138 MECHANICS' MAGAZINE, which has some claim to the title of its parent, may congratulate the nation on the results of its labours. The clear exposition of the opinions of Sir Howard Douglas regarding the Warrior and iron ships (with which the meeting opened) It does not require any comment from us. must, however, be gratifying to know that the Warrior, as an experiment, is regarded as eminently satisfactory by all parties, even by Sir Howard, who still reiterates his statement regarding the utter worthlessness of iron ships But such an admission as for purposes of war. that made regarding the Warrior seems to us fatal to the cause of those who advocate wooden ships, and fatal to the policy of those who persist in building them. THE MECHANICS' MAGAZINE. which prevailed up till lately, are temporary introduce steam fire-engines in America ten drawbacks, and that the breadth and fertility of years afterwards. In the year 1842, the Matthe field to be cultivated will increase annually. teawau Company furnished the fire insurance There is one of the objects which the Insti- companies of the City of New York with a tution proposes to accomplish that should also steam fire-engine of great power. It was made afford regular work for these annual meetings, under the conditions that the engine should be and it may be also for annual or permanent drawn either by men or horses; and that it committees, under the 20th article of their should throw water over the flag-staff on the constitution. We refer to the carrying out by City Hall. The machine was completed to the the collective agency of this Institution such satisfaction of the authorities, under the superexperimental and other inquiries as they deem intendence of Mr. Hodge; and when put in essential to the science and art of shipbuilding. operation, it threw a 15-inch jet over the ap We do not suppose that the Institution propose pointed flag-staff. The engine was stationed in to spend money in experiments, but they should Mercer-street, and was mainly instrumental, certainly make arrangements for ascertaining shortly afterwards, in extinguishing a serious conthe value of new inventions, and should decide flagration in Dover-street, which so chagrined upon the best means of using their influence for and annoyed the fire companies, that it was found A very remarkable change has, testing them. We may ask whether they rely impossible again to bring it into use, and the upon Government or upon private shipbuilders insurance companies eventually sold it for other for following their suggestions, and what influ- purposes. As the result of these experience do they possess with either? No doubt however, taken place in the opinion of our ments we may state that he ascertained plates the naval architects in Her Majesty's service transatlantic cousins on the subject of steam protected in front by a shield of wood to be will co-operate cordially with private ship-fire-engines since that time. Cincinnati was much better for resisting shot than plates builders; but which of them should bear the the first to adopt and regularly employ a steam backed by wood, as in the construction of the expense of testing the value of such new inven- fire-engine of great power; and the number Warrior. Also the opinions expressed by Mr. tions as the Institution of Naval Architects and power of these machines, already built or J. Scott Russell, Mr. Chas. Lungley, and the may endorse or recommend? Questions of building, in the United States is something exgentlemen whose papers will occupy the atten- science will naturally occupy the first place in traordinary, but by no means out of place in a tion of the Institution to-day and to-morrow, their discussions, but the common interests of land where all the accidents by "fire and flood" must be of the highest value to a nation whose the whole body of naval architects in Great are upon the scale gigantic. In several of the existence depends chiefly upon its navy. These Britain affords a wider field for the labours of States, the steamers have entirely superseded rapidly becoming everywhere universal. papers are all most appropriate to the present this Institution than is opened by the papers the hand-worked fire-engines, and their use is position of Great Britain, and we expect the named in their present programme of proleading facts and opinions stated in them will ceedings. be widely circulated. The experiments with iron-covered targets made by Mr. J. D'A. Samuda will doubtless have some influence in deciding the question of vessels for war. STEAM FIRE ENGINES. But there are one or two points regarding which the public naturally feel interested Ir is now just thirty years since Mr. John besides those mentioned in the programme of these meetings. The larger portion of their time Braithwaite, C.E, first applied steam to work The first steam fire-engine he fire-engines. is occupied with questions regarding war-ships; first, "iron vessels of war, iron-cased;" then constructed was of great power, somewhat ob"the construction of iron-cased vessels of war" jectionable from its weight, besides being weak on its carriage; it was for a long time stationed and the prothen "shot-proof vessels of war; on the docks at Liverpool, but was seldom used. ceedings terminate with a paper on "the conHe then built a lighter engine of smaller "struction of unsinkable iron ships." This is certainly what might have been expected, and power, which, in 1832, obtained considerable the country must be deeply indebted to her celebrity, from being brought into action at foremost naval architects for combining their several important conflagrations in the metroexperience and labours for the nation's safety polis. At the burning of the Argyle-rooms, and prosperity. We are pleased to see the the English Opera house, and Barclay's brewery, After working for many naval architects of this country and France Braithwaite's steam fire-engine greatly distinguished itself. acting in concert, and the drawing (made by hours at the latter fire, it was afterwards emher architect) of our neighbour's greatest ployed ten hours a day for twenty-five succesachievement in shipbuilding for the purposes sive days, in pumping up beer; the engine and of war, handed round for the inspection of those who must be our main reliance should pumps of the brewery having been destroyed by the fire. Upon this occasion the capabilities such vessels as the Gloire be used against us. Having But we may remind the Institution of other of the engine were very fully tested, and it highly important questions which should always acquitted itself very satisfactorily. occupy a place in their annual discussions. It demonstrated the value of such a fire-engine at large conflagrations, Mr. Braithwaite subis expected that, at an annual meeting of this mitted to the managing committee of the character, some statement regarding the past progress of the science, a sketch of what has London Fire-engine establishment his plans for the construction of steam-worked land and His propositions were been achieved, and a survey of what remains to floating fire-engines. be done, should be attempted. We regret to state that Sir John Pakington did not attempt met, however, with the most frivolous objecanything of this kind. Also the statistics of tions. His engine was said to be "too powerful" for common use, too heavy for rapid new inventions, the statistics of shipbuilding travelling, and requiring such "large supplies of generally, both at home and abroad, the pro"water" as could not often be obtained in London streets. Instead of employing Mr. gress of foreign nations in this art, the education and training of the men who are to build or Braithwaite's engines to throw water on their navigate our future ships, should always claim a fires, they threw cold water quantum suff. on small portion of time at those annual meetings his plans. The firemen of the brigade too (takOnly one paper touches upon questions of this ing the cue from their masters), perpetrated all 66 American River character, namely, that on manner of annoyances, throwing every possible "Steamers." It would undoubtedly have been for the advantage of the shipbuilders of this impediment in the way of the powerful interloper; and Mr. Braithwaite finally gave up the country if more information regarding the progress of their art abroad were given at their unequal contest in disgust. The fact was, the "hour" was not come, nor the " meetings. We suppose the youth of the Institution and the general ignorance (with a few exceptions) of the art of naval architecture 66 man יי! No better fared it with the first attempt to A public trial of steam fire-engines took place recently at Rensselaer County fair, Troy, New York, upon which occasion seven machines competed, varying in sizes, from Lee and Larwith its Niagara," ned's self-propelling 12-inch jet, throwing 1,200 gallons of water per minute, to the "Mechanics' Own," drawn by hand, with its 11-inch jet, throwing 220 gallons per minute. The Portland Company, in Portland, Maine, are at this time building five steam fire-engines of J. B. Johnson's patent, one of the largest size for Portland, two thirdclass for New York, and one second-class for Philadelphia. The third-class are light engines weighing rather less than 28 cwt., and being mounted on high wheels are easily drawn by hand with great rapidity. An engine of this "hours consecutively without stopping"-a feat class has, it is said, "played upon a fire five which it would seem as if these engines are not always able to accomplish. In consequence of an accident which recently happened to one of the Croton pipes, most of the members of the Board of Aldermen were brought to the every fire company in the city of New York conclusion that it would be advisable to provide with a steam fire-engine. For some few years past the two floating fireengines on the river Thames have been worked by steam power, and in July last a land steam fire-engine, built by Messrs. Shand and Mason, made its debut at a somewhat insignificant fire at a box-maker's in one of the back streets in Doctor's Commons, since which it has figured at several fires of magnitude. A full description of this machine has already appeared in our pages.† Its power and water requirements, certainly not less than were those of Mr. Braithwaite's engine, do not appear to have been found in any way objectionable. At the ordinary rate of working it throws an inch jet 120 feet high, being about equal to the power of two ordinary brigade engines. At one of the meetings of the Association of Foremen Engineers, Mr. Stabler described this principle, pointing out what he considered its engine as of American origin, and unsound in Patented in America and in England, + Vol. 1, page 124, and Vol. 2, page 24, been successfully employed for stopping fires in their earlier stages, as well as for cooling ruins afterwards. weak points. It might have been supposed | that now-a-days there could be no difficulty in producing a steam boiler of any required capability; yet in many of the American steam After all that can be said upon the subject, fire-engines, the production of steam is very the employment of the "common drudge," irregular, and the pressure constantly varying. steam, inevitably resolves itself into a question In that of Messrs. Shand and Mason, however, of pounds, shillings, and pence. The associated the steam is generated as rapidly and with offices subscribing to the fire-engine establishgreater steadiness and uniformity of pressure; ment do so for the purpose of getting fires put indeed, the steam-engine is decidedly the best out quickly to keep their losses at a minimum part of the machine, and appears to have been-and this, of course, at the smallest cost. Very sacrificed to an inferior pump. It is not a little inexpensive means suffice for the suppression of singular that it should be supposed that fire-fires in their earlier stages; but if, as too freengines worked by steam power require a dif- quently happens, the premises are thoroughly ferent kind of pump to that employed in on fire before the mischief is discovered, all manual machines. The Americans are using past experience shows that the fire burns itself both rotary and plunger pumps, some manu-out, and fire-engines produce but little effect facturers strongly advocating the former. until the greater portion of the combustible Messrs. Shand and Mason employ a plunger matters have been consumed or fallen to the pump, but one that is thought to be open to ground. Steam fire-engines could never greatly several serious objections. Common sense change the character of these fires. Newspaper seems to suggest that the form of pump which reporters often enlarge upon the "saving" of long experience has proved to be best for hand- hired auxiliaries effected by the use of the worked fire-engines must also be the best with steam fire-engine-a matter in which the public any other motor. Mr. Superintendent Braid- take very little interest, seeing they are not wood, who cannot be suspected of any intention called upon to pay for either one or the other. to "damn with faint praise," states that the Taking into account the costliness of the maland steam fire-engine requires "very delicate chine, the expenses of wear and tear, fuel, &c., handling;" and there is no doubt that, but probably the "saving"- -as compared with the for the very careful nursing it has had, accidents ordinary hand-worked engines-would figure would have been more numerous. Thanks to on the wrong side of the ledger. the admirable plan introduced by Mr. Baddeley, the London fire-engines are usually supplied with perfectly clean water; but there have been occasions when muddy ditches, gravelly ponds, and common sewers were the only available sources of supply. The jurors of the Great Exhibition of 1851 subjected the fire-engines there exhibited to a test which, considering the circumstances that may, and often do, arise in practice, was not a severe or unreasonable one. They were set to work with the suction-hose buried in gravel, and worked until they cleared themselves. The Canadian fire-engine of Perry, and Mr. Merryweather's brigade engine "Prince "Albert" (the original Hadley and Simpkin engine of 1792) stood the test admirably Messrs. Shand and Mason's improved brigade engine was not subjected to this trial.* This test ought to be a sine qua non with all fire-engines; it is very doubtful, however, if any steam fire-engine hitherto made would stand it-the steam fire-engine recently made for the Tyne Docks by Mr. Merryweather only excepted.+ It would be altogether unfair to regard Messrs. Shand and Mason's steam fire-engine as a chef d'œuvre, or even as a fair specimen of what English manufacturers could do in this line. Probably there is not an engine-maker but would be highly indignant if a doubt was insinuated of his ability to make "a better one "than that" if an opportunity was afforded him. But there exists no demand for the article. It was hardly worth while, in leed, for Mr. Shand to patent the invention, seeing that, in the first place, his relationship to the chief of the brigade gives him a close monopoly of that market (and there is no other); and secondly, because it is quite certain that no other manufacturer would willingly adopt that form of construction. The fact is, that steam fire-engines can never come into very extensive use in this country; serious conflagrations are of comparatively rare occurrence except in London, Liverpool, and Manchester, and in the two latter places an admirable system of high-pressure water supply has almost entirely superseded the use of fire-engines. Many smaller provincial towns have the benefit of similar arrangements, and even in London a jet from the main has often Vide Report of Juries, page 180, In his last report to the Committee of Management, Mr. Braidwood says:-"That at "floating engines, the land steam fire-engine "large fires beyond the reach of the steam "has been of great service. It is not only the "large quantity of water it throws, but the "great height and distance to which it is "thrown that makes it so valuable; at the same time it can be worked as gently as a common (ordinary) engine." There are no doubt several advantages attending the use of steam-worked fire-engines, its untiring capabilities in particular; but realised from its use than can be obtained with unless a much larger amount of salvage can be hand-worked engines, there can be but little inducement-in a pecuniary point of view-for brigade would be "paying too dear for their its employment; and in that case the fire "whistle." Literature. Notes on Screw Propulsion: Its Rise and Progress. By W. M. WALKER, Commander U.S. N. London: Trubner and Co. THIS re-publication of articles which have appeared in the "Atlantic Monthly" is a popular survey of the question, especially with view to the increase of the naval power of the United States. As might be expected, due credit is given to American inventors and improvers of the screw propeller. The author undertakes to form pared for war. "The national safety should be no a public opinion in favour of being always prelonger left to chance, but established on a basis of certainty. A navy cannot be manufactured, nor a fortress built to meet an emergency, but should be kept ready made." While admitting the importance and necessity of providing for special service a small class of fast, full-power steamers, it is submitted that the auxiliary screw steamer is the description of ship to which the largest and best consideration should be devoted, for to the nation possessing the most efficient fleet of such vessels, must belong the dominion of the them the best defence at home. The author's sea. Their capacity of aggression abroad makes idea of a perfect screw frigate may be worthy of consideration by our naval architects. To create such a vessel, a ship with sail power complete, and efficient for any service that may be required, the endeavour should be made, by getting rid of every dispensable article of weight or bulk, and without reducing supplies below three months' provisions, and six weeks' water-to find space and displacement for an engine of sufficient force at least ten days' full consumption of fuel." This to drive her thirteen knots an hour, together with appears to be a correct expression of American opinion on the best means of providing for national defence. Nothing is said of iron-cased ships of war. The Americans have no fears of aggression from abroad, no desire for conquest or dominion on the sea; and questions of rifled cannon, ironcased ships, fortifications, war expenditure are, happily for them, of as little importance to them as to us during the year of the Great Exhibition. They cannot teach us anything on these questions, for they are, at least in this department of progress, ten years behind Great Britain, France, or even Russia. The Engineers', Architects', and Contractors' Pocket-Book for 1861. London: Lockwood and Co., Stationers'-hall-court. 1861. THIS volume contains the latest and most reliable information regarding all the different maand contractors have to deal. terials and forces with which engineers, architects, formula contained in it are well printed, and, so The tables and them correct. The arrangement of the contents far as we have examined them, we have found might be much better, and as a pocket-book its value would be increased by the insertion of blank leaves. This might have been done easily without increasing the size of the volume, if only the results of recent experiments had been stated might be obtained. with references to where further information For instance, the article "On the Present State of the Art of the Manu facture of Iron, with some remarks on the iron trade of Great Britain, and upon iron-plated ships, and upon iron-wire bridges," is highly pocket-book. No information is given regarding valuable, but scarcely suited to the pages of a the construction of ships or naval architecture. None of the learned societies, except the "Institution of Civil Engineers" and the "Institution of British Architects" are mentioned. The index also is meagre. HOW BRONZE MONEY IS MADE AT THE ROYAL MINT. coinage of bronze and its manufacture which are THERE are many facts connected with the new unknown to the public generally, but which are interesting and worthy of remark. As we happen to be in possession of much exclusive information in relation to the subject, we shall not hesitate in communicating it. In former papers on the coinage generally, a full account of the manipulation of ordinary metals at the Royal Mint has been given in our columns, but as there is something quite exceptional in the mode of treating bronze at that place as compared with gold, silver, or copper, it will be well to supplement those papers by one on this peculiar metal. The idea of using a composite instead of a simple metallic substance for coins and medals is a very ancient one, and was, undoubtedly, acted of a resuscitation of that idea in modern times upon in Pagan Rome. The most notable instance the present Emperor Napoleon; and it is a rewas the remodelling of the coinage of France by markable coincidence, if it be not the result of direct arrangement, that the five, two, and one centime pieces of the existing coinage of the French empire are composed of a mixture of metals identical almost with that used in the days of the Caesars. We in this country have also adopted the plan, and no doubt it will be followed largely in other countries. Victor Emmanuel has indeed already given orders for a Italy over which he now holds sovereign sway, bronze coinage for the enfranchised kingdom of and at Milan a gigantic mint is in course of erection for the purpose of striking it. Bronze, therefore, is the popular material for subordinate monies, and a chapter may well be devoted to it. We have before given the precise proportions | the presses, while the honey-combed fillets them- or farthings, they are considered to have done of copper, tin, and zinc, and they need not here selves are relegated to the melting house. excellent service at the Mint. As in the previous be repeated. They produce, after emanating from The next operation in regard to the manufac-stages of manufacture we have shown that the the furnace, a remarkably hard composition, and ture of bronze coin is to pass the "blanks" through processes are numerous, exceptional, and difficult for the purposes of the British Mint it is moulded machines which raise an edge on their circum- in regard to this peculiarly obstinate metal, so it into bars of about three feet in length, 24 inches ferences and make them slightly smaller in dia- will be readily understood that the expenses of its in width, and in. in thickness. These are cast meter. Then comes another annealing, and this coinage are great. It costs, in fact, nearly double vertically in cast-iron moulds of great smooth- time they are put into circular copper tubes about as much to coin a bronze farthing as it does to coin ness, and which divide into halves to allow of the two feet in length and four inches in diameter. a golden sovereign! Fortunately, however, this removal of the bars. The crucibles used are of They are covered with a layer of charcoal, and complication of difficulties is attended by two adprecisely the same nature as those employed in sealed by a lute of fire-clay from the admission of vantages. Counterfeiting becomes almost an immelting gold, and bronze bars when released from air. The tubes thus charged are put into rever-possibility, and there is a wide margin for extra the moulds resemble closely that precious sub beratory furnaces and submitted to a saturating expenditure in the difference of value between the stance. They differ, however, most materially red heat for the space of an hour or an hour and a price of the metal in the market and its current in weight, and those who are in the habit of quarter. Drawn from these uncomfortable quar- value when coined. handling both would not be for a moment mistaken as to "which is which." ters the tubes and their contents are allowed to دو After the bronze bars are cast they are removed to the rolling mills and put through a course of lamination. This is a thing much easier said than done. The rolls are sustained in massive frames, and their surfaces having been chilled after casting are as hard as steel. They are about fourteen inches in diameter, and their circumferences travel at the speed of thirty feet per minute. As in the case of gold and silver, the bars of bronze at the Mint are rolled while quite cold, but those two metals work like lead in comparison with the inferior material. The forty-horse power engine which drives the mills scarcely seems to feel the work of gold and silver rolling, but in that of bronze lamination it is taxed to the uttermost. It is necessary to reduce the thickness of bronze bars by very gradual stages, for if too heavy a pinch were to be attempted the rolls would inevitably suffer. Compression between the rolls naturally increases the density and hardness of bronze, and after several pinches have been administered the bars have to be cut into short lengths and placed in annealing ovens. Submitted to a considerable heat-that of redness-and allowed to remain so in that state for perhaps half-an-hour, they are next withdrawn and permitted to cool gradually. The bright golden hue entirely dis- The coining-press room is their next destinaappears after this process. Oxydation has given tion, and into this, with a view to preventing the bars the appearance of strips of wrought-iron, peculation, they are carefully weighed in detachand before repeating the rolling their black and ments of half a cwt. each. And now arrives another scaly surfaces must be removed. An acid bath is difficulty. The annealing to which they have the medium for effecting this change. It is com- been subjected has softened the blanks as fully as posed of weakened sulphuric acid, and the work- without actually fusing them they are capable of people who deal with it are properly clothed in being softened, but their extreme thinness is a woollen dresses and have their hands protected by barrier to their being easily impressed by the vulcanised india-rubber gloves. Wire scratch dies. Distributed among the press tendersbrushes are used for completely detaching every boys of about fifteen years of age-they are particle of scaling, and when something like the placed in the feeding tubes of the presses. These original brightness of the metal has been restored, are next put in motion, and one by one the blanks the bars are passed forward for further lamination are carried forward to the lower or obverse die of at smaller mills, and at these are brought to each press. The upper or reverse die now degauged thicknesses suitable for the penny, half-scends with much force upon the blank, whilst a penny, and farthing. In this subsequent series of fine" rollings, as they are termed, many pinches have to be administered to the strips, which appear obstinately determined to yield only under heavy and continuous pressure. Not unfrequently they fracture at the edges and sometimes split along the centre from end to end. At last, however, after three or four times the amount of trouble experienced with gold or silver, they are found by the application of the graduated gauge to have assumed the proper dimensions as regards thick ness. The second system of millings ends naturally in compressing the metal again, and thus making it totally unfit for receiving impressions. The "fillets "" of bronze-as the reduced bars are termed-are next advanced to the cutting-press room-described fully in the MECHANICS' MAGAZINE of July, 1859-and are there perforated from end to end by circular-cutting punches a little larger in diameter than the particular coins to be produced. These punches suffer, too, from the hardness of the material, and require more frequent adjustment than when employed on the precious metals. It seems, indeed, as if bronze had an inherent objection to being coined, so stout an opposition does it offer at every stage of progress towards that consummation. The discs of metal cut from the fillets fall into boxes beneath steel collar well polished on its interior circum- | Messrs. Watt and Company, who undertook many months ago a contract for the supply of 1,800 tons of bronze coin to the Mint, have, we believe, experienced the difficulty of working the metal to the fullest extent, for their new minting machinery at Soho, near Birmingham, has failed as yet in producing money at all equal in quality to that which emanates from the Royal Mint presses. With every advantage in the shape of practical information from Mint officials, and the free entrée to the Mint itself of their own workmen, the contractors in question appear to be quite incapable of competing with the Mint in How hopeless, the creation of bronze money. then, for needy counterfeiters to attempt to imitate the new pence, halfpence, or farthings! The extreme lightness of the coins form unquestionably one of their greatest recommendations, and though it is a misfortune that the whole of the heavy copper money was not at once relegated to the furnace when the bronze made its appearance in public, yet we feel assured that its comparative lightness must be generally appreciated. With respect to the artistic portion of the work there exists much diversity of opinion. Many praise it unmeasuredly as a great success, and others as unsparingly condemn it as a failure. For ourselves, we were anxious to get rid of the emblem Britannia as the reverse of the coins, and so suggested before the dies were cut. The suggestion was not attended to, but that was not the fault of the artist, and he has endeavoured to make the most of the stalwart lady. It is impossible for us to agree with Mr. Sebastian Evans, nevertheless, as to the obverse. That gentleman, as shown in a late number, in a paper read before the Numismatic Society criticises with great severity the engraving of Her Majesty's head. "The shape of the head" he states to be "incorrect, particularly in the upper portion of the forehead, and the likeness is bad." Now, we submit that if there is a point about the engraving which is worthy admiration it is that of the extreme fidelity to the original of Mr. Wyon's portrait of the Queen on the new coins. Mr. Evans had better study again-if he be favoured with the opportunity-the "expression" of the royal features which the artist has endeavoured to convey to the metal discs of the new coinage, and then, if he speak conscientiously, he will not pronounce the likeness "bad," but, on the contrary, very good. There seems to be a widely disseminated idea that a percentage will presently be offered for the old copper coins, and that the large pennies of George III. will be especially sought after by the Mint. Hence, collectors of the doomed money are hoarding it in large quantities, and causing thereby much inconvenience to the public. Now, the Mint is not likely ever to offer more than one per cent.-payable in new bronze coin-for the old copper, and that offer will not be made for at least two years to come. It becomes a pertinent question, therefore, whether the hoarders had not better rid themselves of their unprofitable hoardings without delay. THE CLOCK AND WATCH TRADES.-From the trade and navigation returns just issued we find that in the year ending Dec. 31, 1880, 313,362 clocks and 154,024 watches were imported into the United Kingdom. THE NORTH ATLANTIC TELEGRAPH. IN No. 112 we gave a description of the sea sections of the north-about route for the proposed telegraph to America. In this number we give a brief description of the electric circuits, as illustrated by Col. Shaffner, at the late meeting of the Royal Geographical Society. In explanation of Diagram 1, he said:"It represents a voltaic current traversing a line on poles; M is the magnet, A the armature of the lever L, B the battery, and K the key or circuit closer, with contact point C, at station 4. Like apparatus is at station B. By this diagram it will be seen that the course of the electric current leaves the positive end of the battery B, and passes through the metallic key K, when brought into contact with the metallic point C, thence with the line wire L L to station B, and thence through the respective instruments to the metallic plate F, thence through the earth EE to the metallic plate N, along the wire to the magnet M, thence to the negative pole of the battery B, which completes the voltaic circuit. Before proceeding further, it is proper to say that the course of the current, when it takes the earth at station B, remains a mystery in physics, and I assume its return to the battery from whence it originated. By elevating key K the circuit will be broken; and it is the opening and closing of the circuit, in time methodically arranged that constitutes the alphabet for the transmission of intelligence." Diagram 2 represents the combining of two or more electric circuits together, so as to overcome distance and to avoid the re-transmission of despatches by the hand. Mechanism performs the work. The diagram is not intended to represent the translator in common use on telegraph lines. The modern apparatus was exhibited to the Society, but we have not space to describe it. The principle of coupling circuits together is all that we propose at the present time to explain. The diagram contemplates the sending of despatches but one way; but the translator in common use on telegraph lines permits transmission both ways on the same line of wire. It is not necessary for us to explain fully the difference between the working of long and short circuits. Col. Shaffner has for many years contended that a circuit of 2,000 miles can not be practically employed, with the known sciences, ICELAND. THE MECHANICS' MAGAZINE. across the ocean. for commercial telegraphy. there are those who hope to work a line direct On the other hand, that short circuits, such, for example, as those proposed on the North Atlantic telegraph, can be All electricians, however, agree commercially operated, and in this respect the promoters of this great enterprise are calculating upon certainties. There is a retardation of the electric force when transmitted through submarine conductors. The cable becomes a Leyden jar, and with a circuit, such as from Ireland to Newfoundland, this hindrance would be so great, cial telegraphy cannot be possible by that route that in the opinion of many electricians commerto America. The promoters of the north-about telegraph express great confidence in being able per minute. to transmit by that route at least twenty words lines is about forty words per minute, but owing The ordinary speed on telegraph to the retardation, common to long submarine circuits, no such celerity can be attained through an ocean cable. the electric current passes through submarine It has been determined that conductors at the rate of one-third of a second for five hundred miles, and one second for one thousand miles. the proposed North Atlantic telegraph, Col. ShaffTo illustrate more fully the electric circuits of model stations representing Europe, Faroe Isles, ner had arranged around the Geographical-room Iceland, Greenland, and America. He described ELECTRIC CIRCUITS COMBINED. DIAGRAM 2. A 141 represented by diagram 2, and he operated the the mode of manipulating combined circuits, as of the model stations precisely as can be worked on the proposed telegraph. various telepraphic apparatuses at each and all by the large and distinguished auditory. were very successful, and were highly appreciated The experiments tive circuits of the North Atlantic Telegraph will be within the bounds of known practicabilities, and we have no reason to expect other than the In conclusion, Col. Shaffner said, "The respecfullest success and the attainment of a calculated structed on poles that work in circuits more than perhaps 500 miles. There is no retardation on celerity. There are no air lines or lines consuch lines. The telegraph from London to St. Petersburg is about 1900 miles, and upon that dou to Odessa the telegraph is about 3,500 miles, range there are eight relay stations. From Lonand there are about fourteen relay stations. From London to Constantinople it is about 3,200 It is a common occurrence to work to the stations miles, and there are about twelve relay stations. mentioned through the aid of mechanical contrivances. It is in this manner that telegraphic with one bound" from continent to continent by though the original electric spark will not "leap manipulations overcome long distances, and alwill pass between the hemispheres with a celerity the North Atlantic Telegraph, the intelligence commensurate with the wants of the age." SCOTLAND. DESCRIPTION OF THE APPARATUSES.-At Scotland:-K is the key; c, point to close circuit; B the battery connected with earth plate N from negative pole V. At Faroe Isles:-M is the magnet; A the armature of the lever L; F the fulcrum post; C the contact post; B the battery, with its positive pole P; N'and P are earth plates. The black arrows indicate the course of the voltaic current through the cable; dotted line E the current returning to the earth plate N, and to the battery at N. At Iceland :-The apparatus is the same as that at the Faroe Isles. MANIPULATION OF THE APPARATUSES.-When the key Kat Scotland is pressed to make a contact at C, battery B sends its electric current in the direction indicated by the arrows to C; through the key K, the submarine cable to magnet M, through the coils of the magnet M to earth plate P, and thence to earth plate N, as indicated by the dotted line E. In this manner the circuit is completed. At the Faroe Isles, when the current through the cable to the magnet M at Iceland; then to earth plate P; then traverses the magnet coils M, the armature A is attracted down, and the lever L makes a contact with C, which closes the next circuit. The current passes from battery B with the dotted line E E to plate N; then up the fulcrum post F through the metallic lever L, and the contact post C to the battery B. When the current traverses the coils of magnet M at Iceland, the armature of lever L is attracted down, and a connection is made at C, which closes the circuit to Greenland. At Greenland there will be a like recording instrument, and despatches can be received simultaneously at the Faroe Isles, apparatus, which will close the circuit to Labrador; and at Labrador will be another Iceland, Greenland, Labrador, and Quebec. apparatus which will close another circuit to Quebec. At each place there can be a The author stated that his object was merely to record the results of actual trials, and the conclusions to which they led. In 1853, an experimental length of a quarter of a mile (double line) of iron way, on the principle of Mr. I. J. Macdonnell (M. Inst. C.E.), was laid on the Bristol and Exeter Railway. It consisted of a continuous rolled iron rail bearer, weighing, on an ave rage, 831 lbs. per lineal yard, and 11 inches in width. The bearers were united by joint or saddle plates 30 inches in length, weighing 50 lbs. each. The bearers had a rise in the centre of 9-16ths of an inch, and a rib or tongue was rolled on the upper side, which fitted approximately into the hollow of the bridge rail. The rails originally laid weighed only 53 lbs. per yard. Between the rail and the bearer, a thin packing of pine wood was placed, the grain being in the direction of the length of the rail. The rails, the bearers, and the joint plates, were bolted together, the distances between the intermediate bolts being so arranged as to admit of a rail being readily turned by unscrewing the nuts, or of a new rail being put in, without opening out" the ballast. Transoms, or cross ties of angle iron were placed at average intervals of 12 feet between the two rails, and of 24 feet between the two lines. This system differed from the Barlow way, in having the rail or wearing surface separate and easily removable from the bearing surface; but, on the other hand, it considerably exceeded the Barlow rail in weight. After a wear of more than seven years, this length of iron way was in good condition, and bids fair to continue so for some time to come. About one-third of the rails proved defective within the first two years, and had been replaced by rails weighing 60 lbs. to the yard. The ballast, which was very indifferent, being a loamy gravel, had been well drained, and thicker packing, laid with the grain transversely to the direction of the rail, had been introduced. The bearers and joint plates, transoms and rails, were supplied at £7 per ton delivered, and the cost per single mile of this arrangement, exclusive of the cost of matching and laying, was £1,936. The cost of a single mile of the longitudinal timber way, at the same period, taking the rails at the same weight and price, was estimated at £1,850. It should be mentioned that iron was then low in price, whilst timber was high. Owing to the undue lightness of the rail, both of these calculations were below the cost of a well-constructed permanent way. As this experiment appeared on the whole to have been successful, it was determined to extend the trial, by laying one mile of double line on this system, at a further distance from a station, so that all the trains should pass over it at full speed. Some modifications were, however, made. The width of the bearer was soms, was taken at £9 12s. per ton, and, the rails being £8 13s. id. per ton, the cost per single mile was £2,571. In order to test the comparative strength of the different sections of bearer, of rail and bearer com bined as laid, and of the rail and bearer joints with and without joint plates, a series of experiments was form. The distance between the points of support was made, the results of which were given in a tabular 5 feet. Of the three sections of bearer only, that of 1853 (the first) showed the least, and the flat section of 1859 the greatest deflection, under a load of about 5 tons; but in each case the ultimate strength did not exceed 7 tons. Of the three sections of iron way complete, that of 1853 was the weakest, and the curved section of 1857, with a rail weighing 68 lbs. per yard, rather the strongest. The ultimate strengh was reached under loads varying from 19 to 21 tons. An experiment with the flat bearer showed, as was expected, the increased stiffness gained by placing the centre rib downwards, thus practically deepening the girder. The ultimate strength of the timber way than the iron way. It was, therefore, determined was ascertained to be 28 tons, or 50 per cent. higher still further to increase the section of the iron bearer. In this case the width of the bearer was 12 inches, and it was stiffened by a web underneath 3 inches deep and of an inch thick (a plan which was claimed by Mr. W. Bridges Adams). The weight was reduced to 76 lbs. per yard, and the contract for this section was had no plates underneath), and to secure the ends of taken at £9 per ton. To stiffen the rail joints which the rails, an iron plate having a tongue rolled on it was used. This section of way had been laid too short a time to warrant any decided expression of opinion of it, as compared with the other sections; but as a length of between 4 and 5 single miles was under trial, it would soon be seen if it possessed any advantages. It was perceptibly stiffer to travel over, and the middle web gave it a firmer hold in the ballast than either of the other sections. The cost of a single mile was £2,385. This section was the fourth modification of rolled iron bearer under trial, the entire length being 144 single miles. Bridport railway was then referred to; and it was The partial failure of the Macdonnell way on the asserted that it arose from the rails and bearers being too weak, and from a disregard of those appliances which the character of the gradients, curves, ballast, and subsoil rendered more than ordinarily necessary. In May, 1858, a trial length of a single half mile, of the cast iron sleeper way of Mr. Do Bergue, was and on the same kind of clinker ballast. Whilst laid in immediate continuation of the Macdonnell way, still preferring a continuous rolled iron to any cast iron way, the author felt bound to state that not a single sleeper had been broken, the nuts of the bolts did not work loose, the rails wore very well, and with the exception of a little depression at the fished rail joints, the line kept as good a "top" as could be desired, and was as easily maintained, but it was more rigid. The cost of this arrangement per single mile was £2,103, or £300 per mile less than the Macdonnell way of the same period. The merits and defects of the continuous rolled Society of Engineers," On Firc-Clay Manufactures," by W. II. Stephenson, at 7 p.m. TUES. Inst. Civil Engineers, "Description of a Pier Erected at Southport, Lancashire," by Henry Hooper, Assoc. Inst. C.E.; and "On the Construction of Floating Beacons," by B. B. Stoney, at 8 p.m. Architectural Photographic Association, S. P. WED.-Geological Soc., I., "On the Succession of Beds in Chemical Soc., at 8 p.m. Soc. of Antiquaries, at 8.30 p.m. FRI.-London Inst., "On the Reproductive Organs of Flowering Plants," by R. Bentley, Esq., F.R.S., at 7 p.m. Medical Soc., Anniversary and Oration, at 5 p.m. Royal Inst., Dr. E. Frankland, F.R S., "On Some CAPTAIN JERNINGHAM'S EXPERIMENTS WITH MORTAR AND ROCKET LINES. CAPTAIN JERNINGHAM, of H.M.S. Cambridge, has favoured us with an account of his experiments for saving life from shipwreck, made in compliance with the directions of a Select Committee of Privy Council for Trade. We give the substance of his report to their Lordships. The object of these experiments was to ascertain the feasibility of effecting a communication adopted for carrying this out was by attaching with the shore from a stranded ship. The means lines to shot in a similar manner to that in ordinary use with the Manby apparatus. These shots were fired from ship's heavy ordnance of various calibres, viz., 10 inch and 8 inch guns, 32-pounder feet, and from 21-pounder and 12-pounder brass guns, whose length of bore varied from 6 to 9 howitzers. The principal object in view was to ascertain the practicability of retaining the line fast to the shot when fired from guns, as well as the probable range likely to be obtained under the various di rections of the wind, it being presumed that in the majority of cases the wind would blow in the direction of the shore, and thereby aid the flight of the projectile and the line, whereas the con increased to 12 inches, and its thickness was reduced iron permanent way were thus stated. The defects. trary would generally be the case with the Manby to 9-16ths of an inch, so that its weight was 75 lbs. per lineal yard. At the same time the curvature was lightly increased. The pine packing (creosoted) was thicker, and at the rail joints pieces of hardwood, laid with the grain lengthwise, were substituted. The rails weighed 69 lbs. per yard. The contract for the bearers, joint plates, and transoms was taken at £9 10s. per ton, the cost of the rails being £9 8s. 8d. per ton. This length was laid in July, 1857, where the line had not long before been re-ballasted with or supposed defects, appeared to be:-1. The great cost, at present prices, almost precluding its adoption on a railway of limited capital. 2. The difficulty of getting the bearers rolled. 3. The possible increased wear of the rails. 4. The greater "wash" of all but very good ballast, inseparable from all iron ways, resting on or near the surface. And 5. The difficulty of laying on sharp curves, and of keeping in place when laid. Its presumed merits were; 1. Greater economy in the long run, owing to increased durability. It was estimated that the cost of renewal of the longitudinal timber way was £15, and of the iron way only £21, per single mile per annum, or less than half, without reckoning the considerable item of labour As these trials appeared to give a reasonable exin the replacement of the timbers. 2. Saving in pectation of the greater durability and diminished maintenance, and facility for packing, owing to no cost of maintenance of the iron way, the author felt "opening out" being required. 3. The safety of the justified in recommending a further trial, on a more extended scale, and on different districts of the rail-which had been long laid. 4. The facility of exchangiron way, especially as contrasted with a timber way As the rolling and straightening of the curved Ing worn rails. 5. The preservation of correct gauge. section of bearer was alleged to be difficult, it was de6. The lowness of the crown of the rail above the hard clinker ballast. The cost of a single mile, exclusive of laying, amounted to £2,511. One mile of timber way, laid with the same section of rail at the same time, cost about £2,251. way. cided to adopt a flat section. The bearing surface was increased to 13 inches, the centre rib was rolled an inch deeper, and the weight was thus brought up to 81 lbs. per yard. Rail joint plates of a similar section to the bearer joint plates were bolted underneath the bearer at every rail joint. Although this addition had been found disadvantageous, the way was still weaker at the rail joints than at any other part. Additional intermediate bolts were used, so that the upper and the lower sections of the way were held together as a girder. The contract for the bearers, joints and tran bearing surface. 7. Saving in the depth of ballast in the case of a new line. And 8. The equableness of the motion, rendering it probable that less injury would be sustained by the rolling stock. MEETINGS FOR THE WEEK. MON.-London Inst., "On the Progress and Power of Music as Exemplified in Lyric and Dramatic Representations," by T. Pittman, Esq., at 7 p.m. Medical Soc., General Meeting and Election of Officers and Council, at 7 p.m. apparatus fired from the shore. The results have proved most satisfactory, the shot having seldom separated from the line, and when such has taken place the cause has been ascertained, and the experiment kept within control. The lines were all of Italian hemp, manufactured by Mr. T. Burt, of Wellclose-square. It being necessary that the strops attached to explosive force of the powder when ignited, two the shot should be capable of withstanding the sorts were used, viz., plaited hide thongs and Manilla rope. Those of Manilla were found to be most serviceable. In the accompanying report of experiments made by me, it will be observed that pound of powder, elevated at 15 degrees, projected the 10 inch gun, weighing 84 cwt., with one Manilla strops, aud were all successful. 333 yards; the whole of these were fitted with A 32-pounder, 56 cwt., loaded with 12 ounces of powder, and shell, empty, weighing 23 pounds, and shell fired with lead weighing 35 pounds, was fired nine times at an elevation of 15 degrees, giving an average range of 300 yards. Two were fitted with hide strops; and both were failures. Seven with Manilla strops; four were perfectly successful, two carried away the line, strop remaining sound; the strop of the 7th was carried away close to the eye of the shot in consequence of the bolt being so small as to create a short nip. |