show of implements, or at any rate which had not before been shown at the Smithfield Club Meetings. This will, of course, account for the absence of mention of a vast number of well known names as exhibitors, and as well known machines and implements of. those whose names do appear in reference to agricultural machinery recently introduced. We notice the stands in the order in which we examined them. T. Scott, of Drummond-street, Euston-square, exhibited a new machine-a grass-seed separator, for extracting the seeds of couch, twitch, spear, or hair grass, and other impurities from perennial, or Italian rye-grass, &c., as also a carrot-seed bearding and dressing machine for cleansing the seed of the beard or awn, and rendering it fit for sowing. By a slight modification this machine may be used for milling clover, trefoil, and other similar purposes. It is calculated that 5s. per acre is saved in the cost of seed by the use of this machine. Into the details of this saving we cannot enter, but there is no doubt that great advantage arises from thus preparing seed. These machines are manufactured by Middleton, the well known engineer of Southwark. Mr. Romaine exhibited a model of his steam cultivator, as intended to be manufactured by Mr. Nash, of Cubitt Town, Isle of Dogs. This machine contains many important improvements over those hitherto constructed for Mr. Romaine. It is in reality a rotary digger, the digging apparatus being a cylinder with spades placed behind the engine. The spades are firmly bolted to the cylinder by three bolts placed triangularly (two of them at the point of greatest strain) and passed through the metal of the cylinder. The cultivator travels slowly over the land, digging a width of eight feet, but has a faster motion, by which, when not digging, it can travel from place to place at about two miles per hour. The cost of the machines will be about £800 each, the working expenses being set down at about 33s. per day, and the quantity of land cultivated about seven acres. The steering apparatus appears well arranged, and the machine is made to turn almost in its own length. So far as we could judge from the model exhibited, Mr. Romaine appears at length to have succeeded in devising the machine so long and earnestly looked for by many, and even by Mr. Fowler, to be forthcoming some day or other, namely, a machine which can work its way into an unprepared field and ont again, having spaded up the soil to any depth required, and that without the spades or forks clogging-the cylinder on which they are fixed preventing any accumulation of earth which would take place were they merely attached to a shaft, instead of to a large cylinder. We hope in a few weeks to give illustrations, and detail des cription of this interesting implement. Mr. Unite, of the Edgware-road, exhibited some geilow dressed carriage aprons, which, as far as appearances go, are doubtless preferable to black ones, and which, from the nature of the dressing, are not liable to crack or scale. The specimens shown were exceedingly pliable, exhibiting none of that harshness which renders many aprons as stubborn as sheets of metal laid across the knees, and almost as cold and comfortless. Messrs. Hornsby and Sons, of Grantham, exhibited their newly-patented plough, manufactured wholly of wrought-iron, with the exception of the slide, name-plate, and wheels. In this plough, the share and turnfurrow, or breast, are attached to the slide or sole plate, instead of to the frames, as usual; thus the beam, handles, and frame, are solid pieces of wrought-iron work, obtaining the greatest possible lightness, with great strength and durability-doing away with the heavy cast-iron frame in ordinary use, and, at the same time, giving to the plough a light, simple, and pleasing appearance. The shares are attached to lever necks of wrought-iron. They are so constructed that no dirt can possibly work into the joint to interfere with its free action, which is capable of universal movement; and being spherical, it is the firmest, and most easily adjusted arrangement that can be introduced for giving it more or less pitch; as also for directing the point of the share more or less to land. The spherical bearing is fixed close to the share, so that giving it more or less pitch or land move ment does not raise it above or below the front of the breast. The coulter fastenings are made wholly of wrought-iron; the coulter is very easily adjusted for cutting in-land or furrow, and at a greater or less inclination. Skim coulters, with wrought iron stems and steel miniature mould boards are attached to these ploughs, by a wrought-iron clip, and also drag-chains when desired. The wheel stems are fastened to slides passing through holes in the beam, and a piece is welded on the underside of the beam, through which they also pass, giving them a firm wide bearing. By this arrangement the land wheel can be expanded or contracted, dispensing with the slide axle at the bottom, and causing the wheels to run nearly opposite to each other. The wheels are constructed so that no soil can adhere to, or be carried round by them, as is the case with the wheels of most ordinary ploughs, the rims being bevelled on the inside. Messrs. Garrett and Sons exhibited, in addition to their usual collection, a horse hoe with newly arranged steering and elevating apparatus, both operations being effected by means of a single handle. The axletree is made moveable at both ends; thus the width or spread between the wheels can be increased or diminished according to the method of planting, so that the wheels always travel between the rows. Each hoe works on an independent lever, by which means they either rise or fall according to the irregularities of the surface of the land. The steerage, which is in itself very simple, consists of a quadrant gearing into a rack, and affords a ready means of keeping the hoes between the rows of corn or vegetable crops, doing every execution to the weeds without the slightest injury to the crop. The hoes may be varied in distance, to suit all crops, at any given width that may be required. The cutting blades, of different sizes, are made of steel, and attached by screw bolts and nuts to the stalks, which are keyed into the levers, and when worn may readily be replaced by any farm labourer. We should not omit to notice an improvement in what are called the "continental two-horse" thrashing machines, which are known as one-horse machines in this country. The improvement consists in arranging the vertical bevel wheel within the circumference of the horizontal one, which enables the machine to be packed in a square case, thus saving freight. Whitmore and Co. exhibited several crushing and other mills; the most noteworthy, as being the most recent, were the small mills for splitting beans, peas, Indian corn, &c., capable of splitting four bushels per hour, the cost of each mill being under £3. Burgess and Rey exhibited e new grasa mower (Allen's American patent). This machine has been thoroughly tested during the last season, and found to answer perfectly-one machine having cut, on the farm of Mr. C. Hall, of Havering, Romford, Essex, 83 acres; and afterwards, on the farm of Mr. Tabrum, Bovis Hall, Brentwood. 100 acres of grass and 20 acres of clover. The work was done better and lower than by the scythe, and at the rate of one acre per hour. They also exhibited a new potatoe-digging plough (Owen's patent), which weighs only eighty-five pounds, is light of draught, and simple in its construction. One man, it is said, with a pair of small horses, will easily dig potatoes as fast as twenty persons can pick them up. The potatoes are turned out and distributed on the ground so that scarcely one per cent are left covered. It works well on hill sides, on rough or stony land, and on all soils. This implement can be used as a cultivator in the early part of the season, it being admirably adapted to run between rows of potatoes, turnips, &c., to eradicate the weeds and lighten the soil. The next thing we should notice is a "post-hole" augur, also invented by Mr. Owen, which combines the advantages of the shovel, spade, and post-spoon, producing a round smooth hole. The augurs are made of convenient size and length for boring holes in the ground suited to any sized post. They lift the dirt from the hole without the use of a spade or spoon; and as no more is removed than is necessary, the work is much more rapidly performed than usual. Messrs. Burgess and Key also exhibited a number of churns similar to the one which gained the prize at Chester, and considerable attention was paid to the celebrated reaper which occupied a prominent place in the exhibition. We understand that the Prince Consort, owing to his having one of the reapers on his farm at Windsor, had a prolonged interview with Mr. Burgess on the merits and capabilities of the machine, which appeared to have entirely realized the Prince's expectations. Ruston, Proctor, and Co. exhibited one of their portable grinding mills with wooden framing, which lessens its cost about £7. These mills will grind six to ten bushels of meal an hour, according to the fineness of the work. The top stone, being the runner, is driven by an upright shaft, which receives its motion from a pair of bevel wheels at bottom, one of which, to prevent noise, is geared with wood. This firm also exhibited an improved circular sawing bench, which possesses many advantages over those generally in use. It consists of a circular saw fixed in a cast-iron planed table, and is mounted on cross oak soles; turned wrought-iron rollers are fitted to each end of the table, and three sizes of augers to the spindles for boring. It is driven by a double-flanged pulley, and the brasses carrying the spindle are applied in an extra strong manner, and are adjustable by set screws and lock nuts. The fence is an arrangement of screws and pinions, very correct and certain in its action. It has the parallel, transverse, and feather-edged or diagonal cutting motions; may be adjusted to suit any sized saw, and is set to a gauge, marked on the table in eighths of an inch. We must next notice the excellent portable engines of this firm, one of which was exhibited. The most noticeable points of these engines are that the saddle for the fly wheel shaft completely straddles the boiler, thus guarding against any derangement from unequal expansion; and the engine is also fitted with an improved throttle valve, which by means of a governor regulates its motion whether lightly or heavily loaded. The tubes are arranged in vertical rows, leaving a clear half-inch space between them from top to bottom, there being an inch space between the outsides of each pair of tubes. The slide valves are case-hardened. capability of these engines is considerable, as 8 square inches of piston area are allowed for each horse power, the pressure of steam being 45 lb. per square inch. We believe one of these engines tried at Chester, with the eight horse brake, made 130 revolutions per minute, with the steam at 24lbs. only. The force pump is fixed vertically at The the back end of the boiler, thus avoiding a long | ON IMPROVED MODES OF CONSTRUCTING eccentric working rod, and an equally long return THE FLUES OF STEAM BOILERS. pipe, both of which are necessary when the pump is inclined in the usual way. A combined thrashing machine was exhibited by this firm at the Gloucester Mews in the neighbourhood of the show. Messrs. Ruston, Proctor, and Co. are the makers of Smith's ploughing apparatus, which was at work during the show at Flemish Farm, near Windsor. Wallis and Haslam, of Basingstoke, exhibited their self-adjusting spherical bearings, which appear admirably suited to agricultural machinery, the accurate setting of which cannot, from want of good foundations or other causes, be generally depended upon. These bearings are well adapted for shafts or spindles which run at a high speed, or are at all liable to heat, as they adjust themselves to the slightest variation in the line of direction of the shaft, while, at the same time, they are perfectly steady in work, and, as they wear equally through out their whole length, will no doubt last much longer than the ordinary bearings. The spherical bearings are composed of four parts, viz.: the seat or block, the upper and lower brasses, and the cap. The seat or block and the cap are turned, so that when put together, their interior surfaces form a spherical cavity, with a portion removed on each side of the block, forming openings through which the shaft or spindle passes out, surrounded by the brasses in which it revolves; and the upper and lower brasses, after being bored in the usual manner, are turned externally to the form of a sphere of the same diameter as the cavity in the block, so that on their being placed in the cavity, and the cap adjusted over them in its place, they form a universal joint, which will turn freely in any direction within certain limits. On the under side of the lower brass is cast a nipple, which descends into a socket bored in the bottom of the block to receive it. This socket is considerably larger than the nipple, and will therefore allow sufficient motion for the brasses to adjust themselves to the position of the shaft, while, at the same time, it prevents their rotating along with it, which they might otherwise be liable to do. pressure, By W. FAIRBAIRN, Esq., C.E., F.R.S., F.G.S., &c. THROUGHOUT the whole of the experiments on the resistance of tubes to collapse, lately undertaken by me at the joint request of the Royal Society and the British Association for the Advancement of Science, it has been proved that the resistance to collapse from a uniform external ratio of the lengths. This law has been tested to in cylindrical tubes, varies in the inverse lengths not exceeding fifteen diameters of the tube; but the point at which it ceases to hold true is as yet undetermined, and could only be ascertained by a new and laborious series of ex periments on tubes of considerably greater length, in which the strength of the material modifies the above law of resistance to collapse. Such experiments are, doubtless, very desirable; but the vessels necessary for the purpose would be most expensive, and the results already obtained appear strengths and proportioning the material in all to supply all the data necessary for calculating the ordinary cases. If we take a boiler of the ordinary construction, 30 feet long and 7 feet in diameter, with one or more flues 3 feet or 3 feet 6 inches in diameter, we find that the cylindrical external shell is from three to four times stronger in its powers of resistance to the force tending to burst it, than the flues are to resist the same force tending to collapse them. This being the case in boilers of ordinary construction, it is not surprising that so many fatal accidents should have occurred from the collapse of the internal flues, followed immediately by the explosion and rupture of the outer shell. To remedy such evils, and to place the security of vessels so important to the community upon a more certain basis, it is essential that every part should be of uniform strength to resist the forces brought to bear upon it. The equalisation of the powers of resistance is the more important, as the increased strength of the outer shell is absolutely of no value, so long as the internal flues remain, as at present, liable to be destroyed by collapse, at a pressure of only onethird of that required to burst the envelope which surrounds them. We are sorry that our space precludes the possibility of our adding to the above remarks, as certainly not one-third of the matters deserving The following table, deduced from my own exnotice has been as yet touched. We trust, how-periments, exhibits the safe working pressure, and ever, to complete our survey of the show next the bursting pressure of boilers of different week, when we hope all exhibitors will find their diameters, calculated for an external shell of a respective claims to notice duly acknowledged. thickness of 3-8ths of an inch. The names of those whose productions we have as yet spoken of appear in the order in which our notes were made, it not being possible, in the crowded state of the building to take any regular course in examining the several stands. H.M. SCREW STEAM SLOOP "ICARUS.” The trial of the Icarus, Screw Steam Sloop, took place down the river on Tuesday, the 21st December last. She left Woolwich Dockyard at 10.25 a.m. and reached Gravesend at 12.12 with a strong tide against her, after which she made several runs with and against tide, at the measured mile, Lower Hope, under the superintendence of the Woolwich authorities and Messrs. Rennie, the constructors of her engines. The average speed thus obtained was 10 knots. The engines indicated above 600 horse power, making from 90 to 94 revolutions per minute. There was no heating in any part, and the trial was highly satisfactory to all concerned. The dimensions of the Iearus are as follows: ft. in. Length between perpendiculars 151 0 Beam extreme 29 1 Depth........ 15 10 Tonnage, O. M.... 57739 The engines are 150 horse-power collectively, by George Rennie and Sons, on their patent sin gle trunk principle. We are informed that Messrs. Rennie were little more than four months in constructing these engines, and the engines were tried one month after the vessel was handed over to them by the authorities. Bursting pressure. Diameter of Boiler. Working pressure. ft. in. lbs. lbs. 3 0 118 7081 As, Taking from the above table the strength of a boiler 7 feet in diameter, we find its bursting pressure to be 303 lbs. per square inch. For such a boiler the flues would be ordinarily 3 feet in diameter, and of the same thickness of plates as the shell; and by the formula, log P=1·5265+ 2:19 log 100k-log (L.D.), we obtain for their collapsing pressure 87 lbs. per square inch. however, the formula does not apply with strictness to tubes of such length, the actual collapsing pressure will be somewhat greater than this. The immense excess of strength in the outer shell is, however, sufficiently apparent; the extra thickness of boiler plate which causes it being so much material thrown away, adding nothing to the strength whilst the flues remain in so dangerously weak a condition. To meet this disparity of strength, the experiments indicate the necessity of shorter flues, and one of them shows how this may be obtained, practically and efficiently, without interfering With the present construction of boilers. A tube was divided into three parts by two rigid rings soldered upon its exterior, and its powers of resistance were thus increased in the ratio of three to one; virtually, the length was reduced in this ratio, and the strength was actually increased from 43 to 140 lbs per square inch. It is proposed to apply a similar construction to the flues of boilers, to equalise their powers of resistance with those of the outer shell, on the supposition that the law of decrease of strength holds true, within no great limits of error, to tubes of much greater length than in the preceding experiments. That this conclusion is not empirical, will be seen by the following experiments upon boilers of full size, where it will be observed that the flues were distorted with one-third the pressure required to rupture the external shell. These boilers were made for the North-Eastern Division of the London and North-Western Railway Company, and were respectively of 35 and 25 feet in length. They were 7 feet in diameter, CHANDLER AND OLIVER'S STEAM STEAM, which was once so restive as to alarm all Among the persons who have now for some years been working and spending in furtherance of steam ploughing is Mr. Robert W. Chandler, but lately a modest working engineer, at Bow, and associated with him, Mr. Thomas Oliver, a plain and sensible, but enterprising farmer, at Hatfield, Herts, in the neighbourhood of the Marquis of Salisbury's estates. The two together have from time to time patented several valuable improvements in agricultural apparatus, and have recently added to their inventions an improved form of plough, to be hauled by steam power, which many very experienced agriculturists have extolled, which several implement makers have coveted, in so far as its manufacture is concerned, and which Messrs. Howard and Co., of the Britannia Iron Works, Bedford, are now engaged in producing to order. This improved plough has, undoubtedly, many advantages no where else to be met with. It is a balanced inches in diameter, and of the same thickness of To ments is so evident as to need no comment. in their powers of resistance with the other parts of the boiler. The reduction of the strength of flues by the lap joints has already been stated; the deviation from the true cylindrical form which they cause, lessens, in some cases, seriously the strength of the vessels. Hence it is also proposed that flues required to resist an external pressure should be formed with double-riveted butt joints, with longitudinal covering plates, as shown also at b, b, b, fig. 1. Fig. 2 is a sketch showing the positions apparatus, like Fowlers, but the ploughs are wheels C and D work upon short axles, which are Fig. 1 of the annexed engravings is a side elevation, and fig. 2 a plan of the Chandler and Oliver plough. A, A is the general frame of the machine, which is made of either iron or wood. This frame is omitted on one side in Fig. 2, that the ploughshares may be shown more clearly. The frame is supported upon wheels B, C, D, but the inventors do not limit themselves to this number, as four or more may, if considered useful, be employed. The wheel B is placed on one side of the frame, and is supported on and works in bearings formed therein. When the plough is at work, the wheel B runs in the furrow that has been last made. The other wheels, C and D, are placed on the opposite side of the frame, and are arranged as shown in the figures near the extremities of the apparatus. The inventors prefer making these wheels of the peculiar shape illustrated in the figures. The N is given at Fig. 3. There are internal frames T, T, which are on the same shaft as the frames J, J, so that they are raised or lowered as the case may be at one and the same time. To these frames J, J, and T, T, the ploughs or other cultivating instruments are attached, and are raised or lowered with the frames to which they are fastened by turning the handle R as before described. Rods or levers are attached to shafts fixed in the lower part of the brackets N, and to these rods are connected links, which are fastened to the framing. Chains W, W, pass from the rods underneath the apparatus in contrary directions, and to these chains the rope, which passes round the drums of the engine, is attached. Or the rope or chain, by which motion is given to the apparatus, may be passed over a pulley at the extremity of the internal frame. The hauling rope or chain may be driven by any suitable prime mover, but Messrs. Chandler and Oliver prefer to employ for the purpose a portable engine, with two longitudinal winding drums, placed on horizontal axles beneath the engine. Or the engine described in the Specification of a Patent granted to them on the 25th June, 1856, may be employed with advantage for the purpose. For anchoring the hauling ropes or chains, they employ an anchor formed of a bed furnished with putting and holding blades below, and a winding pulley or drum ab876 And Also with a ratelist and pawl arrangement, whereby the pulley or drum may be turned round and a rope (the other end of which is fixed) be wound upon it, so as to draw the FIG. 3. anchor along the head-land as required, the blades cutting through the soil as the anchor advances: THE DRAINAGE OF LONDON. ATTENTION has again been directed to "The Great River Question," by the paper "On the Utilization of the Sewage of London and other Large Towns," read by Dr. Joule, before the Manchester Literary and Philosophical Society. Dr. Joule has been enabled to judge of the value of the works which are now being attempted; and the result of his investigation is but the reiteration of what has long been pointed out by the MECHANICS' MAGAZINE, and by almost every other paper whose sphere includes the practical application of science. It is, perhaps, of little avail that a rate-paying public, which cannot now help itself, and a Board possessed of almost unlimited powers in perpetrating and carrying-out, at a vast expense, their gigantic blunder, and which has now gone too far to retreat, should be informed that a few years must prove that the millions devoted to the drainage of the metropolis have been wasted. But in justice to those men of science and undoubted capability whose opinion has been disregarded; in justice to the Royal Commission, whose scientific suggestions, forming the ground. work of a rational plan, have been publicly ig nored, but privately adopted as a makeweight in a false and pernicious system; this inevitable con. clusion must be insisted upon. The discharge of the songe into the Thames albeit it |