Brighton Railway, it will be remembered that the leading engine was one having only four wheels. But it may not be generally known, that on the day next preceding that on which the fatal accident happened, a four-wheel engine ran off the rails in a tunnel, and furrowed the wall for a considerable distance. I am, Sir, your humble servant,

A PRACTICAL ENGINEER.

LUBRICATORS.

Sir, I was exceedingly pleased with Mr. Houghton's very ingenious Lubricator, described in No. 993 of your invaluable work; but there was one circumstance which I was not quite clear concerning, namely, whether the pressure of the atmosphere, when it closes the top valve, also forces the oil clear from the space between the valves? Or does the valve shut first, and the oil merely trickle out? If the atmospheric pressure sends the oil out with a spurt, I think it would send more out than what is contained between the two valves. I also think it would be an improvement to have a small strainer just above the bottom valve, with the holes so small that the oil would only pass through when under pressure, which would effectually prevent any impurities from entering the cylinder. I have prefixed a slight sketch of a plan which would strain the oil by pressure of the atmosphere, if Mr. Houghton's Lubricator should not do so.

A is the oil-cup; B, the top valve, with a small tube, C, communicating with the bottom of the valve, and working through the top of the oil-cup in the manner of a piston; D, the bottom valve; F, the strainer.

I am, Sir, yours truly,

DOUBT.

THE BUDE AND BOCCIUS LIGHTS.* Report of Dr. A. Ure, F.R.S., Professor of Chemistry, Consulting and Analytical Chemist, &c. &c.

I have carefully perused the specification of Mr. Gurney's patent, also the evidence taken before a Committee of the House of Commons on the advantages of his improvements in the lighting of that house, and I am of opinion, that the patent is perfectly good in law, as by this evidence it is clearly proved that artificial light is thus produced in greater quantities, and of a better quality, than by any other means heretofore known, and at a saving of 50 per cent. A material benefit is consequently conferred upon the public, and such as is intended to be protected by the statute, even if the patentee laid no claim to the novelty of any of the apparatus, or materials used.

and

This construction of the law has been borne out by many recent decisions, but more particularly in the case of Crane against Price and others, in which judgment was given last term. In this case an action was brought for an infringement of a patent obtained for improvements in the manufacture of iron, by using anthracite coal in combination with hot blast, neither of which were new, both of which had been previously used for that purpose, though not in conjunction. The verdict was, nevertheless, for the plaintiff, and Chief Justice Tindal, in pronouncing judgment, observed, that if the result of a combination is either a new article, or a better article, or a cheaper article, to the public, than that produced by the old method, such a combination is an invention, or manufacture intended by the statute to be protected by a patent, even when the invention, or improvement, consisted in no more than the use of things already known, and acting with them in a manner already known, and producing ef

Having already given the Report of Messrs. Brande and Parkes in favour of the Boccius Lightthe intent of which Report, or at least of those who paid for it and first gave it publicity was to deceive the public into a belief that the Boccius Light is superior to the Bude and all others previously invented, we do but an act of equal justice to Mr. Gurney, in now laying before our readers the opinion which Dr. Ure, a most competent authority, has at Mr. G.'s instance given on the subject. We are glad to find, that so far as regards the Charing-cross phenomenon, Dr. Ure's opinion is perfectly in accordance with that which we had ourselves previously expressed.-ED. M. M.

fects already known, but producing those effects, so as to be more economically, or beneficially enjoyed by the public." Now it appears to me that the law as thus laid down, and recognised by the judges, is equally applicable to Mr. Gurney's combination of materials for the production of light, even admitting that there were no novelty in those materials, the result (which is the material point at issue,) being the production of an article of commerce, which is more beneficially enjoyed by the public, as proved in so satisfactory a manner by the Report of this Parliamentary Committee before which I was myself examined.

I have inspected, also, the drawings and specification of the patent obtained

by Gottlieb Boccius, and I have likewise examined the light recently erected opposite Northumberland House, in the Strand, known as the "Boccius Light," and I have no hesitation in pronouncing it to be a manifest piracy and barefaced imitation of Mr. Gurney's patent.

Having been originally consulted on the case of the Queen v. Bynner, whose patent for what is termed the "Solar Lamp" was recently repealed by a scire facias, as defective, false, &c., I am of opinion that, if a similar course was pursued with respect to the Boccius patent, a similar result would follow.

Sir,-In answer to the enquiry of a wharfinger in your 998th Number, I herewith enclose a rough sketch of a weighing machine manufactured by Mr. Robert Maynard, of Whittlesford, near Cambridge, and in common use by the merchants of this town for coals, &c.

It consists of a wooden box or frame, containing the levers, supporting by four steel centres the corners of the platform P. The levers are connected in the interior of the box, in such a manner, that a load placed on any part of the platform has an equal tendency to raise the end of

one of the levers, which is elongated, and terminates with a pin fitting a hole in the centre of each weight. The weights are flat; the two largest weigh exactly 7 lbs. each, and both together balance 2 cwt. on the platform. The whole is extremely portable, weighing about 50 or 60 lbs.; size of platform 18 inches by 15; height from floor 6 inches.

We have several of them in daily use; they cost us 21. 6s. each. I am, Sir, yours, &c.,

CHARLES FINCH FOSTER. Cambridge, October 3, 1842.

A trial of this very ingenious machine, constructed by Mr. Davidson, was made on Thursday on the Edinburgh and Glasgow Railway, in presence of a number of gentlemen, many of whom were eminent for their scientific knowledge. The construction

of the carriage is the first attempt which has been made in this country to apply the powers of electro-magnetism to railway traffic, and from the success which attended this trial sanguine hopes may be entertained that the period is not distant when it will

either supersede, in many cases, the employment of steam, or lend a powerful aid to this mighty instrument in all the operations in which it is at present employed. The carriage was impelled along the railway about a mile and a half, and travelled at the rate of upwards of four miles an hour, a rate which might be increased by giving greater power to the batteries, and enlarging the diameter of the wheels. We understand that the carriage was built at the expense of the Railway Company, and we cannot but congratulate them in having the discernment to employ Mr. Davidson, a gentleman of much practical knowledge and talent, to whose genius great discoveries have been made in electro-magnetism, by whom the carriage was projected, and to whose unwearied exertions the practicability of the scheme is almost placed beyond a doubt.

The dimensions of the carriage are 16 feet long by 7 feet wide, and is propelled by eight powerful electro-magnets. The carriage is supported by four wheels of 3 feet diameter. On each of the two axles there is a wooden cylinder, on which are fastened three bars of iron at equal distances from each other, and extending from end to end of the cylinder. On each side of the cylinder, and resting on the carriage, there are two powerful electro-magnets. When the first bar on the cylinder has passed the faces of two of these magnets, the current of galvanism is then let on to the other two magnets. They immediately pull the second bar until it comes opposite them. The current is then cut off from these two magnets, and is let on to the other two. Again they pull the third bar until it comes opposite, and so on-the current of galvanism being always cut off from the one pair of magnets when it is let on to the other.

The manner in which the current is cut off and let on is simply thus :-At each end of the axles there is a small wooden cylinder, one-half of which is covered by a hoop of copper; the other is divided alternately with copper and wood (three parts of wood and three of copper.) One end of the coil of wire which surrounds the four electro-magnets, presses on one of these cylinders, on the part which is divided with copper and wood; the other end of the coil presses on the other cylinder in the same manner. One end of the wires or conductors which comes from the battery, presses constantly on the undivided part of the copper on each cylinder. When one of the iron bars on the wooden cylinder has passed the faces of two magnets, the current of galvanism is let on to the other two magnets, by one end of the coil which surrounds the magnets, passing from the wood to the copper, and thereby

forming a connexion with the battery. This wire continues to press on the copper until the iron bar has come opposite the faces of the two magnets, which were thus charged with galvanism. On its coming into that position, the current is cut off from these two magnets, by the wire or rod of copper passing from the copper to the wood, and thereby breaking the connexion with the battery. But when the wire or rod of copper leaves the copper on the one cylinder, it leaves the wood, and passes to the copper on the other cylinder at the other end of the axle, and in so doing connects the other two magnets with the battery, and they pull the next iron bar in the same manner. At the other end of the carriage there are other four magnets, and wooden cylinder, with iron bars arranged in the same manner.

The

The battery which is used for propelling the machine is composed of iron and zinc plates immersed in dilute sulphuric acid, the iron plates being fluted so as to expose greater surface in the same space. weight propelled was about six tons. [We are glad to see that the value of the electro-magnetic agency, as a moving power, is at length likely to have a fair trial. The plan of Mr. Davidson is precisely the same as that of Captain Taylor, described in vol. xxxii. page 694; but it will no doubt be in the recollection of our readers, that Mr. Davidson claims to have adopted that plan before it was patented by Captain Taylor. See Mech. Mag. vol. 33, pp. 53, 92.-ED. M. M.]

INSTITUTION OF CIVIL ENGINEERS.
June 28, 1842.

"An Account of the Bridge over the Thames, at Kingston, Surrey." By John Brannis Birch, Grad. Inst. C. E.

Previous to the year 1828, when the present bridge was opened to the public, the communication between the town of Kingston-upon-Thames in Surrey, and the hamlet of Hampton-wick in Middlesex, was carried on by an old and incommodious wooden bridge, which was so dilapidated that any attempt to put it into a substantial condition for the service of the public, would have been equivalent to an entire rebuilding of the structure.

The corporation of Kingston, therefore, resolved upon erecting a new bridge, on a design by Mr. Lapidge, their architect, and in the year 1825 obtained an Act of Parliament, granting them the powers necessary for that purpose.

The trustees appointed under the Act applied to the Exchequer Bill Loan Commis

sioners for pecuniary assistance to the amount of £45,000, but the application was not entertained until the working drawings, specification, &c. had been submitted to their engineer, the late Mr. Telford, when he gave the following opinion

:-

'Having carefully inspected all the working drawings, I consider it only justice to Mr. Lapidge to say, that they are very complete and do credit to his judgment and assiduity; and as the blue clay has been found quite across the bed of the river, I am of opinion that, with the precautions provided in the working drawings and specification, the work is very practicable, and if well executed will prove a substantial and useful edifice." He also said, "I have gone through the detailed estimates, and compared the same with the proposal accepted by the corporation, and am satisfied that the works may be properly executed for the sum therein mentioned, viz., £31,300;" and he stated "the amount of the general estimate including the above sum-the expenses of houses and ground-the floodarches and roads of approach, &c. to be £47,457."

Upon receipt of this report, the Commissioners consented to make the required loan, but it being found that the Act limited the amount to be raised to £40,000, alterations in the structure were suggested by Mr. Lapidge, which received Mr. Telford's approval, and the works were commenced on the reduced scale.

The bridge is of Grecian architecture and consists of five elliptical arches; it is constructed chiefly of brick, with ashlar facing. The abutments are terminated by towers, and the structure is surmounted by a cornice and balustrade, with galleries projecting over the piers. The span of the centre arch is 60 feet, with a versed sine of 19 feet; the side arches are 56 feet and 52 feet span, and 18 feet 3 inches and 16 feet 6 inches rise, respectively. The highest flood rises 6 feet above the springing line, and the lowest summer level is about the same distance below it. The foundations are all laid upon the substratum of blue clay. The length of the bridge is 382 feet to the extremes of the abutments, and the width between the balustrades is 25 feet. The proportion of the piers to the span of the arches is about th. The roadway is formed at an inclination of 1 in 40.

The author then describes fully the construction of the abutments, piers, arches, and the superstructure. The work occupied about 2 years to the completion, the first stone having been laid on the 7th of November, 1825, and the bridge opened in form on the 17th of July, 1828.

On the completion, Mr. Telford again made a report to the Exchequer Bill Loan Commissioners in these terms:-"With Mr. Lapidge, I examined the whole of the bridge and approaches, and taking it for granted that the foundations of the piers and abutments, which are under water, and which I had no opportunity of inspecting while in progress, are according to the working draw. ings, all the other parts are found in a very perfect state, executed in a workman-like manner."

The bridge has in every respect answered the object for which it was intended, and it has justified the good opinion Mr. Telford originally formed of it.

During the fourteen years which have elapsed since its erection, it has required none other than the most trifling repairs, and the expectations of the trustees have been realized by the tolls having paid the allotted portion of the principal, up to the present time, as well as the interest of the money borrowed for its execution, and the cost of it did not exceed the amount of the estimate.

The communication was accompanied by seven remarkably well-executed drawings, showing accurately all the details of the construction, and the Paper contained all the quantities of materials in the work, together with Mr. Telford's reports upon it, with other documents of interest.

"Description of the Harbour of Port Talbot (Glamorganshire)." By Henry Robinson Palmer, V. P. Inst. C. E.

The harbour described in this communication is situated upon the outfall of the river Avon, on the eastern shore of Swansea Bay. The adjacent mountainous district terminates abruptly at about half a mile from the shore, in a tract of marshy land, for the most part composed of sand, with detached beds of clay and peat of various thickness, at about 10 feet below the surface.

The river, which, at its issue from its rocky channel, had been diverted from its course by accumulations of sand, nearly at right angles with its point of discharge into the sea, would appear at some period to have had a direct channel thither. It has been the object of the author, by whom the works were designed and executed, to restore this obvious course for the land water, and by means of embankments, to convert into a dock that portion of the old channel which extends through the marshes. A new channel has also been formed from the outfall to a convenient part of the dock, with a lock 45 feet in width for the passage of vessels.

As the works were undertaken by a few private individuals, every proper economy