Parliamentary Proceedings. CONDENSED FOR THE "MECHANICS' MAGAZINE." FRIDAY, MARCH 25. HOUSE OF LORDS. THE WESTMINSTER CLOCK. Lord CAMPBELL said the clock in the tower was expected to have been long before this of great service to the public, but it was not yet at work, although it had been placed in and especially to the gentlemen attending Westminster-hall, the tower for some time. The clock had four dials, and he observed on passing the tower that day that the fingers on each dial pointed to different figures. He understood that during his absence on circuit the clock had been at work for half an hour. chamber would be ready for the reception of the clock in HOUSE OF COMMONS. PATENTS FOR INVENTIONS (MUNITIONS OF WAR). TUESDAY, MARCH 29. SOCIETY OF ARTS. served that the metallic core of a submarine cable As to the landing and embarkation of passengers and goods, especially during the winter months, they deal with the latter part of this subject first, and consider, first, a landing quay; second, security in the roadstead; and third safety of navigation. Not only for the accommodation, but for the security of passengers, it is absolutely necessary that some immediate steps be taken to provide for the want of a landing quay. At present the large steamers are compelled from their draught of water to anchor in the roadstead at a distance of nearly one mile from the town, and to land their passengers and goods in hookers, open boats, or a small steamer. This may be accomplished at high water, but towards low water the discomfort and risk are very great, and such as no passengers should be subjected to. Mr. Roberts, C.E, the resident engineer, has prepared a plan, by means of which such temporary accommodation may be obtained at a trifling outlay. For the safety and the convenient placing of large packet steamers, three pair of moorings are stated to be required in the roadstead: two pair for the arriving and dedeparting steamers, and a third for a coal depot. And, lastly, the safety of navigation in approaching the harbour absolutely requires, in the judgment of the Commissioners, that a large Ar a meeting of the members of the above Society, conspicuous buoy and a red light be added, at certain points pointed out by them, to the pre-chair, Mr. Alfred Varley read a paper" On the Practical held on Wednesday last, Mr. Fothergill Cooke in the sent lights and beacons at the expense of the Bearing of the Theory of Electricity in Submarine Ballast Board of Dublin. If these three simple Telegraphy, the Electrical Difficulties in long Circuits, works the landing quay, the moorings in the and the Conditions requisite in a Cable to insure roadstead, and the light and buoys-were exe- rapid and certain Communication." Mr. Varley obcuted at once, sufficient would be done to pro- should be composed of a conductor of the highest vide for the now pressing wants of Galway as a specific conducting capacity, that a decrease in the packet harbour; and passengers and goods retardation which is caused by the induction that might then generally be landed and embarked takes place in submarine circuits can only be obtained without risk, and the steamers might be navi- by increasing the thickness of the insulating material, gated with safety, and lie at moorings in the but that it will be better to do this by enlarging the the roadstead with tolerable shelter and security. sectional area of the conductor as much as is practiShould, however, the experience of twelve tions besides those of its simple electrical qualifica cable. In designing a cable there are many consideramonths prove that permanent packet station at tions which have to be entertained. The object to be Galway is required for Ireland, or for the gene- obtained is the best result with the most economical ral advantage of the United Kingdom, and esinvestment of money. Are the proportions which pecially for the carrying of the mails (and the were adopted in the Atlantic cable the best to insure present number of passengers, the amount of is about 63 lbs. to the mile, the value of which, speak this? The weight of the conducting coil in this cable correspondence, and the shortness of the voy-ing roughly, would, I suppose, be about as many age would seem to warrant such a conclusion), shillings; when served with gutta percha its value a more comprehensive scheme would become was raised to £40 per mile; the iron sheathing and necessary, and such a scheme should embrace getting the cable on board brought its value up to a harbour for national purposes, that is, a station cent., at the outside, was invested in the conductor per mile. In this cable, therefore, only four per for coaling and repairing steamers in time of upon which the transmission of the messages dewar, for assembling convoys, for the relief of pended. If the views which I have brought forward troops, and other military communications with are correct, a conductor of double the diameter would the British North American colonies-a want only produce half the amount of retarding force of that, sooner or later, must be provided for outside would not cost more than £16 per mile; and one of half the size; such a conductor at the very somewhere on the west coast of Ireland. Being the increased expenditure in serving such a conductor on the spot, the Commissioners felt it to be with gutta percha and giving it an iron sheathing their duty to consider such an extended plan, would not, comparatively speaking, be very large. and instructed Mr. Roberts, C.E., to have the The expenses of the staff and the hire of ships necessary borings and examinations made that would be about the same in both cases. The latter would be required to enable a decision to be material amount. would be, perhaps, increased slightly, but not to any The paper, which was unusually arrived at on some of the designs that have long, was received at its conclusion with demonstrabeen suggested. They give a general outline of tions of applause by a numerous audience, among these designs, showing their leading features, whom were noticed Professors Walker, Tyndall, and with an estimate of their probable cost. We Hughes. are happy to find that their report is in all respects favourable to the capabilities of the place. Here, then, is good ground for believing that the distance to America, measured by time, has been definitively shortened by several days. All opposition to the Galway line from persons interested in the southern and western ports of England will and must prove unavailing. The public interest, and-what is more exactingthe public convenience, demand that the new route shall be kept open, and it only remains for rival ports to bear their injury as best they can. * £100 INSTITUTION OF ENGINEERS IN Robert Stephenson, Esq., M.P., and Prof. K. Clausius Mr. Hunt, the Secretary, introduced for discussion the subject of PATENT LAW REFORM. After glancing at the existing patent laws, Mr. Hunt said the reduction in the fees on patents in 1852 opened the door to a great number of perfectly worthless inventions, but perhaps the worst evil consisted in the patenting (or in most cases the merely provisionally protecting) of numerous really valuable inventions by parties not in positions to work out their ideas to practical and useful results. An evil arising from the great number of patents was th difficulty of ascertaining what was and what was n t patented. It was extremely fortunate that when in 185. patents increased so enormously, steps were at the same time taken by the Government to mitigate tl is evil by printing and distributing the specifications. Notwithstanding this, the evil referred to must neces sarily continually increase, and a further reduction of taxes must notably enlarge the rate of such increase. The reduction of patent taxes would doubtless be a boon to inventors and to the public, but the value of the boon would be considerably enhanced if a measure could at the same time be devised which would have the effect of reducing the number of patents for value. less and abortive inventions. It was suggested that with the view of remedying existing evils, any new patent act should contain clauses to the effect tha-1. Any publication of an invention by the inventor, for, say six months before the patent is applied for should not invalidate it. 2. The actual use during that period by another party not author. ised by the patentee should invalidate the patent. 3. The publication during that period of a description of the invention should not affect the patent, excepting in so far as it might bear upon the patentee's claim to be an original inventor. This measure would certainly reduce the number of patents; but the cases in which it would cause the public to loose valuable inventions would be few or none. On the other hand, many of the valueless patents would be replaced by patents for valuable inventions, which did not get patented under the existing state of things. It was well known that many valuable in the ordinary course of business, and various cirinventions never had been patented-they had arisen cumstances had prevented their being patented, such as want of funds or want of faith. In a few months better fate; but having been published, valid patents these inventions had proved themselves worthy of a could not then be got for them. The writer believed there were more cases of this kind than was generally tection to all future cases of the same kind. The supposed. The proposed measure would extend proSecretary's remarks concluded with a few observations respecting the Manchester proposals. that the Council of the Institution should consider the After remarks from various members, it was resolved question, and call a special meeting, at which manufacturers and others interested should be invited to attend. A paper was then read "On the effect of a third Lawrie, which was followed by a discussion. cylinder in the Clyde screw engine," by Mr. J. G. Mr. D. MORE exhibited and described a combined of one of the finest of the American river steamers, in engine-counter and clock, devised by Mr. A. Mitchell, Mr. WALTER NEILSON presented a valuable model the name of Messrs. Ross & Winans, of New York. Mr. J. M. ROWAN exhibited a model of his improved marine engines and boilers. RAPID MONEY-MAKING AT THE MINT. WE learn that the mechanical resources of the Mint, although exerted to an unprecedented extent lately. are found quite inadequate to supply establishment; and that, consequently, an addithe constant demand for money made upon that tion to the motive power employed there is being made. A new steam engine of 40-horse power is in course of erection, and this is intended to drive the laminating machinery. Since the year 1810, when the first coin was struck in the existing Mint, an engine of 30-horse power, supplied by Boulton and Watt, gave motion to this branch of the coining machinery; but, as has been said, the pressure for money is now so great that this very creditable specimen of early engineering is not equal to the task imposed upon it. The new engine was contracted for by Messrs. Hall, of Dartford, and is on the combined high and lowwith its ancient predecessor, which will not as yet pressure principle. It will be placed side by side be removed. The united power of the steamengines employed in the cash department is 66horses, reckoning that of the new money-maker. An extension of time is aimed at for the completion by the Commissioners for this object has been declared of the Tyne piers. The preamble of a Bill promoted proved by a Committee of the House of Commons; and the Bill has been so modified as to enable the Commissioners to accept the proposed Government grant for a harbour of refuge (£250,000). THE THEORY OF NAVAL ARCHITECTURE. LET y=247.x be the equation to the curve PPN,represented in figure 13, (next column) in which PN, and a line at right angles to it through P, are the co-ordinate axes. This figure may be regarded, like that of the previous example (p. 168), as a half midship section, approximating to the form of the midship section of a vessel of burthen. The breadth of the ship would be 48 feet to the outside of the planking; and the draught of water from the load line PN, to the lower edge of the rabbet of the keel, 24 feet. Let, as before, the depth P,N, be divided into six equal parts, each being equal to four feet; and let a, a, ɑ3, ɑ4, ɑ5, ɑ6, and a-, be the ordinates drawn through the points of division. From the equation to the curve, putting equal to 24, 20, 16, 12, 8, 4, and 0 respectively, we have a1 = 21000; a=23·460; a=22814; a=22008; a;=20′920; a=19181; and a=0; applying the second Rule, and putting it in a form convenient for calculation, than either the second or third Rules; but the error is still above 3 per cent-much too great to be disregarded by the naval architect. We stated, when approximating to the area of a quadrant, that the errors mainly arose from the deviation of the approximating curve fron the given curve in the neighbourhood of P., the two curves in their other parts being nearly coincident; the same is true in this case also. 6 From an inspection of Fig. 13, which is drawn to scale, we perceive that the direction of the curve at the extremities of the equidistant ordinates deviates tolerably evenly from P to P', but from Po to P, the direction alters very rapidly. In the part, therefore, between P and P especially, the ordinates should be placed near to each other. For example, let N, P, be divided into four equal parts, each being equal to one foot; and at the points of division let H P PS G N FIC.13. D B NECA the ordinates AB, CD, . and EF be drawn parallel to PN; these three, together with PN and P, make five equidistant ordinates, to which the second Rule may be applied to find the approximate area. Again, let NN be divided into two equal parts, each being equal to 10 feet; and at the point of division let G H be drawn parallel to P1 N1; then PN, GH, and P N are three equidistant ordinates, to which the second Rule may also be applied. From the equation to the curve we have, putting x equal to 1, 2, 3, and 14 respectively, AB CD 23 16.132; 17.592; Ordinates. Multipliers. The area of the part between P, N and P No, since the common interval is 10 feet, is equal to 10 1 P1 N1 + 4. G H + P&N2 } 3 10 * 3 = 1 19-184+4 (16·132 +18·507) +2 (17·592) +0 } }. 3 10 The whole area of the figure, or the sum of these two areas, Putting it in a form convenient for calculation, •2 (17·592)+0}. 3rd and 5th Ordinates. Ordinates. 23.460 22.814 0.0 22.008 272 The error here does not amount to one per cent., and we have only taken the same number of ordinates (seven) as in the other methods of approximation, but have placed them differently. These examples show very clearly that by placing the ordinates with a due regard to the curvi ture, and applying the second or third Rules, a very close approximation to the true area will be obtained, with a small amount of labour in the calculations. We should, however, strongly recommend the student to apply, in other examples, the rules before given in a table, for finding the approximate area when a continuous parabolic curve passes through the extremities of the ordinates; and they will find that the second or third Rules applied to the same cases, in the manner already pointed out, will give more accurate results, with much less labour in making the calculations. The figures to which the rules may be applied, and their exact areas, and ordinates readily obtained are ellipses and parabolas. The ellipse is a figure too well known to require us to indicate the method of obtaining the lengths of the ordinates, and the exact area. The family of parabolas is perhaps not so generally known. The equation to the parabola from the vertex is y = pa-1.x, in which p (the parameter) is constant in the same parabola, and in the example above given was equal to 24; giving a different values in this equation, the values of y, the corresponding ordinates, can be obtained. The exact area corresponding to any length of axie, X-where Y is the ordinate drawn at the distance X from the vertex-is MR. COLLINSON HALL, of Navestock, Essex, who is well known for his improvements in the application of steam power to agricultural operations, has introduced an invention which will greatly facilitate steam ploughing. Having had very ample experience of the difficulties which Mr. Hall's apparatus is designed to obviate, Mr. Fowler has taken steps to secure that apparatus, and has become the proprietor, we believe, of the patent granted for it to Mr. Hall. The invention is certainly a most valuable one, as it will obviate the principal defects of the existing steam-plough tackle. The following are the principal portions of Mr. Hall's specification of his patent: "Heretofore, in applying power to the cultivation of the soil by means of ropes, bands, or chains passing around drums or pulleys, the adhesion between the said ropes, bands, or chains and the drums or pulleys has, in the ordinary arrangements of apparatus, been found too small, and has in some cases been increased by additional contrivances. And my invention consists, first, of a new arrangement of drums or pulleys which obviates this objection. I employ a single drum or pulley upon one axle, and two or more drums or pulleys upon another. The rope, band, or chain is so passed round the drums or pulleys that one of the two, or more, which are upon the same axle turn in a direction opposite to that of the others, when the rope, band, or chain, is put in motion. The number of turns which the rope, band, or chain is made to take round the drums or pulleys will vary with the amount of power to be applied, the one increasing with the other. The arrangement described is that which I prefer; but I reserve to myself the employment of any and every equivalent arrangement whereby essentially the same action may be obtained. Secondly, in turning ploughs and other implements at the headlands, one wheel (usually the offwheel) runs round and the near or opposite wheel remains at rest (in relation to its axis) or nearly so, and consequently obstructs the turning of the implement by encountering and displacing the soil. In order to remedy this evil, and thus facilitate the turning of the implement, I provide a small sole-piece or turntable, upon which the near wheel runs on reaching the headlands, and then is supported by it and turns upon it. Thirdly, in FIG. 4. gearing from the first driving shaft. II are guide pulleys fitted in the simple manner shown for guiding the rope on to cr off from the drum and pulleys, and J, J are other guide pulleys carried by independent arms similarly fitted for keeping the rope in its proper grooves. The second part of my invention needs no illustrative drawings, inasmuch as any simple flat or concave sole piece, either working loosely within another so as to turn upon it, or simply remaining at rest itself and allowing the wheel to turn upon or within it, is sufficient for the purpose set forth. The of manner in which I prefer to carry the third part my invention into effect is illustrated in Fig. 4 of the K is the ploughing ploughing and otherwise cultivating by power it drawings hereunto annexed. is, with ordinary apparatus, necessary for an at-rope which is supposed to be advancing in the direc tion of the arrow. L is a frame carrying a fixed tendant to signal to the engine driver (by means block M, and a moveable block N, which is pressed of flags or otherwise) when the implement reaches upon by the toe." the headlands, that the engine may be stopped at a proper time. This signalling is often difficult and liable to failure, owing to certain states of weather, &c., and accidents to the apparatus sometimes result. To prevent this I connect with the implement a self-acting contrivance for loosening the rope from the implement at the required time. This contrivance may consist of an eccentric or a quick screw connected with a lever, and caused to join the rope ordinarily used and to be withdrawn from the rope by a fixed bar acting upon the lever; but any other equivalent contrivance may be employed for the purpose. "In Fig. 1, 2, and 3 of the drawings hereunto annexed I have illustrated the manner in which I carry the first part of my invention into effect. Fig. 1 is a plan of the underside of a portable steam engine with my improved arrangement of drum and pulleys attached thereto. Fig. 2 is a side elevation of the said arrange ment of drum and pulleys. Fig. 3 is a detached axle. The drum and sets of pulleys are suspended section of the set of separate pulleys on the same from the boiler by means of the cotters a a', which are passed through the castings 4 4' and the spindles of the drum and pulleys respectively. The castings 4 and 4' are bolted permanently to the underside of the boiler, but the drum and pulleys may at any time be detached by removing the cotters a a. The lower ends of the drum and pulley spindles are connected by a rigid bar of iron B, fixed by nuts screwed upon the threaded ends of the spindles. This bar gives perfect rigidity and all necessary support to the system of drum and pulleys without any other species of framework. C is the single drum upon the one axle, and D, E, F, G are the separate pulleys upon the other axle. The rope is wound about the drum and pulleys by preference after the fashion of a figure 8, as shown in Fig. 1, in order to get the best possible action. This arrangement renders it necessary that either the upper pulley D, or the lower pulley G, as the case may be, shall turn in a direction opposite to that of the remainder of the set. The whole system is driven by means of the cogged wheel H, into which gears a pinion driven by an upright shaft set in motion by JOBSON'S IMPROVED MOULDS FOR MR. ROBERT JOBSON, of Wordsley, Stafford, has which the box is placed, and when in the first instance the pattern has been correctly adjusted on the table on which the flask or box is placed to have the sand rammed, the pins and the ends of the sockets (which receive them) are filed off, so as to make the ends of the pins and of the sockets coincide. By these means should any sand or material get in between the table and the pattern, the least incorrectness in the placing of the pattern will at once be detected by the workman when he passes his fingers over the pins and the sockets. În some cases like means are resorted to in placing cores into moulds. IMPROVED WATER-PRESSURE MACHINERY. In order to dispense as much as possible with By Sir W. G. ARMSTRONG, C.E., F.R.S., Engineer from the pipes communicating with the town hand labour, in order to remove the sand after it has been used, and to damp it and to bring it into position to be again used by the moulders, apparatus is arranged whereby the sand is shovelled on to sieves, which are worked mechanically; the sand is damped, and the sifted sand is carried by a screw in a suitable trough or tube to the mixer, where fresh sand and other matters are added, and whence the sand is conveyed through another trough or tube by a screw into a position to be used by the moulder. Again, in order, where heavy boxes or flasks are used, to reduce manual labour, a peculiar form of crane or apparatus is used, which consists of a quadrant, over which a chain or band passes; this quadrant receives motion by the moulder turning or giving motion to a fly-wheel, on the axis of which is a pinion which takes into and drives a cog-wheel, and on the axis of this is a pinion which takes into a curved rack fixed to the quadrant, which is counterbalanced when necessary, and which, in addition to turning on a horizontal axis, also turns to the right and left of the post or upright which carries it. Fig. 1 shows a vertical section of so much of a table and apparatus used for forming sand moulds as will enable us to describe the peculiar character of Mr. Jobson's improvements. A is the table on which the flask or box B and the pattern Care placed when forming a sand mould in the box or flask B. The table 4 inay be stationary on a suitable stand or frame, or it may be arranged in a suitable frame in such manner as to move on axes, necks, or gudgeons, and to turn thereon or therewith, so as for a time to bring its under surface uppermost, and its upper surface with the flask or box thereon undermost; the latter arrangement is preferred. When the table 4 is fixed, the box or flask B and the mould therein will have to be lifted and turned over in the ordinary manner; but when the table or surface 4 is made to move on or with axes, necks, or gudgeons, the table or surface A with the box or flask B and pattern C may be turned over by moving the table or surface 4 on or with its axes, after having first placed the cover D on the mould box or flask, in which case the flask or box will be temporarily fixed to the table or surface 4, and when brought below there must, as heretofore, be provision for detaching and lowering the flask or box and the mould therein. The pattern C shown in the engraving is a half sphere, but any suitable pattern may be used in the place thereof, according to the article desired to be cast in the mould. The pattern C is formed with four arms C, C, with pins C, Ca, which enter sockets D', D', formed on the table or surface 4 as is shown, or in any other convenient manner. The pattern C is moved and partly withdrawn from the mould by means of a screw E, which passes through the fixed screw nut F. In constructing and adjusting the pattern and parts connected therewith in the first instance, in order to insure great exactness of castings made in a succession of moulds produced on the same patterns, the pins or projections C, C, are allowed to project through and beyond the sockets, and when the pattern C has been accurately adjusted in respect to the upper surface of the table 4, the ends of the pins or projections Care to be accurately filed off or removed, so that they may be smooth and flush with the ends of the sockets, by which means the workman, when he is about to make a mould in a box or flask placed on the table, will by simply passing a finger against the ends of the pins or projections C and their sockets, immediately ascertain whether the pattern is correctly in position, and if not, he may readily adjust it correctly by moving the pattern upwards or downwards till the ends of the pins C are exactly flush with the ends of their sockets. The arrangement and form of the pins or projections and their sockets may be varied, and such is the case in respect to the apparatus for moving the pattern. In like manner may cores be made with projections and moulds with sockets or receivers, so as to enable the workman readily to judge when a core is properly placed within a mould. The European and American Steam Shipping Company is to be dissolved. A proposal made by Mr. J. L. O'Beenie to charter, on the part of a number of gentlemen, the eight ships of the company for three years was not accepted, to the War Department for Rifled Ordnance. [BEFORE his great gun gave Sir William Armstrong his novel pre-eminence, he was well known among engineers as the most successful improver of water-pressure machinery, and in the last volume of the MECHANICS' MAGAZINE we reported an elaborate lecture of Sir William's upon the subject. The official report of the proceedings of the August meeting of the Institution of Mechanical Engineers having now come to hand, we are enabled to lay before our readers illustrations of the improved machinery, with Sir William's own description of the same. We cannot do this without repeating a few sentences which appeared in our last volume; but we prefer to do this rather than render the paper incomplete. Although written in the third person, the paper which follows is by Sir William himself.] The subject of water-pressure machinery first attracted the writer's attention about twenty-three years ago, on occasion of his noticing a small stream of water which flowed from a great elevation down a steep declivity and turned a singing that the por. tion of the fall which was thus utilised by the wheel near the end course. Observing was not more than a twentieth part of the whole descent, he was forcibly struck with the inadequacy of the wheel as a means of realising the power of such a fall; and conceiving it practicable to render the entire head available by bringing down the water in a pipe, and causing it to act by pressure upon a suitable machine at the bottom, he applied himself to devising an engine to be worked by such a pressure. Other inventors, guided by the same idea, had been previously led to apply water-pressure in various ways to driving machinery, although the employment of that power had never been extensively adopted; but with these applications the writer was at the time wholly unacquainted. After meeting with many difficulties and discouragements, the machine was produced, which after many years of seclusion in a lumber-room has now been brought out for inspection upon this occasion. It is, as will be perceived, a species of rotary engine, admitting of a continuous and uniform flow of water through it, and exempt from all contracted passages. This machine was tried first in Newcastle, with the pressure from the street pipes equivalent to a column of about 200 feet; then in Gateshead, with a still greater pressure; and in both cases it yielded a very high effect in relation to the theoretical power of the moving column. to provide a machine for turning to profitable account Up to this time the writer's object had been merely the power which great altitude gives to mountain streams; believing then, as now, that when roads and railways have rendered accessible the valleys where such streams abound, the water which descends from the heights will ultimately prove an efficient source of motive power. But having then had practical experience of the power residing in street waterpipes, he conceived the idea of applying such power to the cranes at that time so slowly and expensively worked by hand upon the quay of this town. Accordingly after duly considering the means of effecting this purpose, a working model of a hydraulic crane was constructed, and exhibited at a meeting of the Literary and Philosophical Society of Newcastle, where it was connected with the town water-pipes, and went through the several operations of lifting, lowering, and slewing in a very satisfactory manner. The next step was to carry this scheme into actual practice; and in the year 1846 the first hydraulic crane was erected at the upper end of the Newcastle Quay, where it has ever since continued to do good service in discharging ships. The crane model exhibited to the present meeting is nearly identical with the original model, and does not differ materially from the first actual crane erected in this town. The writer was soon enabled to introduce the hydraulic crane at Liverpool, and shortly afterwards at the New Dock at Grimsby, where, at the instance of his friend, the late Mr. Kendel, the engineer who constructed that dock, he also applied the same kind of machinery for opening and closing the lock gates and sluices. An extensive system of water-pressure machinery was accordingly carried out at that dock; and the result afforded the first practical demonstration that the pressure of a column of water could be advantageously applied as a substitute for manual labour, not merely for the cranage of goods, but also for various mechanical operations in connection with the entrances to docks. At all these places the effective column of water was about 200 feet head. At Newcastle and Liverpool the supply was derived supporting a tank, into which water was pumped by reservoirs; but at Grimsby a tower was built for a steam-engine. In the former cases the irregularity of pressure, consequent upon the variable draught from the pipes for the ordinary purposes of consumption, proved a serious disadvantage; but this objection was not experienced at Grimsby, where the tank upon the tower furnished a separate source of power, undisturbed by any interferences. But the erection of a tower was a formidable undertaking, and so long as it remained a necessity, a great extension of the principle could not be anticipated. The writer therefore resorted to another form of artificial head, which possessed the advantage of being applicable, at a moderate cost, in all situations, and of lessening the size of the pipes and cylinders by affording a pressure of greatly increased intensity. The apparatus by which this is effected is named the "accumulator," from the circumstance of its accumulating the power exerted by the engine in charging it. The accumulator is in fact a reservoir giving pressure by load instead of by elevation; and its use, like that of every provision of this kind, is to equalise the duty of the engine in cases where the quantity of power to be The construction of the accumulator is shown in I sudden fluctuations. the vertical section, Fig. 1. It consists of a large castiron cylinder 4 fitted with a plunger B, from which a loaded weight case C is suspended, to give pressure to the water injected by the engine. The load upon the plunger B is usually such as to produce a pressure in the cylinder equal to a column of 1,500 feet head; and the cylinder is made sufficiently capacious to contain the largest quantity of water which can be drawn from it at once by the simultaneous action of all the hydraulic machines connected with it. Whenever the engine pumps more water into the accumulator than passes to the hydraulic machines, the plunger rises and makes room in the cylinder for the surplus; but when, on the other hand, the supply from the engine is less for the moment than the quantity used, the plunger with its load descends and makes up the deficiency out of store. The accumulator serves also regulator to the engine; for when the plunger rises to a certain height, it begins to close the throttle valve in the steam-pipe so as gradually to reduce the speed of the engine, until the descent of the plunger again calls for an increased production of power. With regard to the pumping-engine used for charging the accumulator, the most approved form is that of two high pressure cylinders fixed horizontally, with double-acting pumps directly connected with the piston rods. At first a simple plunger pump at each end of the cylinder was used; then, with a view to greater compactness, the pump behind the cylinder was discontinued, and the other made a double-acting one upon the combined bucket-and-plunger system. Finally, a modification of this form of pump was adopted, by dispensing with the in the bucket and substituting an external delivery valve D, as elivery shown in Fig. 2. In this arrangement the out-stroke of the pump causes the water contained in the annular space surrounding the plunger E, to be forced into the accumulator, while a further supply of water enters behind the piston F through the suction valve G; in the in-stroke the water behind the piston is discharged through the delivery valve D, and half of it passes round into the annular space on the other side of the piston, while the remaining half is forced into the accumulator, the area of the plunger E being exactly half that of the piston F. Each stroke of the pump thus delivers the same quantity of water into the accumulator. This neat modification of the bucketand-plunger principle, by which equally easy access is given both to the suction and the delivery valves, was the suggestion of Mr. Henry Thompson, the writer's late intelligent foreman. The introduction of the accumulator in the year 1851 removed all obstacles to the extension of water pressure machinery, which has since been applied in nearly all the principal docks, and in many of the Government establishments in this country Nearly 1,200 hydraulic cranes, hoists, and other machines of that description have been applied; and 125 steam engines, collectively of more than 3,000 horse power, are now daily at work to supply the pressure for working them. The system has also been adopted in many of the principal railway stations, not only for cranage, but also for working turntables, traversing machines, waggon lifts, hauling machines, &c. It is also extensively used for raising and tipping waggons in the shipment of coal, for opening and closing swing bridges, and for many other purposes. New forms of application are continually being developed, and no The form of mechanism which prevails to the greatest extent in these various applications of water pressure consists of a hydraulic press with a set of sheaves used in the inverted order of blocks and pulleys, the object being to obtain an extended motion in the chain from a comparatively short stroke of piston. The general arrangement of the machinery for working a hydraulic crane is shown in Figs. 4 and 5; Fig. 4 being an elevation and Fig. 5 a plan. The pressure cylinder 4 for lifting the load is fixed horizontally below the surface of the ground in a chamber at the foot of the crane, and is fitted with the ram B carry ing the pulleys C at its outer extremity. The lifting chain is made fast at one end to the cylinder 4, and passes alternately round the moveable pulleys C and the fixed pulleys D, at the inner end of the cylinder 4; and is then led round the guide pulley E, up the crane post F, and along the jib to the load. The motion of the lifting chain is controlled by means of the handle G, acting upon the inlet and outlet valves, which are kept closed by the weights H and I; by opening the inlet valve H the water is let into the cylinder 4, from the pressure pipe J, and raises the load; and by opening the outlet valve I the water escapes from the cylinder into the exhaust pipe K, allowing the load to descend. The travel of the ram B in the outward stroke is prevented from exceeding the proper limit by the pulley block C coming in contact with a stop connected with the handle G, | which closes the inlet valve H, and prevents the load from being raised too high. The return stroke of the ram is effected by the load suspended from the chain; and in the absence of any load a small supplementary ram L is employed to force the main ram B back, the slack chain being made to run out by the weight M. (To be continued.) its width about 12 feet, and it was capable of holding 12 men. A complete tent so constructed only weighed 43 pounds. The following are the dimensions, &c., of the "circular conical single-poled tent" at present in use. I may premise by stating, that the British army tents vary both in size and weight. The diameter of this tent is 12 feet and 6 inches; height, or length of pole, 10 feet and 4 inches; accommodation for 12 to 14 men; weight of the linen tent (complete) when dry, is from 68 to 75 pounds, and when wet about 104 pounds. The height of the vertical circular wall is 12 inches, and its object is to give increased head-room to the soldiers when lying down. The number of pins required for this tent is 43; viz., 40 for the tension ropes and loops, and 3 for the long storm ropes. This tent is provided with one triangular entrance, and is deficient of a proper means of ventilation. The above sized tent contains about 512 cubic feet of capacity, allowing to each soldier cubic feet, 10 men per tent; about 42 cubic feet, about 64 cubic feet, 8 men per tent; about 51 12 men per tent; and about 34 cubic feet, 15 men per tent. GENERAL DEFECTS OF THE BRITISH ARMY TENTS. Their general defects consist-1st., the canvas of which they are made is not always of the best |