Journal of the Society of Arts, Announcements by the Council. ORDINARY MEETINGS. Wednesday Evenings at 8 o'clock. MARCH 22.—“On the Preservation of Food, especially Fresh Meat and Fish, and the best form for Import and Provisioning Armies, Ships, and Expeditions." By G. C. STEET, Esq. MARCH 29.-" On Window Horticulture, and the Cultivation of Plants and Flowers in Cities and Crowded Localities." By JOHN BELL, Esq. CANTOR LECtures. The Third Course for the present Session will consist of six Lectures "On Some of the Most Important Chemical Discoveries made within the last Two Years," to be delivered by Dr. F. F. CRACE CALVERT, F.R.S, F.C.S. (Corresponding Member of the Royal Academy of Turin; of the Société Industrielle de Mulhouse; of the Société Imperiale de Pharmacie de Paris, &c.), on Tuesday evenings, at Eight o'clock, as follows: APRIL 4TH.-LECTURE 1.-On the discoveries in Chemistry applied to Arts and Manufactures. APRIL 18TH-LECTURE 2.-On the Discoveries in Chemistry applied to Arts and Manufactures (continued). APRIL 25TH.-LECTURE 3.-On the Discoveries in Agricultural Chemistry. MAY 2ND.-LECTURE 4.-On the Discoveries in Physiological Chemistry. 304 305 [No. 643. VOL. XIII. Works in New South Wales-Salmon and Trout in Tasmania ... 305 Publications Issued :-Le Monde de la Mer Le Ciel Les Plantes - Le Monde des Insectes 306 Notes:-Southern Counties Association for the Encouragement of Agriculture, Arts, Science, Manufactures, and Commerce-Renewal of Old Fruit TreesBrome-Climate of England-Education in Russia Meetings for the Ensuing Week Parliamentary Reports Patents ... 307 307 ... 308 308 tion at home and abroad, consists of the follow ing gentlemen: Wm. Hawes, Esq., Chairman of Council. Lord Henry Gordon Lennox, M.P. Lord Gerald Fitzgerald. Sir John P. Boileau, Bart. Sir George Clerk, Bart. Sir John Harington, Bart. Edgar A. Bowring, Esq., C.B. His Royal Highness the Prince of Wales, President of the Society, has consented to honour the Committee by acting as its chairman. Proceedings of the Society. CANTOR LECTURES. SECOND COURSE.-SIXTH LEOTURE.-MONDAY, Mar. 13. MINERAL VEINS, ORES, AND MINING. Professor ANSTED commenced by stating that the last division of his subject included mineral veins, their contents, and the methods adopted to extract these contents. Metals are obtained either native or as crystalline minerals, called ores, from certain fissures and veins in altered rocks. The obtaining of ores from veins is metal mining. MAY 9TH.-LECTURE 5.-On the Discoveries in the All rocks now above the water have been raised to Chemistry of Rocks and Minerals. MAY 16TH-LECTURE 6.-On the Discoveries in the Chemistry of Metals and Alloys. These Lectures are free to Members (without ticket), and every Member has the privilege of admitting ONE Friend to each Lecture. MUSICAL EDUCATION. The Committee appointed by the Council to inquire into the present state of Musical Educa their present position by some powerful upheaving force. They must have been dried before being elevated, and this involves contraction. Contraction and elevation must have produced cracks and fractures, whose nature depends partly on the rock itself, and partly on the mode of action of the moving force. It is not possible to conceive upheavals without fissures; but they are of two kinds, as due to two causes. Those caused by contraction will be governed by chemical laws. Those caused by upheaval will be regulated by the amount of force exerted, the weight to be lifted, the direction of the upheaving force. and the mechanical condition of the rock at the time of up heaval. The first kind may have begun as soon as the rock existed. The second kind commenced with the first upheaval. They may be due to a multitude of movements going on for a long time. During long periods such fissures may have remained unaltered. From time to time they may have been interfered with by other fissures. But cracks once formed, and then neglected, may have been filled up with fragments of the adjacent rock, or with crystals that have grown in the cavity. A crack in a mass of limestone may be occupied with calc spar. A wide fissure in such rock may be filled with rolled blocks of limestone. An empty space may have become filled with lumps of zinc or lead ore. All rocks present phenomena that have some resemblance to those of mineral veins; the formation is an ordinary event in nature. Crevices formed during the elaboration of a rock, are small, and filled up with crystalline material derived from the rock itself. The rock is purged of foreign contents by aid of these cracks, and by the facilities they offer for throwing off substances of which there is only a small proportion, But the filling up of crevices formed by contraction need not differ from the filling of wider cracks. The crevice must be formed before the filling up can begin, and thus every true crack must have defined walls. This distinguishes true veins from differences of condition and of mineral composition which belong to some process of segregation. The successive veins in slates and granites, elvans, bands in clays, and coloured lines and marks in sandstones, are of this nature. They are modifications of the rock, but not mineral veins. Of the two classes of fissures those produced during the formation of the rock are the simpler and the most common. All fissures in rocks, filled with crystalline minerals may be called mineral veins, but only those which contain valuable ores are lodes or metalliferous veins. The origin of the vein is of small importance, but its history is interesting, and will guide the miner in following the traces of the vein when it is lost sight of. Metalliferous veins in stratified rocks are chiefly confined to accumulations of lead and zinc ore and carbonate of iron in natural open spaces or caverns in limestone. It is difficult to explain this, but it is a law of nature, at least with certain limitations. Let us see what these veins are like, and what clue we can obtain to their history. Between and amongst limestones, where the bedding is regular, and cavities occur at the interval between two beds, there may be deposits of galena and calamine. These cavities com municate with others by crevices across and bet een the strata. How far the natural cracks may } ive beep enlarged by subsequent upheaval it impossible to say, but the main deposits often seem dependent on the stratification. nero is little guide to the discovery of veins of the "ind when lost, beyond a careful following rath, de afforded by a thread of ore. Useful mineral veins are the result of disturbances that are ysterie, and they often correspond with the structure of the part of the country where they occur. Thus, in Cornwall and Devon there is a chain of granite bosses ralling east and west, and a quantity of slates, schists, & having a similar range. In the slates, schists, and granite are numerous metalliferous veins. Of these some are more regular, and better defined than the rest. Such veins are called master lodes or champion lodes. They are parallel to each other, and may be recognized as be longing to a system. These main lodes range in the same direction as the axis of elevation of the district. The general range of the local geological axis of the country being made out, then the direction of the main lodes are parallel to it, and the lodes of next importance at right angles to it. And this law is an expression of the fact that mineral veins are fissures in altered rocks, produced systematically by mechanical force elevating the whole district, and breaking up the rocks in a manner that may be estimated mathematically. If a rigid solid, tied down on all sides, be exposed to pressure from below, sufficient to overcome the tension of its parts, it must crack on yielding, and these cracks will follow certain laws. They must be parallel and at right angles to each other and to the elevating force. One important conclusion from this mode of considering mineral veins is, that in different countries the systems of veins must exhibit different directions. Thus, while the ore-bearing veins in Cornwall are east and west, in other districts they may be north and south. The direction of elevation must govern the formation of each system of veins. But if veins are due to disturbances that have acted at intervals during a long period of time, and not always in the same direction, the axis of disturbing forces may change, and there may be new systems of veins crossing older systems. Or successive elevations may produce complication in a different way, breaking up and heaving the mineral veins after they have been filled. Thus are produced faults and throws. In the determination of the law that governs the distribution of lodes, we should know the direction of the axes of elevation that have effected them, and the order of the occurrence of the disturbance. The fissures formed in rocks, whether on solidifying or whilst elevation was going on, must approximate rather to a vertical than horizontal direction. Thus mineral veins are often almost vertical, or if inclined they are so slightly and irregularly. But fissures in rocks are not lodes until they have been filled with mineral matters. These are usually crystalline. The filling up distinguishes the mineral vein from the open fault, or crevice, and the lode from the mineral vein. There is no reason why a fissure open at the top, or a crack formed during the construction of an ordinary fault, should not become filled with stones from above or from the walls. Occasionally the vein contains substances washed in by water from a distance. But when mineral veins are filled with spar the case is different. The material may have been carried in from above and deposited from water. In this way some ve in limestone contained in a solid mass angular and rolled lumps of limestone, galena, blende, calamine and shells. The cementing medium is carbonate of lime, and the agent water. So it is possible that Cevices open below have received minerals in the state of vapour. Of these sulphur and arsenic are filiar examples. The former is found lining the walls of cavities. in volcanic districts examples of this are common. Thus deposits from above, brought in with or without water, and deposits from below, with or without steam, are methods adopted by nature. But no one familiar with veins will suppose that all known cases can be thus explained. The vast majority of lodes are lined with crystalline minerals which have commenced to form on each wall of the vein, and not either at the top or lower part. When the deposit has begun, the crystals have accumulated symmetrically. Assuming that crevices have become converted into veins by chemical action within the rock, this either involves the conveyance of foreign material by water circulating through the veins, or the passage of this foreign material through the mass of the rock itself. Both are possible. Water circulates through all free spaces in the interior of the earth. It is often hot, and loaded with a variety of minerals. Hot water no doubt has been largely concerned in bringing various ores as well as earthy minerals into veins. The filling up of veins is a subject of the deepest interest to the miner. He would willingly discover a law by which he could convince himself of the existence of ore from the nature of the surrounding rocks, or from the surface appearance of the lode, or from the intersections of lodes with each other, or with some particular kind of rock or from the degree of inclination of the lode. Such laws are not known, and it will be long before observations on these conditions justify absolute conclusions. But there is some relation between the contents of a lode and the conditions under which it has become filled. By observing facts, and studying their mutual relations, miners have found that a gossan or iron oxide at the top of a lode is an indication of a course of ore. The condition of the gossan is significant, some iron stones being recognized as favourable and some unfavourable. A "kindly gossan" is to a Cornish miner an indication of a valuable lode. So the fact that in lodes crossing each other, or in lodes traversing both granite and slate, there is generally a deposit of ere either at the intersection of two lodes, or at the point where a lode passing out of one rock enters another, must be regarded as tolerably well established. Little is known of the cause of this result. It may have been due to an electric or galvanic action, or it may have reference to causes altogether distinct. The study of the observations illustrating this rule cannot fail to be useful; but we are met by the difficulty of assigning a satisfactory reason for a phenomenon certainly very common. The condition of the enclosing rock is not without influence on the contents of a lode. An experienced miner will judge by reference to this of the value of an unworked vein. Certain conditions of softness in slate and granite are considered favourable, but a compact rock rarely contains large quantities of valuable ore. This applies to quantity rather than quality. Less important is the inclination of a lode. The valuable lodes of a mining district have certain mutual relations, but there is no clear identification of the cause. Certain metals and ores are common in lodes having one general direction, while other ores belong to other rocks and to cross courses. This is the case in all mining districts. In Cornwall the copper and tin lodes are usually in the direction of the axis of elevation, and are far the richest in ore; the lead veins are in the cross-courses, and are less important. In other districts, where the lead ores are in the main line of upheaval, the copper ores are of small amount, and occur in the transverse fissures. Mineral veins contain native metals, oxides, sulphides, or carbonates. Other combinations are less common and less abundant. All these are found in veins mixed with quartz, with crystalline salts of lime, and with clay, in large quantities. It is in mineral veins that the larger proportion of those combinations occur that seem to have little importance on the earth's crust, but that must certainly have uses and influence. Few metals and ores are sought with much care. The chief are, iron oxides and carbonates, iron pyrites, native copper, oxides, sulphides, and carbonates of copper, oxide of tin, sulphide and carbonate of lead and zinc, sulphide and oxide of silver, native gold and silver, native mercury, and sulphide of mercury. The metals and minerals of which the supply and nature are such that they are unknown in the general market are not here referred to. All ores are not found in abundance in the same district, in the same kind of rock, or in the same kind of vein. Certain laws exist, in obedience to which they may be looked for, and these laws must be ascertained by observation. What is true for Cornwall is true in principle, but not in detail, for Wales, for Chili, for Cuba, and Australia; and if the experience acquired in Cornwall is taken abroad, and there applied without consideration of the change of circumstances in the deposits, it will fail. Mineral veins containing ore are of very various dimensions. Of their length little is known. They are traceable in some cases for many miles at the surface, and below the surface they probably run on for far greater distances. It is difficult to say what is the inferior limit of length, for pipe veins and shoots are often in sets, and connected by narrow crevices. The width is more determinable than the length, and varies from a few inches to many yards. A silver vein in Mexico exceeds fifty yards, though not for any great distance. The width is sometimes increased by parallel fissures filled with ore, and threads of ore pervading the rock that encloses the vein. This condition of veins is a stockwerk, and lateral veins are called also strings. The depth to which mineral veins bear useful deposits of ore is unknown. Tin and gold have been supposed to abound near the tops of lodes more than at great depths but this is not likely. The tops of lodes often consist chiefly of quartz and iron oxide where the lode con tains a large quantity of iron, with or without copper or other metals, and where the vein stone is siliceous." Veins in granite and slate are vertical or nearly so, and the same system of lodes generally shows the same underlie. In limestone they are often zigzag, mere gaps of small depth, or open spaces between certain beds of limestone and shale. There are certain associations of earthy minerals with metal. The sulphides of copper are generally accompanied by siliceous minerals. Rich ores of silver are often found in gneiss, with quartz, while silver-lead ores and galena are abundant in limestones. These general indications of habitat are useful, but they cannot be trusted in all cases. Owing to the nature of mineral veins and lodes, their hardness always differs from that of the enclosing rock. If harder, they stand out above the surface as walls; if softer, the top of the lode is more rapidly weathered than the walls, leaving a depression. In either case the lode is broken away, and carried along the surface by water. When left behind the heavier portions containing the ore will be accumulated in certain places, but in smaller quantities and smaller particles, as they are more distant from the lode. By following up from point to point the traces of a lode from these fragments, a miner will discover the position of the lode. This is called shoding. When a lode is reached it is necessary to prove its direction and underlie, its width, and its condition at various points of outcrop. For this purpose trenches are cut across the direction of the lode at certain points where it ought to be. These are called costeaning pits. These are generally the best means of discovery, without the outlay of much money and labour, and the lapse of a long period of time. Mining is speculative; and of all kinds of mining that which is most elementary, namely, the discovery of valuable lodes is the most speculative. At one time a trial and the expenditure of a few hundred pounds will lay bare a deposit of enormous value; at another, the utmost prudence and intelligence, with capital, will end in failure. Lead and zinc deposits in limestone are different from veins in granite and slate, and the search for lead is thus different from that adopted in reference to copper. Lead deposits are irregular, and the process of shoding adopted on the surface with regard to copper, is applicable underground for lead. In some lead districts, were the ore is found between bands of limestone, this method is applicable; Derbyshire is an example in point. It is not so in Flintshire and the Isle of Man, which are also leadmining districts. Mining districts are to some extent indicated in a good geological map. They occur where rocks have been metamorphosed; where granites and slates and schistose rocks are found; where granite appears; where the contact of granite with sandy and clayey material is marked by changes in sands and clays, and where limestone is disturbed, we may look for fissures systematically grouped, and containing crystalline minerals and ores. The more remarkable of such districts are those in England, Cornwall and Devon. Derbyshire, Northumberland, and Cumberland are the chief mining counties for metalliferous ores in mineral veins. North Wales supplies lead and copper, and the Isle of Man is rich in silver-lead ore. In North Wales gold has been found. Ireland contains copper mines. Scotland contains lodes in its south-western counties. France presents five metalliferous districts. Belgium is rich in zinc and lead. Spain is exceedingly rich in most of the metals. Italy is very rich in iron and copper. Germany was the cradle and is the school of scientific mining, and the variety of minerals found there is very great. Silver, copper, lead, tin, cobalt, nickel, bismuth, antimony, and iron are all found there, and some under circumstances of extreme interest. Scandinavia abounds in iron and copper. In Russia there are many mining districts, and silver and lead are worked in the Altai mountains. Throughout Asia mining districts are known to exist; and the islands of the Southern Archipelago, as well as Australia, contain important supplies of useful metals. Both North and South America are metalliferous, and Central America still yields the shafts, but when the depth is great the descent and chief supplies of silver. The native copper on the shores ascent become extremely exhausting, and waste time as of Lake Superior is one of the most remarkable deposits well as strength. Of late years, man-engines have been in the world. When a lode is known to exist, and the indi- adopted, by means of which the men can reach their cations justify operations, it is usual to sink a pit on it or cut work and leave it with comparative comfort. Manit by a level or adit driven in from the nearest hill-side. If engines are not needed for shallow mines, and would not ore is found it may be run out from such an adit, and if be advantageous where the depth is less than 200 fathoms; water comes in it may be drained without cost from all below this the gain is very great. Almost all the mining workings above the point at which the adit cuts the lode. work in Cornwall is executed by contract. There are Assuming that the lode improves on going down, and two classes-the "tutmen," who excavate at a price per justifies a farther outlay, a shaft is put down to cut it at fathom of ground, and the "tributers," who speculate on some convenient point. At various depths cross-cuts may ore ground when reached. Poor mines are worked by be made towards the lode to prove its position and the tut-work, but when good ore is reached the tutman state of the ground and of the ore. All lodes are in their engages to raise it at a certain price per fathom. In other nature irregular. They contain what are called courses cases the tributers come in and speculate. They agree of ore, or they are bunchy and contain pockets of ore. The to work a portion of the lode for a given time, receiving former condition is that of a deposit of ore uniform within a certain agreed portion of the ores raised. If the ore certain limits of depth and distance, succeeded by barren be rich, they accept a small percentage of the value, if portions. Experience has too often proved that there poor, they demand a larger percentage. The captains, is no dependence to be placed on the presumed con- having decided the value to the best of their judgment, tinuance of courses of ore in any direction. Bunches put up a portion or pitch to auction, the bidding being and pockets of ore consist of expansions of a lode filled downwards, and the parties who bid being each reprewith ore, or portions of a large lode exceptionally rich. sented by one man. The ores are generally raised by Courses of ore occur not unfrequently in the great copper machinery and broken at the surface. In addition to the mines of Cornwall. Pockets of ore are most common in quantity of rubbish left below there is thus generally a the lead-mining districts. Mining work includes-first, waste heap, or attle, at the pit-mouth. This is prothe removal of ore already discovered; secondly, the lay- duced during the operation of dressing. Professor ing out, and bringing into a convenient state for extrac- Ansted then gave a brief recapitulation of the general tion, the courses and bunches of ore already discovered; subject, and concluded with the following remarks:and, thirdly, the organising of trials and discoveries in Thus it is that geology, applied to the arts, is a subject of those parts of the lode not yet proved to bear ore. Judg-real and vital interest to all of us. In endeavouring to ment is needed in laying out a mine so as to secure illustrate this, and interest you in the subject, I have cona supply of ore to pay expenses, retaining a reserve in fined myself as much as possible to familiar facts and exthe event of the supply failing, and expending a fair emplifications. I need not point out to you that to follow proportion of the profits in trial work. Owing to the irre- these generalisations into detail one must possess a very gularity of lodes, shafts must be put down to suit the wide range of knowledge and great practical experience. condition of the lode. Thus slant shafts are sunk either These can rarely be combined in one person; and thus from the surface or from some point below, and, by per- the agriculturist, the engineer, the miner, and the manupetually following the ore and removing it wherever there facturer must each learn his own department of practical is sufficient to make it profitable, the works become ex-geology, and apply it to his own purposes. The search tremely complicated. It is impossible to carry on mining after this knowledge is as interesting as the knowledge operations on a large scale in mineral veins without tim- itself is useful; and the interest is increased when the bering. When the vein is nearly vertical, it requires little student, before seeking out that which belongs to his own timbering to prevent the walls from coming together, department, will make himself master of so much of the especially when the country is solid, and the walls clearly general subject as to see the bearings of theoretical views on all the details that come before him. There are other so large as to render timbering a very costly operation. applications of geology that I have not brought under Sometimes the waters of the mine tend to rot the timbers your notice in these lectures. Among them I would espethat are used to shore up walls, and keep the overhanging cially point out its application to the fine arts. I mention wall from closing in on the foot-wall. There is no objec- it now to remind you that the subject of applied geology tion to the use of gunpowder in blasting in metal mines. is far from being exhausted; that, in fact, I have only Judgment is needed in deciding on the position and depth considered it in one aspect, and that the many-sided of the bore-holes, to take advantage of natural joints in science that deals with the earth, its history, its structure, the rock, and remove large blocks. The plan of a metal its grand physical features, and the causes that have promine is rarely systematic. But there is always one lead-duced and are daily modifying them, is no less calculated ing idea based on the method of removal of the water, to interest the artist and the poet than the farmer and and connecting this with discovery. Where the rainfall the manufacturer. There is no limit to the study when is large, the water that accumulates in a deep mine may we engage in the comparison of the works of Nature, become very considerable, as it comes in from above, from with their application to the requirements of man, and the sides where the lode connects with small branches and the operations of man's intellect. strings, and from below. It must be removed at the smallest possible cost; but, unless care is taken, the water lifted from one mine may find its way down another, or require to be lifted over and over again from the same workings. To avoid this, systematic drainage of groups of mines is desirable, and deep adits are cut, which receive the waters of a number of properties and convey them to a distance. In Cornwall the great adit receives the waters of the numerous mines in Gwennap and Redruth districts, and measures thirty miles in length. One branch penetrates ground seventy fathoms below the surface. The water thus conveyed is discharged into the sea forty feet above high-water mark. In the construction of long lines of deep adit, it is desirable to cross at right angles the direction of the principal lodes of the district. Metal mines are reached by ladders placed vertically in the defined. But there are cases where the excavations are FIFTEENTH ORDINARY MEETING. Wednesday, March 15th, 1865; Thomas B. Winter, Esq., in the chair. The following candidates were proposed for Drake, Francis, Friar-lane, Leicester. ON MARINE ENGINES FROM 1851 TO THE drag-link kinds. Paddle-wheels were exhibited with PRESENT TIME. By N. P. BURGH, Esq., Engineer. parts in action without disarrangement. The following is a brief account of the writer's observation of the class of marine engines exhibited:-The paddle engines were vertical and inclined, oscillating, of the ordinary type and arrangement. The valve gear was of two kinds-the counter-balanced eccentric, and the ordinary link motion. The air pumps were worked by eccentrics in some instances, the ordinary ratchet or wheel and pinion-the bilge and and in others by cranks. The mode of starting was by feed pumps were, in some cases, worked by the oscillation of the cylinder, and in others by separate eccentrics. The means for disconnecting were of the disc and the fixed and feathering floats. Five examples of oscillating engines were exhibited, including models and drawings. The engines for the screw propeller were as follows:One pair of double trunk engines, having injection con-densers with an improved arrangement of air-pumps and valves. The double piston-rod return connecting-rod type was well represented; this arrangement is used on account of the great length of stroke and connecting-rod attainable in a given space. In the Exhibition now alluded to there were six pairs of engines of this class, with injection condensers and air-pumps of the ordinary arrangement, and one pair of engines with the improved arrangement of condensers, pumps, and valves. The single piston type of engine was not largely represented and valves, and one pair with those of the ordinary kind. The single trunk arrangement was represented by one pair, with single-acting trunk air-pumps in the condensers.. The air-pump trunk with double piston-rods return connecting-rod engine was shown by drawings only. Vertical direct-acting engines were represented thus-one pair with annular cylinders, double piston-rods, and injection condensers of the ordinary kind; one pair with single piston-rods and surface condensers; and another pair as the last, with ordinary condensers. The history of the origin of the marine engine, and its slow advance, has been so often written, that I feel assured I shall not cause much disappointment if I pass over that already worn-out subject. I propose, therefore, to introduce to your notice the marine engine as it was in .1851, and the improvements which have taken place from that period to the present time. As the present paper alludes to the year 1851, it will not be deemed out of place to describe briefly the marine engines shown in the Exhibition of that date. The screw propeller was then making but slow progress, consequently the attention-one pair with the improved injection condenser, pumps, of our engineers was diverted from straining their talents to produce more perfect arrangements. The following examples of marine engines were exhibited. For the paddle wheel, the engines were arranged as follows:-Vertical, angular or inclined, direct-acting, and Oscillating; for the screw-propeller, a more varied and numerous collection was given, comprising disc, rotary; for horizontal direct-acting types, were the following, double piston-rod, return connecting-rod, trunk; after which, annular cylinder, vertical direct-acting, inclined direct-acting, single piston rod; and, lastly, a beam engine. The largest pair of engines were 700 horse power collectively, horizontal, direct-acting, single piston-rod. The trunk engines were 60 horse-power collectively; these two examples were adapted for the screw. For paddlewheels, the engines of the greatest power were a pair of 140 horse-power, of Belgian repute, the framing and paddle-centres being of wrought-iron, thus ensuring sufficient strength with a reduction of material and weight. To describe each engine in detail would be tedious, as well as of little value to the engineer of the present day. Allusion to the defects and improvements will be found under the different descriptions of the necessary appendages. 1 will now proceed with a brief notice of the marine engines exhibited in the year 1862, when it will be seen that a great improvement had taken place between the two dates alluded to. We are, I am happy to state, still making an advance, and I trust to be able this evening to describe these improvements; but, at the same time, I beg to suggest that there is plenty of room for further improvement in the detail of marine engines, which, doubtless, will be ere long taken into consideration by those interested in these matters. In the year 1862, our International Exhibition was again held, and with much success as far as regards marine engines. The class exhibited showed great improvement, both in design and arrangement. The oscillating engines adapted for the paddle-wheel did not exhibit much alteration, although it cannot but be said that in detail a change for the better was perceptible. With reference to the engine adapted for the screw, a complete revolution had taken place since the Exhibition of 1851. Valves and gear were altered, starting gear simplified; positions of condensers, air pumps and valves, in a much more correct state; number of details lessened; and, in fact, the entire arrangement fast approaching to a nearer state of perfection, viz., accessibility to all the It will be understood that in the previous examples the cylinders were arranged in pairs, the cranks being at right angles. In order to obviate the strains imposed at the extremity of each stroke, one firm exhibited engines with three cylinders, with spur gearing for reversing, stopping, &c., which were termed the expansive and economical principle. Lastly, I allude to the writer's invention Burgh and Cowan's patent antifriction trunk engine," so arranged, that the friction of the trunks is dispensed with, and no area lost in the cylinder. This arrangement was represented by a pair of engines and drawings. Having thus briefly alluded to the marine engines exhibited in the two International Exhibitions of 1851 and 1862, I will now proceed to give a detailed description of each portion. The arrangement of marine engines in the hold of the ship is, perhaps, not generally thought to be of so much importance as it really is.. It should be strictly understood that the attention required for engines of river steamers bears no comparison with that required for marine engines; imagine a ship in a gale, and heated bearings, and a faint idea can be formed of the duties required, and the reason for a free access to all the working parts. For the purpose of illustration to those present, not professional engineers, I will briefly specify what the necessary component parts of a pair of marine engines of the present day consist of, viz., cylinders, pistons, slide valves, piston rods, slide casings, expansion valves, blow-through valves, piston rod guides, connecting rods, cross-heads, main frames, crank-shaft, eccentrics, rods, links, valve rods, guides, condensers, air-pumps and valves, injection valves, snifting valves, discharge, valves, bilge and feed-pumps, valves for the same, starting gear, and turning gear, lubricators, and all the necessary levers, bolts, nuts, &c. It will thus be seen that marine engineers have more difficulties to contend with than is generally known. To understand the use and real character of each of the above details is not the work |