allowed only a single half hour for refreshment, which is brought to them on the spot. The wages paid are high, as much as 40s. and 45s. per week, and hence the engineer is enabled to command the services of first-rate bricklayers. The men are not called upon to perform task work; all that is required is, that they keep steadily at work, and that the bricks be laid in a workmanlike manner. The cement furnished is of the very best qua lity, only about a barrel of fine sand being used to 100 barrels of cement. The concrete thus formed hardens very rapidly, and within two hours after any new work is completed, its solidity is put to a very severe test. The overseers go round with hammers of fourteen pounds weight, with which each separate brick is struck a hard below. If the cement yields so as to disclose the smallest fissure between the bricks, the workman is immediately called back to repair the defect, and is, besides, fined one shilling to the sick fund. If the brick shakes in its place on being struck, nothing but a special plea in excuse can save the workman from an immediate discharge. With every exertion, from its peculiar nature the work is unavoidably tedious and slow. It is considered a good piece of work when at the end of twenty-four hours the shield can be advanced nine inches. The shield contains thirty-six boxes, and the work is being simultaneously carried on in each, so that the pushing forward the shield can only take place when the work of the arch is perfected to the extent from the bases to the key-stone. It will sometimes happen that a whole day is occupied in the mere work of pushing forward the shield. The extent of archway perfected is above 620 feet, and what remains to be done is about 1,200 feet, but of this extent a large portion being beyond low water mark, and through a solid stratum of earth, can be carried forward without such extreme caution as at the present part of the work, through a loose sandy soil, and under the very centre of the bed of the stream, is indispensably necessary.-Morning Chronicle.

A New Light of the Age.-In the course of a recent lecture on the properties of caoutchouc, Dr. Birkbeck introduced to public notice a pair of can dles made of that material, at his own suggestion. After many unsuccessful attempts, they were at length fairly lighted; and it is only justice to the worthy Doctor to say, that ais invention is likely to prove of great importance, whenever it shall come to pass that candles which are very difficult to light, which burn badly and gutter immensely when they are lighted, and which pretty soon go out of their own accord, are considered a desideratum. Until then, those less expensive, but more appropriate articles-tallow and wax-are likely to remain in general use for the purposes of domestic illumination.-F. H.

Cheap Locomotion.-Such is the march of competition abroad, that (if we may put faith in coachproprietors' advertisements) the whole fare by dili gence from Boulogne to Paris is only nine shillings. If this were quite true, the journey from London to Paris throughout might be performed for no more than fourteen shillings, the fare per steamer to Boulogne being only five! The fact however is, we believe, that what with the regular fee of the French conducteur, and other extras, the trip can hardly be expected to cost much less than a sove reign, or fully three farthings a mile!-F. H.

A flint.-Mr. Alderman Wood, by his recent accession of fortune, under the will of his name. sake of Gloucester, enjoys a rare opportunity of immortalising his name. It is well known that the Alderman, some short time back, promulgated a plan for the general improvemant of London, anong other things, by throwing open Waterloo and Southwark Bridges toll-free to the public; erecting a new street from the Mansion House to Southwark Bridge; straightening the upper end of

Holborn, so as to affect a direct junction with Ox. ford-street; and executing divers other plans of, unques ionable utilify. And all this, and more, the Alderman calculated (it is not known by what elaborate process) might be done at an outlay of only 800,000l.! By a turn of Fortune's wheel, the projector of these mighty alterations has this sum at his own disposal; and how could he more glorious. ly display his civic patriotism than by carrying into effect his magnificent ideas for changing the whole aspect of the metropolis over which he twice presided as Lord Mayor? It is to be feared, how. ever, maugre his own estimate, that he would arrive at the bottom of his purse, some time before he had got to the end of his trifling undertaking.-F. H.

French Theory and English Practice.-It is not a little singular, that, while England is making so great a progress in the actual establish ent of Jailways, the French have published a much larger number of works on their mathematical theory; although this is, perhaps, not by any means the first instance in which the same state of things has occurred. A Colonel de Pambour has just added to the rather long list of publications by his cour trymen on the subject, a very elaborate book of calculations on railway theorems, in which he lays down his positions rather more dogmatically than his little experience (all apparently gained in Eng. land) seems to warrant. He has not, however, much to fear from bis English competitors in the line, the principal of whom are Mr. Macneil, of "canal navigation" celebrity, and-John Herapath, Esq.-F. H.

Truth stronger than Fiction.-It is a well-ascer. tained, but rather unaccountable fact, that, notwithstanding the amazing increase of late years in the manufacture of steel pens, there has not been the slightest falling off in the extent of the quill trade.-F. H.

Communications received from Mr. Tracey Dickson Mr. Barton A Country

Mr. Teacher.

Mr. Baddeley's satisfactory defence of Messrs. Mordan and Co. shall appear next week.

The communication referred to by P. P. has been received, and shall be attended to.

The Supplement to Vol. XXIV., containing Title, Contents, Index, &c., and embellished with a Portrait of Mr. Walter Hancock, C. E., is now published, price 6d, Also the Volume complete in boards, price 9s. 6d.

British and Foreign Patents taken out with economy and despatch; Specifications, Dis. claimers, and Amendments, prepared or revised : Caveats entered; and generally every Branch of Patent Business promptly transacted. Drawings of Machinery also executed by skilful assistants, on the shortest notice.

LONDON: Published by J. CUNNINGHAM, at the Mechanics Magazine Office, No. 6 Peterbo rough-court, between 135 and 136, Fleet-street. Agent for the American Edition. Mr. O. RICH, 12, Red Lion-square. Sold by G. W. M. REY. NOLDS, Proprie or of the French, English, and American Library, 55, Rue Neuve, Saint Augustin, Paris.

CUNNINGHAM and SALMON, Printers,
Fleet-street.

146

CURTIS'S SAFETY-BREAK FOR RAILWAY

CARRIAGES.

Sir, I forward a drawing of my safety-break as applied to the engines of the London and Greenwich Railway, shall feel much obliged by your publishing the same in your valuable miscellany for the public information. The leading features of this invention are its simplicity and effectiveness, producing a degree of resistance to the progress of the engine and train far greater than can be effected by any other brake at present in use; and, at the same time, no shock or jar is felt either by engine or train. These results are produced by a cycloidal cam placed behind the crank-wheels, which, when brought into contact with the rail by the lever 7, lifts the wheels off the rail, when they assume the position shown by the dotted line, thus throwing them out of gear; the whole weight of the engine resting upon the crankwheels are thus transferred to the cam (in the present instance, about seven tons), producing thus a degree of friction greater than can be obtained by any other force however applied. The lever l is only necessary to bring the cam into contact with the rail, as the momentum, of the engine turns the cam round until it reaches the stop e, when the distance lifted is about 1 inches, as shown by the dotted line; then the wheel is off the rail 1-8th of an inch clear, the difference being taken up by the recoil of the springs r, the engine and train at the top of their speed have been pulled up within about 40 yards, and without stopping the wheels; so that for pumping water into the boiler, taking up passengers, avoiding accidents on the line, the crank-axle breaking, &c., the engineer is supplied with an important auxiliary.

Too much praise cannot be conceded to the enlightened management directing the interests of this undertaking, for the promptness with which my suggestions were at once taken up, in order that a degree of security might be assured to the public,which will render accidents upon this railway in future almost impossible.

Description of the Engravings.

Fig. 1 is a side, and fig. 2 an end view; a, crank-wheels; b, fore-wheels; c, engine-frame; d, cycloidal cam; e, stopper; f, beam, connecting the two stan

HALE'S HYDRAULIC APPARATUS.

Sir,-A paragraph having appeared in a Morning Paper a few months since, eulogising the extraordinary ingenuity of a wonderful machine for producing motive power, which was patented, or about being patented, by a Mr. Hale, of Colchester. I naturally felt a desire, being curious in these matters, to become acquainted with the invention, which having accomplished, the result I will now briefly narrate.

The machine is composed of a horizontal cylinder closed at both ends, fluidtight; through the centre of these ends project the shaft of a drum working in stuffings, which drum fills the chamber of the external cylinder all to about one quarter of an inch all round the ends of the said drum, working fluid-tight against the ends of the external cylinder; on the upper side of the drum, and between it, and the external cylinder, there is a stop which is also fluid-tight, being kept to the surface of the revolving drum by springs for that purpose; and on each side of this stop, there is an aperture in the external cylinder for the admission and emission of water. The action is shortly this the chamberof one quarter of an inch in thickness, extending over the whole of the drum, excepting that part covered by the stop, is filled with water, which is termed a fluid band; this water, it is stated, is put in motion and caused to flow out through one of the apertures, whilst a supply is admitted by the other, either through the agency of a fall of water, a pump, or a fire, applied to one side of the external cylinder; and the power giving motion to the said drum, is also stated to be solely derived from the friction of the said fluid band passing round its external surface. It is unnecessary to offer any comment on this apparatus-but millwrights will, doubtless, immediately knock off the float-boards from all the water-wheels in the country as useless appendages! Yours, &c.

Oxford-street.

ALAN MACKENZIE,

Fig. 1 is a side view of the wheels, &c. of a railroad-carriage; and AA represent buffers fixed, as is, I believe, usual on the ends of the lower framework of the coach bodies. Fig. 2 is a plan of my improvement. B1 is a buffer, situate, as I propose, on the end of a frame of iron-work, CCCC, in line with the axletrees; DD are breaks fixed in this frame to press against the wheels when the buffer is struck; E E are sockets fixed to the axletree-blocks, or any where convenient, through which

the side rods of the iron frame acts; and FF are stops by which the carriage is drawn. Now it will be seen, that when the buffer B1 is struck, the breaks DD will close against the periphery of the wheels; and as all the carriages of a train are pressing upon each other, the application of the breaks would be instant and effective. B 2, at the hind end, is the drawing-buffer fixed firm to the carriage, independent of CCCC; and G G are the wheels of the carriage.

A

Fig. 3 is a theoretic view of the buffers as acted upon at different heights from the line of the axletrees. I will

suppose B in this figure about the usual height of the buffers above the axletrees; C I have placed at an extreme, to show

148

the disadvantage of deviating from the line of the axletrees, A; now I can conceive, that when the buffers at C come in contact, the hind wheels of one carriage, and the fore wheels of the other, might be lifted from the rails. The same principle and proportionate tendency would be found at B, the rebound tending to raise each end of the carriages so struck throughout the whole train; and if such is the case, the present method must tend to increase the shaking of the carriages as well as to retard them; hence the great lapse before they can be brought to a stand. Now by the arrangement of the buffers and breaks I propose, the check to the wheels would be much more effective, and, to the passengers, I think, more agreeable; the frame-work of the carriages would be also considerably relieved from the destructive effects which must result from the present method; and, lastly, as every wheel would have a break against its periphery, a whole train of carriages would be brought to a stand in a third the space of distance they possibly can be by the present method."

I think the method which I have described is worthy of a trial, but as I have not any knowledge of persons likely to introduce it, your Magazine may be the means of putting it into practice.

I remain most respectfully, Sir,
Your very obliged servant,
G. MILLICHAP.

85, Aston-street, Birmingham,
May 11, 1836.

MACKINTOSH'S ELECTRICAL THEORY OF THE UNIVERSE.

"If the voice of the scientific world should pronounce it visionary and absurd, no one will smile with more complacency than the author himself."-Vide Introduction.

Sir,-As in my motto, so thought Whiston when he dispatched the comets, in his whimsical reveries, alternately from the hot region of the sun into the dark and chilled regions of far-off-space, carrying with them the perplexed spirits of the lost:-he "smiled" with equal "complacency" upon his own ingeniousness, and the verdict of the "world." So also smiled Dante at his purgatorial theorizing, and his visions of Limbo. So

Some years ago, when I was an infant (I am yet but a very youth) in such matters, I, like Mr. Mackintosh, conceived a vast notion of the powers of electricity. It was an all-efficient agent, invisible-delightful from its very mysteriousness. It was possessed of every quality that man could conceive to exist. It had the power of attracting, of repulsing, of compounding, and decomposing of creating and exterminating; was the origin of light, of heat, of magnetism; had the first principle of life and motion, universally. It gave birth to vegetation; was the parent of all progression and of all changes, either in the inorganic or the organic world: it was perchance, the very essence of matter itself, as well as the author of its varied changes, and its varied forms. It sucked up the juices of the earth into heaven in peace, and threw them back in wrath, with all the havoc of angry and contending elements. It was alike the creator of the earthquake, the volcano, the tempest-or the fall of the gentlest shower, and the budding of the prettiest leaf. As it willed, it peppered the earth with hail, or sprinkled it with refreshing dew. It was procreative of all meteors-of falling stars; the aurora of phosphorescence-of all growth and all decay-of all rest and of all motion. It was omnipotent, omnipresent in things physical; the parent of all good and of all ill: in short, to express myself with precision, it was the wondorous originator of " both the larger operations exhibited in the motions of the planets, and the minuter processes of vegetation, oxidation, and vitrification !" All this, and much more, alas! was put into my head by a certain learned work, called a Key to the Knowledge of Nature," written about twelve years ago by a Rev. Mr. Taylor, of Hart, in the county of Durham. It was a philosophical excrescence, and was touched with