THE MECHANICS' MAGAZINE. LONDON, FRIDAY, JANUARY 18, 1861. THE INSTITUTION OF NAVAL THIS Institution, which a score of eminent shipbuilders met to organise in London exactly a year ago*, is this week sending forth to the world, as its first-fruit, a splendid quarto volume of Transactions-the first, we hope, of many. The distribution of several hundreds of large volumes like this will necessarily occupy some days; but many scores of them are already in the hands of the Members and Associates of the Institution, and, so far as we have yet learnt, have been received with even more than satisfaction. The contents of the volume are full of interest and value, comprising as they do a great variety of papers, both theoretical and practical, by some of the foremost authorities of the day. After the lists of Officers, Members, and Associates, the Rules and Regulations, &c., and an account of the origin of the Institution in the form of an introduction by the Secretary, the volume proceeds with the addresses, papers, and discussions of the inaugural meetings in March last. The inaugural address of Sir John Pakington is a model of good sense, and proves that the officers of the Institution have acted wisely in electing him as their President. The Earl of Hardwicke's address, although less free from the colour of political feeling, is a very cordial manifestation of sympathy with the objects of the Institution. These addresses are followed by the first paper read-that on "The Present State of the Mathe"matical Theory of Naval Architecture," by the Rev. Dr. Woolley. This paper is in every respect worthy of its prominent position, being a masterly review of its subject, and one which displays an independence of thought and a freedom of inquiry which are somewhat novel in connection with the science of naval architecture, and which promise much for its progress under the auspices of the Institution. Mr. Barnes' account of "Some Experiments for "Finding the Heights of the Centres of Gravity "of Her Majesty's Ships" follows Dr. Woolley's exposition; of this paper Mr. Scott Russell said,- This is one of the most valuable papers 66 we naval architects have had submitted to us "for many years." "On a Proposed Form of Ship, with a Diagonal Mr. Maudslay's paper "Midship Section" succeeds, and is followed by an interesting discussion. Then come the papers "On the Strength of Iron Ships," by Mr. Grantham and Mr. W. Fairbairn, and a discussion upon them of a most serious and weighty character. In this discussion, Messrs. Martin and Ritchie, the two princi THE MECHANICS' MAGAZINE. on 33 and is itself succeeded by a discussion of the | J. R. Drummond, R.N., C.B., Rear-Admiral topic, in which Mr. Archibald Smith and other the Hon. A. Duncombe, the Earl of Durgentlemen shared. Mr. White's account of ham, the Earl of Gifford, Captain G. Goldhis mode of building diagonal ships follows, smith, R.N., Vice-Admiral Sir Thomas Herand, after a discussion upon this, we meet with bert, K.C.B., Vice-Admiral W. J. Hope Johna paper on "Tonnage Measurement," by Mr. stone, Rear-Admiral Sir T. Maitland, C.B., Samuel Read, late Master Shipwright of Sheer- Vice-Admiral W. F. Martin, Captain Sir F. ness Dockyard, and with another on the "New Leopold M'Clintock, R.N., Vice-Admiral H. veyor-General for Tonnage. In the latter paper C.B., Rear-Admiral W. Ramsay, C.B., the "Tonnage Law of 1854," by Mr. Moorsom, Sur- Meynell, Rear-Admiral the Hon. F. T. Pelham, ried out by the Board of Customs, with the Viscount Somerton, C. R. M. Talbot, Esq., are urged those changes which have been car-Earl of Rosse, J. H. Smyth-Pigott, Esq., sanction of the Board of Trade, since the paper M.P., Viscount Templeton, G. Tomline, Esq., was read. We next have Mr. Barnaby's essay M.P., Lord Willoughby d'Eresby, and many at some length, and which, in addition to the than 320 names-many of them representing, Inventions for the Improvement of Naval other persons of like distinction. "Architecture," to which we last week referred of the first year of its existence we find no less portions which we then more particularly as we have seen, some of the most influential At the end noticed, contains a very able sketch of the pro- classes in the kingdom-on the Institution's gress of naval construction at successive periods lists. No surer guarantee of success than this introduction of gunpowder up to the present of 100 years, from a time just anterior to the could be desired. moment. From this paper we also gather a fact which is well worth recording here, viz., that the University of Cambridge has had the distinguished honour of contributing to the science of naval architecture no less than five of its ablest writers, viz., the celebrated Phineas Pett, the equally celebrated Attwood, Professor Inman, Canon Moseley, and Dr. Woolley, the latter two of whom are living authors. Mr. Barnaby's essay is followed by a paper on "Chain Cables," contributed by Mr. Lenox, the first chain cable manufacturer in the kingdom. Mr. Robert Murray's paper on "Means and Appliances for Economising Fuel "in Steamships" comes next, and then Mr. Scott Russell's two lectures on the "Wave-line Priuwhich the March meetings concluded. "ciple of Construction," with the second of The publication of these lectures in the present volume affords the first convenient opportunity The of studying this remarkable theory that shippresented to them. builders and other men of science have had of the wave-line principle could only be obtained from scattered publications. The author Previously, a knowledge promises, we are happy to observe, a further paper in which he will investigate the practical changes which are involved in the application of the wave-line principle to ships. The volume concludes with a table of dimensions of fifty steamers, prepared by Mr. Robert Murray. ings, extending over three days, was held by the Institution. During the present year the holding of two series of such meetings is conDuring the past year but one series of meettemplated, we believe, by the Council. The first series will be held about the first week in March; the second about the beginning of July; a volume containing the proceedings of all these meetings will be published at the end of the year, and will form the second annual volume of the Institution's Transactions. At the meetings that are to be held in March the construction of iron-plated ships-of-war will be discussed by several shipbuilders, engineers, and naval officers of eminence; and as Parliament will then have assembled, many of its Members will, in all probability, attend for the purpose of enlightening themselves on this grave and national question. Where WHAT is a mechanical invention ? the same gentleman; but, although this may We All these questions, and some others, are sent to sell this volume to the public, they we publish on another page. At first sight it If the Council of the Institution would con- Wallich, on deep-sea sounding machines, which suggested by the letter from the pen of Dr. be strictly limited to the Members and Asso-to this, as well as a former communication from But this they refuse to do. Its circulation will our article of the 28th December has given rise would doubtless soon dispose of the edition. may appear that a sentence which occurred in ciates of the Institution, to all of whom it is sent by the Secretary. Those of our readers who want the book must, therefore, make application for entrance to the Institution. For the following clause:"The class of Associates their encouragement we extract from the laws pal Surveyors of Lloyd's, bore important« either by profession or occupation, or by parts, while Mr. Scott Russell undertook "shall consist of persons who are qualified, the task of criticising Mr. Fairbairn's views, with naval architects the qualities of a ship, and showing that his suggestions, where they" or the construction, manufacture, or arrange"scientific or other attainments, to discuss were practicable, had been anticipated by some shipbuilders. This discussion, dealing as it does from first to last with considerations that "ment of some part or parts of a ship or her words that the class of Associates embraces equipment." It will be seen from these gentlemen of very varied professions. We are happy to observe that persons of very high the Institution, for in the list of Associates we find such names as those of Captain A. B. position have hastened to become Associates of G. Bentinck, Esq., M.P., Admiral W. Bowles, C.B., the Marquis of Breadalbane, the Duke Beecher, R.N., Captain Sir E. Belcher, R.N., of Bucclench, Lord Colchester, Captain the Hon. J. Denman, R.N., Captain the Hon. are vital to the shipbuilding profession, will doubtless be read with great interest. 'It is followed by Lloyd's Table of Dimensions, and by a full report of Lloyd's experiments upon iron plates and modes of riveting applicable to the construction of iron ships. Airy's paper on the "Connection between the "Mode of Building Iron Ships and the Ultimate “Correction of their Compasses" succeeds these, We write on the 16th of January. Professor sistent with perfect good faith on the part of The whole business is very simple, and conall concerned. A little excess of sensitiveness -a little haste in the use of words has caused it all. The matter presents itself to us as follows:-During the late expedition of the Bulldog, the officers of the ship, as was natural M'Clintock, exerted themselves to forward the special objects of the voyage, and, among under such a commander as Sir Leopold feet machines which had been furnished to them for bringing up bottom from great depths. other things, sought to improve upon the imperIn this work the commander was particularly aided by Dr. Wallich, the naturalist of the expedition, Mr. Roughton, the chief engineer of the ship, and Mr. Steil, the second engineer. Various apparatuses were contrived, and some of them tried; an arrangement devised exclusively by Mr. Steil (described and illustrated in our Magazine for the 28th of December) being attended with the greatest success. The fact of this instrument having been planned by Mr. Steil without assistance, afforded the commander of the expedition an opportunity of connecting the inventor's name with it. And it is important to observe how spontaneously and how completely Sir Leopold M'Clintock awarded Mr. Steil the credit of having invented the machine. He named it "Steil's machine;" submitted it to the Admiralty under that name, and drew the attention of their lordships to its merits, as our former article showed; and shortly afterwards Mr. Steil received his promotion. With no other machine, however, was this course possible, because no other machine was exclusively the invention of a single person. Before leaving the Bulldog at Killybegs, however, Dr. Wallich suggested (as he explains in this week's letter) a certain other form of instrument, comprising some new features; and during a conversation respecting it, Capt. M'Clintock suggested certain changes which he thought desirable. Other suggestions likewise were made by other officers. No opportunity of constructing and testing this instrument was, however, afforded before the return of the ship; but on her arrival at Portsmouth, Captain M'Clintock undertook the construction and trial of it, being aided in the work by Mr. Steil-who, although the object was to supersede his own apparatus by a better, if possible, generously did his best to carry out the wishes of his superior officer. The machine was made -with the features suggested by Sir Leopold himself, be it observed-and when tried, was found to answer admirably. A notice of this fact having appeared in the Times, and with it the circumstance of Sir Leopold having named it the "Bulldog machine" having been mentioned, Dr. Wallich wrote to Sir Leopold upon the subject, and received an answer, which he now quotes in his letter. He (Dr. Wallich) then attended a meeting at the Institution of Civil Engineers, and publicly claimed the "essential parts of the machine" as his own invention. It was in reference to this last pro ceeding that our remarks of the 28th December were penned. After this review of the facts of the case, it will be seen that Dr. Wallich was the first to bring the question of the inventorship of the machine before the public, and that he did this by claiming all its "essential features" as his own; not, as he now assures us, for the purpose of profiting by the invention, but with the view of securing to himself the credit of having devised a successful scientific apparatus. He put this claim forward impulsively, and, we think, unadvisedly; because, in the first place, the new machine comprised several parts to which he laid no claim, and some of which had been suggested by Sir Leopold himself; and, in the second place, the success of the actual machine tried at Spithead was unquestionably due to a certain extent to the pains taken by Sir Leopold and Mr. Steil during its construction. For both these reasons-to say nothing of others which, under the peculiar circumstances of scientific expeditions, always deserve consideration-we think Dr. Wallich should not have made a public claim to the machine. But, having said this, we are free to admit that his view of the case was a natural one, and his course of proceeding such as many estimable men might have taken at the time. There is nothing easier in the world than to | to be published at the Great Seal Patent Office at cost price; and the price at which each copy is published is printed on the wrapper in which it is contained. Now as soon as each specification is printed, the "circularizing" gentry send a circular to the patentee, stating that his specification is printed, and that he can be supplied with as many copies as he may desire at a certain price which is named. think lightly of the suggestions which other In order that the real price may not appear, a strip of paper of the same tint as that of the is printed, and the name of the "circularizing" wrapper is pasted over the part where the price party is set forth as the seller, in such manner as to imply a recognised connection between the authorities and himself. In order to protect inventors, the Commissioners have issued a notice, from which the following is an extract : Great Seal Patent Office, 25 Southampton-buildings, Chancery-lane, London, W.C. SPECIFICATION DEPARTMENT. purchasing the printed copies of Specifications at this As some unauthorized persons are in the habit of office and then selling them at a charge considerably greater than the cost price,-previously pasting over or obliterating the last two lines on the cover and also the price, to prevent detection,-Inventors and the Public generally are informed that the printed Specifications are published only at this office, where they are sold invariably at cost price; and they will be forwarded by post on receipt of the amount of price and postage. In all cases the selling price is printed at the bottom of the blue cover in the left-hand corner. We advise all persons having any business to be transacted in connection with patents to avoid the circularizing would-be patent agents," whether their circulars relate to the securing of patents or the supplying of printed specifications. Let any person seeking advice or requiring assistance on subjects connected with Patents make full inquiry as to whom he should apply to. We hope we have now said enough to put CAUTION TO PATENTEES. The specifications of all British patents are 66 We conclude with an extract from another paper, issued from the Great Seal Patent Office, under the authority of the Commissioners of Patents :-"The Commissioners "of Patents do not give advice or opinions on any subject connected with the Patent Laws. These, like other laws, are left to the interpretation of professional men. Any solicitor enabled, either from his own knowledge or [or man of position] in the country will be through his London agent [or correspondent], to point out to his client an agent qualified "to give advice or obtain patents." GASLIGHTS IN RAILWAY TRAINS.-A very successful effort has been made on the East Lancashire section of the Lancashire and Yorkshire Railway, to light the carriages of a passenger-train with gas. The INDIA RUBBER. No. V. In a work on india-rubber, written by the late Charles Goodyear, and printed, for private circulation, at Newhaven, United States, in the year 1855, he says, that "almost every person, in whatever situation in life, will find in the history of india-rubber something useful for him individually to know ;" and that though he himself was considered sanguine as to his inventions, he rubber as a drink, though it is taken with impunity by the Indians. This, however, was about the only exception to his varied suggestions with In every imaginable form in a soft state he patented its application; scores of which, speaking literally within bounds, have never been carried out, excepting in the production of specimens, to show the practicability of the idea. was not so infatuated as to recommend india reference to it. Thus fields of wealth are left untouched, and await skilful hands, and the application of capital, for their realisation. In the book referred to,-a thick royal octavo,-each page runs over with riches, and this in reality. We have enumerated some few of the appliances of the present day, but we have said nothing of the educational, naval and maritime, life preserving, and others, under which heads are given many valuable suggestions. Take educational : and you find that maps in outline, embossed, or illuminated,-globes, in sections or inflated, inkstands, pencils, and rulers, may all be made from it; and for naval and maritime use,-ships' sails, ships' tanks, letter bags, hammocks, buoys, boats, &c. To the manufacture of life-preserving apparatus, however, Mr. Goodyear gave very particular attention. The great loss of life constantly occurring in the passage of the Atlantic between the United States and this country led him to devote much time and capital to the furtherance of this object, and it was the very last thing he was engaged on previous to leaving this country. The manner in which he proposed chiefly to effect his purpose, was by making hitherto-unthought-of things life preservers in case of necessity. For instance, we remember seeing a waistcoat, a dress. ing gown, and a Turkish cap, any of which would support a man in the water, and yet the garments themselves were more than usually unique and handsome. This was effected by, to all appearance, a quilting, which sisted of two surfaces of india-rubber, coated cloth, silk, or any other suitable material, being brought together, excepting in vacant squares or diamonds, which were kept open, that is, prevented from adhesion to one another, by small quantities of cotton wool; in this way forming a series of air cells which caused the garment to be buoyant in the water. con This invention, to which it is difficult to do justice in a cursory description, we believe he had not completely perfected at the time of his death. In other things, as portmanteans and travelling bags, hat-boxes, and such like articles of travelling gear, he applied the same principle in a different way, making them buoyant by air-tight, closing, or distended sides or tops. The great loss of life in case of wrecks and accidents is such as to appal any one who reads the statistics bearing upon the subject; and though it may only seem a prolonging of misery, being cast upon the sea with an article which brings no relief, excepting a support in the buffeting of the element which is wild to devour you, yet life is sufficiently sweet to all to make it a matter of importance that such assistance should be available, in the hope that strength may remain long enough to ensure the chance of relief being of value. With reference to ships' sails, some important experiments were tried in the United States some years back, which fully proved their value; being found in severe weather to stand the force of a storm which would have destroyed an ordinary sail, and in frosty weather not to get hard and stiff, but remain pliant when others were com This con unsightly by wear. are not aware that it has ever been tested. We do not see, however, why it should not prove effectual, possessing as it does many qualities superior to metal, and being uninjured by sea water. This is a point which we should think worthy the attention of our shipbuilders. The cost, we imagine, would be less, and it might be tried on a small surface, to see the result. To compare the durability of india-rubber with that of metal or wood, may, at first thought, appear absurd; yet there is very little doubt that when the manufacture has arrived at a greater degree of perfection, it will be found more durable than either of these, and will take their place in many articles, and for many purposes, where they are now alone used. pletely frozen. India-rubber boats and pontoons | advantage appertaining to hard india-rubber is, are now frequently made, and are valuable, from that it may be electro-plated, and from its pecuthe ease with which they may be stored or trans- liar elasticity is not defaced by blows, or rendered Sheathing for ships, in place ported from place to place. Another application of india-rubber to boat-building we remember of copper, has been suggested of india-rubber, in seeing some years back, but are not aware whether sheets of a hard or semi-hard nature; though we it was ever carried into practical use. sisted of a thin sheet of the gum placed between two veneers of mahogany. Being submitted to great pressure with a moderate heat, it became one firm board, which could be bent or shaped into any form required; the india-rubber giving great strength as well as forming a thoroughly waterhard or semi-hard rubber, which would combine tight material. Boats may also be made from the advantages of lightness and durability. The great interest which Goodyear felt in means for preserving life, is best evidenced by a quotation from his work. He says "The ap. plication of a material like this in all its combina tions to the various articles required, is an object It is a subject in which the writer feels a deep and that might well demand the efforts of a lifetime. absorbing interest, and one to which he would gladly devote the evening of his life. He fears, however, that it will not be sufficiently understood and appreciated, so that the present generation can be benefited thereby, as they otherwise In another part he says might and should be." The inventor would appeal to mankind in general, by affirming that there is no real necessity for such constant loss of life and property, by the sea and waters as annually occurs. A proper investigation and public trial of the articles proposed will demonstrate the truth of what is here stated." The paramount importance of security to life and property by sea is, of course, evident to all, and anything tending to ameliorate or lessen the risk of traversing the great waters, deserving of attention. Goodyear's devotion to this did not arise from any sordid motive, but from a pure love of his species; the money he spent upon his experiments never having produced him any return. His suggestions are consequently of additional value, and are worthy the consideration of those who are in a position to develope and carry them into practical use. ON THE LARGE BLASTS AT HOLYHEAD. BLASTING operations may be divided into three distinct classes, according to the effect intended, and the intensity of the charge of gunpowder :1st. Where rock has to be separated by weak charges, with as little injury or fracture as possible, principally for building purposes; 2nd, Blasting for engineering works, as breakwaters, &c., where quantity and regularity of supply are of more importance than size and regularity of fracture; 3rd, Military blasting, where total destruction is aimed at, and where an excess of powder is little or no objection. By G. ROBERTSON, C.E., F.R.S.E., &c. In the first class the charges of gunpowder can hardly be too weak, so long as the stone be sepa rated, and small charges are preferable to a large quantity at once-the object being to procure stones fit for masonry, with as few cracks and shakes as possible. In the third class the charge can hardly be too strong, the chief difficulties being those of carrying on operations under an enemy's fire, with the speed and secrecy consequent thereon. It is to the second class, that of " engineering blasting," that the following observations are directed. The application to globes for school or home use, derives its value from the fact that they are simply air balls, which can be distended at pleasure, and hanging by a string from the ceiling, can be After describing the system pursued in workturned round with the greatest ease. The maing the quarries by large blasts, I shall give the terial takes with great distinctness the impres- calculations for regulating the charges, and, sion from ordinary printing types or plates, and is lastly, the cost of "getting and filling" stone on almost indestructible. The same remarks apply the large scale. In an engineering point of view to maps, of which we have seen some truly beauti- the subject is one of considerable importance. ful specimens. works. The period more immediately referred to in the India-rubber has been applied successfully in its paper is from 1850 to 1853, when the large blasts hardened condition, as a substitute for whalebone were first introduced at Holyhead-the late Mr. in umbrella ribs, and like purposes. As handles Rendel being at that time engineer-in-chief. for knives it may be moulded to any form, thus After his death in 1856, Mr. Hawkshaw was apgiving beautiful imitations of carving, at a very pointed engineer. Mr. G. C. Dobson has been much less price; also miniature frames, photo-resident engineer since the commencement of the graphic portrait cases, brooches, and other articles. Funnels and syringes which withstand acids, are not fragile, and much lighter than metal, are valuable adjuncts to surgical purposes. The same also applies to stethoscopes and ear trumpets, which for the conveyance of sound surpass wood from their non-porosity and the beautifully smooth surface given to their interior, and metal from their much greater lightness and comfort in use. In all cases where iron or other metal is liable to rust, or become unpleasant by exposure to the air, this hard material imparts a beauty of appearance, and prevents all injury to the substance. Buttons, which are a branch of manufacture by themselves in America, are made in every form, and can be produced so closely imitating cloth, that to a casual observer the difference is not perceptible. They also have the advantage of not wearing out, as the ordinary cloth-covered one so soon does. Bracelets in imitation, or rather we should say, as substitutes for jet, are beautiful productions, which surpass that material for the reasons that they are not fragile, and can be worked into much finer patterns. Another At Since 1853 the large blasts have gone on regularly, as matters of everyday occurrence, exciting little curiosity, and giving little trouble. first, however, they were the subjects much anxiety and experiment, both in. cal and an economic point of view. The best method of working the quarry on the large scale, and the calculations for the charges of powder, were not determined upon without considerable expense, danger, and even loss of life. The rock of which the breakwater is composed is a very hard quartzose and micaceous schist, slightly stratified; in some places bearing marks of former flexibility, the strata being twisted and contorted in a curious manner. It is intersected by vertical joints, running in a north-east and south-west direction, presenting faces fronting As will be seen the north-west and south-east. hereafter, these joints were taken advantage of in fixing the position of mines, and in calculating the expected produce of a charge. Read at the Royal Scottish Society of Arts, and published here by permission of the Council. To supply the great demand for the stone required for a bank 350 feet broad at the base in deep water, within a limited contract time, evidently necessitated the most vigorous efforts; and accordingly an extensive system of small shots was at first arranged, giving employment to above 1,000 men. The holes for these shots were of all sizes and depths, according to the judgment of the foremen of the quarries. For convenience sake the quarries were divided into portions, consecutively numbered, or were called by the names of the different foremen, as "Jones's quarry," "Fisher's quarry," &c. The boundaries were, however, ideal, as the face of the rock altered with each great blast. To avoid the danger and delay of firing shots at all times of the day, whenever the holes were ready and charged, a general grand firing took place twice, or, if necessary, thrice a day. When a large bell sounded, the quarries were emptied of men, horses, cranes, and all plant easily destroyed. The fuses were simultaneously lighted, on a red barrel being hoisted to the top of a tall mast. Each man, as he lighted his fuse, cried "Fire!" (or "Tan" in Welsh), and made the best of his way by scrambling up ropes to a place of security, or to one of the bomb-proof huts erected for the purpose. As the face of the rock was often above 100 feet high, this was a service of no small danger, and accidents frequently happened. The average work done over the whole quarries, in drilling holes for the small shots, was 14 inches per hour, by three men using 1 inch drills. The charges were regulated chiefly by the "rule of thumb," or at most by the ordinary miner's rule of one-third of the hole, independent of the diameter-a rough rule, certainly, but better than so many "capfulls," the cap being a very common measure. Indeed, where 100 or more shots went off twice a-day, it was impossible to be very par ticular. I do not intend going into further details regarding these small shots. The system will be found fully described in Sir John Burgoyne's treatise on "Blasting." Wherever it was possible, powder was poured into cracks in the rocks, and the rent tamped as well as its form would admit. There was often a considerable waste of powder, but the shots were very effectual in bringing down large masses of rock. This system is pursued to great advantage at North Queensferry, in blasting columns of whinstone. the depth of shaft was sufficient to allow the weight of the tamping to resist the powder. The rule was, that the shaft should have one-third less grip (or distance from the face) than depth as a maximum; and the depth was oftener twice the line of least resistance, or even more. This is, however, not so great a proportion as in small shots; bat in the shafts the chamber at the bottom for the powder was bent to one side, so that the tamping was never in the direct upward line of fire. (See fig. 1.) About the year 1850, the contractors for Holyhead breakwater, Messrs. Joseph and Charles Rigby, commenced a system of large mines, rightly conceiving that a quantity of powder fired at once would in the end prove cheaper, and afford a greater and steadier supply of stone, than a number of small shots. Since then the supply has been over 3,000 tons per diem-often 4,000, weather permitting: 5,000 tons a-day was seldom if ever reached, not from want of stone, but from the difficulty of depositing such a quantity during working hours, even with five lines of railway on the staging. To do this requires 125 waggons for each line of rails, or a total of 625, to be loaded, run down from the quarries, tipped into the sea, and drawn up again to the quarries, every day. FIG. 1 a. Charge, 600 lbs. ; produce, 3,000 tons. The most favourable FIG. 1 6. position for a shaft is in the centre of a projecting column of rock, lines of least resistance where (as in fig. 1,a) the are nearly equal on all sides. This mine (one of the first) was fired on November 13, 1850, and was 42 feet deep, with half that, or 21 feet of least resistance on all Bo sides. It was charged with 600 lbs. of powder, and yielded 3,000 tons Enlarged section of chamber. of stone; one of the highest comparative results obtained, being 5 tons of stone for each pound of powder. An enlarged section of the chamber is given in fig. 1b. Had it not been for the remains of a previous blast on one side, the result would have been even higher. The waggons held about eight tons each; were made of wrought iron, and furnished with tipping gear, which released the scoop when the trigger struck a catch on the rail. The scoop was counterbalanced, to return again to its original position when the stone was discharged. The first large shots tried were shafts sunk from the top of the quarry. They were about 6 feet by 4 feet, of different depths, of course, according to the height of the rock; and were charged with reference to the lines of least resistance, or the shortest distance of the shaft from the face of the quarry. As the danger of blowing out the tamping was greater than in small shots, from the increased diameter of the hole, care had to be taken that face of rock has to be broken up, and where the powder has to tear its way out under disadvantages. The miners called this a "rooter out," and it was almost always placed so as to have a joint on one side, which determined the line of fracture. The example shown (Fig. 3) had a depth of 44 feet, with a line of least resistance of 21 feet. The charge was 900lbs., and the produce 2,000 tons, or 24 tons per pound of powder. The very worst position for a shaft is at a reentering angle, or nearly so, as in Fig. 4, where FIG. 4. A blew the tamping out; B did not explode. the rock binds it in on all sides. The ratio of powder for a mine like this had to be greatly increased, according to circumstances. The powder was not always in one spot, but was often divided into two or three charges, placed at the end of galleries driven from the foot of the shaft in directions determined by the neigbouring joints or cracks. In Fig. 5, for example, the whole charge, 8,000 lbs., was divided into P, of 2,800 lbs., and P2, P3, each of 2,6000 lbs. The depth of the shaft was 67 feet, and the line of least resistance 42 feet. This mine produced 23,000 tons of stone, or nearly 3 tons of stone to the pound of powder. Fig. 3 shows a very common, but very unfavourable position for a shaft; where a straight respective shafts, were fired simultaneously side Occasionally, two separate mines, with their by side. There was some little danger of the two shots (which were fired by a galvanic battery) not going off together. This actually occurred on the 24th Feb., 1851, when two contiguous shafts were to have been fired at once; but, owing to the accidental fracture of one of the battery wires by a previous small shot, B (Fig. 4) did not explode. The mass of rock in front was too great to be moved by A without the assistance of B; and the whole tamping in 4 was blown out. An immense shower of stones was hurled into the air to a great height, and fell amongst the spectators, who lined the side of the mountain. Strange to say, the only person seriously hurt was the gentleman who had planned and directed the mine, Captain Hutchinson, of the Royal Engineers. He was struck down with a broken thigh, and died the same night. His wife and several ladies, who were talking to me at the time, had their clothes torn by great stones falling on them, but escaped with some trifling injuries. Captain Hutchinson had had great experience in blasting; having been engaged both at Gibraltar and at Dover, when the Round Down Cliff was blasted in 1845. The objections to shafts are as follows: The miners not only work in a confined space, but to great disadvantage, as their work is below their feet. The materials and men have all to be drawn to the top by a windlass; and the ventilation is bad; so much so, that after a small shot in the shaft was fired, the men could not return to their work for some time, notwithstanding the windsails, watertubs, and other contrivances that were used to help to remove the foul air. Any water, also, which may collect in a shaft, either from rain or wet joints, has to be removed, and will not drain out of itself. Shafts have some advantages, however, over headings. They weaken the whole column of rock, from the top to the bottom, greatly helping the powder, and determining the line of fracture. They are also very quickly tamped, as the débris which came out in sinking the shaft has merely to be thrown down again. This is of some advantage in wet situations, where the powder should be fired off as soon as possible. It is obvious that the same point in the rock may be reached as well from the face as from the top of the quarry, and often by a shorter route. Headings, or galleries at right angles, or nearly so, to the face, are evidently in some points preferable to shafts sunk from the top. They are of a more convenient form to work in, the men having the rock in front of them instead of below their feet; the chippings can be easily wheeled out; the ventilation is better; no rain falls into the mouth as in a shaft, and any water from joints drains itself out. A heading also forms a convenient place of safety for the miners while neighbouring shots are being fired. The usual size for a heading was 5 feet to 5' 6" in height, by 3' 6" wide. Wherever it was possible headings were driven by the side of joints, and were generally placed so as to blow away a corner (as in Figs. 6, 7, 8, 9). When it was desirable to clear the bottom of the quarry well, the powder was placed several feet below the level of the rails. Headings are more nearly in the direction of the line of least resistance than shafts are, and the tampering is in consequence more liable to be blown out. They have, therefore, to be filled with greater care, and the direction of the gallery changed and sunk at parts, as shown in the diagrams. FIG. 6. Charge, 2,340 lbs. ; produce, 5,500 tons. Fig. 6 had a line of least resistance of 28 feet, with a height of face of 70 feet. The charge was 2,340 lbs., placed 3 feet below the rails, and the produce 5,500 tons, or 2 tons for each pound of powder. Fig. 7 is a very simple form of heading, run along a joint not at right angles to the face. The line of least resistance was a foot more than in Fig 6, but the charge of powder was rather less, viz., 2,300 lbs., as the face was but 60 feet high; and in Fig. 6 there was also a heap of loose Charge, 5,100 lbs. ; produce, 12,000 tons. height, and the lines of least resistance 29 feet. The produce was 12,000 tons with a charge of 5,100 lbs. During the period referred to in this paper the largest mine fired was one of 5 tons of powder, producing about 40,000 tons of stone; but since then there have been others larger. One of the most successful ever fired at Holyhead was a heading with four charges, in which the joints of the rock were very favourably situated, as is seen in Fig. 11. The height of face was 146 feet, the length 140 feet, and the grip of heading 35 feet. The total charge was 13,000 lbs. of powder, or 64 tons (2,000 pounds of powder going to the ton), P=4,500, P=4,000, P=3,000, and P=1,500 lbs. The produce was stated in the newspapers to be 70,000 tons of stone, or fully 5 tons to the pound of powder. (Unless the rock was very overhanging, I think this quantity rather full.) It may give a more popular notion of the enormous supply of stone brought down by these large blasts, when I state that Fig. 11 furnished an ample quantity to build the division of Georgestreet in which this hall stands, with enough over probably for half of the opposite side; or, there would be sufficient to macadamise the road from Edinburgh to Linlithgow. Larger charges were required for headings than for shafts, as the superincumbent rock was not weakened by the shaft column, and the height of face was generally great where headings were most advantageously used. It will be seen, therefore, that shafts and headings have each their peculiar merits and defects, and that a judicious mixture of both is the only proper way of working a quarry on the large scale. On the whole headings preponderated, especially after the first two years' experience. The usual method, when the face of the rock was not perpendicular, was to remove the upper half by a shaft and the lower by a heading. When the face was nearly upright, the heading alone was sufficient, as the top fell in when the root was blown out. A heading and a shaft fired together left a clean perpendicular face for the next mine. A good deal of forethought had to be exercised in placing the shafts so that they might be ready in rotation to keep up a steady supply of properly broken stone. They took many weeks to sink; headings, on the other hand, were driven in a much shorter time, and in this respect had the advantage. = The blasting powder was kept in strong vaulted magazines, and was landed from the hoys while the men were at dinner and the locomotives out of the way. It was delivered in small barrels holding fifty pounds each, or half a hundred weight (100 lbs. being the hundred weight of powder). One pound of powder thirty cubic inches. The strength was tried in two ways, either by a gun, in which the recoil was measured on a graduated arc, or by a small mortar elevated at an angle of 45°. One ounce of good powder ought to throw a ball of sixty-eight pounds weight to a distance of 180 feet. The different qualities of powder were sometimes mixed to bring the strength near this effective standard. It was delivered at Holyhead for about £55 the ton. There is an idea amongst quarrymen that it is an advantage to mix powder with sawdust or quicklime; the former to divide the particles and cause them to ignite slowly, the latter to absorb any moisture. Both are erroneous notions; true economy is to use good powder, though for blasting it may be coarse grained. In the shafts a space was sometimes left round the charge. Theoretically, I believe this is of use in permitting the expanding gases to acquire momentum; but the space was so small in comparison with the quantity of gas evolved from such large charges that it was practically of little |