THE Following our usual course, we commence and from other causes so common to the ordiwith the ground floor department, the sides nary cast-iron roller. Besides securing in one of which are appropriated to the heavy ma- roller a one, two, or three-horse implement at chinery. Heavy indeed is the first machine pleasure, the increased weight is employed MECHANICS' MAGAZINE. LONDON: FRIDAY, DECEMBER 11, 1868. Wofficial, and social which tell of the ing mortar and for the various other purposes amies and Barford also show their clod the great superiority over all others. Unlike all steel-surface cutting mills, which have hitherto been known, it requires no re-cutting deed, not allowing of it; but when the grinding the extremely hard nature of the metal, insurfaces become dull they can be sharpened by running coarse sand through the mill, and when worn out can be replaced entirely at a very small cost. Messrs. Amies also show a model of their new combined straw, hay, and corn elevator. This machine is constructed to carry straw from the steam thrashing machine, and hay, as well as sheaved or loose corn, during the hay and harvest seasons, without any separate horse works. This is accomplished by raising the body of the machine, by means of racks and pinions, to such a height that a horse can work underneath it, and the produce is then delivered to an elevation of 30ft., and the most severe part of the hitherto laborious manual operation is saved-a light nag horse being equal to the work. When harvest is over, the machine is let down to the ordinary height, and is then suitable for being driven in the usual manner from any steam thrashing machine. occupied by Mr. II. Sykes, of Upper Thames-highest percentage of crushing power, yet street. Here was a gigantic 20-horse power without increasing the friction on the bearings -nominal, of course-portable engine, the (and consequently the draught of the implelargest we ever saw in the building, and which ment), as is the case when the old clumsy plan in this sense was a novelty. Mr. Sykes also of loading the frame is resorted to. We conexhibited a very good vertical engine, and sider this such a special improvement that we THE SMITHFIELD CLUB SHOW. an improved mill for steam power. This is propose in our next number to illustrate and E all have our landmarks-political, a mill that will be found very useful for mix-describe this apparatus in detail. Messrs. flight of time and announce the close of another to which crushing mills are applied. Messrs. crusher and press wheel roller, into which period of existence. Ours certainly is the Robey, of Lincoln, had as usual a good implement a great improvement has been Smithfield Club Show, and the one which to-day show of engines, which are worthy of some-introduced by substituting a solid wroughtsees close at the Agricultural Hall, Islington, thing more than a passing allusion, especially iron frame, with steerage wheel and guide reminds us of the approaching end of another their vertical stationary engine, which pos- rod, for the ordinary wood frame and shafts, year, and the close of another volume. As sesses great advantages over those of the whereby a saving of at least one-third in has been our wont for many years past, we horizontal type. Messrs. Robey's vertical horse-power is effected, and the man is enabled purpose placing before our readers the leading engine is well attached to the boiler, a strong to drive three horses abreast and steer the features of the Show for 1868, as regards the foundation plate carrying the whole. This implement to the greatest nicety without the agricultural implements and machinery. But foundation plate serves two other pur-assistance of a boy. This firm also exhibit before so doing, we have a word to say with the poses, being made to form the ash-pan a corn-grinding mill, in which the grinding Committee of the Smithfield Club. For years and to serve as a tank, in which the feed surfaces are made of cold blast white iron of past, we have been in the habit of receiving-water is heated. Altogether these engines a kind specially prepared, and in this consists in common with our brethren of the press are worthy of commendation. We would -a pass to the exhibition on the first day of the call especial attention to their single cornShow. On the present occasion, however, we grinding mill, which has been much imdid not receive one, and when we found that proved in make since last year. This mil others had, conceiving we had been accidentally is well adapted for large occupations where overlooked, we wrote to the secretary asking a portable steam engine is employed, as the usual favour, in order to facilitate the pre- it will grind all kinds of grain for farm purparation of our notice. After waiting nearly poses. The stones and machinery are fixed in a week without receiving either reply or a metal frame of a neat and compact design, acknowledgment, our representative called whereby it is rendered both strong and porton the secretary upon the subject. No ex-able. This mill is simple in construction, being planation was given to him, but he was briefly thus easy to manage and adjust; the top or informed that the Committee had issued all runner stone is carried round by the upright the passes they intended to issue to the press. spindle, which receives its motion from a pair Of course, the Committee have a perfect right of bevel wheels, one of which is geared with to admit whom they will free of charge; but wood. It is fitted with fast and loose pulleys, as old servants of the public, and faithful and altogether is very compact and well made. chroniclers of the Smithfield Club Show, we Messrs. Garrett and Sons, of the Leiston did expect the usual compliment of a pass, or Works, Saxmundham, appear in their usual at least the courtesy of a reply to our written strength, with seed and other drills, thrashing, application. However, we waited until the finishing, dressing, and other machines, porthour of two on Monday last, paid our five able and other engines. Their chief feature shillings, and walked in, feeling perfectly is an excellent agricultural self-moving engine, independent, and glad to have contributed which weighs some three tons less than the our mite towards the support of an institu- usual engines of this class. In many districts, tion which we have always held to be worthy objection is now raised against the trouble of of every support. And, now, having had moving portable engines from farm to farm, our say, we will turn to the Show itself. and the attempts which have hitherto been Messrs. Hornsby and Sons, of Grantham, made to introduce self-moving engines have having made steam engines their leading manugenerally failed, on account of the weight and facture ever since their introduction, of course cumbersomeness of the engines employed. To occupy a prominent position in the Show in obviate the difficulties which have arisen from respect of quality and finish. The resources the use of such engines (which were never in- and experience of this firm have enabled them tended for anything but heavy road draught), successfully to carry into effect the motto Messrs. Garrett and Sons have brought out of the Royal Agricultural Society of Engthis light self-moving engine, which will draw a thrashing machine and elevator with ease, and pass over soft land and other places where it would be almost impossible to take machinery by horses. The weight of the new engines is but a few hundred-weights more than a portable engine of the same power. It can be steered either by a man in front, or a horse can be attached with shafts. The tender carries water and fuel sufficient for ordinary thrashing journeys. Thus we have a step in advance, which will secure a demand for engines of these makers. We understand that Lywood's patent rick ventilator, as manufactured by Messrs. Garrett, continues in great favour with agriculturists. Of course, the beasts were the great public attraction, and these, although apparently not SO numerous as last year, were splendid examples of breeding. We are, however, quite unable to recognize the necessity for developing pigs to such an extent, that it is almost impossible to tell which is one end and which is t'other. To see these semi-animated land, "Practice with Science," so that their masses of fat, spasmodically gasping for patent portable engines have for years past breath, their snouts-where sufficiently promimaintained a high position, and every modern nent-propped up by chocks of wood, and improvement and appliance of mechanical their organs of vision completely shut in, does skill is employed to keep them in advance of seem to us a condition of things in which all competition. Messrs. Tasker and Sons, neither purposes of utility nor ornament are of the Waterloo Iron Works, near Andover, attained. On the contrary, a fine healthy have, amongst other things, a good 8-horse feeding we think-and it may be want of taste power portable steam engine, in which some on our part-would do much more to improve details of construction are worth notice. It the interests of the pig market, than the prehas a large amount of heating surface, as well sent system of feeding swine up to the condias ample water space around the tubes and tion of panting ungainly rolls of fat. But fire-box, is strongly stayed, and constructed passing on to our more legitimate spherewith regard to efficiency and economy in fuel. the mechanical developments-we first note But perhaps the chief feature of the engine a decided improvement in the arrangement of is that it is fitted with, a new adjustable the Show in this department. The Committee Messrs. Amies and Barford, of Peter- eccentric, which has been patented by Messrs. have done well in preventing that overcrowd-borough, have several matters well worthy of Tasker, By means of this eccentric the ing and commingling of the stands which we attention, the first of which is their adjustable travel of the valve can be altered in the same have observed in past years. The exhibitors, water-ballast wrought-iron field roller. These manner as is usually done by the ordinary doubtless, have also to be commended in this rollers possess the great advantage of being expansion valve, and with the same results, respect, for by not attempting to show every- adjustable as regards weight, one roller secur- viz., a smaller amount of steam is required thing they make, they enable their leading ing the same results as two of ordinary con- for working the engine, and the amount of manufactures to be properly examined. Tak- struction. For light work, the cylinder is fuel consumed is consequently less. The ing the Show as a whole, there are not so used empty, for heavy duty it is filled with extra valve, valve rod, and eccentric required many striking novelties this year as usual; water. The cylinders and frames are made for the expansion valve are dispensed with, although upon investigation we discovered entirely of wrought iron, combining great the working parts are fewer in number, the many detail improvements which will interest strength with durability, and are entirely free friction is considerably reduced, and a great our readers. from the liability to breakage on bad roads, saving is effected in the use of oil. The patent eccentric appears in every way as corn elevator was driven off the first blower superior style, and with all the most recent durable as the ordinary one, and is so simple spindle; it is now driven separately, so that improvements. Messrs. E., R. and F. Turner, that it can be adjusted by a common labourer. the speed of the elevator can be altered with- of Ipswich, had a couple of good portable At the adjoining stand we found an altera- out affecting the blast. There is also an engines, but their speciality is mills, cake tion in the name of the firm, that of Barrows extra joggle board in communication with breakers, &c., of which they had a good show. and Stewart, of Banbury, replacing that of the second fan, and altogether the machine In their stone-grinding mills, the upper stone Barrows snd Carmichael. We regret to find is very satisfactorily arranged. In the grub-revolves and is made to raise or lower by a this to be owing to the death of Mr. Car-bers a moulding board has been added, by hand wheel, as more or less pressure may be michael, whose name was well known in con- which a very good furrow is made. Mr. required. They are more particularly for nection with agricultural machinery. We Underhill shows a plain but good portable steam power, and are fitted either with Derbyhave nothing new or special to report of the engine. shire Grey or French Burr stones. Messrs. new firm, who still maintain the high chaTurners' roller malt mill is made in conjuncracter of the old for engines and machinery. tion with Boby's screen, and the combination Their portable engines have been improved proves exceedingly useful for breweries. The in various points of detail; the boilers are general complaint of bad wear in these kind multitubular, and constructed so as to secure of rolls is obviated here by the pressure being unusual strength, and the greatest amount equalized on both bearings by means of a of steam space, the shell being continuous compound wedge, and rendered elastic by from end to end, avoiding the divisions known strong spiral springs. The oilcake breaker as fire-box, barrel, and smoke-box. by this firm breaks cake for lambs equally as well as for beasts or sheep. Besides the ordinary rollers, which by reversing the direction enables it to break for sheep or beasts, it has a second pair intercepting the cake as it falls from the sheep rolls and reducing it to a suitable size for lambs; these rolls admit of adjusting to vary the sample, and may be instantaneously thrown in and out of use. Messrs. J. and F. Howard, of Bedford, are, as usual, strong in steam cultivating apparatus. This firm has now been engaged in the manufacture of steam cultivating machinery for upwards of eleven years, during which period they have cultivated their own farms by steam power. With so extensive an experience both in using and manufacturing, they have of necessity acquired an intimate Passing on to the next stand-that of acquaintance with the subject of cultivation Messrs. John Fowler and Co., of Leeds-we by steam. They have re-arranged some porfind the usual array of steam ploughing ma- tions of their engine; the steam cylinder, chinery, for which they are so justly cele- which was formerly mounted on the boiler, is brated. The special novelty at this stand is now placed under it, as in the locomotive. Messrs. Fowler's improved patent cultivator The crank shaft and gearing are attached to to turn at the ends. The construction of the framework, and are independent of the this implement is simple and effective, com- boiler, which relieves the strains on the latter. bining strength with a minimum of weight; Another important feature is that the windthe appliances for steering, lifting the imple- ing drums are both geared direct from the Messrs. Woods, Cocksedge, and Warner, ment out of work, and turning it, are so well crank shaft. This engine will work upon any of Stowmarket, have some excellent examples adapted and nicely arranged that it is managed system, either fixed or moving. Messrs. of vertical engines, and a large assortment of with the greatest ease. This implement can Howard exhibit a great variety of mowing mills, root cutters, &c. We especially noticed be made any breadth, to suit the varying re- and reaping machines, which they construct a very complete 24-horse power engine, fitted quirements of different farms, and by aid of almost entirely of iron and steel, and fit on with a new horizontal two-ball governor. moveable parts, each implememt of itself is the interchangeable system. This firm also The feed apparatus was very neatly arranged, adapted to meet these requirements; the body showed a full-sized model of their safety a circulating pump being fitted. The great of the implement can be made 6ft. or 8ft. steam boiler on the tubulous principle, which advantage of these engines is that they occupy wide, it is then adapted for strong land; when has been fully described and illustrated in less room than any other form of engine. on lighter soils, sides or wings can be applied our columns, and which is meeting with every They require no fixing; brickwork or foundato make it any breadth required. The plan success in practical use. Messrs. Holmes tion is not necessary; they can be readily of working is as follows:-The rope on each and Sons, of Norwich, show some excellent removed and worked by an ordinary labourer, engine is attached to a straight lever in front portable combined thrashing and dressing and may be used in places which would be of the cultivator, this lever is fixed on an machines. In their last new machines, Messrs. otherwise excluded from using steam power. upright spindle, on which is a segment con- Holmes have retained all the valuable patented The boiler is of the best description, and nected by a chain to the road wheel axle improvements of their 1862 machine; but tested to a very high pressure. The ash-pan (which is a double crank and carries the have, in constructing this machine as a finish- is provided with a door for removing the frame); when the cultivator is pulled up to ing machine, had special regard to the best ashes and regulating the draught. The flythe headland by one engine, the other engine position of the finishing apparatus, so as to wheel shaft is on bearings separate from the across the field starts away immediately, the have the corn delivered in that part of the boiler, so that they never get heated. Mr. rope pulls the lever in front round, the seg-machine free from dust, and the least affected C. Burrell, of Thetford, exhibited a traction ment draws up the chain, which turns the by the wind, and in the most convenient posi- engine, single cylinder, of 10-horse power, crank axle and lifts the implement out of tion for taking away. The arrangement of for agricultural purposes. This engine is work, the rope continuing to pull brings it well finished, and is fitted with a driving round into new work; the man (who has chain on each side, which distributes the never left his seat) drops it into the land, and power, being driven from each end of the when across the field the same operation is crank shaft. The driving pinions are of repeated. wrought iron, case hardened; clutches with expansive levers are attached, so as to be under the control of the driver when turning corners. The driving wheels are made of cast and wrought iron, combined with a wrought-iron tyre on the outer edge of the rim. It has a large tank to supply the boiler, and the man stand has ample room for carrying coals. The steerage is very good, being worked by a pitch chain round a segment to take up the slack chain. All the working parts are well arranged, and the workmanship is sound. Mr. Burrell also exhibits a machine for drawing clover or trefoil seed, with a patent separating screen for taking out stone, glass, &c., from the trefoil seed. This machine is well finished in all its parts. these machines is simple, due regard being Messrs. Clayton, Shuttleworth, and Co., are well represented by their portable engines, which they make their speciality. They have now manufactured some thousands of these engines; the number on one in the show was 8,864. In this engine the cylinder is steam jacketed, and all the working parts are on the outside or top of the boiler, and can be seen and got at by the person in charge at a moment's notice. It may be readily reversed, so as to drive in either direction. The exhaust pipe is on the outside of the boiler, and is formed with a branch, to which a tube is attached for conveying a portion of the steam to the feed water, thus effecting a considerable saving in fuel. We would also call attention to the fixed steam engines made by this firm, which are well Although we have noticed the stands of a constructed, special regard being had to great many exhibitors, our task is but half economy, efficiency, and simplicity. Their Messrs. Aveling and Porter, of Rochester, performed. We shall, however, resume the traction engine, too, is worthy of notice. An show a 12-horse power steam ploughing en-subject in our next number. We cannot, important feature here is the self-acting gine, and an 8-horse power agricultural loco- however, close our present notice without redifferential motion, which enables the driving motive. We also found at their stand a very ferring to a novelty in umbrella construction, wheels to accommodate themselves to the light but strong engine which has been con- which we met with in the arcade when leavsharpest curves, without strain or loss of structed for the purpose of drawing heavy ing the Show. This is the invention of Mr. power; both wheels at the same time are guns and other matériel for the War Depart- Henry Smyth, of No. 21, Little Trinity-lane, kept in gear, and receive the full power from ment. This engine is fitted with differential Cannon-street, City, and is a very perfect the engine. The absence of this feature in gear for turning sharp corners, and is steered umbrella. It embodies an entirely new prina traction engine is a defect, detrimental from behind by the driver. The engine isciple of action, by which wire springs and alike to its efficiency and durability. Mr. named the "Prince Arthur," and on leaving connections are all dispensed with. It is W. S. Underhill, of Newport, Salop, has im- the Show will be handed over to the Royal exceedingly strong, and will bear very rough proved some details of his thrashing machine, Engineer Department. It is fitted and finished usage without fear of dislocated joints, and which has added to its value. Formerly, the in Messrs. Aveling and Porter's well-known from its construction is not liable to be turned "inside out" by the wind. It is, in effect, constructed on sound mechanical principles, and waits only to become known to render it popular. SENGERS AND GUARDS. A come apparatus carriage great Eastern train, fitted with Walker's electrical the test of time? Certainly not. With system, was tried. This consists of a wire run- regard to the different plans of electrical ning throughout the train, connected to each communication, we find, in examining them, compartment with a small instrument, which, that they not only fulfil all the necessary rewhen pulled, releases an indicator outside the quirements, but that they also have stood the COMMUNICATION BETWEEN PAS- carriage, and makes electrical contact between test of time-of time not of days, but of years. the wire and rails. It is connected also to a The principal objection to them in railway bell and battery on the van, and to an indi- eyes is, it seems to be, that the plan is elecT length it seems that some steps are to cator and semaphore on the engine. When the trical, and railway managers have not yet got panies to provide the long wished-for com- in the van immediately rings, and the indi- Let us see how the electrical system has munication in trains in motion between pas- cator on the engine is moved. It is possible stood the test of time. Since May, 1865, the sengers and guards, and between guards and throughout the journey for the guard to in-up and down Exeter expresses have been drivers. By the Act passed in the last session, terchange communications at any time by running, fitted with Preece's system, it was enacted that communication should be means of this bell. The trial was not satis- with perfect success, communication being carried out in certain trains after the 1st of factory with this plan, as signals were weak, continuously kept up from one end of the January; a clause for this purpose being and the bell would not ring; this was evi- train to the other. The trains are still runspecially introduced, the bill for a similar dently due to the fact that the train had been ning with the same success. On the South purpose, brought in by Mr. H. B. Sheridan, allowed to run the night before, and experi- Eastern, the Dover express was fitted with was, in consequence, not proceeded with. The ments tried with it; the apparatus was left Walker's plan, a plan almost identical to the near approach of the stipulated time will ac- with the battery on, so that it got exhausted. above. It ran with such success that the count for some little energy on the part of It cannot be said to be due to the faults of the South-Eastern have now running four up and railway managers, but we may expect some system, as it has stood for some time the four down trains daily, running in the aggrelittle time yet to elapse before any definite practical test of time. The remainder of the gate 624 miles per day. For this purpose, scheme is settled upon. We must, however, journey was occupied with experiments on 200 vehicles of various kinds have been fitted make some exception in favour of the South-Harrison's plan; in these trials it was found up. On the North-Western, the London and Eastern Railway, who have eight of their ex- that the whistle would sound, but it required Wolverhampton express has been fitted up press trains fitted up with an electrical system great force to pull the cord, and it was quite with Martin's plan since January last, and of communication; the South-Western have possible to raise the alarm without disturbing has been running 250 miles per day with also for a long time had both their up and the indicator. unvaried success. These three plans, or, down Exeter expresses fitted with a commu- On the following day, experiments were indeed, we may with safety say, the same nication between passengers and guards; the tried with a train made up partly of South-electrical system, as applied to communicaNorth-Western also have been running a Western carriages fitted up with Preece's tion between passengers and guards in trains train fitted with communication, but as re-electrical system, and partly of North- in motion, is at the present moment fitted gards the other railways they have done but Western carriages fitted up on Martin's plan, to trains which are now doing, and have little. With a view to find out some parti-The system adopted in the latter is identical been doing for some time past, an aggregate cular plan that might be recommended for with the former, differing only in detail. A journey of over 1,300 miles per day. We have general adoption, a meeting was lately at-wire is carried through the train, connected here as strong a practical proof of its success tended at York, by most of the general maand its perfect adaptability to the requirenagers, to experiment upon a variety of plans ments of the case as can be wished; of its fitted to various trains, specially sent there to test as regards time we have stated sufficient be experimented upon. The meeting was under to convince the most sceptical. The three the presidency of Mr. Allport, general maplans, with but a slight modification, can be nager of the Midland, and lasted for two days. invariably worked together, so that the inMr. Allport has been well known for some sertion of foreign stock will have no effect. time as being greatly opposed to the public Can we say the same of any other plan? having means placed in their possession for exercising any control over a train, and it, therefore, may be well imagined that the experiments were of a crucial nature. between the carriages with double couplings; in the vans are bells and batteries, and in the carriage is an apparatus for raising the alarm. In Martin's, it consists of a handle, which is to be pulled, and then becomes locked. In Preece's, the hand is moved as indicated, but before it can be moved it is necessary to break the glass face of the case. The object of the glass is obvious-to prevent mischievous per- We have watched the various plans brought sons from raising an alarm unnecessarily. forward from the first, and have, on more than These plans were tried every way, and one occasion, brought the subject before our answered admirably. They were then joined readers. We again bring the matter forward, The following is a concise description of together and were equally successful, com- as being now in a more advanced state than the various plans experimented upon :-On munication being maintained from the one heretofore. The new Act is already beginning the first day were tried the plan of Mr. Rams- van to the other; in fact, the results perfectly to bear its fruit, and we may trust that soon, bottom, fitted to a North-Western train; Mr. justified the anticipations formed from the whenever our readers may wish to travel exWalker's system, fitted to South-Eastern statements given of the amount of experience press, they will always have within their stock; and Mr. Harrison's, fitted to a North- obtained from them. Signals were readily reach a means of communicating, when absoEastern train. The first and last are purely received on the engine and answered back.lutely necessary, with the guard. mechanical, and in some respects similar; the In Preece's, an indicator was used; in second is purely electrical. In the two me- Martin's, a bell only-the latter, in the clatter chanical systems, a rope is used; in Ramsbot- and noise of the engine, being rather difficult EFFECT tom's, cach vehicle or coach is fitted at the to hear when not expecting it. A plan of ends with a heavy iron hook, projecting out Mr. Kiersley's was also tried. This consisted about 15in., and made so as to fall inwards of a gong in the carriage, struck by a revolv OF THE POSITION OF THE LOAD UPON CONTINUOUS GIRDERS.-No. IV. ET us now examine the action of a load when not required; the cord traverses the en-ing fan. If we remember aright, this plan placed in different positions, and first sup has been proved over and over again that tire train, about mid-height, from the rear has been largely tried in Norway. We will pose it uniformly distributed over one of the side spans, A B. Manifestly, the influence of this load will be felt to some extent upon both of the other spans, the intensity of it diminishing We may remark that with regard to the as the span is situated more remotely from it, first plans tried-those of the cord-there are until it becomes at last inappreciable. If, in many objections. In Ramsbottom's, the cord addition to the load upon the side span A B, is in the way of the door, and projecting another is placed upon the central and adjahooks must be objectionable. In starting cent one B C, the strain upon the former betrains and making them up in a hurry, adding comes diminished, as the load upon the carriages on at the last moment, it is almost central span strengthens that part of the impossible to keep the cord perfect. We girder between B and F. This is also perhave ourselves seen it over and over again ceptible from the similarity that exists bewith the common bell and cord plan. When tween loading the central girder, and fixing the train is heavy the force necessary to apply the part over the pier firmly and immoveably. sufficient tension is frequently, from hitches In the latter case, the girder A B would beand other causes, sufficient to break the cord. come converted into a beam with one of its We have been assured by men having prac- ends firmly fixed, and would thus be stronger tical experience of many years, that the cord than if both ends were free. Consequently, cannot be depended upon over a certain num- the greatest strain upon the booms or flanges ber of carriages. Looking upon the require- of the side spans occurs when they are covered Experiments were first tried with Rams-ments of the case, and the necessary ends to by a moving load, and the central span unbottom's plan, running from York to Scar- fulfil, we unhesitatingly give our opinion that loaded. By similar reasoning, the greatest borough, and answered satisfactorily, although the cord system falls short of anything like strain will occur upon the flanges of the when the cord was cut it took some time to perfect means of establishing communication central span B C, when it is uniformly loaded, repair it. On the return journey, the South-between passengers and guards. Has it stood and the two side spans free from the action of a a moving weight. A load upon either of the of the independent girder S, we have S L L (1-7325)', can = advantageous position she occupies with respect to fuel, it is no wonder, accustomed as we are to be foremost in all matters of a remunerative commercial character, that we have almost a monopoly of this indispensable aid to construction. Mr. Reid has followed in the wake of Mr. Grant, and has added to our very scanty practical information upon the manufacture of Portland cement by the excellent treatise he has lately given to the public. Without desiring to accuse our engineers and architects of being remiss in their duties, yet it must be acknowledged that the credit is due to our professional brethren, on the other side of the water, for directing attention to the admirable qualities possessed by cement for foundations under water and damp and spongy situations. As a rule, the French were long before us in the use of cement, concrete, "pierre perdue," bêton, agglomeré, and, in fact, every description of artificial masonry. We for some time refused to abandon stone, and bricks and mortar, and adhered to the ancient types of construction, with true Anglo-Saxon obstinacy and perversity. Gradually, however, we were brought to see the error of our ways, and the commercial element mingling strongly with the adoption of cement, we now not only manufacture it on a very extensive scale, but use it also to a considerable extent in subaqueous and other works. The application of this important material appears to be almost illimitable even at present, and it promises to embrace a still wider sphere of action. All the engineers, foreign as well as English, concur in co.nmending it highly in whatever works they have availed themselves of its the strength and quality required, there is no services; and now that it can be obtained of longer any doubt remaining regarding its being a thorougly reliable and trustworthy material. (L-2)=17325 By these equations the vert the latter into a beam with both its ends firmly fixed. The action of the web in a con- points of contrary flexure be accutinuous girder, if the spans be equally and rately fixed, and, from them, the spans and uniformly loaded, is precisely analogous to loads being given, all the pressures can be that in a detached and independent one. found in the same manner as for a continuous Where a uniformity of loading does not exist, girder of three spans. Taking the span B C, the position of the points of inflexure vary, and regarding it as an independent girder of and also the individual proportions of the a span equal to L, we shall have the strain at cantilever and girder parts of the structure. the centre, to the strain at the centre of the The greatest strain upon the web must, there- girder of a length equal to S, to which B C fore, be calculated in accordance with this is reduced by the principle of continuity, as variation. If it be determined upon the asL2: S or as L 2: or as 2.99 sumption that the cantilever and girder segments remain of a constant length during the to 1, practically as 3 to 1. If the reactions transit of a passing load, the strain will be of the abutments and intermediate piers be less than its proper value. A very little re- given, the positions of the points of contrary flection will suffice to point out that the flexure may be deduced from them, as was greatest shearing strain or vertical pressure exemplified in the case of the girder of three over either of the intermediate supports BC, Mr. Reid enters at full length into the spans. As the character of these articles will take place when the leverage acts upon has been of a practical tendency, it describes in detail the various processes it has practical manufacture of the article, and both sides, and the pier becomes a kind of would be foreign to cur purpose to inquire to pass through before its raw constituents, pivot upon which the two opposing forces deeply into the question of the deflection of the chalk and the clay, can be presented to balance one another. The greatest vertical continuous beams, more especially as their the public in a marketable form. Washing, pressure upon a pier, therefore, occurs when determination involves the use of the higher mixing, burning, and grinding constitute the the two adjacent spans are covered by the mathematics. So far as the general case repassing load. presented in fig. 2 is concerned, it may be principal phases of the ordeal it is submitted It would be to no purpose to multiply stated that supposing the girder to be perfect to, and in the first and second of these, which examples, differing only from one another by in its continuity, the deflection of any span operation, there exists a difference between are really accomplished at one and the same the number of spans, so we will now consider will be only one-fifth of that which would the plans adopted by the English and the the general case of a continuous girder with be undergone by an independent girder of the German manufacturers. The former use the any number of equal spans. In fig. 1, let same dimensions. For bridges of large span, ABCD be a continuous girder; A B one of where the vis inertia of the structure would wet and the latter the dry systems. Each of the end spans, and B C, CD, two of the cen- be considerable, and its own weight would and it is perhaps as much a matter of habit them have certain advantages of their own, tral spans. From what has been previously bear a very large proportion to the rolling and national individuality as of any practical stated respecting the action of the web, it will load, the advantages of the continuous prin- superiority. Our author, on the whole, gives not be difficult to perceive that under a uniform ciple are incontestable. In this case, the ac- the preference to the wet system, although he load it does not differ from that in an inde- tion of a rolling load exercises but very little fairly admits all the advantages that may be pendent girder, and when the load is variable, influence upon the position of the points of provision must be made in the manner already contrary flexure, and the range of their mo- German method. The necessity for sampling possessed, and are urged in favour of the described. The position of the points of tion is bounded by very narrow limits. There the cement, that is, testing it after the operacontrary flexure in a continuous beam, such as is in consequence little or no ambiguity tions of washing and mixing have been carried represented in fig. 2, does not vary much respecting the strains, and but comparatively from those already found for a girder of a very small portion of the flanges has to be out, is strongly insisted on as one that should three spans, and without any practical error designed, so as to withstand the strains of tions in which the chalk, clay, and water never be omitted, for if the proper proporthey might be regarded as identical. It will, both tension and compression. For bridges should be mixed are not discovered at this however, be well to give the means of finding of small spans, and in large ones where there them accurately. Let L equal the span, and is any doubt or uncertainty about the solid juncture, it will be too late to remedy the the distance of the points of contrary flex- nature of the foundations, the continuous evil afterwards. Two descriptions of tests, ure from the intermediate supports of the principle should be unhesitatingly discarded. namely, the water and the air or dry test, are central spans. Thus, in the span B C, y The subsidence of one of the supports of an employed, and the experienced hand can tell The value of y may be ascertained independent girder, provided it is not exces-mixture has been properly accomplished, and by the united aid of the two, whether the from the equation, y = L. L. Reducing sive, is of little or no moment, but it would whether it should be allowed to pass on to cause injury to, and possibly dangerously the kiln. With respect to this latter part of affect, the security of a bridge designed upon the machinery employed, it does not appear the former principle. The French engineers to have arrived at the condition of comparaare strong advocates for the continuous system, and have adopted it for a railway bridge at Asnières, carrying four lines of railways, and having five spans. y Br. the double fraction, we have Y (1·7325 × L) — L. This value for y also gives the length of the WITH tive perfection it should have done. The original lime kiln shape has not been much departed from, and the whole operation is conducted in a very rough unscientific manner. In the appendix-or, rather, the second por "A Practical Treatise on the Manufacture of Portland Cement." By HENRY REID, C.E. To which is added a Translation of M. A. LIPOWITZ's Work, describing & New Method Adopted in Germany of Manufacturing that Cement. By W. F. REID. London: E. and F. N. Spon, 48, Charing-cross. 1868. DEC. 11, 1868. tion of the volume, a description is given of THE MECHANICS' MAGAZINE. its kind, and one very much wanted. It is structure. TRY MARKET. E this week give further engravings of this 465 expended in the voyage from India to England renders unproductive for a longer time the money represented by the cotton bales; and four months' interest is of no small consequence in these days of close competition. It will be seen, therefore, that of expense, and that every detail of cost and inthe cotton producer in India must study every item cidental outlay is of greater importance to him than to his more highly-favoured rival in the United States. If the Suez Canal were but open, the voyage by the Cape would be avoided; but opinions differ as to the ultimate success of that scheme, and the route certainly does not exist at present. The Isthmus Railway was intended for the same purpose, but the cost of transhipment and land carriage is so great that there is practically little advantage in bringing cotton that way, and till lately it was only silk and other expensive goods that were brought overland. Recently, a considerIsthmus, but until better arrangements are made for its transport by the Suez Railway, only an inappreciable quantity of cotton will come by that route. It will be seen, therefore, there is every inducement to save, if possible, in the cost of freight. Now, the freight payable on bales of cotton is calculated by the ton of measurement, and not by the ton of weight; and therefore the more cotton that can be compressed into a bale of given size, the lower the rate becomes per lb., and the greater The foregoing becomes the amount of profit. shows the important service that can be rendered by powerful baling presses; and while this is especially the case with India and Australia, it is true also for Egypt and other less distant places, where assert that had it not been for the Metro- treats. Most of the applications of cement, whether in its pure state, or any one of its numerous combinations, are known to our readers, especially its recent application to the construction of dwellings, warehouses, and other buildings of large size. There has one been made which is not so very generally known. It is the application of the material to prevent oxidization in the holds of iron vessels, and also to the external use of it in coating ships. Captain Cowper Coles, C.B., has applied it in the latter manner upon several vessels, and apparently with much success. Another comparatively novel method of utilizing this valuable material is in concrete for the construction and repair of the surfaces of roads. Although partially this experiment has been successful, it has also failed lamentably in one or two instances. Mr. Reid candidly admits that it proved a failure in St. James's Park, although he gives a ready explanation of the cause of failure, of the reason why the surface broke up under the action of the rapid traffic over that part of the Mall. towers. SOCIETY OF ENGINEERS. the expenses of irrigation and tillage may form a not sleep in the United States, and it might be pre- While the cotton culture in India was in its infancy, the quantity produced was too small to create a demand for any special apparatus. Baling machines were sent out from England, but they were of a very primitive kind. Screw presses, something like those used for making cheese, were contrived. The next step was to work the vertical screws by bevel gearing and a winch. Then, as the cotton trade grew in importance, there was devised a number of inventions and contrivances, some by engineers, and others by the cotton growers, whose ingenuity was stimulated by necessity, the mother of all invention. Levers, screws, and wedges were tried alone and in combination. The use of hydraulic pressure naturally suggested itself for trial, but it was not very successful; no very great power was obtained, and the process by pumping This success has survived its immediate cause, The second portion of this valuable treatise is devoted to a translation of the work of M. A. Lipowitz. It is in a more condensed form than the preceding portion, and is not by any means of the same value. In fact, it would do the work not the least harm if it were omitted altogether, as a portion of it must of necessity be repetition. It treats principally of the German methods and class of machinery, and contains some good plans and sections of those employed in that country. Mr. Reid's volume is, in fact, the only book of There are several disadvantages with which India has to struggle. Assuming that the first cost of tillage and agricultural labour is the same, there then remains the immense difference between India and America in distance and time of transit from the port of departure to the port of arrival. From New Orleans to Liverpool, the distance is 6,000 miles, and twenty days' voyage for a steamer. From Bombay to Liverpool (round the Cape) the distance is 12,000 miles, and takes 120 days. Thus in the race India is heavily handicapped. The carriage of the cotton costs more, and the time A Gradually, improvements were made in the lever presses, and these were generally preforred. Some of them may be mentioned. Mr. M'Comb took great pains to make a good baling machine, and patented several of his improvements. His cotton was forced up by two compound levers, drawn together by a chain worked by hand or steam. Mason's press had somewhat the same principle of levers, but was worked in a different way. A horizontal engine drove two machines, the crankshaft running right and left from the engine. By gearing, a shaft parallel to the crank shaft was driven at a reduced speed, and by means of right and left-hand screws on these shafts two powerful levers were drawn together and forced upwards against the follower of the cotton box. Both these presses are still in favour, and are used in considerable numbers; yet, however well they may be made, it is obvious that there must be severe strains upon the points through which the power is trans(Continued on page 467). |