concluded; but as Mr. Borrie, by his remark (irrelevant to the subject), "that from what I have had to do with hydraulic presses, I know that it requires some practice to make them," permit me to observe in reply to the insinuation conveyed by these words, that, such as my knowledge is of hydraulic presses, Mr. Borrie has been glad enough to avail himself of it in the erection of certain presses constructed under his superintendence (through my introduction) —that though I do occasionally, like other engineers, supply hydraulic pumps as well as presses, I have never advertised such pumps as patent when I had no patent for them-and that neither have I ever applied for any patent for an hydraulic engine which I was afterwards obliged to abandon. Anon, the matters to which I allude shall be more fully explained through another and more proper channel than the pages of your valuable Magazine.

I remain, Mr. Editor,
Your obliged servant,

H. C.

59, King William-street, 11th June, 1844.

NEW STEAMERS.

A new steamer, called the Princess Mary, has been just built for the South Eastern Railway Company, by Messrs. Ditchburn and Mare, and fitted with annular cylinder engines, on the patent plan of Mr. Joseph Maudslay, constructed by the firm of Messrs. Maudslay, Sons, and Field. On Tuesday last she made a trial trip, which resulted in what may be considered as a trial of speed between her and the Prince of Wales and Isle of Thanet, reputed to be two of the fastest vessels belonging to the port of London.

The Isle of Thanet left Blackwall at 10h. 37 min., the Prince of Wales at 10h. 41 min., and the Princess Mary at 10h. 44 min. All three vessels then proceeded in this order. At Gravesend the Prince stopped for one minute to let a passenger out; but after getting under way again she was still considerably ahead. The Princess being built expressly for a sea boat, and to take the ground in Boulogne and Folkestone harbours, draws 18 inches more water than either of her opponents, and was obliged, therefore, between Blackwall and Gravesend, to keep out in the stream, whilst the others

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kept close in shore, in the slack of the tide, which was running up very strong. After passing Gravesend, it was soon seen that neither of the competing vessels could hold with the Princess. She then began to gain on the Prince of Wales, the latter at the same time coming up rapidly with the Isle of Thanet. At the Nore Light, the three vessels were still in the order of starting, but quite close to each other, and in a very short time (at 2 h. 7 min.) they were all three abreast. In ten minutes more the Princess was far enough ahead to cut right across her two rivals, and sweep round both. None of the vessels had sail set, the wind being right ahead, and the constant and copious escape of steam from the respective waste steam heads showed that all three were doing their best to win. The Prince of Wales, hitherto believed to be the fastest, and the Isle of Thanet, said to be the fastest boat afloat, must now yield the palm to the Princess Mary.

Between Blackwall and Woolwich the Mary came up with another crack vessel, the Waterman, No. 11, and passed her easily. When off Sheerness, going down, she met the Fawn, which has also a high reputation for speed, going up with a strong tide in her favour; and, after proceeding against wind and tide to the east end of the Isle of Sheppy, to the point where she went round the Prince and Thanet, she overtook on her return the Fawn in Northfleet Hope, passed her, and arrived at Blackwall in time to land her party, and be moored, before the Fawn made her appearance.

The Princess Mary is 143 feet long, and 20 feet broad; her draft of water is 6 ft. 3 in. The engines are of the collective power of 120 horses; the boilers tubular; and the wheels of the same feathering description as those fitted to the Princess Alice, which were described in the Mechanics' Magazine, Sept. 16, 1843.

It may be right to observe that the Princess Mary had on board on this occasion, in addition to a numerous party of visitors, a great number of workmen, engaged in finishing the cabin fittings, so that the competing

vessels cannot be considered as having laboured under any disadvantage from having passengers on board; certainly neither of them carried more than the Princess.

Her

The Gipsy Queen, said to be the largest iron steamer ever built on the river Thames, has been also launched this week from a new yard established by the Messrs. Samuda, at Orchard-place, Blackwall. Her length, from the figure-head to the taffrail is 197 feet 6 inches, and between perpendiculars 175 feet; her breadth between the paddle-boxes is 24 feet. Her burden is 496 tons. engines, which are on a new plan, patented by Messrs. Samuda, are of 240 horses power. They are to be placed fore and aft, and not, as the engines of most steam vessels are, on each side of the keel; the cylinders will be directly over the keel, and being in one frame-work, it is expected that all strain will be avoided on any part of the vessel; their total weight, including boilers, &c., which are tubular, water and paddle-wheels, is only 87 tons. The form of the steamer is well calculated for speed. She has a considerable rise of floor, and for a sea-going vessel (she is built for the Waterford Steam-packet Company, and will travel between London and Waterford) her lines are remarkably fine.

MECHANICAL CURE OF CATARACT.

Sir,-Your correspondent, Mr. George Cumberland, Sen., may have made optics a branch of study, but he has evidently but little experimental knowledge of the structure of the eye, or he would have been aware that the crystalline humour is not of a consistency which admits of any part of it being withdrawn through the tube he proposes to use. There is a small quantity of a pellucid fluid between the lens and the delicate capsule in which it is enclosed, but the disease called "Cataract" is generally admitted to consist of an opacity of the crystalline itself, the least dense portion of which (for your correspondent's information) is much too thick to be drawn off through a narrow tube. In cases, if such there be, where the opacity any resides in the liquor morgagni, it might be possible to withdraw that fluid in the way your correspondent suggests; but with what purer fluid" he would replace it, or whether he supposes any fresh secretion would take place, he has not ventured to state.

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I do not wish to depreciate your correspondent's suggestion, but I may perhaps be allowed to remind him that he will fail to share the laurel with the "carpenter of St.

Thomas's hospital," unless he become more practically acquainted with the subjects on which he ventures to address the public. I am, Sir, Your obedient servant,

T. C. MAYHEW.

Waltham Abbey, June 12, 1844.

SOCIETY OF ARTS.

The following is a list of the premiums awarded in the Mechanical Arts at the last annual distribution of this Society:

To Mr. P. Lucas, 19, Hyde-park Gardens, for a self-adjusting step-ladder for wharfs, the silver medal.

To A. E. Brae, Esq., Leeds, for his improved chimes for house clocks, the silver medal.

To Mr. R. Brown, Ewell, Surrey, for his improved method of making ornamentál grooved ridge tiles, the silver medal.

To Mr. Cornelius Varley, 1, Charles-street, Clarendon-square, for his improved lever microscope, the gold Isis medal.

To Commander H. Downes, R.N., Ladbroke-terrace, Notting-hill, for an annular scupper mouth for ships' decks, the silver medal.

To Mr. Bowery, Bermondsey, for an improved clamp for joiners, the silver medal.

To Mr. S. Franklin, Fleet-lane, for an improved plumbers' force, 31.

To Mr. S. Nicholls, 19, Harrold's-row, Green-bank, St. George's East, for an improved cramp for carpenters, the silver Isis medal.

To Mr. W. F. Warner, 11, Spann's-buildings, St. Pancras, for his improved ruling machine for engravers, the gold Isis medal.

To W. F. L. Gompertz, Esq., 236, Maida Vale, Edgeware-road, for his method of anatomical modelling, the silver medal.

To Mr. J. Franklin, 91, Goswell-road, for his expanding centre-bit, the silver Isis medal and 27.

To Mr. J. Common, Denwick, Northumberland, for his mode of putting new roots to old trees, &c., the silver medal.

stances, to a limited extent, accomplished, but whose plans will never be generally adopted. Mr. C. W. Williams's patent acts well, apparently, when applied to the great furnaces in manufactories; it does away with the visible smoke, alias the unburnt coal, alias the carbon, but it converts it, by its union with the oxygen of the atmosphere, into carbonic acid gas, which, in my opinion, is quite as injurious to the constitution of those who breathe it, as the mere dust or soot, that is, the visible smoke, would be. The only question therefore is, whether or not, to obtain sufficient heat, it is necessary, by increase of fuel, to generate as much carbonic acid gas in addition to the unburnt coal, or visible smoke, without the consuming apparatus as would be generated where the visible smoke is consumed? For even supposing that by its mixture with the atmosphere, the carbonic acid gas is so much diluted as to be rendered innoxious, the benefit promised can never be appreciated, in this neighbourhood at least, either on the score of health or cleanliness, there being for one furnace where the conditions can be complied with, 30 coke fires, and from 200 to 300 fires in open grates where they cannot. Yet its accomplishment (the means of getting rid of the nuisance) is looked upon as a very grave matter, for even Parliament deems it worth its interference, and many talented, respectable, and wise men are engaged in devising means to effect the object, or in endeavouring to carry out the means already known.

"What is the origin of coal? It is generally supposed to be vegetable. How is this opinion supported? By finding the remains of vegetable substances only partly converted, and by a comparison of the products of coal, and of vegetables when subjected to chemical analysis. Coal contains carbon, hydrogen, sulphur, ammonia, lime, alkali, tar, &c., and so do vegetables-'

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"Have you heard anything from the landlady concerning the candle-house you want to build ?" asked my wife, interrupting the flow of my ideas. No, only that a gentleman is gone over to Belgium, who will see her there, and return with an answer in about ten days," said I, and resumed my meditations thus.-"How shall I arrange the building most advantageously? I will have the walls so-the windows here-the door there the roof to slope. I don't know how the roof should slope to be most cool. Have a flat iron roof, and cover it with soil for a garden! Yes, enclose the garden, and cover it with glass for a greenhouse, said the spirit within me; have a chimney a-top with a strong draft, to draw the smoke from the furnace below through the soil. You may do that if you have an iron ceiling, iron raf

ters, and perforated iron plates above to carry the soil. The soil will absorb the carbonic acid gas, the water, sulphur, ammonia, and other matters generated by combustion, and it will arrest the particles of soot, and so the fire will manure the soil, feed the plants, water them, and heat them all at one and the same time. As the plants deprive the soil of these alimentary ingredients, they will be replaced continually; for while the fire is burning, atmospheric air, uncombined with the products of combustion, will pass up the chimney, circulate under and through the pores of the soil, in sufficient quantity to furnish oxygen and nitrogen to perform their functions in the vegetative economy. A portion of ashes may occasionally be carried up and mixed with the earth. Yes, make a garden, plant your seeds and shrubs therein, give them smoke to eat, smoke to drink, and smoke for clothing to keep them warm. You will then be able to consume the smoke, and fatten upon it. Bravo! Excellent idea! I will fill my pipe again, and examine the soundness of it; for if it be as good in practice as it now seems in theory, in course of time all the house-tops may be converted into gardens, and that destruction, to all agricultural purposes, of the earth's surface, consequent on the building of large manufactories, towns and cities, will be half prevented; diseases malignant as various, caused by the influence of smoke, will vanish from among us; that which is now a curse will be a blessing; smoke will no longer be a nuisance."

Such, Mr. Editor, were my speculations; if you think them worth insertion in the Mechanics' Magazine, they are at your service. I should be very glad to see the subject taken up by some of your more talented correspondents; it is by no means so extravagant as at first sight may appear. I have asked myself and others why some vegetables do not thrive in the neighbourhood of large towns? The answer is, The smoke is injurious. To the question, How does the smoke act upon them all? all the answer I can obtain is, that it deposits itself on the leaves, stops the pores, and obstructs the perspiration. But this would not be the case if it were applied to the roots only; soot is well known to be an excellent manure; so is the lime impregnated with ammonia, sulphur, &c. from the gas works; carbonic acid gas is not injurious; on the contrary, its presence is necessary to the leaves and roots also; and I have never heard that seeds would not germinate as well in towns and their vicinities as in the open country.

I am, with much respect, yours, E. MATTHEWS. Wolverhampton, May 17, 1834.

DRAYTON'S NEW MODE OF SILVERING

GLASS.

According to the ordinary mode of silvering glass, a surface of tinfoil is first bathed with mercury, and then flooded with it. On this tinfoil the plate of glass, having been previously cleansed with extreme care, is so floated as to exclude all dust or dirt; this is accomplished by the intervention of in. of mercury (afterwards pressed out by heavy weights) between the reflecting surface of the amalgam of the mercury and the glass; and when the glass and amalgam are closely brought together by the exclusion of the intervening fluid metal, the operation is completed. By the invention of Mr. Drayton, the mercury and tin are entirely dispensed with. The mirror is, for the first time, literally speaking, silvered, inasmuch as silver is precipitated on it from its nitrate (lunar caustic) in the form of a brilliant lamina. The process is this: on a plate of glass, surrounded with an edge of putty, is poured a solution of nitrate of silver in water and spirit, mixed with ammonia and the oils of cassia and of cloves. These oils precipitate the metal in somewhat the same manner as vegetable fibre does in the case of marking ink-the quantity of oil influencing the rapidity of the precipitation.

NOTES AND NOTICES.

Heath's Cast-Steel.-Before the introduction of Mr. Heath's process (which consists in adding carburet of manganese to the melting pot) all steel which was to be worked into a fine edge was made of iron procured from one mine only, that of Dannemora, in Sweden. It was consigned to a house at Hull, at a cost of 381. per ton, in quantities not exceeding 1100 tons per annum, and marked L in a hoop. The price limited its use; but by means of this patent the inferior sorts of iron, as those at 157. per ton, may be made available. Steel is made by it which has all the beauty of cast-steel, and all the welding advantages of shear-steel. In the manufacture of table-knives its advantages have been manifest. Formerly these articles were made by tilting or rolling square bars of steel into the necessary shape, thus making blade, shoulder, and tang in one piece; so difficult was this process, that two wasters in a dozen knives were always thrown aside, and workmen's wages were double. Now, the steel blade, made by this process, is welded with the iron tang.-Mining Journal.

Air Propelled Locomotive.-The following description of a new locomotive has been addressed by Mr. J. B. Cotter to the Railway Chronicle:-The writer describes the machine as propelled by condensed air. "I cannot express in sufficiently strong terms my gratification and astonishment when I was placed by the inventor on his carriage, which he immediately put in motion, and gradually increased its speed until it attained a rate of more than thirty miles an hour. This engine was brought out last March, and the trial I witnessed took place on the left bank of the Versailles Railroad. During its progress 1 examined the working of the machinery with the greatest attention, and

almost every part of it appeared admirably adapted to its purposes. The only fault I perceived was in the workmanship of the pumps and pistons, which I must admit are not of the first order, a defect that would at once be remedied in this country. M. Andrand's first experiments were made in 1840, and he has since followed them up with the greatest assiduity and success. The engine runs on the rails with perfect ease, without noise, fire, smoke, or danger. The recipient is a beautiful piece of workmanship. The air with which it is charged is conveyed by copper pipes to the regulator, then to the dilator, and from it to the cylinders. To put the carriage in motion the stop-cock is turned; to cause a reverse movement you have only to press on a button, which changes the action of the side valves, and the engine is backed."

Great Western Steam-Ship.-A curious dispute has arisen between the Peninsular Company and the Great Western Company. The former, it appears, purchased the ship Great Western for 32,000l., the owners undertaking to do whatever the Admiralty surveyors might deem necessary to qualify the vessel for the mail service. A considerable delay taking place in completing a set of new boilers on the tubular principle, some time was requested and granted. All being ready, a trial was had down the Severn, under the inspection of the Admiralty surveyor, who found all right with the exception of the supply of steam, on which he declined to pass the survey. Some alterations having been made in the boilers, the vessel was announced as ready for a second trial, at the request of the owners. A delay of a few days occurring in sending the Admiralty surveyor down, the owners, with Captain Claxton, the manager, took on themselves to withhold the vessel, thus virtually cancelling the contract, and, without notice to the Peninsular Company, advertised her departure for New York. The Peninsular Company feeling that whatever the delay might have been, it was not to be laid to their account, but to that of the Admiralty, and not being disposed to yield to this summary extinguishment of what was considered a desirable purchase, an application was made to the Court of Chancery to prohibit the vessel being sent to sea, and immediately granted.-Liverpool Albion.-The injunction has been since dissolved.-ED. M.-M.

Steamers in Siberia.-A letter from St. Petersburgh, of May 26, states that the Government has just granted to M. Theodore Pasnilau, a merchant of Tobolsk, an authorisation to establish steamboats in Siberia, on the Lake of Baikal, and the rivers Ab, Tobol, Irtish, Jenissei, and Lena, on condition that two boats shall commence plying before the end of the year. The building of these vessels, to be called the Emperor Nicholas and the Czarewitch, is now going on; they will be the first steamers introduced into Siberia.-Mining Journal.

The Artesian Well of Grenelle.-The volume of water supplied by the Artesian well of Grenelle was measured a few days ago, and found to have lost nothing of its force or quantity. The source furnishes 2,000,000 quarts of water per twenty-four hours, which is more than sufficient for the consumption of the quarter of the Pantheon, where immense reservoirs have been constructed to receive it. The water is as limpid as filtered Seine water, and has continued clear since tubes have been inserted in the aperture.

INTENDING PATENTEES may be supplied gratis with Instructions, by application (post paid) to Messrs. Robertson and Co., 166, Fleet-street, by whom is kept the only COMPLETE REGISTRY OF PATENTS EXTANT from 1617 to the present time.