Putting for B, C, and D their values already found, given in the general equation (4); multiplying out and arranging we have, area = m (a +за +зaz +α). ON A QUICK-WORKING POWER ENGINE. (Continued from p. 91) THE PLAN. SUPPOSE a double pump, with cylinders of large diameter, short, and set far enough apart for the The area between the ordinates a, and a will be, writing a, a, a, and a for a1, ɑ ɑ„, and a strokes of the pistons to be sufficiently long. Sup respectively, Between the ordinates a, and a the area will be 3m (a,+3a+3ag + a7). and so on continually. Consequently the whole area between the first ordinate a, and 3p+1 ordi- reach the top of the pump, so as to form one pipe. nate, represented by aзp+1 (where p is any natural number), is îm {ą +as+1+3 (a2+as+as+az + &c.) +2 (a ̧+a7+a‚+ &c. + a3p) } Whence the following rule, to find any cuvilinear area like that represented in Fig. 8 when the number of equidistant ordinates is some multiple of three increased by one, or when the number of equal spaces is a multiple of three RULE. 1° Add together the first and last ordinates. 2° Add together the second, third, fifth, and all the other ordinates except those which are multiples of three increased by one: and muliply by three. 3° Add together all those ordinates which are multiples of three increased by one, multiply the sum by 2. The sum of the three results here found, multiplied by ths the common interval, will give the whole area required. This is called Rule 3. By an artifice similar to that employed by M. Poncelet for proving the rule to find the curvilinear area when there are three equidistant ordinates, we may prove the above rule for finding the area when there are four equidistant ordinates. Let P,P,N,N, (Fig. 11) be the curvilinear area required, the ordinates of which are represented by a, a, a, and a,, and the common interval between them by m. Divide N,N, into four equal portions in the points A, B, and C, and through these points draw AD, BE, and CF, perpendicular to N,N, meeting the curve in the points D, E, and F, respectively: join P,D, DE, EF, and FP, by straight lines, thus forming four trapeziums. .. 2AD + BE = far apart. 11 8 {a+a+2AD+2CF + 2BE 2AD + BE 3 ; 2BE}. N 4 pose at its front, two pipes of large bore rising from near the bottoms of the cylinders at the nearest opposite sides, and united before they This should pass over between the cylinders and descend perpendicularly at the back, tapering to an end on a very shallow close reservoir. Suppose that, besides the valves in the bottoms, there is a at the lower edge of the opening into the pipe. vertical one at the side of each cylinder, hinged Lastly, suppose the single pipe formed by the its bend, by a space which an oblique sliding-valve junction of the other two to be divided just under should fill, and this part to be inclosed, to form a small chamber where a vacuum might be made. There should also be a valve to be slid up and down at the junction of the pipes; because, otherwise, when the working was stopped by thrusting in the other valve, the water which could circulate through the junction of the pipes would not instantly hold the pistons fast, as would be necessary with a view to starting again-a point that will be further explained. The above are the main features of the plan: the following are minor details, but in part not less essential to the success. The valves in the bottoms should be coupled under the pump by a bar moveable up and down on a support at the middle and bent upwards at the ends, where it should be attached to the under surface of the valve, so that, when horizontal, it should hold them a little open, in order that when one was raised to double the extent, it might, through the bar, hold the other down tight. The reason is, that the pressure from the reservoir tending to open the valve that should be closed would be very far stronger than the downward pressure from the piston over it, tending to keep it closed. The coupling bar, its fastenings, and the valves must be strong. The influx, the force of which would be relied upon, might be strengthened by the bottoms of the cylinders being shaped like hollow cones, with openings at the truncated summits, to which a body of water would run up as through a short tapering pipe. The strokes being intended to be much longer than in common pumping, the parrellel motion should be applied to the pistons. Then opposite to where the rods in that mechanism would issue from the tubes that contain them, four worm springs should be placed so that, with the pistons fixed at the highest and lowest levels by the ends 3N,G = 3PN, nearly, since G is very near to P, the ordinates not being of the beam preparatively to the pivot stroke, one In the same manner it may be proved that 2CF + BE = 3P ̧Ñ2 nearly; sum of all the trapeziums (a1+a+3α2+3α); and since putting PN, and PN3 instead of NG and N.I will give a small increase to the area above that of the trapeziums, and the curvilinear area is also a small increase over that of the same trapeziums, it is readily seen that, approximately, the curvilinear area = (α1 + a1 + 3α + 3αz). 3m 8 spring above and one below might be pressed by screws in framework into tension against the upper end of one and the lower of the other. The other two would be screwed forwards not so much (and the first two should be screwed a little ing), to be forced into tension at the end of the back after they had served the purpose of start stroke. The reaction of the two couples in their turns would cause the changes of the strokes to Proceeding as above with the other sets of four equidistant ordinates, the Rule 3, just stated, is be without any interval of time. readily obtained. There should be a stopper on an opening of the reservoir, to be loaded or unloaded for safety all the other terms after E being separately equal to Zero, since there is no term on the left hand against bursting, and for the regulation of the side of the equation in n1. .. 27n3 +27n2+9n+1=108 En 3 + (54E+27D)n2+(12E+9D+6C)n+B+C+D+E. Equating like powers of n we have internal force. A very small forcing pump, worked by the beam of the main one near the middle, would supply, by injecting once in two strokes obliquely upwards into one of the pipes, any deficiency from waste of water up the sides of the pistons and by exudation. If it throw in too much, the excess would settle in the small chamber, whence it would run into the cistern of the little pump. RAILWAY AND CANAL BILLS.-The number of bills for railways in Great Britain deposited this session is 172, of which 129 authorize new works to the extent of 1,129 miles, in the whole of the United Kingdom; besides 95 miles of deviation lines, and 12 projects for enlargement of stations. M. BRUSSAUT'S INVENTIONS. ANTI-FRICTION ROLLERS AND WEIGHING MACHINES. M. BRUSSAUT, a French engineer, whose inventions have been mentioned with great favour in the scientific journals of Paris and Brussels, is now in this country, drawing attention to his improved apparatuses. They comprise, first, a modification of the well-known anti-friction axles, an improved arrangement of which (the invention of Mr. Rowan, of Belfast) was described and illustrated in the MECHANICS' MAGAZINE for June 15, 1844, No. 1088, Vol. 40. The chief feature of M. Brussaut's invention consists in leaving each anti-friction roller free to revolve, and at the same time connecting all the adjacent rollers to each other by small endless belts of vulcanised India-rubber or other suitable material, as shown in Figs. 1 and 2 of the annexed engravings. The rollers are thus allowed all necessary freedom, while rolling action only is produced between the surfaces in contact. In Fig. 1 the rollers a and the belts only are shown; in Fig. 2 the rollers are supposed to FIG.B. be interposed between the axle-box and axle of a vehicle. In the latter fig. a a are the rollers, and d is the portion of the axle e, which receives the wear; f is the axle-box, with which, as well as with the surface of d, the rollers a a are in contact. By the employment of apparatus of this kind, not only is the friction reduced to an extremely small amount, but lubrication is entirely dispensed with, and yet no heating takes place, even with the highest working velocities, under great pressures. The apparatus is, of course, applicable, in modified forms, to shafts and axles of all descriptions. The giving the anti-friction rollers sufficient strength of resistance in order to prevent their becoming crusted or deformed is simply a matter of proportion. In many cases, however, the diameter of the axle or shaft must be increased; and then Mr. Brussaut employs hollow iron, the superior strength of which is well understood, but the use of which would be impossible with the shafts at present in use, which, so to speak, are merely greased brakes. M. Brussaut's inventions next comprise a set of weighing machines in which all coiled springs, moveable weights, &c., are dispensed with. Fig. 3 is a transverse view partly in section, Fig. 4 a longitudinal view partly in section, and Fig. 5 a plain view of one of the improved machines, with the scale, &c., removed. A is the scale or weighing platform, supported on the plate B, which is carried by the bands s s. These bands are attached to short cylinders rr, carried by other similar bands s' s' secured to the uprights CC. To the cylinders rr are attached the cross-bars DD,which, by means of a series of levers connected and arranged as shown in the engravings, communicate, with the arcs E E, which roll on the rails FF and have a weight, G, fixed at their extremities. From the other end of these arcs a connecting rod, H, leads to a crank on the spindle I, on which the indicating needle L is mounted. This needle carries a vernier M, where necessary, in order to indicate the divisions on the card or face N, as minutely as may be desired. It will be apparent, from the foregoing description, that when the parts are once properly adjusted, the weight of any article placed on the platform A, will be in-sitions of the parts are very different from whrt dicated by the needle on the card. The apparatus they are in the former case, the action is essentially is found to be exceedingly sensitive. In Figs. 6, 7, the same. In Fig. 9 we have illustrated an and 8, we have shown views of a modified form of arrangement in which the arcs are employed the apparatus, in which, although the relative po- | in a modified manner, adapted for use on a counter. The whole of these machines depend upon the action of the bands, &c., only for the motion of the needle, on the weight being applied, and are therefore but little liable to get out of order. In the various dispositions of parts above described the principle of the apparatus is the same throughout. The absence of all variable or delicate parts renders them peculiarly well fitted for weighing luggage at railway stations, retailed goods, and other like articles. indeed probable future cause of failure originating in the construction of the cable itself, which though not so likely to take effect as that to which I have adverted, is still worth considering. It is that a cable with a soft core and rigid exterior is always liable to injury by stretching. Take a length of four-stranded rope which, in a measure, fulfils these conditions, and examine it after having been long in use, or subjected to any considerable strain, and it will be found that the "heart" or "core" has separated into lengths of a ON TELEGRAPHIC CABLES. few inches, while externally the rope appears perfect. And it is useless to say that in the trials of By CAPT. JASPER SELWYN, R.N. strength to which the Atlantic telegraph cable CAPTAIN SELWYN, R.N., of Woodland Crag, was subjected, the outer wire always gave way Grasmere, sends the following able paper for first; for this will no doubt be the case in short publication. We give it place with much pleasure, lengths, but not so when the strain is brought on not doubting that its value will be duly appre-miles at once. Four-stranded rope might be called five stranded, being in fact composed of four outer tightly twisted strands, and an inner central less-twisted soft core, not laid up with, but running straight through the four outer. The result of strain is, of course, that the outer spiral presses on the soft centre, that centre yields to compression, the spiral consequently diminishes in diameter and increases in length, and the centre not doing so proportionably gives way. This would occur the more certainly in proportion as the softer centre occupies a greater space, which in the telegraphic cables is very considerably the case. The cables proposed by Mr. Allan appear to be the only ones which provide for and obviate this fault. ciated: GENTLEMEN,—Believing that where conjectures on nautical matters have to be made, seamen are of all the most fitted to give those conjectures the nearest possible approach to truth, I venture to submit to your readers the belief which I entertain as to the causes of failure in the present Atlantic cable, and the means to be adopted to remedy, and in future to prevent such failures. The cable, we may assume, was, previously to its being laid, perfect in its insulation, and only gradually, after being laid, ceased to be so. I reject here from consideration the fault said to have been cut out on board the Agamemnon, because that does not appear to have affected the first messages; and what I now seek are the causes which were evidently at work shortly after the cable was laid, in diminishing and eventually in destroying the insulation. I will first show cause against, and attempt to eliminate, two suggestions on this head which have been made, and which do not seem to me, as a seaman, to carry probability with them. The precipices which mark the deep-sea boundary on both sides have been supposed to be, by the cable sawing over them, causes of injury. Had this been the case, and had the cable in the first week after laying been so injured from this cause as to expose the gutta perchia and damage the insulation, no long time could have elapsed before the cable would have been cut through, which does not appear even yet to be the case; and besides, our knowledge, such as it is, of the action of water at that depth does not encourage the idea that any such force is there at work. (I will say, in passing that this precipice ought to have been avoided, unless such sudden descents extend much farther under water than they generally do on land. A little more time given to soundings would have been well employed.) There is next the idea that the water pressure due to the great depth has damaged the insulation. But if that were the case, it would have shown itself in a few hours at most after submersion, and would, (as it would have affected equally, and at the same time, nearly the whole length) have been complete, not partial. I take these two, because, if really existing it is evident they would be fatal to the whole scheme; but neither I believe is to be feared or lamented. I will now consider those causes which I regard as probable. FIC.. In the old Mediterranean cable, which was supposed before its failure to have been laid in a perfect state, and parts of which have been recovered, several "kinks" exist, beginning as in Fig. 1, and when strained, resembling Fig. 2; and where, from the strain of raising, or from any other force, these, as at Fig. 1. have been partially straightened, the result is that the cable is untwisted, as at Fig. 2, at the point where the "kink" was, and the gutta percha, or even the copper wire, exposed. I believe the existence of these kinks" to be the main cause of failure in FIG. 2. the Atlantic cable. There is a second possible and I will now return to the question of "kinks," with the view of showing how they are now caused, and how they may in future be avoided. Let a common cotton reel be taken, and having smoothly wound about it some narrow tape, let it be set on end on the table. This will fitly repre in the comparatively shoal water, may be attributed the present defective state of the cable. I will now proceed to consider how these or any other defects may be remedied. This can only be done either by raising entirely, or by the operation known to seamen as underrunning, which in its ordinary form may be thus described:-We will suppose that a line or rope has been laid across water between any two points, and that it has sunk to the bottom. It is clear that if a floating body of sufficient size to bear the weight be brought under the rope at one end near the shore, and by any force, say by hauling ahead by the rope, that floating body be impelled towards the other end, the whole rope will be exposed to view while passing over it. So, practically, a boat is used to underrun a hawser or small cable. It is hauled in at the bow, and passes out as fast over the stern, but meanwhile we can examine it as it passes, and stop it for repair if necessary. I believe some twelve miles of the cable have been thus treated and found to be in good order. Such a mode of under-runing is, however, necessarily slow, and could scarcely be employed with effect for any great distance or depth. I propose a different method by means of a large cylinder, which I will hereafter explain. But the greatest danger, and it is one which can but partially be obviated, is that a “kink" or "kinks" should have so weakened the cable as that it shall no longer be able to bear its own weight in water. This indeed might be fatal to any attempt to raise it, but we must hope that such faults will not be in the deepest parts, as in fact, there is every reason to believe. any rate, the value of the property at stake (about £200,000) is so great that the experiment must be well worth trying; and I believe that if done without loss of time, and either by the method which I propose or by some better one, if that can be found, there is the greatest probability of success in attempting the operation of repairing, or lifting altogether and relaying, the present Atlantic cable. At sent the state of the coil of cable in the hold of a But if as I am informed was the case-such an act of suicidal folly be committed as, on arriving in shoal water, to pay over any considerable amount of slack, then the result would inevitably be that the cable so deposited would first take its place on the bottom in the form of coils, which, when the strain of currents or tides inshore, or of the settling in the deep water came upon the cable, would be converted into kinks, destroying the cable, each in proportion to the strain brought upon it, by opening the strands, and exposing the copper wire. The damage thus caused would, theoretically, present all the phases of gradual increase which have actually been observed. As I have said, I see little reason to doubt that to the existence of these kinks, mostly situated easily-regulated amount of slack can be always thrown off at each turn. The electric communication is kept up by passing the inner end of the cable as coiled on through one end of the axles, and thence on board the towing vessel, where it is dipped into a cup of mercury. I will now furnish a list of the advantages which I suppose to be derivable from the use of these cylinders, premising that, with a model made from a 50 gallon cask, with a small line in proportion, in the presence and to the satisfaction of Commander Gibson, R.N., late first lieutenant of the Agamemnon, I performed on the lake at Grasmere the operations of laying, under-running, and raising most sucessfully. Advantages.—1st. The cylinder is the strongest, smallest, and cheapest known form for carrying a given weight in water. 2nd. The coil is nowhere smaller than 50 feet diameter; the cable is, therefore, but little bent. 3rd. Once coiled on from the works, it is never again moved or bent till laid. 4th. The resistance or brake power being derived from the water, is always proportionate to the strain on the cable, and this without any attention being needed. 5th. No extra weight or impediment is placed on board the vessel towing, her safety is not endangered, and though the resistance to towing approaches that of a vessel of the same draught of water, minus the friction, yet this diminishes with every turn of the cable which is thrown off. 6th. The cable is laid without any strain, and with as great a per centage of slack as may be desired, suitable means of expanding or reefing the paddle floats being provided; thus the slack can be increased or diminished at pleasure. 7th. The cylinder can be made to reel up the cable simply by passing the | end on the opposite way, and towing as before, or if necessary in circles. 8th. The cable may be laid without danger at whatever speed the towing vessel can accomplish. 9th. The cylinder may be left as a buoy on the cable (the towing vessel lying by it), if from bad weather or any other cause, it be necessary to discontinue the operation for a time. 10th. The whole operation will be less expensive, and the first cost for cylinders will suffice for the laying or repairing many lines. 11th. The cable is little subject to the ordinary risks by fire, leakage, or storms. 12th. It can be coiled on the cylinder with little trouble or expense as fast as the cylinder can be turned in the water, with the floats off, and by means of portable steam engines from the wharf, the cylinder being moored off. 13th. The cable can be laid in almost any weather; nothing but such a gale as would stop the towing vessel, or else ice, would interfere with it. 14th. No twist or kinks can by any means be taken in, as may be seen by experi menting with the tape on a reel, before referred to. 15th. No change in the weights on board the towing vessel takes place, such as was found injurious to the stability of the Agamemnon, and nearly caused her loss. 16th. A leak, if existing, could easily be got at, as the cylinder, at each revolution, is in fact turned bottom up, but this need scarcely be feared, as it may be proved by hydraulic pressure before being used. 17th. The cable, instead of being a cause of straining and weakness to the structure carrying it, is, in fact, a source-and a great one-of strength, as, when coiled on the cylinder, its effect, like hoops on a cask, is to bind the whole together. 18th. No heat injurious to the gutta percha, and, therefore, to the insulation, need be feared, which has SHAND AND MASON'S STEAM FIREENGINE. MESSRS SHAND and MASON, the well-known fireengine manufacturers, of Blackfriars-road, Southwark, have lately introduced a class of steam fireengines, the first of which was despatched to St. Petersburg a month or two since. As one of these engines is found to deliver as much water in a given time as three engines of like size worked by twenty-eight men each, and as the manufacturers have had great experience in the construction of fire engines-being the makers of the floating Thames engines, among others-we shall now probably make a considerable advance towards the general application of steam to the extinction of fires. The above engraving represents a side elevation of the engine, with the pumps and details connected therewith shown in section, for the purpose of more clearly illustrating their construction and arrangement. A is the main framing of the engine, composed of wood and wrought iron combined, and supporting a vertical tubular or other suitably-formed boiler, B. This frame is suspended on suitable bearing springs on the hind axle, which is made to surround, without being in actual contact with, the lower portion of the boiler, suitable arms projecting from each side RICHMOND AND CHANDLER'S IMPROVED MACHINES FOR CUTTING HAY, STRAW, &c. of this annular part of the axle serving to carry the large hind wheels. F is a wrought-iron fore locking carriage, furnished with bearing springs C, wheels E', and a pole or shaft (not shown for horses. Above this front portion of the framing is fixed the driver's seat H, and foot board I, a box, K, beneath the seat serving to contain the hose and implements, or, if preferred, a hose reel. The suction pipes are carried on each side of the framing. The combined steam and fire engine is fixed to the framing, A, between the front and hind axles in such a position as to admit of the front wheels locking round freely on a centre. The steam cylinder L is cast in one piece with, or is bolted on to, the top of the air vessel M in an inverted po sition, and the piston rod, after passing downwards through a double stuffing box has keyed or otherwise secured on to it the piston of the upper pump, the barrel of which is placed immediately beneath the steam cylinder. The piston and pump thus serve as effectual guides to the piston rod of the steam cylinder. A connecting rod jointed to the underside of the pump piston connects that piston and the piston rod of the steam cylinder with the crank R, on the engine shaft S, fitted with a fly wheel. This shaft works fluid tight by the aid of the stuffing boxs tt, in the casing c. The lower pump piston, or bucket working in the lower barrel is connected by the rod W with the crank at R', set diametrically opposite to the crank R of the upper pump and cylinder, by which means the two pumps will be kept in constant or continuous action. The slide valves of the engine are worked from an eccentric at x, another eccentric not shown in the drawing serving to work the boiler feed-pump; another feed-pump to be worked by hand being also provided. Steam is admitted to the steam cylinder from the boiler by the steam pipe, and when the pumps are thereby set simultaneously to work, water is drawn in by means of ordinary flexible suction pipes through one of two inlets Z (one of which only is shown in the drawing, the other one being cut away) into the suction air vessel a, into the lower pump barrel through the valve in the piston or bucket thereof into the air tight casing c, and into the upper pump barrel, the piston of which forces it through a valve or valves, d, into the air vessel M, and thence through outlets in the bottom of the air vessel into the hose pipes. In order that the water may be allowed to flow in one direction only through the pumps in place of being driven back through the valve d by the descent of the upper pump piston this latter piston may be furnished with a valve or valves similar to those in the lower piston and the valve d dispensed with, by which arrangement the water will be lifted in one unvarying direction into the air vessel. The crank may be readily got at for repairs by simply removing the side cover f of the casing c. The boiler, B, is supported on the framing, 4, by short arms or girders riveted to the boiler sides, and let into the framing on the inner sides; and a bracket piece is also riveted to the boiler on each side, which rests upon the top edge of the framing. i is a foot board for the stoker to stand upon, the boiler being stoked from the back end of the engine. A suitable damper is provided at j for the purpose of regulating the draught. RICHMOND AND CHANDLER'S MESSRS. RICHMOND & CHANDLER, the well- machine to which their improvements are applied; |