BAYLE'S LAMP CHIMNEY.
The different types of lamps used in domestic lighting present several imperfections, and daily experience shows too often how difficult it is, even with the most careful and best studied models, to have a perfect combustion of the usual liquids—oil, kerosene, etc.
BAYLE'S NEW LAMP CHIMNEY.
Mr. P. Bayle has endeavored to remedy this state of things by experiments upon the chimney, inasmuch as he could not think of modifying the arrangements of the lamps of commerce "without injury to man" interests, and encountering material difficulties.
The chimney is not only an apparatus designed to carry off the smoke and gases due to combustion, for its principal role is to break the equilibrium of the atmospheric air, which is the great reservoir of oxygen, and to suck into the flame, through the difference of densities, this indispensable agent to combustion. The lamps which we now use are provided with cylindrical chimneys either with or without a shoulder at the base. The shouldered chimney would be sufficient to suck in the quantity of air necessary for a good combustion if we could at will increase its dimensions in the direction of the diameter or height. But, on account of the fragile nature of the material of which it consists, as also because of the arrangement of the lighting apparatus, we are forced lo give the chimney limited dimensions. The result is an insufficient draught, and consequently an imperfect combustion. It became a question, then, of finding a chimney which, with small dimensions, should have great suctional power. Mr. Bayle has taken advantage of the properties of convergent-divergent ajutages, and of the discovery of Mr. Romilly that a current of gas directed into the axis and toward the small base of a truncated cone, at a definite distance therefrom, has the property of drawing along with it a quantity of air nearly double that which this same current could carry along if it were directed toward a cylinder. In getting up his new chimney, Mr. Bayle has utilized these principles as follows: Round-burner lamps have, as well known, two currents of air—an internal current which traverses the small tube that carries the wick, and an external one which passes under the chimney-holder externally to the wick. In giving the upper part of the chimney, properly so called, the form of a truncated cone whose smaller base is turned toward the internal current of air, that is to say, in directing this current toward the contracted part of the upper cone, at the point where the depression is greatest, a strong suction is brought about, which has the effect of carrying along the air between the wick and glass, and giving it its own velocity. The draught of the two currents having been effected through the conical form of the upper part of the chimney, it remained to regulate the entrance of the external current into the flame. If this current should enter the latter at too sharp an angle, it would carry it toward the mouth of the chimney before the chemical combustion of the carbon and oxygen was finished; and if, on the contrary, it should traverse it at too obtuse an angle, it would depress and contract it. Experience has shown that in the majority of cases the most favorable angle at which the external current of air can be led into the flame varies between 35° and 45°. We say in the majority of cases, for there are exceptions; this depends upon the combustive materials and upon the conditions under which they enter the flame. The annexed figure shows the form adopted by the inventor for oil and kerosene lamps. As may be seen, the chimney consists of two cones, A and B, connected end to end by their small bases. The upper one, A, or divergent cone, is constructed according to a variable angle, but one which, in order to produce its maximum effect, ought not to differ much from 5°. This cone rests upon the convergent one, B, whose angle, as we have said, varies between 35° and 45°. To the large base of this cone there is soldered a cylindrical part, c, designed for fixing the chimney to the holder. The height given the divergent cone is likewise variable, but a very beautiful light is obtained, when it is equal to six times the diameter of the contracted part. When the lamp is designed to be used in a still atmosphere, free from abrupt currents of air, the height may be reduced to four times the diameter of the base, without the light being thereby rendered any the less bright. As for the height to be given the convergent cone, B, that is determined by the opening of the angle according to which it has been constructed. Finally, as a general thing, the diameter of the small base should be equal to half the large base of the convergent cone, B.
The new chimney should be placed upon the holder in such a way that the upper part of the wick tube, D, is a few millimeters beneath the base of the convergent cone. The height to be given the wick varies according to the lamp used. It is regulated so as to obtain a steady and regular combustion. In oil lamps it must project about 1½ centimeters. If two lamps of the same size be observed, one of which is fitted with the new chimney and the other with the old style, we shall be struck with the difference that exists in the color of the flame as well as in its intensity. While in the case of the cylindrical glass the flame is red and dull, in that of the circuit it is white and very bright. This, however, is not surprising when we reflect upon the theoretical conditions upon which the construction of the new chimney is based—the strong influx of air having the result of causing a more active combustion of the liquid, and consequently of raising to white heat the particles of carbon disseminated through the flame. As it was of interest to ascertain what the increase of illuminating power was in a given lamp provided with the new chimney, Mr. Felix le Blanc undertook some photometric experiments. The trials were made with a Gagneau lamp provided with a chimney of the ordinary shape, and then with one of Mr. Bayle's. The measurements were made after each had been burned half an hour. The light of the standard Carcel lamp being 1, there was obtained with the Gagneau lamp with the ordinary chimney 1.113 carcels, and with the Bayle chimney 1.404 carcels. Thus 1.113:1.404 represents the ratio of the same lamp with the ordinary chimney and with that of Bayle. Whence it follows that the light of the lamp with the old chimney being 1, that with the new one is 1.26, say an increase of about 25 per cent. There is nothing absolute about this figure, however. On kerosene lamps the new chimney, compared with the contracted Prussian one, gives an increase of 40 per cent. in illuminating power, and the oil is burned without odor or smoke.
As it was of interest to see whether this increase in intensity was not due to a greater consumption of oil, a determination was made of the quantity of the latter consumed per hour. The Gagneau lamp, with the old chimney, burned 62.25 grammes per hour, and with the Bayle 63 grammes in the same length of time.
It may be concluded, then, that the increase in light is due to the special form given the chimney. This new burner is applicable to gas lamps as well as to oil and petroleum ones.
The effects obtained by the new chimney may be summed up as follows: increase in illuminating power, as a natural result of a better combustion; suppression of smoke; and a more active combustion, which dries the carbon of the wick and thus facilitates the ascent of the oil. The velocity of the current of air likewise facilitates the action of capillarity by carrying the oil to the top of the wick. Moreover, the great influx of air under the flame continually cools the base of the chimney as well as the wick tube, and the result is that the excess of oil falls limpid and unaltered into the reservoir, and produces none of those gummy deposits that soil the external movements and clog up the conduits through which the oil ascends. Finally, the influx of air produced by this chimney permits of burning, without smoke and without charring the wick, those oils of poor quality that are unfortunately too often met with in commerce.—La Nature.
MODERN LOCOMOTIVE PRACTICE.[[1]]
By H. MICHELL WHITLEY, Assoc. M.I.C.E., F.G.S.
A little more than half a century ago, but yet at a period not so far distant as to be beyond the remembrance of many still living, a clear-headed North-countryman, on the banks of the Tyne, was working out, in spite of all opposition, the great problem of adapting the steam engine to railway locomotion. Buoyed up by an almost prophetic confidence in his ultimate triumph over all obstacles, he continued to labor to complete an invention which promised the grandest benefits to mankind. What was thought of Stephenson and his schemes may be judged by the following extracts from the Quarterly Review of 1825, in which the introduction of locomotive traction is condemned in the most pointed manner:
"As to those persons who speculate on making railways general throughout the kingdom, and superseding every other mode of conveyance by land and water, we deem them and their visionary schemes unworthy of notice.... The gross exaggeration of the locomotive steam engine may delude for a time, but must end in the mortification of all concerned.... It is certainly some consolation to those who are to be whirled, at the rate of 18 or 20 miles per hour, by means of a high-pressure engine, to be told that they are in no danger of being sea-sick while on shore, that they are not to be scalded to death or drowned by the bursting of a boiler, and that they need not mind being shot by the shattered fragments, or dashed in pieces by the flying off or breaking of a wheel. But with all these assurances, we would as soon expect the people of Woolwich to suffer themselves to be fired off upon one of Congreve's ricochet rockets, as trust themselves to the mercy of such a machine going at such a rate."
These words, strange and ludicrous as they seem to us, but tersely expressed the general opinion of the day; but fortunately the clear head and the undaunted will persevered, until success was at last attained, and the magnificent railway system of the present, which has revolutionized the world, is the issue. And the results are almost overwhelming in their magnitude. Here, in Great Britain alone, 654,000,000 people travel annually. There are 14,000 locomotives, and the rolling stock would form a train nearly 2,000 miles long; while the number of miles traveled in a year by trains is more than 10,000 times round the world; and the passengers would form a procession 100 abreast, a yard apart, and 3,700 miles long.
These stupendous results have been attained gradually; if we go back to 1848, we find that on the London and Birmingham Railway the number of trains in and out of Euston was forty-four per day. The average weight of the engines was 18 tons, and the gross loads were, for passenger trains 76 tons, and for goods 160. Now, the weight of an express engine and tender is about 65 tons, and gross loads of 250 to 300 tons for an express, and 500 tons for a coal train are not uncommon, while not only have the trains materially increased in weight, owing to the carriage of third-class passengers by all (except a few special) trains, and also to the lowering of fares and consequent more frequent traveling, but the speed, and therefore the duty of the engines, is greatly enhanced. A "Bradshaw's Guide" of thirty-five years ago is now a rare book, but it is very interesting to glance over its pages, and in doing so it will be found that the fastest speed in all cases but one falls far short of that which obtains at present. The following table will show what the alteration has been:
| 1849. Speed miles per hour. | 1884. Speed miles per hour. | |
| Great Western—London to Didcot. | 56 | — |
| Great Western—Londonto Swindon. | — | 53 |
| North-Western—Euston to Wolverton. | 37 | — |
| North-Western—Northampton to Willesden. | — | 51½ |
| South-Western—Waterloo to Farnborough. | 39 | — |
| South-Western—Yeovil to Exeter. | — | 46 |
| Brighton—London Bridge to Reigate. | 36 | — |
| Brighton—Victoria to Eastbourne. | — | 45 |
| Midland—Derby to Masborough. | 43 | — |
| Midland—London to Kettering. | — | 47 |
| North-Eastern—York to Darlington. | 38 | — |
| North-Eastern—York to Darlington. | — | 50 |
| Great Eastern—London to Broxbourne. | 29 | — |
| Great Eastern—Lincoln to Spalding. | — | 49 |
| Great Northern—King's Cross to Grantham. | — | 51 |
| Cheshire Lines—Manchester to Liverpool. | — | 51 |
With this problem then before them, increased weight, increased speed, and increased duty, the locomotive superintendents of our various railways have designed numerous types of engines, of which the author proposes to give a brief account, confining himself entirely to English practice, as foreign practice in addition would open too wide a field for a single paper.
Commencing then with passenger engines for fast traffic, and taking first in order the Great Western Railway, we find that it holds a unique position, as its fast broad gauge trains are worked by the same type of engine as that designed by Sir Daniel Grooch in 1848, although, of course, the bulk of the stock has been rebuilt, almost on the same lines, and rendered substantially new engines. They are single engines of 7 ft. gauge with inside cylinders 18 in. diameter, and 24 in. stroke; the driving-wheels are 8 ft. in diameter, and there are two pairs of leading wheels, and one of trailing, all of 4 ft. 6 in. diameter. The total wheel base is 18 ft. 6 in.; the boiler is 4 ft. 6 in. diameter, and 11 ft. 3 in. long. The grate area is 21 square feet, and the heating surface is, in the fire-box, 153 square feet; tubes, 1,800 square feet; total, 1,953 square feet. The weight in full working order is, on the four leading wheels, 15 ton 18 cwt.; driving wheels, 16 tons; trailing wheels, 9 tons 10 cwt.; total, 41 tons 8 cwt. The tender, which is low-sided and very graceful in appearance, weighs 15 tons 10 cwt., and will hold 2,700 gallons of water.
The boiler pressure is 140 lb. on the square inch, and the tractive power per pound of steam pressure in the cylinders is 81 lb. These engines take the fast trains to the West of England; the Flying Dutchman averages 170 tons gross load, and runs at a mean time-table speed of 53 miles per hour, which allowing for starting, stopping, and slowing down to 25 miles per hour through Didcot gives a speed of nearly 60 miles an hour.
FIG. 1.—GREAT WESTERN RAILWAY.
The average consumption of coal per mile, of thirteen of these engines, with the express trains between London and Bristol, during the half-year averaged 24.67 lb. per mile, the lowest being 23.22 lb., and the highest 26.17 lb., the average load being about eight coaches, or 243 tons. We have already seen that in 1849 the Great Western express ran at a higher rate than at present, being an exception to the general rule; and the fastest journey on record was performed at this time by one of these engines, when on May 14, 1848, the Great Britain took this Bristol express, consisting of four coaches and a van, to Didcot, fifty-three miles, in forty-seven minutes, or at the average speed of sixty-eight miles an hour. The maximum running speed was seventy-five miles an hour, and the indicated horse-power 1,000. A class of engines corresponding to this type in their general dimensions, but with 7 ft. coupled wheels, was introduced on the line, but it was not found successful. Through the courtesy of Mr. Dean, I am enabled to give a table showing the running speeds and loads of the principal express trains, broad and narrow gauge, to the West and North of England, run on the Great Western Railway.
| Train. | Speed to first stoppingstation. | Weight of train. | ||||
| Station. | Distance. miles. | Average speed--miles per hour. | Engine and tender. tons. | Carriages and vans, empty. tons. | Total | |
| BROAD GAUGE TO WEST OF ENGLAND: | ||||||
| 9.0 Paddington to Plymouth | Reading | 36 | 47 | 67 | 149 | 216 |
| 11.45 do. | Swindon | 77¼ | 53 | 67 | 104 | 171 |
| NARROW GAUGE TO THE NORTH | ||||||
| 10.0 Paddington to Birkenhead | Reading | 36 | 39.2 | 60 | 190 | 250 |
| 4.45 do. | Oxford | 63½ | 48.8 | 60 | 129 | 189 |
FIG 2.—GREAT WESTERN RAILWAY.
The narrow gauge trains are worked by two classes of engines. The first is a single engine with inside cylinders 18 in. diameter, 24 in. stroke. The driving wheels are 7 ft. diameter, and the leading and trailing wheels 4 ft. The frames are double, giving outside bearings to the leading and trailing axles, and outside and inside bearings to the driving axle; this arrangement gives a very steady running engine, and insures, as far as can possibly be done, safety in case of the fracture of a crank axle. The frames are 15 inches deep, of BB Staffordshire iron. The wheel base is, leading to driving wheels, 8 ft. 6 in; driving to trailing wheels, 9 ft.; total, 17 ft. 6 in. The boiler is of Lowmoor iron, 10 ft. 6 in. long and 4 ft. 2 in. outside diameter. The grate area is 17 square feet, and the heating surface is, tubes, 1,145½ square feet; fire-box 133 square feet; total, 1,278½ square feet. The boiler pressure is 140 lb. on the square inch, and the tractive power per lb. of mean pressure in cylinders, 92 lb. The weight in full working order is, engine, leading wheel, 10 tons; ditto driving wheels, 14 tons; ditto trailing wheels, 9 tons 10 cwt.; tender, with 40 cwt. coal and 2,600 gals. water, 26 tons 10 cwt.; total, 60 tons. These engines are extremely simple, but well proportioned, and are a very handsome type, and their average consumption of coal, working trains averaging ten coaches, is about 24.87 lb. per mile. The standard coupled passenger express engine on the narrow gauge has inside cylinders 17 in. diameter and 24 in. stroke; the coupled wheels are 6 ft. 6 in. diameter, and the leading wheels 4 ft.; the wheel base is 16 ft. 9 in. The frames are double, giving outside bearings to the leading axle, and inside bearings to the coupled wheels. The boiler is 11 ft. long by 4 ft. 2 in. diameter; the grate area is 16.25 square feet; and the heating surface is, tubes, 1,216.5 square feet; fire-box, 97.0 square feet; total, 1,313.5 square feet. The boiler pressure is 140 lb., and the tractive power per lb. of steam pressure in the cylinders, 88 lb. The weight in full working order is on the leading wheels, 10 tons 5 cwt.; driving wheels, 11 tons; trailing wheels, 9 tons 15 cwt.; total, 31 tons.
FIG. 3.—LONDON & NORTH-WESTERN RAILWAY.
FIG. 4—JOY'S VALVE GEAR.
Turning now to the London and North-Western Railway, we find that between 1862 and 1865 the express trains were worked with a handsome type of engines, known as the "Lady of the Lake" class. They have outside cylinders 16 in. diameter and 24 in. stroke, with single driving wheels of 7 ft. 6 in. diameter, and leading and trailing wheels 3 ft. 6 in. diameter, with a total wheel base of 15 ft. 5 in. The frames are single, with inside bearings to all the wheels. The boiler is 11 ft. long and 4 ft. diameter, and the heating surface is in the tubes, 1,013 feet; fire-box, 85 ft.; total, 1,098 feet. The tractive power per lb. of steam pressure in the cylinders is 68 lb. The weight in full working order is on the leading wheels, 9 tons 8 cwt.; driving wheels, 11 tons 10 cwt.; trailing wheels, 6 tons 2 cwt.; total, 27 tons. The tender weighs 17½ tons in working order. These engines burn about 27 lb. of coal per mile with trains of the gross weight of 117 tons, which is not at all an economical duty. About 1872, the weight of the heavier express trains on the North-Western had so increased, that a new standard type for this service was designed, and is now the standard passenger engine; it has inside cylinders 17 in. diameter and 24 in. stroke; the driving and trailing wheels are coupled, and are 6 ft. 6 in. diameter, and the leading wheels 3 ft. 6 in. The frames of steel are single, with inside bearings to all the wheels, and the boiler, of steel, is 9 ft. 10 in. long and 4 ft. 2 in. diameter. The steel used has a tensile strength of 32 to 34 tons per square inch, all the rivets are put in by hydraulic pressure, and the magnetic oxide on the surface of the plates where they overlap is washed off by a little weak sal-ammoniac and water. In testing, steam is first got up to 30 lb. on the square inch, the boiler is then allowed to cool, it is then proved to 200 lb. with hydraulic pressure, and afterward to 160 lb. with steam. The fire-box is of copper, fitted with a fire brick arch for coal burning, and the grate area is 15 square feet. The heating surface is, in the tubes, 1,013 square feet; fire-box, 89 square feet; total, 1,102 square feet. The wheel base is 15 ft. 8 in., and the tractive power 88 lb. for each lb. of steam pressure in the cylinders. These engines, working the fast passenger trains at a speed of about 45 miles per hour, burn about 35 lb. of coal per mile, when taking trains weighing about 230 tons gross. A variation from this type has been adopted on the Northern and Welsh sections, known as the "Precursor" class. These engines have 5 ft. 6 in. coupled wheels, and weigh 31 tons 8 cwt. in working order, but in other respects are very similar to the standard engines just described; with the Scotch express, averaging in total weight 187 tons, between Crewe and Carlisle, over heavy gradients, they burn 33 lb. of coal per mile. These engines, although much more powerful than the standard type, are not nearly of so handsome an appearance, the drivers seeming much too small for the boiler under which they are placed. But by far the boldest innovation on existing practice is the new class of compound locomotives now being introduced by Mr. Webb. It is a six wheel engine, with leading wheels 4 ft. diameter, and two pairs of drivers, 6 ft. 6 in. diameter. The trailing drivers are driven by a pair of outside cylinders, 18 in. diameter and 24 in. stroke; and the leading drivers by a single low-pressure cylinder—which takes the exhaust steam from the high-pressure cylinders—of 26 in. diameter and 24 in. stroke, placed under the center of the smoke-box. The boiler is the same as that in the standard type of engine, but the wheel base is 17 ft. 7 in., and in order to allow it to traverse curves easily, the front axle is fitted with a radial axle-box, which is in one casting from journal to journal, and fitted at each end with brass steps for the bearings; the box is radial, struck from the center of the rigid wheel base, and the horn plates are curved to suit the box, the lateral motion being controlled by strong springs. Another peculiarity of this engine is that, instead of the ordinary link motion, it is fitted with Joy's valve gear, which is now being more and more adopted. This gear—which is of a most ingenious decription—dispenses altogether with eccentrics, and so allows the inside bearings to be much increased, those on these engines being 13½ in. long; and it is also claimed for it that it is simpler and less costly, weighs less, and is more correct in its action than the ordinary link motion; the friction is less, the working parts are simplified, it takes less oil, and is well under the driver's eye. It also allows larger cylinders to be got in between the frames of inside cylinder engines, as, the slide valves may be placed on the top or bottom of the cylinders. This latter advantage is a great one, as, with the ordinary link motion, large cylinders are exceedingly difficult to design so as to get the requisite clear exhaust. The action of the gear is as follows: A rod, a, is fixed by a pin at b, on which it is free to turn, and is attached to a rod, c, at d, the other end of which link is fastened to the connecting rod at e. At the point, f, in this rod another lever, g, is connected to it, the upper end of which is coupled to the valve rod, h, at i, and just below this point a second connection is made to a block at j, sliding in a short curved piece, k. The inclination of the block, k, governs the travel of the valve. The total weight of the engine in working order is: On the leading wheels, 10 tons 8 cwt.; front drivers, 14 tons 4 cwt.; rear drivers, 13 tons 10 cwt.; total, 37.75 tons. The tender weighs 25 tons in full working order. The boiler pressure is 150 lb., and the usual point of cut-off in the high pressure cylinders, when running at speed, is half-stroke, while the pressure of steam admitted to the large cylinder is never to exceed 75 lb. per square inch. The average consumption of coal between London and Crewe is 26.6 lb. per train mile, or about 8 lb. per mile less than the standard coupled engine. In an experiment made in October, 1883, one of these engines took the Scotch express from Euston to Carlisle at an average speed, between stations, of 44 miles an hour, the engine, tender, and train weighing 230 tons, with a consumption of 29½ lb. of coal per mile, and an evaporation of 8.5 lb. of water per pound of fuel.
Mr. Webb's object, in designing this engine was to secure in the first place a greater economy of fuel, and secondly, to do away with coupling rods, while at the same time obtaining greater adhesion, with the freedom of a single engine. The cost is much more than an ordinary locomotive, but the saving in fuel is said to be 20 per cent. over the other engines of the North Western Rail way. These engines run very sweetly, and are said to steam freely, although with only half the usual number of blasts; but from the small size of the high pressure cylinders, they are liable to slip when starting heavy trains, as the low pressure cylinders are not then effective, while the consumption of coal does not seem to show the saving that would have been expected, when compared with ordinary engines doing similar duty on other lines; for instance, the Great Northern single engine takes trains of the same weight with the same consumption of coal and at a somewhat higher speed. But it must, of course, be borne in mind in making such a comparison, that the fuel used may not be of the same quality.
Mr. Stirling, of the Great Northern, has adopted an entirely different type of engine to those last described. Holding strongly that single engines are more economical not only in running, but in repairs, and that cylinder power is generally inadequate to the adhesion, he has designed his magnificent well-known class of express engines. They have single driving wheels 8 ft. in diameter, with a four-wheel bogie in front and a pair of trailing wheels, 4 ft. diameter, behind. The frames are single, and inside of one solid piece; the cylinders are outside 18 in. diameter and 28 in. stroke; and the valve gear is of the usual shifting link description. The boiler is of Yorkshire plates, 11 ft. 5 in. long and 4 ft. diameter, and the steam pressure is 140 lb.; while the tractive power per lb. of steam in the cylinders is 94 lb. The fire-box is of copper, and the roof is stayed to the outer shell by wrought iron radiating stays screwed into both; a sloping mid-feather is placed in the fire-box.
FIG. 5.—GREAT NORTHERN RAILWAY.
The tubes, 217 in number, are of brass, 1-9/16 in. diameter; and the heating surface is in the tubes, 1,043 square feet; fire-box, 122 square feet; total, 1,165 square feet. The fire-grate area is 17.6 square feet. The wheel base from the center of the bogie pin to the trailing axle is 19 ft. 5 in., and the weight in working order is, on the bogie wheels, 15 tons; driving wheels, 15 tons; trailing wheels, 8 tons; total, 38 tons. The tender weighs 27 tons. These engines are remarkable for their efficiency; the traffic of the Great Northern Railway is exceedingly heavy, and the trains run at a high rate, the average speed of the Flying Scotchman being fifty miles an hour, and no train in the kingdom keeps better time. "Those who remember this express at York in the icy winter of 1879-80, when the few travelers who did not remain thawing themselves at the waiting-room fires used to stamp up and down a sawdusted platform, under a darkened roof, while day after day the train came gliding in from Grantham with couplings like wool, icicles pendent from the carriage eaves, and an air of punctual unconcern; or those who have known some of our other equally sterling trains—these will hardly mind if friendship does let them drift into exaggeration when speaking of expresses." The author well remembers how, when living some years ago at Newcastle-on-Tyne, it was often his custom to stroll on the platform of the Central Station to watch the arrival of the Flying Scotchman, and as the hands of the station clock marked seven minutes past four he would turn around, and in nine cases out of ten the express was gliding into the station, punctual to the minute after its run of 272 miles. Such results speak for themselves, and for the power of the engines employed, and one of the best runs on record was that of the special train, drawn by one of these locomotives, which in 1880 took the Lord Mayor of London, to Scarborough. The train consisted of six Great Northern coaches, and ran the 188 miles to York in 217 minutes, including a stop of ten minutes at Grantham, or at the average rate of 54½ miles an hour. The speed from Grantham to York, 82½ miles, with three slowing downs at Retford, Doncaster, and Selby, averaged 57 miles an hour, and the 59 miles from Claypole, near Newark, to Selby, were run in 60½ minutes, and for 22½ consecutive miles the speed was 64 miles an hour. In ordinary working these engines convey trains of sixteen to twenty-six coaches from King's-Cross with ease, and often twenty-eight are taken and time kept. Considering that the Great Northern main line rises almost continuously to Potter's Bar, 13 miles, with gradients varying from 1 in 105 to 1 in 200, this is a very high duty, while, with regard to speed, they have run with sixteen coaches for 15 miles at the rate of 75 miles an hour. Their consumption of coal with trains averaging sixteen ten ton carriages is 27 lb. per mile, or 8 lb. per mile less than the standard coupled engine of the North-Western with similar loads. Mr. Stirling's view, that the larger the wheel the better the adhesion, seems borne out of these facts; thus to take twenty-eight coaches, or a gross load of 345 tons, up 1 in 200 at a speed of 35 miles an hour, would require an adhesive force of 8,970 lb., or 600 lb. per ton—more than a quarter the weight on the driving wheels. These engines are magnificent samples of the most powerful express engines of the present day.
The London, Brighton, and South Coast Railway Company has in the last few years had its locomotive stock almost entirely replaced, and instead of seventy-two different varieties of engines out of a total of 233, which was the state of locomotive stock in 1871. a small number of well-considered types, suited to the different class of work required, are now in use. Mr. Stroudley considers—contrary to the opinion once almost universally held—that engines with a high center of gravity are the safest to traverse curves at high speed, as the centrifugal force throws the greatest weight on the outer wheels, and prevents their mounting; also that the greatest weight should be on the leading wheels, and that there is no objection to these wheels being of a much larger diameter than that usually adopted; in fact, by coupling the leading and driving wheels where the main weight is placed a lighter load is thrown on the trailing wheels, thus enabling them to traverse curves at a high speed with safety, while it permits of a larger fire-box being used; and these principles have been carried out in the newest class of engines, especially designed for working the heavy fast passenger traffic of the line.
The modern express engines are of two types. The first is a single engine with 6 ft. 6 in. driving wheels, and leading and trailing wheels 4 ft. 6 in. in diameter and a wheel base of 15 ft. 9 in. The frames are single, with inside bearings to all the wheels; the cylinders are inside, 17 in. diameter and 24 in. stroke. The boiler is 10 ft. 2 in. long and 4 ft. 3 in. diameter; the fire-box is of copper with a fire-grate area of 17.8 square feet, and the heating surface is in the tubes 1,080 square feet, fire-box 102 square feet; total, 1182 square feet. The weight in working order is about 35 tons. These engines have a tractive power of 89 lb. per pound of mean steam pressure in the cylinders, and their consumption of coal with trains averaging nine coaches is about 20 lb. per mile. The next type of engine designed has coupled wheels under the barrel of the boiler 6 ft. 6 in. diameter, with cylinders 17¼ in. diameter and 26 in. stroke, and were found so successful that Mr. Stroudley designed a more powerful engine of the same class, especially to take the heaviest fast trains in all weathers.
The 8:45 A.M. train from Brighton has grown to be one of the heaviest fast trains in the kingdom, although the distance it runs is but very short, while it is also exceptional in consisting entirely of first class coaches, and the passengers mainly season ticket holders; it often weighs in the gross 350 tons, and to take this weight at a mean speed of forty-five to fifty miles an hour over gradients of 1 in 264 is no light work.
FIG. 6.—LONDON, BRIGHTON, AND SOUTH COAST RAILWAY.
The engines known as the "Gladstone" type have inside cylinders 18¼ in. diameter and 26 in. stroke, with coupled wheels 6 ft. 6 in. diameter under the barrel of the boiler; the trailing wheels are 4 ft. 6 in. diameter, and the total wheel base is 15 ft. 7 in. The frames are inside, of steel 1 in. thick, with inside bearings to all the axles. The cylinders are cast in one piece 2 ft. 1 in. apart, but in order to get them so close together the valves are placed below the cylinders, the leading axle coming between the piston and slide valve. The boiler is of iron, 10 ft. 2 in. long, and 4 ft. 6 in. diameter; and the heating surface is, in the tubes, 1,373 square feet; fire-box, 112 square feet; total, 1,485 square feet. The grate area is 20.65 square feet, and the tractive power per pound of mean cylinder pressure is 111 lb. The weight in full working order is—leading wheels, 13 tons 16 cwt.; driving wheels, 14 tons 10 cwt.; trailing wheels, 10 tons 8 cwt.; total, 38 tons 14 cwt. The tender weighs 27 tons.
To enable these engines to traverse curves easily a special arrangement of draw-bar is used, consisting of a T-piece with a wheel at each end working in a curved path in the back of the frame under the foot plate; on the back buffer beam a curved plate abuts against a rubbing piece on the tender, through which the draw-bar is passed and screwed up against an India-rubber washer, thus allowing the engine to move free of the tender as the curvature of the road road requires; the flanges on the driving wheel are also cut away, so as not to touch the rail. In order to reduce the wear of the leading flanges, a jet of steam from the exhaust is directed against the outer side of each wheel. The center line of the boiler is 7 ft. 5 in. above the rails, and the tubes, of which there are as many as 331, are bent upward 1½ in., which permits expansion and contraction to take place without starting the tubes, and they are stated never to leak or give trouble. The feed-water is heated by a portion of the exhaust steam and the exhaust from the Westinghouse brake, and the boiler is consequently fed by pumps, is kept cleaner, and makes steam better. The reversing gear is automatic and exceedingly ingenious, the compressed air from the Westinghouse brake reservoir being employed to do the heavy work. A cylinder 4½ in. diameter is fitted with a piston and rod attached to the nut of the reversing screw, and a three-way cock supplies the compressed air behind the piston; this forces the engine into back gear, and by allowing the air to escape, the weight of the valve motion puts the engine in forward gear. There are no balance weights, and the screw regulates the movement. There is also a very ingenious speed indicator, which consists of a small brass case filled with water, in which is a small fan driven by a cord from the driving wheel; a copper pipe leads from the fan case to a glass gauge tube; the faster the fan runs the higher the water will stand in the tube, thus indicating the speed.
The author has been led to describe this engine fully on account of the numerous ingenious appliances which have been adopted in its design. In a trial trip on October 3, 1883, from Brighton to London Bridge and back, with an average load of 19½ coaches, or 285 tons gross, and with a speed of 45 miles per hour, the consumption of coal was 31 lb. per train mile, evaporating 8.45 lb. of water per pound of coal, and with as much as 1,100 indicated horse-power at one portion of the run. The finish and painting of these engines is well considered, but the large coupled wheels give a very high shouldered appearance, and as a type they are not nearly as handsome as the single engines previously described.
From the Brighton to the South-Western Railway is but a step; but here a totally different practice obtains to that adopted on most lines, all the passenger engines having outside cylinders, where they are more exposed to damage in case of accident, and, from being less protected, there is more condensation of steam, while the width between the cylinders tends to make an unsteady running engine at high speeds, unless the balancing is perfect; but the costly crank axle, with its risk of fracture, is avoided, and the center of gravity of the boiler may be consequently lowered, while larger cylinders may be employed. On the other hand, inside cylinders are well secured, protected, and kept hot in the smoke-box, thus minimizing the condensation of steam. The steam ports are short, and the engine runs steadier at high speeds, while with Joy's valve gear much larger cylinders can be got in than with the link motion. Thus modern improvements have minimized the advantages of the outside class.
The passenger engines for the fast traffic are of two types, the six-wheel engines with 7 ft. coupled wheels, and the new bogie engines which are being built to replace them. The former have 17 in. cylinders with 22 in. stroke, and a pair of coupled wheels 7 ft. in diameter, the leading wheels being 4 ft. diameter, and the wheel base 14 ft. 3 in. The grate area is 16.1 square feet, and the heating surface 1,141 square feet. The total weight in working order is 33 tons. The chief peculiarity of this type of engine consists in the boiler, which is fitted with a combustion chamber stocked with perforated bricks, the tubes being only 5 ft. 4 in. long. These engines are very expensive to build and maintain, owing to the complicated character of the boiler and fire-box, but as a coal burning engine there is no doubt the class was very efficient, but no more are being built, and a new type has been substituted. This is an outside cylinder bogie engine, with cylinders 18½ in. diameter and 26 in. stroke; the driving and trailing coupled wheels are 6 ft. 6 in. diameter, and the bogie wheels 3 ft. 3 in. The wheel base to the center of the bogie pin is 18 ft. 6 in.; the heating surface is, in the tubes, 1,112; fire box, 104; total, 1,216 sq. ft. The weight of the engine in working order is 42 tons.
FIG. 7.—MIDLAND RAILWAY.
The Midland Railway route to the North is distinguished by the heavy nature of its gradients; between Settle and Carlisle, running through the Cumberland hills, attaining a height of 1,170 ft. above sea level, the highest point of any express route in the kingdom; and to work heavy fast traffic over such a line necessitates the employment of coupled engines. The standard express locomotive of this company has inside cylinders 18 in. in diameter and 26 in. stroke. The coupled wheels are 6 ft. 9 in. diameter, and the leading wheels 4 ft. 3 in., the total wheel base being 16 ft. 6 in., and the tractive force 104 lb. for each lb. of mean cylinder pressure. The boiler is of best Yorkshire iron, 10 ft. 4 in. long and 4 ft. 1 in. diameter. The grate area is 17.5 square feet, and the heating surface is, in the tubes, 1,096; fire-box, 110; total, 1,206. There are double frames to give outside bearings to the leading axle, as in the Great Western engine, and the engine is fitted with a steam brake. The weight in full working order is—leading wheels, 12 tons 2 cwt.; driving wheels, 15 tons; trailing wheels, 11 tons 6 cwt.; total, 38 tons 8 cwt. The tender weighs 26 tons 2 cwt., and holds 3,300 gallons of water and 5 tons of coal. Latterly a fine type of bogie express engine has been introduced, with inside cylinders 18 in. diameter and 26 in. stroke, and four coupled driving wheels 7 ft. diameter. The total wheel base to the center of the bogie pin is 18 ft. 6 in. The grate area is 17.5 square feet, and the heating surface is, in tubes, 1,203 square feet, and fire-box, 110; total, 1,313; and the engine weighs 42 tons in working order. These engines take fourteen coaches, or a gross load of 222 tons, at 50 miles an hour over gradients of 1 in 120 to 1 in 130, with a consumption of 28 lb. of coal per mile. The London, Chatham, and Dover Company has also some fine engines of a similar type. They have inside cylinders 17½ in. diameter and 26 in. stroke; the coupled wheels are 6 ft. 6 in. diameter, and the bogie wheels 3 ft. 6 in., the wheel base to the center of the bogie pin being 18 ft. 2 in. The boiler is 10 ft. 2 in. long and 4 ft. 2 in. diameter, the grate area is 16.3 square feet, and the heating surface is, in the tubes, 962 square feet; fire-box, 107 square feet; total, 1,069. The boiler pressure is 140 lb., and the tractive force per lb. of steam in the cylinder 102 lb. The weight in full working order is, on the bogie wheels, 15 tons 10 cwt.; driving wheels, 13 tons 10 cwt.; trailing wheels, 13 tons; total, 42 tons.
Mr. Worsdell has lately designed for the Great Eastern Railway a fine type of coupled express engine, which deserves mention. It has inside cylinders 18 in. diameter and 24 in. stroke, with coupled wheels 7 ft. diameter and leading wheels 4 ft. diameter, the latter being fitted with a radial axle on a somewhat similar plan to that previously described as adopted by Mr. Webb for the new North-Western engines; the frames are single, with inside bearings to all the wheels, and Joy's valve gear is used. The boiler pressure is 140 lb., and the tractive power per lb. of mean cylinder pressure 92 lb. The total wheel base is 17 ft. 6 in. The boiler, which is fed by two injectors, is of steel, 11 ft. 5 in. long and 4 ft. 2 in. diameter. The grate area is 17.3 square feet, and the heating surface is, in the tubes, 1,083; fire-box, 117; total, 1,200 sq. ft. The weight in working order is, on the leading wheels, 12 tons 19 cwt.; driving wheels, 15 tons; trailing wheels, 13 tons 4 cwt.; total, 41 tons 3 cwt. These engines burn 27 lb. of coal per train mile with trains averaging thirteen coaches. It has been seen that the Cheshire lines express between Liverpool and Manchester is one of the fastest in England, and the Manchester, Sheffield, and Lincolnshire Railway Company, who works the trains, has just introduced a new class of engine specially for this and other express trains on the line. The cylinders are outside, 17½ in. diameter and 26 in. stroke, with single driving wheels 7 ft. 5 in. diameter, the leading and trailing wheels being 3 ft. 8 in. diameter. The total wheel base is 15 ft. 9 in., and the frames are double, giving outside bearings to the leading and trailing axles, and inside bearings to the driving axle. The boiler is 11 ft. 6 in. long and 3 ft. 11 in. diameter, and the grate area is 17 square feet. The heating surface is in the tubes 1,057 square feet; fire-box, 87 square feet; total, 1,144 square feet. The tractive force per pound of mean cylinder pressure is 88.4 lb. The weight in full working order is, on the leading wheels, 11 tons 3 cwt.; driving wheels, 17 tons 11 cwt.; trailing wheels, 11 tons 18 cwt.; total, 40 tons 12 cwt. This engine is remarkable for the great weight thrown on the driving wheels, and its cylinder power is great in proportion to its adhesion, thus allowing the steam to be worked at a high rate of expansion, which is most favorable to the economical consumption of fuel. There are numerous fine engines running on other lines, such as the new bogie locomotives on the North-Eastern and Lancashire and Yorkshire railways, and the coupled express engines on the Caledonian; but those already described represent fairly the lending features of modern practice, and the author will now notice briefly the two other classes of engines—tank passenger engines for suburban and local traffic and goods engines. The Brighton tank passenger engine is a good example of the former class; it has inside cylinders 17 in. diameter and 24 in. stroke. The two coupled wheels under the barrel of the boiler are 5 ft. 6 in. diameter, and the trailing wheels 4 ft. 6 in.; there are single frames with inside bearings to all the axles. The boiler pressure is 140 lb., and the tractive force per pound of mean cylinder pressure 106 lb.; the total wheel base is 14 ft. 6 in. The boiler is 10 ft. 2 in. long and 4 ft. 4 in. diameter, and the heating surface is in the tubes, 858 square feet; fire-box, 90 square feet; total, 948 square feet. The engine is furnished with wing tanks holding 860 gallons of water, and carries 30 cwt. of coal. The weight in working order is 38 tons. These engines have taken a maximum load of twenty-five coaches between London and Brighton, but are mainly employed in working the suburban and branch line traffic; their average consumption of coal is 23.5 lb. per mile, with trains averaging about ten coaches.
Another example is Mr. Webb's tank engine on the North-Western Railway, which presents a contrast to the foregoing. It has inside cylinders 17 in. diameter and 20 in. stroke, coupled wheels 4 ft. 6 in. diameter, and a tractive power per lb. of mean cylinder pressure of 107 lb.; the wheel base is 14 ft. 6 in. with a radial box to the leading axle; the heating surface is in the tubes, 887; fire-box, 84; total, 971 square feet; the weight in working order is 35 tons 15 cwt. The engine is fitted with Webb's hydraulic brake, and steel, manufactured at Crewe, is largely used in its construction. The consumption of coal-working fast passenger trains has been 28½ lb. per mile. There are many other types, such as the ten wheel bogie tank engines of the London, Tilbury, and Southend and South-Western railways; the saddle tank bogie engines, working the broad gauge trains on the Great Western Railway, west of Newton; and the familiar class working the Metropolitan and North London traffic. But the same principle is adopted in nearly all—a flexible wheel base to enable them to traverse sharp curves, small driving wheels coupled for adhesion, and wing or saddle tanks to take the water. One notable exception is, however, the little six wheel all-coupled engines weighing only 24 tons, which work the South London traffic, burning 24¼ lb. of coal per mile, with an average load of eleven coaches.
Goods engines on all lines do not vary much. As a rule they are six wheel all-coupled engines, with generally 5 ft. wheels, and cylinders varying between 17 in. and 18 in. diameter and 24 in. to 26 in. stroke; the grate area is about 17 square feet, and the total heating surface from 1,000 to 1,200 sq. ft.; the average weight in full working order varies from 30 to 38 tons. One noteworthy exception occurs, however, on the Great Eastern Railway, where a type of goods engine with a pony truck in front has been introduced. The cylinders are outside 19 in. diameter and 26 in. stroke, there are six coupled wheels 4 ft. 10 in. diameter, and the pony truck wheels are 2 ft. 10 in. diameter; the total wheel wheel base is 23 ft. 2 in., but there are no flanges on the driving wheels. The boiler is 11 ft. 5 in. long and 4 ft. 5 in. diameter, the boiler pressure is 140 lb., and the tractive force per lb. of mean cylinder pressure 162 lb.; the grate area is 18.3 square feet, and the heating surface is in the tubes, 1,334 square feet; fire-box, 122 square feet; total, 1,456 square feet.
The weight in working order is on the pony truck, 8 tons 10 cwt.; leading coupled, 12 tons 8 cwt.; driving coupled, 13 tons 5 cwt.; trailing coupled, 12 tons 15 cwt.; total, 47 tons.
The tender weighs 28 tons in full working order. These engines take 40 loaded coal trucks or sixty empty ones, and burn 52 lb. of coal per train mile, the worst gradient being 1 in 176. A notice of goods engines would not be complete without alluding to a steep gradient locomotive, and a good example is the engine which works the Redheugh Bank on the North-Eastern Railway. This incline is 1,040 yards long, and rises for 570 yards 1 in 33, then for 260 yards 1 in 21.7, for 200 yards 1 in 25, and finally for 110 yards 1 in 27. The engine, which is an all-coupled six wheel tank engine, weighs 48½ tons in working order, it has cylinders 18 in. diameter and 24 in. stroke, and 4 ft. wheels, the boiler pressure is 160 lb., and the tractive force per lb. of mean steam pressure in the cylinders is 162 lb. This engine will take up the incline twenty-six coal wagons, or a gross load of 218 tons, which is a very good duty indeed.
Having now passed in review the general types of engines adopted in modern English practice, the author would briefly draw attention to some points of design and some improvements effected in late years. And first, as to the question of single or coupled engines, there is a great diversity of opinion. Mr. Stirling conducts his traffic at a higher rate of speed, and certainly with equal punctuality, with his magnificent single 8 ft. engines, as Mr. Webb on the North-Western with coupled engines, and the economy of fuel of the former class over the latter is very remarkable; this is, no doubt, owing, as has been previously pointed out, to their ample cylinder power, which permits of the steam being worked at a high rate of expansion. There is no doubt that if single engines can take the load they will do so more freely and at a less cost than coupled engines, burning on the average 2 lb. of coal per mile less with similar trains. With, regard to loads, it is a question whether any express train should be made up with more than twenty-five coaches. The Great Northern engine will take twenty-six and keep time, and the Brighton single engine has taken the five P.M. express from London Bridge to Brighton, consisting of twenty-two coaches, at a speed of forty-five miles per hour. Of course where heavy gradients have to be surmounted, such as those on the Midland route to Scotland, coupled engines are a necessity. Single engines are said to slip more than coupled; thus an 8 ft. single Great Northern engine running down the incline from Potter's Bar to Wood Green with twelve coaches at the rate of sixty miles an hour was found to be making 242 revolutions per mile instead of 210; and in an experiment tried on the Midland Railway it was found that a coupled engine with ten coaches at fifty miles an hour made seventeen extra revolutions a mile, but when the side rods were removed it made forty-three. The Great Western, Great Northern, and Brighton mainly employ single engines for their fast traffic; and the Manchester, Sheffield, and Lincolnshire have now adopted the single type in preference to the coupled for their express trains; while the North-Western, Midland, South-Western, and Chatham adopted the coupled type. One noticeable feature in modern practice is the increased height of the center line of boiler; formerly it was the great aim to keep this low, and numerous schemes to this effect were propounded, but now it has become generally recognized that a high pitched engine will travel as steadily and more safely round a curve—given a good road—than a low pitched one; and thus while in 1850 the average height of the center line of boilers varied between 5 ft. 3 in. and 6 ft. 3 in., now in the latest designs it lies between 7 ft. and 7 ft. 6 in. Single frames are very generally adopted, but double frames and outside bearings to the leading and trailing wheels, as in the Great Western engines, give great steadiness in running, and this class has also double bearings to the driving wheels, thus entailing greater security in case of the facture of a crank axle. The general adoption of cabs on the foot-plate for the men is another improvement of late introduction, although at first not universally appreciated by those for whose comfort it was designed—"I felt as if I was in my coffin," said an old driver when asked how he liked the new shelter. Mild steel fire-boxes, which have been employed in America, are not in favor here, copper being universally used; they have been tried on the Caledonian, Great Southern and Western, North London, and North-Western, and were found not to succeed. Brake blocks of cast iron have now generally superseded wood; steel is being more and more used, especially on the North Western. There is less use of brasswork for domes and fittings, although it is claimed for brass that it looks brighter and can easily be kept clean. There is greater simplicity of design generally, and the universal substitution of coal as coke for fuel, with its consequent economy; and last, but not least, the adoption of standard types of engines, are among the changes which have taken place in locomotive practice during the past quarter of a century.
FIG. 8.—LONDON, CHATHAM, & DOVER RAILWAY.
FIG. 9.—GREAT EASTERN RAILWAY.
FIG. 10.—MANCHESTER, SHEFFIELD, AND LINCOLNSHIRE RAILWAY.
Having now reviewed, as far as the limits of this paper will allow, the locomotive practice of the present day, the author would in conclusion draw attention to what may possibly be one course of locomotive development in the future. Time is money, and it may be in the coming years that a demand will arise for faster means of transit than that which we possess at present. How can we meet it? With our railways laid out with the curves and gradients existing, and with our national gauge, and our present type of locomotive, no great advance in speed is very probable; the mean speed of express trains is about fifty miles an hour, and to take an average train of 200 tons weight at this speed over a level line requires between 650 and 700 effective horse-power, within the compass of the best engines of the present day. But if instead of fifty miles an hour seventy is required, an entirely different state of things obtains. Taking a train of 100 tons, with engine and tender weighing 75 tons, or 175 tons gross, the first question to determine will be the train resistance, and with reference to this we much want careful experiments on the subject, like those which Sir Daniel Gooch made in 1848, on the Bristol and Exeter Railway, which are even now the standard authority; the general use of oil axle-boxes and long bogie coaches, irrespective of other improvements, would render this course desirable. With regard to the former, they appear to run with less friction, but are heavier to start, oil boxes in some experiments made on the South-Western Railway giving a resistance of 2.5 lb. per ton, while grease boxes ranged from 6 lb. to 9 lb. per ton. Again, the long and heavy bogie Pullman and other coaches have the reputation among drivers, rightly or wrongly, of being hard to pull. The resistance of an express train on the Great Western Railway at seventy-five miles an hour was 42 lb. per ton, and taking 40 lb. per ton for seventy miles an hour would give a total resistance on the level of 7,000 lb., corresponding to 1,400 horse-power—about double the average duty of an express engine of the present day. The weight on the driving wheels required would be 18¾ tons, allowing one-sixth for adhesion, about the same as that on the driving axle of the Bristol and Exeter old bogie engines. Allowing 2½ lb. of coal per horse-power per hour would give a total combustion of 3,500 lb. per hour and to burn this even at the maximum economic rate of 85 lb. per square foot of grate per hour would require a grate area of 41 square feet, and about 2,800 square feet of heating surface. Unless a most exceptional construction combined with small wheels is adopted, it appears almost impossible to get this amount on the ordinary gauge. It is true the Wootten locomotives on the Philadelphia and Reading Railway have fire-boxes with a grate area of as much as 76 square feet, but these boxes extend clean over the wheels, and the heating surface in the tubes is only 982 square feet; but although these engines run at a speed of forty-two miles an hour, they are hardly the type to be adopted for such a service as is being considered. On the broad gauge, however, such an engine could easily be designed on the lines now recognized as being essential for express engines without introducing any exceptional construction, and there appears but little doubt that were Brunei's magnificent gauge the national one, competition would have introduced a higher rate of speed between London and our great towns than that which obtains at present.
The whole question of the future introduction of trunk lines, exclusively for fast passenger traffic, is fraught with the highest interest, but it would be foreign to the subject matter of this paper to enter more fully on it, the author merely desiring to state his opinion that if the future trade and wealth of our country require their construction, and if a very high rate of speed much above our present is to be attained, their gauge will have to be seriously considered and settled, not by the reasons which caused the adoption of the present gauge, but by the power required to carry on the traffic—in fact, to adapt the rail to the engine, and not, as at present, the engine to the rail. High speed requires great power, and great power can only be obtained by ample fire-grate area, which for a steady running engine means a broad gauge. The Gauge Commissioners of 1846 in their report esteemed the importance of the highest speed on express trains for the accommodation of a comparatively small number of persons, however desirable that may be to them, as of far less moment than affording increased convenience to the general commercial traffic of the country. The commercial traffic of England has grown and prospered under our present system, and if its ever increasing importance demands high speed passenger lines, we may rest assured that the ingenuity of man, to which it is impossible to assign limits, will satisfactorily solve the problem.
Paper read before the Civil and Mechanical Engineers' Society, April 2, 1884.