paratively still part of a river. In the case stated, the air was supposed to be saturated with vapour, but if it should not be fully saturated, but have a dew-point of, say 1° below the temperature, the only difference would be that condensation would not begin until the mass of air climbed 300 feet,-a dew-point of 2°, 600 feet; and other dew-points in proportion.

We see, then, why the largest quantity of rain should fall in Seathwaite when a south-west wind blows from the sea over Styhead, as Seathwaite is favourably placed to receive much of the rain brought by that wind; but other winds blow in this district during a large portion of the year, and as much more rain falls at Seathwaite than in any other part, these other winds must, we presume, also bring rain to that place. To see how this is effected, we have to examine the shape of the neighbouring country, and particularly in the directions from which rainy winds come; and we may perhaps obtain a tolerably good idea of what that shape is from an account given in Hudson's 'Guide to the Lakes.' In this work, page 118, it is said "I know not how to give the reader a distinct image of the main outlines of the country, more readily than by requesting him to place himself with me in imagination upon some given point, let it be the top of either of the mountains, Great Gable or Scaw-fell; or rather, let us suppose our station to be a cloud hanging midway between those two mountains, at not more than half a mile's distance from the summit of each, and not many yards above their highest elevation; we shall then see stretched at our feet a number of valleys, not fewer than eight, diverging from the point on which we are supposed to stand, like spokes from the nave of a wheel." Now, this imaginary point in the air is nearly over Sty-head Pass. The writer then proceeds to describe Langdale, the Vale of Coniston, the Vale of Duddon, Eskdale, Wastdale, Ennerdale, and the Vale of Crummockwater, and Buttermere. And he goes on to say, that "such is the general topographical view of the country of the lakes; and it may be observed that, from the circumference to the centre, that is, from the sea or plain country to the mountains specified, Great Gable and Scawfell, there is in the several ridges that inclose these vales, and divide them from each other-I mean, in the forms and surfaces -first, of the swelling ground, next, of the hills and rocks, and, lastly, of the mountains-an ascent of almost regular gradation from elegance and richness to their highest point of grandeur and sublimity." Nearly all these eight valleys, in the low flat country, present wide openings to receive any wind that may be blowing towards them-they contract towards the centre where the ground rises; and the wind, whether it blows from, say, the south, south-west, the west, or the north-west, will force its way over the lowest points of the central chain, and be disposed to discharge rain on the country a little beyond those points. Borrodale is just in this situation, and must therefore receive rain from every moist wind that comes from a southern or western quarter, in the way that has been described; and Seathwaite seems to be in that part of Borrodale which receives the largest quantity of rain.*

The large fall of rain in this village is then to be considered a result of various rainy winds blowing up the different valleys, and particularly those which lie to the south and west of it, as those winds force the mixed masses of air and vapour to rise to the lower parts of the elevated ridges that are at the heads of these valleys. At or above these parts the vapour is largely condensed, and the rain that is formed is carried forwards and deposited on the low ground beyond the ridge; but though deposifed there it evidently descends from a great height.

Speaking in general language, it may be said that the largest quantities of rain fall from warm and moist atmospheres, as such atmospheres contain the largest quantities of aqueous vapour; and the rain is formed by the condensation of a part of the vapour, at a height dependent on the elevation that is attained by the atmospheric mass when forced to ascend, and the difference between the temperature and the dew-point in that mass. If the rise of the land is great and abrupt, approaching a vertical cliff, the larger part of the rain might possibly fall on the low ground in front of the cliff, the mass of air being unable to pass over it, until such a height was attained as would leave little uncondensed vapour existing in the air. In such a situation it is evident, that one gauge placed at a low level in front of the cliff

* Since this was written, another part that is contiguous has been found to receive more rain. It is stated that the quantity of rain that fell annually at Seathwaite, on an average of five years, 1845 to 49, was 142:19 inches. In 1850, it was 143.96 inches, whilst it was computed that at Sprinkling Pass no less than 189 49 inches fell.

might receive more rain than another fixed at any height above it. And it is equally clear, that when rain is formed whilst passing over an elevated ridge, that rain might be received either in a gauge placed beyond it, only a little lower, or in one not farther beyond it, but fixed in a deep valley below, as is, in fact, the case with the gauge at Seathwaite, We may therefore conclude, that in a country containing lofty mountains and deep valleys, with much irregularity of surface, the height of the gauge into which rain falls does not indicate the elevation at which it was formed-that elevation being determined by the laws of cooling of the aqueous vapour that is contained in our mixed atmosphere, whilst the vapour is diffused through the gases.

The following account has been furnished to me of the

Fall of Rain in a year at Cuchullin Lodge, in the Isle of Skye, being the Mean of the Two Years, from Sept. 1, 1849, to Sept. 1, 1851.

MOSES POOLE, Patentee, August 8, 1853.

THIS invention consists in an apparatus for regulating the supply of gas or other aëriform fluid. The main or supply pipe, where the regulation is to take place, is arranged to communicate in succession with two or more chambers, each having a governor or regulator.

The annexed engraving shows a vertical section of an apparatus combined according to the invention, having two regulators or governors acting in succesion, but other apparatus may be made with more than two to act in succession in a similar manner. The form of regulator or governor preferred is that where an inverted vessel is employed fixed to the valve, the action of which is to be regulated: but the form of the parts may be varied, so long as two or more regulators are combined to act in succession as herein shown and described. No claim, however, is made to the governors or regulators separately when two or more are not combined to act on and regulate the same supply. A, is the

M

K

inlet for the gas or aëriform fluid; B, is a chamber, the opening CC, out of which is capable of being more or less closed by the valve O, which is on the stem F, to which the inverted vessel D, is fixed, the edges of which dip into mercury or other suitable fluid at EE, there being weights G G, on the vessel D, according to the degree of pressure it is desired to regulate or bring the supply of gas or other aëriform fluid to, when it passes away at the outlet K. The gas or other aëriform fluid coming into the chamber B (above the desired pressure), will to some extent be regulated by its acting on the first regulator by raising the vessel D, which will also raise the valve O, in the compartment B, towards the opening CC, till the quantity of the gas allowed to pass into the chamber H, of the apparatus will be brought to nearly the desired pressure. The gas or aëriform fluid in the chamber H, passes through the opening J J, into the compartment K, and acts on the inverted vessel L (which is affixed to the stem N), by which the valve O, in the chamber H, is more or less closed, according to the pressure of the gas or aëriform fluid in the chamber H, is more or less an excess of the pressure that it is desired the gas or aëriform fluid should go off at the outlet K. By using a succession of regulators or governors, any want of correctness of the regulation of the first will be compensated for by the succeeding one or ones.

Claim.-The combination of two or more governors or regulators so that they may come into action in succession.

* Reported in the 'Repertory of Patent Inventions.'

IMPROVED LOCOMOTIVE ENGINE.*

By JOSEPH BEATTIE, of London.

(With Engravings, Plate XXIII.)

[Paper read at the Institution of Mechanical Engineers.] THE economy of fuel in working locomotive engines is a subject of great importance to railway companies, and has attracted considerable attention for many years; but at no period since the introduction of railways has this subject been of such moment as at the present, by reason of the great demand for coal, and consequent increase of price.

The writer having been connected with one of the metropolitan railways for many years, and coal being so very expensive in the south, was led to the consideration of economy in fuel and the production of steam at the lowest possible cost, the accomplishment of which appeared to be in the employment of coal to be used in a separate and distinct fire-box, but in connection with the coke fire-box of the locomotive engine; and this idea was strengthened by the observation of the working of coke ovens in the manufacturing of coke, where he often lamented to see the great amount of flame and combustible gases pass off into the flues and chimney without producing any useful effect; and when it is remembered that 14 ton of good coking coal is required to produce one ton of coke, some estimate may be formed of the quantity of combustible gases that is thrown off.

Being anxious to secure the advantages which appeared to be got by the use of coal in connection with coke in the generation of steam, the writer considered the proper mode was to use coal and coke in separate furnaces, so arranged that the flame and combustible gases thrown off the coal fire would enter into and pass over that of the coke fire, and entering by short tubes into a combustion chamber, situated partly central between two sets of tubes in the cylindrical portion of the boiler, and where complete combustion would be effected.

A new engine on this principle has not yet been completed, but it has been applied in part to six engines with the ordinary boiler on the London and South-Western Railway, and the results of working have been found most satisfactory. One of them, the 'Britannia Engine,' with 15-inch cylinders, 21-inch stroke, and 7 feet driving-wheels, has been working since August 1853, and run 13,600 miles between Southampton and London, a distance of 78 miles, taking the regular running of passenger trains; the average consumption has been 17 lb. per mile, onethird of which was coal, but charged in weight as coke. An experimental trip was made with this engine by Mr. Edward Woods, in October last, with one of the passenger trains to Southampton, and back to London; and another experimental trip was made by Mr. W. P. Marshall, Secretary of the Institution, on the same engine with the 10-15 a.m mail train from London to Southampton, on the 17th January, returning with the 3 p.m train to London; the particulars of these experiments are appended, and the general results are as follows:Experiments with the 'Britannia' Engine and Passenger Trains from London to Southampton and back.

coal fire-box A A, figs. 1 and 2, Plate XXIII., is attached to the back of the fire-box B B, of the ordinary locomotive engine, as shown in the plan, fig. 2, and placed partly below the foot-plate, the water-space of which is in connection with that of the coke fire-box by two branch pipes CC, at bottom and two at top. The flame and combustible gases thrown off the coal fire pass into the coke fire-box through tubes D D, inserted into the intervening water-space; and to promote the combustion of the gases, by giving more time for better admixture, a curved fire-tile bridge E, forming a sort of combustion-chamber, is placed within the coke fire-box, fronting the tubes leading from the coal firebox, thereby checking the velocity of the flame in its passage over the surface of the coke fire. The coal fire-box and the coke fire-box are provided with separate ash-boxes and close-fitting dampers F, G, whereby the draught to each can be regulated with the greatest nicety, and independent of each other. The damper of the coke fire-box F, is generally kept nearly closed, and is only opened 1 inch with trains of 20 to 24 carriages; but the damper of the coal fire-box G, is generally kept quite open, to admit the full draught of the blast, by which means, the coal fire being excited to the utmost, the gases and flame pass into the coke fire, and with them the air in a heated state; the high temperature of the coke fire is maintained, and more perfect combustion is the result. The combustion of the smoke is completely effected, the smoke being scarcely perceptible. An important practical advantage is gained from the circumstance of the ordinary coke fire-door being kept almost constantly closed, the door being opened only three times to put on coke during the whole trip of 783 miles, thus preventing the frequent rush of cold air cooling the fire-box and tubes, and causing a liability to leakage: in the present case, all the air entering at the coal fire-door, becomes highly heated before coming in contact with the main fire-box and tubes.

The next subject which attracted the author's attention was, the fact that all the water required for the supply of the engine when working was sent cold into the boiler, and to obviate this evil, attempts were made to warm the water in the tender by steam from the boiler before the engine started to work, but this was obtained at the expense of the fuel, and was only available as far as the first quantity of water in the tender would supply the engine. The next supply of water taken into the tender must be used cold, because the engine being on the journey could not afford to part with steam to heat the water, as in the first instance, before starting. The great evil of frequent loss of time in travelling was a consequence of the cold-water system of working, and so much was this felt, that when an engine was heavily loaded and taxed to her utmost capability, and having to ascend a long steep gradient, the extra steam to be generated to accomplish this task necessitated an extra supply of cold water to be pumped into the boiler, thus checking the generation of steam, reducing the pressure in the boiler, and crippling the engine. This evil being so great, the author attentively reviewed the whole action of the engine, with a view to improvement as well as economy; seeing that nearly the whole of the caloric which had cost so much was finally dismissed as useless at the chimney, it occurred to him that part of such caloric might be intercepted and communicated to the cold water used for supplying the boiler, a source of heat being thus available.

Various apparatus for this purpose have been contrived and put in operation, one of which is that attached to the 'Britannia' engine. It consists of an oblong rectangular chamber HH, placed in the smoke-box, and cast in one piece with the exhaustpipe, and communicating to the upper part of the ordinary blastpipe; this chamber is filled with a series of small tubes shown in section in fig. 3, fixed in tube-plates at each end, and communicating with inlet and outlet chambers in connection with the A branch pipe I, from this rectangular engine, pump, and boiler. chamber communicates with an outer condensing apparatus fixed in front of the chimney, consisting of three upright pipes K K L, standing on a cast-iron foundation, shown in plan in fig. 4, and connected at top by a hollow cap. Two of these pipes, K K, are provided with jets or injections supplied by the cold-water pump, which draws its supply direct from the tender. There is an overflow-pipe M, for conveying the water after it is heated to the hot-water pump, and an overflow-pipe N N, leading to the tender to convey any surplus water which may not be taken by the hotwater pump. The third upright pipe L, is provided with a disc or throttle-valve O, by which the exhaust steam from the lower chamber H H, can be admitted into the condenser. PP, is an

air-pipe inserted in the centre of the orifice of the blast-pipe, with a funnel-shaped mouth at the lower end, to catch the air and assist the blast.

The action of the apparatus is as follows:-When the engine is working, the exhaust steam from the exhaust steam-pipe, before it reaches the orifice of the blast-pipe, fills the lower chamber, forming a steam bath around the small tubes (through which the water passes into the boiler), and flows upwards into the outer condenser, where it is condensed by the jets from the cold-water pump, and such water, together with that obtained from the condensed steam falling to the bottom of the condenser, is carried off by the overflow-pipe before named to the hot-water pump, which propels it through the small tubes in the lower chamber; and as the water passes slowly through these pipes on its way to the boiler, it absorbs heat from the constant supply of steam rushing to the condenser to be condensed, and enters the boiler at a very high degree of temperature, and causing little or no check to the generation of steam in the boiler, thereby maintaining the full power and energy of the engine. The average pressure in the experiment throughout the whole down trip was 105 lb., and 100 lb. in the up trip; the total fluctuation in pressure during the trip being very limited.

This is a desideratum of no small value, and is experienced especially in the working of the engine between Southampton and London, as there are many long and sharp gradients, particularly that between Bishopstoke and Basingstoke, the gradient averaging 1 in 250 for 17 iniles; the Southampton, Portsmouth, Gosport, and Salisbury trains, being all joined at Basingstoke, and taken in one train to London, which generally contains from 20 to 26 carriages. The advantages of the improvements just described are particularly apparent whilst ascending this long gradient, as was shown in the experiment last referred to, in which a uniform pressure of 120 lb. per square inch was maintained up this incline of 17 miles 1 in 250, with a load of 21 carriages; in consequence a high rate of expansion could be employed throughout, the steam being cut off at 5 inches out of 21-inch stroke, or at less than one-fourth of the stroke during the whole time, an important source of economy.

There are six engines, adapted for burning coal and coke upon this principle, working on the London and Southampton line (the 'Britannia' being one of them), whose united running amounts to 100,360 miles, and the average consumption of fuel, coal and coke together, has been 156 per mile, the 'Britannia' having run 13,600 miles with an average consumption of fuel of 17 lb. per mile. In conclusion, it may be remarked, that in no one instance have any of these engines failed in any part of the apparatus connected with these improvements; also the same remark applies to the fourteen other engines (although in daily use) which are furnished with the heating and condensing apparatus. Should any mishap occur, the engine-driver can cut off the communication from the heating apparatus in an instant, and supply the boiler and work the engine in the ordinary way, and without stopping the train.

ON AN APPLICATION OF THE PROPERTIES OF THE WEDGE.*

PROPOSED BY M. MINOTTO FOR IMPROVING THE METHODS OF TRANSMITTING MOTION IN MACHINERY.t

By H. HENNESSY, M.R.I.A., Librarian to Queen's College, Cork AMONG the most usual methods of transmitting motion from one part of a machine to another are trains of wheels, acting on each other either by friction alone, or more frequently by the contact of projecting teeth placed along their edges. The disadvantages of both of these methods have been so long recognised, that it would be almost superfluous to point them out; and any proposal which would be likely to remove such disadvantages must be regarded with considerable interest. In order to transmit force by a train of wheels, it is essential that their surfaces of contact should adhere with a force greater than that required to be transmitted. This adhesion will depend-1st, upon the nature of their materials; 2nd, the form of their surfaces of contact; and 3rd, the pressure at these surfaces. The second of

From the Journal of Industrial Progress,' No. V.

The views of M. Minotto were first published in Italian, at Turin, and attracted a great deal of attention last year on the Continent, having been examined or noticed in several scientific journals, and having been made the subject of a report to the Institute of France by M. Poncelet.

these conditions is that to which the improvement proposed by M. Minotto refers. He proposed that the edges of every alternate wheel in a train of geering should be indented with a groove of trapezoidal section, the other wheels having each a corresponding truncated wedge-like projecting rim. The properties of the wedge immediately explain the object of such an arrangement. The power applied at the head of a wedge, or that side of it opposite the vertex, is to the resistances opposed by its lateral faces as the area of the head to the area of the faces; consequently, in an isosceles wedge with rectangular faces, if i, represent the angle at the vertex, p the pressure at the head, P the pressure at one of its faces, we have

p = 2 P sin. i; or Pp cosec. i. Therefore, by diminishing the angle at the vertex we have a means for indefinitely augmenting the pressure exercised by the faces of the wedge. These results are evidently unaltered if the wedge is truncated; consequently, the adhesion at the surfaces of contact in such wheels as those described, may be made very great without augmenting the actual pressure between them, but simply by diminishing the inclinations of the surfaces of the truncated wedge in one, and of the groove in the other.

As the nature of the materials used in machinery must influence the adhesion at the surfaces of contact, some experimental illustrations of the resistance produced by the application of the wedge would be useful. From experiments made by M. Minotto on the motion of wedges of different angles and substances through grooves similarly varying in their angles and the substances of which they were made, he has drawn up a table of results, a few of which will serve to illustrate the point in question. A wedge of cast-iron with an angle of 30°, moving in a cast-iron groove with the pressure or weight 5, produced the resistance 375. A wedge of the same substance with an angle of 20°, and carrying the same weight, produced the resistance 5:06. Another wedge with an angle of 10°, and in all other respects similar to the last, produced the resistance 9:53. A wedge of brass, shaped as the fast, and carrying the same weight, produced the resistance 10-60.

These experiments fully confirm the principle on which the wedge is to be applied in machinery. The nature of the new system of geering is best understood by comparing it with a system of friction wheels, such as are sometimes used for the transmission of motion. Let us suppose two such wheels in the same plane, touching at their convex edges. They are in contact only on a line equal to their common thickness, and would slide over each other without any resistance, if their surfaces were totally free from friction. In order that they should be capable of transmitting force, their surfaces must not only possess a certain degree of friction, but also must adhere with a normal pressure, the direction of which necessarily passes through their centres, thus throwing a considerable pressure upon their axes and gudgeons. This pressure is evidently diminished in a system of wedge and groove wheels, for the entire pressure at the surfaces of contact may be decomposed into two-one perpendicular to the axes, the other parallel to the axes. When the angle of the wedge is small, the former must be considerably less than the latter. Thus it appears that in the wedge system a part of the injurious pressure on the axes is not only removed but utilised. A series of experiments have been made by M. Minotto on the friction and adhesion at the edges of wedge and groove wheels of different dimensions and materials, a few of the principal results of which are appended in the following table. The pressures are given in kilogrammes, but the results are precisely the same if we suppose them changed to any other units of weight:

Pressure of one wheel on the other.

Ratio of Friction at edges to the Pressure

Ratio of Adherence to the Pressure

Conditions of Experiment. Angle of 30°, iron on ironBoth wheels large Small grooved wheel with large wedge wheel.....

Ditto

Small wedge wheel with large grooved wheel Ditto

From these experiments it appears that the friction is greater