THE MECHANICS' MAGAZINE. LONDON: FRIDAY, NOVEMBER 27, 1868. great explosion takes place. Disc papier THE WHITWORTH GUN AT SHOE- throughout, and the following results were BURYNESS. BOUT two months since we noted, very A briefly, the advent of ce we weit, very reported in the "Standard" at the time:- Nature of Common Ditto...... Ditto Ditto Ditto. Ditto.... rear Round. 128466 7800 Powder Charge. About Fell in to Shell, 9 10 Ditto......... rear Ditto..... 4943888 3 333 13 13 13 13 13 13 draulic lifts, which are now being erected. At the present moment, the Metropolitan, the Midland, the London, Chatham, and Dover, and the Great Western Railways have direct communication with the depôt. The passenger trains of the Metropolitan run through it every two minutes, and the Great Western Company have an extensive receiving store for goods there. The building itself is admirably laid out for its intended purpose, and offers every facility to the public. The Corporation of London obtained an Act for erecting market buildings on the site of Smithfield in 1860, and in the following year they procured one giving them power to abolish Newgate Market. The business was confided to the Markets Improvement Committee, and a design was prepared by Mr. Horace Jones, the City architect. Their parliamentary powers enabled the Corporation to raise a a sum of £235,000 for the purchase of property, and £200,000 for the erection of the buildings. The Markets Improvement Committee, having obtained estimates from several builders, concluded a contract with Messrs. Browne and Robinson at a sum within the estimated amount of £200,000. The ceremony of laying the first stone of the market itself was performed on the 5th of June, 1867, when a corner stone weighing five tons was placed by Mr. Lowman Taylor, the chairman of the committee. It was not, however, till the 2nd of March last that the gun at Shoeburyness, and from which great things were expected. Nor has expectation been doomed to disappointment in this respect, for with it the longest range on record has been obtained. The piece of ordnance in question is a 9-inch steel-rifled 310-pounder gun, weighing 14 tons Scwt., breech preponderance, 61cwt.; length of bore, 140.06in.; over all, 163-80in.; calibre, major axis, 9.025in.; minor axis, 8-250in.; rifling Whitworth's hexagonal, spiral uniform, one turn Hollow Shot taper in 171in. Vent through the cascable in prolongation of centre of axis, the hole being covered with a metal tube-catcher for naval Common shell, taper service. The gun is constructed on the builtup system, the inner tube being of Firth's steel, the same as the Woolwich guns. This is covered by a second steel tube, over the The experiments which took place on rear portion of which is a steel jacket. Over Friday and Saturday last, gave some of the this again are two jackets of Whitworth most extraordinary results for range ever metal, or steel, compressed by hydraulic pres- known. On Friday, the range was at least This metal can be made of any degree 10,300yds., with a 250lb. shot, a 50lb. of hardnsss or ductibility, and Mr. Whitworth powder charge, and a maximum elevation of states that the tensile strengths of cast iron, 33deg. On Saturday, this gun beat even its wrought iron, and his steel metal, as used for previous performance, and with 33deg. 5min. ordnance, are respectively as 30, 100, and 250. elevation, and a 50lb. charge, threw a 310lb. Some preliminary trials of this gun were shell 11,127yds. to the first graze, being made by the Ordnance Select Committee in about 1,000yds. further than any projectile the middle of September last, when, after firing seven rounds, it was tested by Mr. return to the details of these interesting structure in detail in our next and following was ever hurled by any other gun. We shall we propose to illustrate and describe this Whitworth's machines (which gauge to the trials in our next; in the meantime, we may impressions, we need not now enter upon ten-thousandth part of an inch) for detection congratulate Mr. Whitworth upon having further particulars. Few public buildings of the slightest enlargement of the bore, or obtained ranges which we believe to be un-have been erected in so short a time as has any permanent set, Mr. Whitworth consider- approached by any other gun in the world. ing that the first sign of the yielding of the metal marks the commencement of the destruc sure. tion of the gun, and these delicate testings THE NEW METROPOLITAN MEAT enable the immediate determination of the maximum charge to which the gun could be exposed without injury. The measurements showed a set of one two-thousandth of an inch at the extreme rear end of the chamber; of one seven-thousandth at the front of the chamber, and thence to the muzzle there was absolutely no difference before and after the firing. The exceedingly minute difference shown may be readily accounted for by the wear even of the instrument or of the face of the bore, or by compression of the mass of metal. In fact, there was no real or actual distension of the rated" the new street to the Holborn Valley NY steps taken to increase the certainty bore. as well as the market itself. For seven Mr. Whitworth's projectiles are entirely of centuries Smithfield had continued to be the iron, hexagonal in form, and made spiral to market for live stock, until within recent follow the rifling of the gun, having a years-in 1852-an Act of Parliament windage over the major axis of 0.065in., and over the minor axis of 0.070in. abolished the nuisance, and transferred the cattle market operations to CopenhagenIn the preliminary trials the projectiles were fields. This market was constructed by the of three kinds, viz. :-Common shells having Corporation of London, and now they have parallel rears, and weighing 29041b. empty; added vastly to their former good services by length 31.6in.; diameter, major axis, 8.96in.; the erection of a dead meat market upon the minor axis, 8-18in.; capacity for bursting waste of Smithfield. This, of course, will powder, 18lb. Common shell with taper lead to the closing of Newgate Market, a rears, 285lb. empty; 31.6in. long; in dia- step which no one who has had to pass down meter, 8.96in. by 8·18in.; bursting charge ca- Newgate-street and its neighbourhood during pacity, 181b. And hollow shot with taper rears, market hours will regret. The arrangements 2491b. weight; 24.7in. long; in diameter, of the new market are complete in every 8.96in. by 8.18in. Mr. Whitworth's car- respect; various lines of railway converge to tridges are specially arranged so that the it, beneath the surface, as a central point, powder may be ignited well to the front and by which the supplies of meat will first. A thin copper tube perforated with a arrive. In fact, the basement of the market number of small holes for half its length, is is a through railway station, from which passed through the centre of the charge. there will be communication not only with all Into this at one end is inserted a small parts of the country but with all the funnel-shaped primer cartridge, containing suburban lines. It is intended that, when 120 grains of powder, the object of which is the meat arriving by rail reaches the dep t to ignite the charge of the gun rapidly, and underneath the market, it shall be raised to to begin to move the projectile before the the level of the floorway by powerful hy of action of railway signals must always be welcomed by the travelling public, and, indeed, by the world at large, as an advance in rendering travelling more safe. Junction and station signals have of late been wonderfully improved upon by the "locking apparatus," rendering points and signals dependent upon each other. These are all steps in the right direction, but with regard to distant signals there is still room for improvement. We do not mean to such signals generally, but to a large number in particular cases. To distant signals in curves, cuttings, or in situations invisible from the signal box, allusion is specially made. With regard to distant signals generally, it is usually considered advisable to have them at such a good distance-800, 1,000 yards or more-from the signal box, so as to be easily manageable and easily seen; but of course it is impossible in many cases to fulfil both conditions; either the distance must be shortened, in order to keep the signal in sight, or the distance maintained and the signal left out of sight. In the latter case, it would be impossible for the signalman to know whether his signal acted properly. And in the former the distance would be so reduced as probably to prevent a train from pulling up a sufficient distance | is an important element in the safety of There are many circumstances which may prevent a distant signal being seen-curves, inequalities of the country, intervening bridges, buildings, or other erections, stopping the view. Again, in many districts, fogs prevail to so great an extent throughout the year that a signal at any distance could not be perceptible. There are innumerable instances where such things occur, and it is an important element of safety that the signal should always be visible to the signalman, in order that he may know when he pulls the lever that the signal obeys. If it were not so, how little safety there would be in travelling! The importance of this has been acknowledged as so great that where it is absolutely necessary to have a distant signal out of sight, it is usual to place a second, intermediate between the box and the distant signal, worked by the distant and visible from the box. They are usually termed "repeating signals," but whatever elements there are in the distant signal that are liable to fail, such as the wire catching, &c., there must also be in the "repeater," so that it is quite possible that a distant signal may and the repeater may not work. A serious consideration with regard to these repeaters is the large increase in the expense necessitated by doubling the signals. It must be acknowledged that if it is necessary that the signal should be visible during the day, it must be equally necessary that it be visible during the night. This cannot be done by the same repeater, which would only show its own light; but here, again, we have the double risk of the light going out. This signals. We may possess the expensive arrangement of repeater, that will inform the signalman that the distant semaphore arm is to" danger," but what use would that be if the light were out. The repeater, however useful it may be in the daytime, utterly fails at night. For many years there has been working on the South-Western line a small electric repeater at the Surbiton station. The up side there consists of a sharp curve in a cutting, and the distant signal is quite out of sight. From the signal itself proceeds a wire along the telegraph poles to the signal box, where it is attached to a miniature signal worked by electricity. In the box is a battery connected through the "miniature" along the wire to the distant signal. On the signal is a contact arrangement, which, when the signal is brought by the signalman to "danger," makes contact, and completes the electric circuit, the "miniature" signal immediately shows a similar signal. In this case, the peculiar form is that of the "disc." As soon as the signalman pulls his lever and throws the distant disc to "danger," the electric disc in front of him immediately is turned, and he is at once satisfied that his signal is all right. The experiment answered so satisfactorily that the adoption of the electric "repeater" became more general on the South-Western line, and gradually became extended to other lines. Its original conception and carrying out is entirely due to its inventor, Mr. W. H. Preece, of the South-Western Railway. It is, in reality, an adaptation of his railway electric signals for the block system. It was, however, found that more could be made of this, and under its most recent form it contains not only a correct repetition of the state of the distant signal, but also of the condition of its lamp, whether it be alight or not. We have, therefore, the great desideratum for a distant signal. With such an arrangement, a signal can be placed at its maximum distance, and the signalman will have an indicator in face of him that will give him a faithful register by day and by night of the state of his signal. By a reference to figs. 1, 2, and 3, our readers will perceive the instrument we speak of. (It is equally easy to make the instrument a "semaphore" instead of a "disc" signal). In fig. 2 the disc mounted on a long upright rod D pivoted at the bottom carries at its lower extremity a soft iron armature A; behind is an electro-magnet E E-one end in connection with the line wire to the contact arrangement on the semaphore arm, the other end through a battery to earth; the spring S maintains the disc in its normal position. Immediately the signalman moves his lever, the distant disc is turned; the arrangement on it completes an electric contact between the line and the earth establishing an electric circuit, the battery actuates the electro-magnet, the armature is attracted, and the disc is held over so long as the circuit is maintained. When the signal is reversed, the circuit is broken, the electro-magnet loses its magnetism, the armature is no longer attracted; the spring S, consequently, forces the disc back to its normal position. Fig. 1 shows an ordinary view of the repeater, showing the disc, and the tell-tale in front with the words LIGHT IN. Figs. 2 and 3 will enable our readers to understand this latter arrangement, which is, we believe, principally the invention of Mr. Warwick, of Derby. CC is an electro-magnet of a similar construction to the one we have already described; in front of it is a rod having a hammer H at its lower free extremity, the upper end being attached to a loose spring, and having a soft iron armature a, a short way from that extremity, and exactly in front of the poles of the electro-magnet; a spring keeps this 1 Nov. 27, 1868. THE MECHANICS' MAGAZINE. rod at some distance from the electro-magnet. B is a bell placed under the instrument to be struck by Ĥ. Above the electro-magnet between its poles (fig. 3) is placed a magnetic needle F, carrying on the same axle an indicator I having on it the words IN, OUT. The electro-magnet is connected one end to a battery to earth, the other end to the line wire to the distant signal; but to enable our readers to understand the complete action, it will be necessary to explain the arrangement in the lamp itself. Figs. 4, 5, and 6, will make this clear. A is a strong cast-iron framework. B, a brass tube firmly fixed at C, but free to move at D, its other extremity. E, a lever centred at F, and in its normal position making contact (fig. 6) with the adjusting screw H; the spiral spring G exercises sufficient force on E to keep it in contact with H. 423 ders, iron masts, and miscellaneous details, manipulation which the rivet has to undergo The line wire is in connection with the insulated point H, whilst the framework-and, consequently, the lever-is in connection with the earth. In the normal position of things, a circuit is established at the point H, the current from the battery acts upon the electromagnet, attracting the magnetic needle to one of its poles and showing the signal LIGHT OUT. As this is the position during the day, the handle K is an arrangement for breaking the circuit, and preventing the needless waste of the battery. At dark, when the lamp is lighted, the heat from the flame acts upon the tube B; this gradually expands, but it being fixed at one end it expands at its free extremity D, gradually pressing upon the end of the lever E; as the expansion rapidly increases, the pressure on E becomes so great that the opposite end is forced from H, and the circuit becomes broken, the electro-magnet is no longer active, and the indicator I falls to the position LIGHT in. So long as the lamp burns, so long the indicator will remain in that position. Now watch the effect of the light going out. The temperature suddenly falls, the tube B responds to the change of temperature and contracts, lessening its pressure on E until it presses no longer, when the spring G, now no longer opposed, exerts an opposite pressure on E and establishes its contact at H, the circuit is immediately established, the electromagnet becomes active, attracts the armature, causing the hammer to strike the bell, and calling the signalman's immediate attention to the indicator, which now faithfully shows that the light is OUT. It gives instant warning, and time for the lamp to be put right before danger can arise. Contrast this with the mechanical repeater we have before mentioned, and how favourable the comparison. In usefulness and faithfulness, it is superior; in cost, far less. Need we say more? The foregoing description is, it is to be hoped, perfectly clear to our readers, and the instrument is brought forward as a most useful invention-one calculated to lessen the risk of travelling, and lessen the danger of accident to life and property. Of its perfect success, the number that are now being fixed will give ample proof, the new Brighton branch from Peckham to Sutton having every signal fitted with these repeaters. SHIPBUILDING IN IRON AND WE last week left Mr. Reed's practical ened. To take an example of a three- cause of this loss of strength in the finished read by the author, before the Institution of Naval Architects, on the "Warrior," "Lord Warden," and "Hercules" targets. Lloyd's and the Liverpool rules form an appropriate appendix, because of the numerous references which must necessarily be made to them in any work on practical iron shipbuilding. We have now run-somewhat rapidly, perhaps, but by no means carelessly--over the broad fields of valuable practical matter which Mr. Reed places before us. We would willingly have extended our research, but our limited space precludes this; in fact, our chief difficulty has been to condense and abbreviate. We have, however, said enough to indicate the high character of the volume, and to show that an important addition has been inade to one department of scientific literature. The questions upon which it treats are by no means finite, nor incapable of further extension. On the contrary, the science of shipbuilding is, like most other sciences, capable of further development. | the cause-or, perhaps, one of the causes-con- | metry, and we are glad to see that the author tributing to such a result is the presence of a has produced a volume which is admirably superior ore. Our English ore, it is uni- calculated to promote that object. He haversally admitted, is not of a rich description, divested the subject as much as can be pos and cannot compare with either the magnetic sibly done, consistent with preserving its oxide of Sweden and the northern countries, characteristic features, of all abstruseness or with the hæmatites which constitute a and mathematical complexity, and has sucvaluable source of future wealth in our Indian ceeded in rendering it easy of perusal by possessions. The volume we have noticed is anyone who has had the commonest rudiments arranged upon the paragraph system, which of education. The diagrams are well chosen renders it easy of reference, and affords com- and clearly cut, and the type is all that could plete information upon all points connected be desired in a work of the kind. with a subject so important. The conception of yesterday becomes the theory of to-day, and speedily merges into the practice of to-morrow. But, as far as the subject has been developed in the direction treated of by Mr. Reed, he has fully informed his readers upon every point. The entire volume bears ample testimony to the practical knowledge possessed by the Chief Constructor of the Navy, and his work will remain a standard of reference to shipbuilders so long as true engineering principles and practice continue to be applied to naval construction. The best evidence that can be adduced in favour of the practical nature of the work is that the Lords of the Admiralty have directed that the examinations in practical iron shipbuilding of candidates for promotion in the royal dockyards will, in the main, be based upon Mr. Reed's treatise. NOTICES OF BOOKS. The condensation of valuable matter, so as It may be a somewhat bold statement to to accomplish what may be termed a literary make, but nevertheless we fully believe and scientific multum in parvo, is one of the Euclid, so far as the translation has come most difficult tasks ever undertaken by comdown to us, to be virtually obsolete. Does pilers. In the attempt to do too much, they any single one of his readers remember to generally fail in successfully carrying out have learned it at school otherwise than by what might otherwise be effected. Mr. rote? We confess we acquired it in no other | Humber's latest compilation* embraces the manner, and being blessed with a very reten- results of nearly everything that has been tive memory, were considered to have excellent written respecting moments of strain, action mathematical proclivities, solely upon the of loads, calculation of areas, and proporN consequence of the natural wealth placed merit of knowing Euclid like a parrot. The tions of beams and girders. It would be imstyle and novelty anal skill with which we availed ourselves of their tedious, prolix, and complicated as to abso- office companion similar to that under consiresources, in the shape of iron and coal, may lutely disgust the youthful student who re-deration, but, nevertheless, the manner in be attributed the foremost place that we have quires to have some slight incentives to which the diagrams of strains are treated preever occupied as the votaries of Vulcan.. At enable him to undertake the arduous task of sents many points of interest and value to the the same time, it must be confessed, that our the acquisition of knowledge. We fully pupil and beginner. They serve the purpose once boasted monopoly no longer exists, and endorse the opinions of the author of the pre- of good examples to be worked out on a larger that other nations have followed our example face to the work before us* upon this point, scale. We should be inclined, ourselves, to in exploring and utilizing the mineral stores at and consider that no real progress towards have omitted the first portion of the book, their command. We have a proof of the fact a comprehension of the subject will ever be relating to moments of rupture, as it is not that our French neighbours can fully appre- arrived at by the youthful and immature in- of immediate practical importance. What an ciate the advantage to be derived from a tellect, until the principles of geometry are engineer requires in working out the details thorough knowledge of the subject and art of taught upon a more modern and more agree- of a girder is not the moment of the strain, metallurgy, in the volume before us.* The able system. The manner in which they but the actual strain itself. In the calculaintroduction includes a complete history of are disseminated through the contents of tion of the latter, the depth of the girder, one steel, and its successful employment by Euclid, renders that book a complete scien- of its most important proportions, is taken different nations, with a description of the tific conundrum to anyone but an advanced into account, whereas it is not included in means employed respectively by them for mathematician, who cares little about consult- the simple moments of the strain. This holds developing its useful qualities. After treating ing it, since, by means of ordinary geometry, good so far as the flanges are concerned, but of the action of sulphur, phosphorus, water, algebra, and other higher branches of the not for the web. The depth of the latter has and lime upon the material, the author proceeds same order, he is perfectly independent of its no effect upon the strains brought upon it, to the subject of iron ores and the various fuels theorems and propositions. In addition to provided it be secured from lateral flexure, employed in their smelting. Part the first observing the usual routine of lines, triangles, which can easily be accomplished, in the case introduces us to the theory of steel, including circles, polygons, ratio, and areas, Mr. of a plate girder, by proper angles, tie, or that of the well-known savan Réaumur, and Wright introduces some new applications of other sectional stiffening irons, and in that of also treats of the quantitative analysis of the art, and endeavours, as far as is possible an open web, by first employing a section of that substance. This is a very important in a subject so hackneyed, to throw a new iron suitable for resisting compressive strains, question, as steel is liable to be intermixed with dress over very old materials. The proper and secondly by interbracing the diagonals many foreign bodies, such as alumina, chrome, way for the beginner to learn plane geometry, themselves, if the web be double. The effect of lime, manganese, and magnesium. These and to profit by his knowledge, is to take a the various positions of a load upon a girder may all be discovered and estimated by the small drawing board, pencil, compasses, and are accurately investigated, and give the action of suitable chemical reagents, com- scale or ruler, and work out the propositions same results as those arrived at by ourselves bined with the ordinary mechanical means before him, carrying on, at the same time, in in our articles upon that subject. We regret usually at command in all laboratories. The his mind the process of reasoning that will to find that the author has not more fully inmetallurgy and working of steel occupy the lead him, in conjunction with the diagram, to vestigated the cases of wrought-iron arches second and third parts of the volume, which thoroughly master the problem he has in hand. and those of curved roofs, which are now so includes an account of the new processes. Either of the two operations may not be suf- much used by engineers in the Metropolitan These the author alludes to as the Chenot, ficient without great labour, but when the and other stations. This is a branch of the Bessemer, Taylor, and Uchatius processes. two are carried on simultaneously, there is subject of beams and strains regarding which An interesting reference is made to the little or no doubt but that a complete under- very scanty information exists, while the others Damascus blades, so highly prized by oriental standing of the case will be obtained. At are all more or less trite and familiar to prowarriors, and which, it appears, all the efforts the termination of each of the four books or fessional men. Those who are acquainted of their western brethren, aided by their subdivisions comprising the volume, the author with Mr. Stoney's admirable work on strains greater skill and knowledge, have been unable has added a series of exercises embracing a will at once perceive that Mr. Humber has to imitate. Part the fourth is devoted to the number of questions, calculated to test the trodden in the same path, his object evidently properties and the uses of steel, embracing the proficiency of the student in the contents of being to reproduce in a handy form the majority various forms of files, plates, saws, needles, the previous pages. There is no doubt but of the instances and examples afforded in that and wires. A valuable appendix brings this that the greatest amount of attention is de- larger and more comprehensive volume, and useful volume to a close. It is an extract from manded by the third "book," which treats of so far he has succeeded. Short rules are given the report upon Bessemer steel by Abram ratio and proportion. It is not difficult to per- for the calculation of the proper proportions S. Hewitt, the United States Commissioner.ceive, without any great mental exertion, the of bolts, rivets, and other usual methods of From this report it appears that Sweden pro-ratios of dissimilar lines, but it requires a forming constructive connections, and a deduces a superior description of metal to ourscription of the various ways of delineating selves, and is able to turn out a finer kind of the parabola, concludes the contents of the wire. The ore used in that country is the little book. The diagrams and plates are well-known magnetic ore and is represented small but well defined, clear, and explanatory by the chemical formula Fe 3 O 4, or, as it is of the text. It would have been an improvesometimes written, Fe 2 O 3 + Fe O. A ment if the type selected had been a little similar superiority over English steel is also larger, although the heading of each proposiexhibited by that produced in Austria, and tion being printed in black letters renders them sufficiently distinct. "A Treatise on Steel, comprising its Theory, Metallurgy, Properties, Practical Working, and Use." By M.H. C. SANDRIN, jun., Civil Engineer. Translated from the French, with notes, by A. A. FESQUET, Chemist and Engineer. With an Appendix on the Bessemer and the Martin Processes for Manufacturing Steel, from the report of ABRAM S. HEWITT, United States Commissioner to the Universal Exposition, Paris, 1867. Philadelphia: Henry Carey Baird, Industrial Publisher, 406, Walnut-street. London: Trubner and Co., 60, Paternoster-row. 1868. higher exercise of the intellect to follow the "A Handy Book for the Calculation of Strains on Girders and Similar Structures, and their Strength; con"The Elements of Plane Geometry, for the Use of sisting of Formula and Corresponding Diagrams, with Schools and Colleges." By RICHARD P. WRIGHT, formerly Numerous Details for Practical Application," &c. By Teacher of Geometrical Drawing in Quenwood College, WILLIAM HUMBER, Assoc. Inst. C.E., Author of "A PracHampshire. With a preface by T. ARCHER HIRST, F.R.S., tical Treatise on Cast and Wrought-Iron Bridge Con&c., Professor of Mathematics in University College, struction," "A_Record of the Progress of Modern EaLondon. London: Longmans, Green, Reader, and Dyer.gineering," &c. London: "Lockwood and Co., 7, Stationer's 1868. Hall-court. 1868, |