employed and situated, who have used intoxicating drinks as beverages, and our unprejudiced opinion has been and is, that the abstainers were stronger and healthier men.-ED. E M.] E. [2543.)-THE NICOL PRISM-"The Nicol's prisma. which our readers will have seen mentioned so often in the recent papers of Professor Tyndall, are expensive to obtain of any size. They are made of a crystal of calespar. cut across diagonally, the two sections being afterwards joined together by means of Canada balsam. It has recently been discovered that a prism, possessing the sams optical properties, may be made by eonstructing a vessel of glass, inserting a thin plate of calc-apar across the diagonal, the vessel being filled up with bisulphide of carbon. If this be so, Nicol's prisms of considerable size may be made cheaply, since blocks of cale-spar of conFebruary 26, 1869. I eat the above from a scientifle siderable size are often met with."-Mechanic's Magazine. periodical. Has any subscriber met with it, and, if so, I should be glad to obtain further details ?-CARTHUSIAN. [2544.]-HEATING WATER IN BATHS-L there not a patent apparatus to be placed in a bath to heat it in a short time?-A. M. M. prising. Can any of your readers give me any information as to the durability of the india-rubber wheel tires? I have seen on hand-trucks at railway stations similar tires. How do they wear? I should be afraid the rough [2512.]-SODA CRYSTALS.-Thanks for G. stoned roads would destroy the tire of the steamer. Also Davis's able article in No. 261 of your publication, but although the tires doubtless will expand under the pres sure of the steamer, still the weight must be there, and not having any drying or heating apparatus, I must abandon the idea of commencing the manufacture, how can they be prevented sinking on soft land?-AGRIand having two pans, both idle, one to contain 120 CULTURE. gallons, and the other about 80, I should like to know [2531.]-BRAZING CAST IRON-The impression for how to manufacture an article of simple process, and April 8th contains an answer to my query from "Blue marketable, to keep them going these bad times. Being Ruin;" my best thanks to the correspondent for his no chemist myself, probably G. E. D. would kindly kindness. The method of laying the work in moulding suggest something.-SODA CRYSTALS. sand will not suit my purpose, and pouring melted iron [2513.]-TAR DISTILLING.-TO "FEU FOL-over the joint is not what I should term "brazing." I will LET.-Will "Fen Follet" be so kind as to describe define more particularly the information I seek. I very to me the process of tar distilling; how long it is frequently have to repair important bright parts of The boiled before the pitch is run off; how to separate the machinery, cast iron (small pieces generally). articles when the pitch is run off, such as naphtha, defects are caused by friction. I file a slot in the cast oil, benzole, carbolic acid, ammonia, crude anthra- iron, and fit a piece of wrought iron in its place to comcene, &c., or where can I procure a book that will tell pensate for wear. My difficulty is this: I cannot get the what I wish to know; the price, and where to be had? spelter to unite the cast and the wrought iron-it has an -T. BROWN. affinity for the wrought iron, but will not take on the cast iron. It can be accomplished I am certain, as I [2514.]-SPICE MANUFACTURING.-Would any brother reader tell me where I can get the informa-have seen specimens of cast-iron neatly mended by tion how to make spice, or where I can get a book to brazing pieces of wrought iron to compensate for wear. tell me; also the means to colour it, price of book, For the information of St. George, I can assert that the process of Mr. Armitage, of Kirkstall, for case-hardening, is not new. I have seen prussiate of potass used in the way described twenty years since. I always use prussiate of potass for hardening my work (wrought iron), if there is much friction, especially bolts and pins.-RECIPROCITY. and where to be had ?-T. BROWN. [2515.]-BOILER-A few days ago I was told that if a boiler, the first time it is used is made to get up steam quickly, it will ever afterwards be easy to get up steam. If, on the other hand, the boiler is heated slowly on first using it, a difficulty will always be experienced in generating steam. Is there any truth in this statement, and if so, what is the reason?-W. H. THORPE. [2516.]-EXPLOSIVE COMPOUND.-Are there any two liquids, inexplosive in themselves, which will, when mixed together, explode directly, or become cap able of being exploded; if so, what are they? In what proportion should they be mixed?-E. KENNEDY. [2517.]-ELECTRIC ENGINE.-Is there such a thing as an engine worked by electricity of one horse power? What is its total size and weight? What the cost, and where could it be bought ?-E. KENNEDY. [2518.]-GAUGE FOR A KITCHEN BOILER. -Would it not be a useful and comparatively inexpensive thing to affix to all common kitchen boilers a small water gauge? It might be secured from fracture by being loosely cased in the manner of spirit levels, and its action having been once explained to the kitchen servants, I feel sure that many a boiler would be saved from cracking and uselessness. Is there any objection to this idea beyond that of cost ?-A. C. G. [2519]-VULCANISING INDIA RUBBER.-Will one of your readers kindly inform me how to vulcanise india rubber? Can the apparatus used by dentists for hardening vulcanite (which I possess) be used for the purpose, and how ?-GUMMY. [2545]-EMIGRATION TO NEW ZEALAND.-Will "Josh." "H. Coggins," or any reader, favour me with a few hints, as I am going to emigrate to New Zealand? I have saved £48, and I am a single young man, a Jack of many trades, but master of none.-W. STONE. [2546.]-BATTERN-MAKING.-Will anyone be kind enough to tell me if there is any work published on "Pattern-making? If so, the price, and where to be had.GALLOWAY. [2532.]-LEAD FOR "RELWOT'S" ENGINE.-(To [2520]-WATERPROOFING PAPER.-Can any of my brother readers inform me of the best method of making paper waterproof?-A. SPEIGHT. [2521] CURIOUS AFFECTION OF THE TEETH. -Can any reader tell me the cause of the following strange affection of my teeth? Some time back a rough deposit began to be deposited on my teeth, till it had accumulated to the thickness of a sixpence, gradually covering the tooth and eating away the gum all round until the tooth fell out without pain, and scarcely any loss of blood. Nine of my teeth have fallen out in this manner. A druggist whom I consulted told me it was canker, and a doctor said it was scurvy; neither of their remedies did me any good. When the limelike coating, with which the tooth is covered, is scraped away, the tooth beneath appears to be as perfect as ever. Will some one help me, and prevent the loss of the rest of my teeth?-SUBSCRIBER FROM THE FIRST. nut?-MINNEHAHA. [2547.]-PRINTING NAMES ON PLANS.-Will some brother reader be kind enough to inform me of a method of printing the names of fields, trees, &c., on plans of estates? I have lately used a printer's pallet and type, but with not much success.-LAND SURVEYOR [2534.J-SOLUTION WANTED.-The straight lines [2523.)-RUST IN WATER.-BREWING.-Will any of your numerous readers inform me the way to construct a cheap filter, which will separate rust from water; also has water, impregnated with rust, any injurious effect on the brewing of ale, especially as to flavouring it in any way; also the best and cheapest form of attemperator for checking the rise of heat in a fermenting square, dimensions 6ft. square, and 5ft. deep, usual length of brewing 25 barrels, temperature of water direct from the well 538 ?-CROMWELL. [2524]-LONGITUDE.-Will some reader tell me the difference of time between Belfast and Glasgow? -SCIRE VOLO. [2548] GILDING BATTERY.-Will any reader lend me a little assistance? I have a gildingbattery, Daniell's two cells, and cannot get it to work, as I am in error somewhere. The copper cells are about of an inch larger in diameter than the porous pots, which are 24 inches across. half-way up, and banked round at the top on the copper I have put sulphate of copper round outside of pot nearly rim, that keeps the pot upright, and filled op with water inside the pot to immerse the poles. I put oil of vitriol and water, one part vitriol and two parts water; but I could get no action on the poles. The wires-one from each-were ordinary stout copper, and I led them into some strong cyanide of potassium dissolved in water, and kept it over a gas-burner, putting a piece of 22-carat gold but I could make nothing of it. If any reader will set on one wire, and the article I wished to gild on the other. me right I shall feel extremely obliged.-ONE IN A FOG. Will Mr. H. W. Henfrey, or any of your readers, kindly [2525.]-CONTENTS OF PART OF SPHERE.Will some brother reader inform me how to find the content of part of a sphere greater or less than a the two plane surfaces at right angles?-ANTHONY. [2526.]-SUBMARINE LAMP.-I have made several fruitless efforts to make a lamp some 3in. diameter by 5 or 6 long, that will burn under water. Could you get me any information on the subject? I want it to burn when submerged some 4 to 6ft. in fresh or salt water. I have tried a candle in a lamp fed with air by india-rubber tubing, but it went out speedily. Information as to the construc tion of such a lamp would oblige.-W. A. HACKETT. [2586.]-ELECTRO-PLATING.-About twelve months ago I plated some tea-spoons, and they have a most disagreeable taste and smell when used for eggs, custard puddings, or plain boiled rice; I should be glad if some correspondent would kindly tell me the cause of this, and how it can be remedied.-A. R. [2537.]-WRITING TELEGRAPH.-Is Meyer's telegraph, consisting of two cylinders having an isochronical motion, a new invention ?-THOMAS. steel requires any preparation. If he will do so, he will very greatly oblige.-B. S. BURDEN. [2551.]-THE SPECTROSCOPE.-It has often occurred to me that some of our numerous brethren who practise with the spectroscope might, if they were asked. give us a paper or two concerning the practical working of the instrument. And if any one has made one of these instruments at a cheaper rate than paid for at an optician's (of course it is not the elaborate construction of the instrument but its efficient working when completed, perhaps he will give a description and probable cost of making the same. It any will do this I think he will receive the hearty thanks of many others besides myself. -A. J. JARMAN. [2538.]-INCRUSTATION ON POROUS CELLS.- [2540]-SMOKE ON WALLS.-I beg to submit the following question to the investigation of the scientific correspondents of our E. M. I observe that, in a kitchen or any other place of which the walls have been whitewashed, the smoke is deposited on the whole surface of the walls and ceiling, with exception of the edges or intersections. What may be the reason of this? Are there at those places currents which prevent the deposition, or is this phenomenon of the same order as the one that is observed with the iodine vapours in presence of a relief or of an engraving?-V. M. BEECHY. 2541.]-GALVANIC BATTERIES.I have been studying for some time past the problem how to make I tried many substances, and heard afterwards that an economical, constant, energetic, and lasting battery. several had been already tried and had failed; might it not prove very useful to many readers to have a list of all the substances proposed or tried, with the results? This would spare much time and prevent waste: many readers could bring their brick to the building besides learned "Sigma," who has promised, I believe, to give us a note "On Batteries."-V. M. BEECHY. [2527.J-ROSCOE'S LUBRICATOR.-Will some one of our practical correspondents kindly inform me whether Roscoe's patent lubricator lubricates the slide-valves of a locomotive engine when the engine is running with steam on, or only when the steam is shut off?-G. W. R. [2528.]-MUSICAL BOX-Would some kind and competent reader give a full description of a musical-box? I would be particularly obliged if some one would tell me how the uniform motion is obtained.-OMAR. [2529.]-INVENTOR OF THE MANGANESE BATTERY.-Will Mr. W. H. Stone," who gave a description [2542.]--PHOTOS. OF AUSTRALIAN SCENERY. of the manganese battery, state the name of the inventor-Would any kind brother reader tell me where I can of the same?-X. Y. Z. procure photographs of an Eucalypt tree, and of an [2530]-THOMSON'S ROAD STEAMER.-The ac- Australian acacia, or of an Australian landscape with coint in your paper of Thomson's road steamer is sur-those trees?-BERNARDIN, dents inform me what the copper coin is, a copy of which I enclose-FLINT. [2558]-SUN DIAL.-I have made a sundial, horizontal, and want to have the meridian line correct. Will some of our brother correspondents be kind enough to tell me the exact declination of the needle for the present time, as I can have access to a compass? I have asked three persons who used the compass in mines, and they all said it pointed north: not one of them knew there was any de elination at all, and one would not believe it until he asked an optic an, who informed him that it was so.-A. H. Z. [2550.-ANTIQUE.-I have in my possession a cornelian ring with an antique head cut on the stone. The inside of the cutting is beautifully polished, and I lave been told that the secret of polishing the engraving is lost; is this so? Perhaps some of your readers, "gem collectors," would kindly inform me, or give me any hint whereby I could judge if the cutting is an setique or a modern one?-VIVIS SPERANDUM. [2560.]-MICROSCOPIC.-I should feel under obligation to your microscopical readers who would inform me what is the view of first-class observers as to the lenses in the compound eyes of insects-the dragon-fly for instance. Do they consider the hexaronal piece is all lens, or that a minuter circular lens is fixed in this hexagonal setting?-F. F. [2561.]-BOOKS.-' should be glad in reading of the sizes of books to be able to know exactly what is meant, as I am neither in the trade nor otherwise able to learn. My requirements are the sizes in inches of the page of all from imperial 4to to 32mo?-F. F. [2562.]-HARMONIUM.-I intend to make a harmonium pan according to " Eleve's" instructions to a "Country Amateur, No. 245, page 279, but there are one or two things I should like to know before I begin, that is, the size of the reed hibs in the veneer at top and bottom, and also if the veneer is the very thin kind that is sold in the shops? I should think that the reed veneer at least would require some thickness in order that the reeds may be screwed to it. Perhaps "Eleve" would be so kind as to enlighten me on the subject. I would also take it very kindly if some of your harmonium correspondents would show me the way how two or more rows of reeds are placed in a harmonium-how the channels are connected with one another? I may mention that I have an apparatus under the keys of my harmonium by means of which a tune in any key may be played on the white keys alone, except where an accident occurs. when the black is used. This is done by merely shifting a small knob in front of the key-board, according to the key to be played upon. Perhaps some of your musical correspondents would say whether it is an improvement or not. It must be an advantage to those who would like to play a common tune in as easy a manner as possible, who are not very well versed in the mysteries of sharps or flats, as by this a tune in four or five sharps or flats is as easy to play as one in the key of C.-VALVE. [256]-SMALL COPPER COIN.-Obv., a shield of arms, "A Halfe Penny, 1668;" rev., two men holding a piece of cloth, For the Poor of Dover." Why was it struck, and by whom?-OLD COIN. 2564.1-LEADEN COIN SIZE OF A HALFPENNY.-On one side a rude "W," on the other a device probably intended for an anchor. Should like information about it ?-OLD COIN. 255-HERBAL OF THE BIBLE.-Will any reader of the MECHANIC tell me of a book treating of the plants named in the Bible?-IXION. [2566]-TOOTH POWDER.-Will some brother subscriber kindly give a good recipe for a tooth powder?-INQUIRER. (2507.)-CHIMING CLOCK.-I have a chiming clock, the weights of which are so heavy (281b. each) that whenever a line breaks, the weight, falling from a height of perhaps 5ft, has an unpleasant way of breaking through the floor. Can any reader suggest any means by which this may be prevented? I have thought of a bag filled with hay, or something similar, to be placed at the bottom of the clock-case, and so act as a buffer. In that case, what wonld be the best material to stuff the bag with ?-TooDLES. [2568]-HARD WATER.-I find the Thames water is soft, but that the same water when it has passed through the water works gets hard. How has this change been brought about? Can anyone explain the mystery ?-STEADY HAND. [2560.]-BAT HANDLES.-Can any of my brother subscribers tell me how to prepare and glue up bat handles?-95, VOL. 4. [2579.]-MALLET.- The enclosed drawing is a THE SIZE OF ATOMS.-Sir William Thomson, who contributes an important paper on the "Size of Atoms" to last week's Nature, thus sums up: The four lines of argument which I have indicated lead all to substantially the same estimate of the dimensions of molecular structure. Jointly they establish, with what we cannot but regard as a very high degree of probability, the conclusion that in any ordinary liquid, trausparent solid, or seemingly opaque-solid, the mean distance between the centres of contiguous molecules is less than the hundred-millionth, and greater than the two thousand-millionth, of a centimetre. To form some conception of the degree of coarse grainedness indicated by this conclusion, imagine a raindrop, or a globe of glass as big as a pea, to be magnified up to the size of the earth, each constituent molecule to be magnifiied in the same proportion. The magnified structure would be coarser grained than a heap of small shot, but probability less coarse grained than a heap of cricket-balls." THE COLOURING MATTER OF BLOOD.-Herr iron. THE LATEST EXCAVATIONS IN POMPEII, &c.-The Giornale di Napoli, of March 26, states that on the occasion of a royal visit to Pompeii on the preeeding day, some excavations were made in some houses situated on the right of the Via Stabiana, and a variety of treasures were found, viz.: a large number of objects in terra cotta, iron, and bronze, a beautifully-chiselled silver cup, a very rare glass oil lamp, a still rarer and perhaps unique object, cousisting of a small terra cotta cup with a metallic cup inside containing a night-lamp like those in modern use, a large gladiator's sword, with the metallic portions of the scabbard; many copper and silver coins of the time of Vespasian, and an amphora full of small onions near the skeleton of a woman. The skeleton of a man was also discovered, holding a pickaxe in one hand, au iron bar in the other, and with many bronze objects scattered at his feet, near a wall which had been partially broken through. [2570.]-GLAZIERS' DIAMOND.-Will any sub- W. H., Cinderford. [2572]-LARGE FILTER-Would some person of experience advise me about a filter? I require about 5000 gallons of clean water every 24 hours. My water carries a considerable quantity of sand, insects, vegetable matter, &c., and is often during the day quite turbid. Could I construct a filter, using a large treacle or other cask in the manner described on page 578, Vol. X? Would "W. H. H.", 611, Vol. X., tell me where he got his "moulded carbon filter blocks"? Would common wood charcoal answer?-HYDRO. [2573.]-EOLIAN HARP.- Would someone tell me the best way to make an Eolian harp; also the best Katerials for same? A small drawing with measurements for one to fit in a common window sill would help me very much.-R. B (2574)-BRONZING MODEL VESSEL. I am making a small model vessel, which I wish to bronze in imitation of copper on the bottom, and I want to know if the best copal varnish put on will cause the bronze to stick; if not, what wili?-ONE IN THE support the London and Clerkenwell Operative Watchmakers' Manufacturing Company." Several objections to the schetne having been replied to, to the apparent satisfaction of the meeting, the proceedidgs concluded with a vote of thanks to the chairman. A STEAM-ENGINE WITHOUT A CRANK.— The Milwaukee Daily News thus describes the performance of an engine, which, however, we fear our readers will read with considerable doubt. The engine is very simple, and consists of a cylinder 12in. lohg and 6in. bore (in one already built), with the shaft passing through the centre of it. The cylinder is furnished with a piston at each end, precisely like the pistons of common crank engines; to these pistons are connected short rods, with a friction roller at the outside end working in the inside of an elliptical ring, which passes around the shaft outside of the cylinder; outside of the ellipse is another friction roller, connected to the piston by compensation levers in such a manner that when the pistons are moving towards the cylinder, the rollers act on opposite sides of the ellipse, both pulling directly towards the centre, thus causing them to move forward on the ellipse, and communicating a rotary motion to the shaft. After the rollers have passed forward to the shortest diameter of the ellipse, the steam is exhausted from the ends of the cylinder and let into the middle, between the pistons, pressing them outward, causing the rollers in the ends of the piston rods to act on the inside of the ellipse, and coutinuing the forward motion of the shaft until they arrive at the long diameter, when the steam is exhausted from the middle of the cylinder, andis again applied at the ends. The results obtained were surprising, and can hardly be credited by helievers in the infallibility of the crank motion. The cylinder is about the size of the cylinder of an eight-horse crank engine, with a stroke of 3in. for each piston, and the power evolved was at least 22-horse power, and some present at the trial placed it as high as 25-horse power, with a speed of 100 revolutions per minue, and 501b of steam, consuming about the amount of fuel required for a 10horse engine. THE PULSE.-Dr. Omanza describes a method of registering photographically, the beats of the pulse. The appartus essentially consists of a small inverted funnel, having a long narrow stem and a caoutchouc base. This instrument is filled with mercury to a certain distance and its base is applied to the heart or an artery; the oscillations of the mercurial column are then photographed by well-known processes. It is said that with this apparatus the apparently single stroke of the pulse is shown to consist of three, or even four, in succes sion. and form, He DIMINUTION OF WEIGHT IN MAN DURING THE COLD MONTHIS.-Mr. Milner, of Wakefield (Am. Jour. of Med. Science), some years since performed a series of experimen ts with a view of determining the periodical fluctuations in weight, substance, which the whole body undergoes. weighed every prisoner upon his entrance into the convict establishment at Wakefield, and subsequently at the end of every calendar month, all of them being subjected to similar conditions of temperature, food, The number of men exercise, and ventilation. weighed exceeded 4000, and the total number of individual weighings was 44,004. From his experiments it was found that there was a progressive loss of weight in January, February, and March, and a gain in April, May, June, July, and August, and a loss in September, October, November, and December; or, in other words, an increase of weight during he hot These months, and a diminution during the cold. results are in accordance with physiological truth, for Dr. E. Smith has shown that the quantity of carbonic acid exhaled in winter is largely in excess of that given out in summer, and the sudden weight in April is found to correspond with an equally abrupt diminution in the quantity of carbonic acid expired. UNIVERSAL STANDARD OF MEASURE MENT. According to the Memorial Diplum atique the Austrian Government has just signified its ass en to a proposal of the French Government for an International Commission to assemble in Paris in order to Already 15 European Powers agree upon a common standard of measurement for all civilised nations. have announced their willingness to take part in the commission. Even England, which hitherto has been disinclined to depart from old customs, will be represented by the Directors of the Observatories of Greenwich and Oxford. The French Government now only awaits replies from the United States, Brazil, and the South American Republics previously to calling together the commission. The Minister of Foreign Affairs would of right be the honorary president, but the proceedings will really be directed by the vicepresident, General Morin, Director of the Conservatoire des Arts et Metiers, in whose archives is deposited the official standard of the metre recognised in France. ing the above company, established by operative watchmakers to promote the production of genuine London work. Mr. C. Young, who occupied the chair, opened the proceedings by declaring his conviction that the only way to retrieve the present depressed state of the trade, owing to the large importation of foreign watches duty free, was by the workmen combining together in a co-operative company to produce a watch equal in every respect to the best foreign watches imported, and at as low a price. There were three points upon which he believed there was no difference of opinion-viz., that if the watchmaking A CURIOUS DISCOVERY.-Dr. Milio, the celetrade was to be kept in this country, the whole system of production must be changed; that watches should brated surgeon of Kieff, has recently been at St. be of one uniform gauge; and that all foreign watches Petersburg explaining a means he has invented of sold in England should have the maker's name, and illuminating the body by means of the electric light to thus prevent them being palmed off on the public by such an extent that the working of the human machine may be observed, almost as if skin and flesh unprincipled sellers as English lever watches. The were transparent. The Moscow Gazette asserts that, meeting was then addressed by Mr. Ganney, who described the system of watchmaking by machiwery as to demonstrate the feasibility of his process, Dr. Milio placed a bullet inside his mouth and then lighted practised in America. It was acknowledged by all that the Clerkenwell watchmakers were the best work- up his face, upon which the bullet became distinctly [2575.]-GUTTA PERCHA v. ROPE BANDS.-Will men in the world, and the company were prepared to visible through his cheek. Dr. Milio does not propose any machine worker tell me which bands work best-supply a silver lever-plate watch, jewelled in four to lay bare all the secrets of the flesh, to explore the This watch had been designed and recesses of the heart, or to perform any miracles, phyutta percha or hemp rope, and which do their work holes, for 50s. sical or metaphysical. But he claims to have discovered best ? I believe rope is affected by the damp or dry produced by a committee, composed of the very best weather-I mean round bauds.-SUSSEX. a new and effective way of dealing with gun-shot workmen in every branch of the trade, and every part of the watch would be made in one building, thus wounds; first, by means of electric illumination he effecting a great saving in time and expense upon the discovers the precise situation of the bullet: next, by present system. Messrs. Newton, Holdsworth, Jones, means of magnetism, he proposes to extract the bullet Hislop, Mead, and others addressed the meeting in-provided always that the bullet contain some portion of steel. Against leaden bullets his system is powerless, and he therefore intends to represent to the were carried by large majorities:-"That in the International Committee, which lately met at Geneva, opinion of this meeting the union of labour and capital under a well-organised system of co-operation the desirability of recommending an admixture of is essential to the maintenance of the watch trade in steel in the manufacture of all future bullets. Dr. Milo's experiments with bullets containing only a That watches should be made by a Clerkenwell." said to have been uniform gauge, and that every watch should bear the slight admixture of steel are ་་ maker's name." "That this meeting pledges itself to thoroughly successful. DARK. [2576.]-PNEUMATIC PARADOX.- Could any of your ingenious readers give me an explanation of the action of this little instrument?-SWANSEA. [2577-BORING GLASS.-Can auy of my fellow-support of its objects, and the following resolutious readers inform me how to cut a hole, 2in. in diam., in the centre of a common piece of glass?-C. H. [2578.]-CONTACT BREAKER.-Will "Tangent kindly say where I can purcase one of Rhumkorff's double quicksilver contact breakers, and at what price? Are they difficult to make?-THOMAS J O'CONNOR. ANSWERS TO CORRESPONDENTS. All communications should be addressed to the EDITOR of the ENGLISH MECHANIC, 31, Tavistockstreet, Covent Garden, W.C. ENGLISH MECHANIC MUTUAL IMPROVEMENT LAST week we inserted a letter (p. 89) from Mr. D. William THE following are the initials, &c., of letters received up to first post, Thursday, April 14: B. Forster, J. M. Proctor, W. W., R. M., J. H., Rev. H. E. G., W. H. C., Capt. Fawcett, W. H. B., Rev. N. W. G., Rev. G. B. G., T. C. and Sons, Rev. E. K., J. Crowther, D. W. K., S. S., E. A. K., J. A. Watt, J. P. J., F. King, F. W. T., B. Edwards, J. A. M., J. A. B. and Co., F. A. M. D., J. H. and Co., J. R. Williams, W. B. H., H. H., A. Granville, J. A., E. W. H., W. A. H., W. H. G., R. F. H., G. R. M., L. and Co., C. Paget, H. C. C., Geo. Luff, C. B. A., Veritas, H. E. G., G. Firth, Casual Observer, Hugo, West Indian, W. Stephenson, Swansea, Anti Egyptian, W. B., C Holday, A Smoker. J. E. COSTARD.-No. 124, Newgate-street. See our advertisement pages. CICERO Beginners do not get £100 per annum in the Bank of England. Your other queries would take up too much space. S. W.-Results prove you wrong. LAMBDA. We know of no institution in which Greek is taught conversationally. INQUIRER.-Under the circumstances it would be waste of money for B to patent his invention if it were covered by A's previous patent. We can, however, scarcely give reliable advice as to the course to be pursued with only your general statement to found our opinion on, and should advise you to consult some respectable patent agent. PAT HAGAN is more than half a fool. T. S. REYNARD.-No stamps enclosed. NORTHUMBRIA.-We could not in any case consent to "exchange" articles sent through our office.. We know nothing as to the respectability of the Exchange Mart alluded to. W. BOYD.-The inventor of the pedespeed is an American. THANKS.-"Carthusian" thanks Alexander Hall for the trouble he has taken with the distance measurer." He thinks it, however, too complicated to be constructed by any but a regular watchmaker. A. MORRIS-On page 87, under the heading "China Grass." PAINFUL. Your disorder would seem from your description to be some neuralgic affection; but it would be exceedingly unsafe to advise. Consult a medical man. HUMANE MAN.- It is a question we cannot well treat of in these Tell pages. friend to discontinue his evil pracyour tices at once, or he will die early or become insane. He has debiltated his constitntion by vice; he can only restore it-or partially restore it--by virtue. JAMES BELL Douglas, Isle of Man, writes us that he does not agree with M. Somner's opinion on the cause of sleep. J. B. says. "My opinion is that the heart continues to strike less the pericardium when the person continues to sit or rest; hence the constant current of blood which flows from the heart is not so strong." We opine" J. B.'s" opinion is conclusive. W. H. Goss-The numbers were forwarded. We cannot be responsible for postal irregularities. THE BRICK FROM LIVERPOOL. Not the sert asked for ; the shape of the parcel betrayed its contents. We returned it to the railway company unopened without paying the carriage. THE ENGLISH MECHANIC LIFE-BOAT FUND 1024 L. A. Brode, Glasgow, fibre suitable for making paper and a brown colouring matter 1025 C. H. Gardner, West Harding-street, Fetter-lane. London, improvement in typographic, lithographic, and zincographic printing machines 1026 C. Montague, Cannon-street. London, improvement ia the manufacture of overcoats and other garments 1027 J. Shackleton, Bradford. York, improvements in apparatus for heating or warming rooms 1028 T. Robinson, Widnes, apparatus for skimming cast iron during the process of casting 1029 C. Clinch. Witney, apparatus for" cleansing" beer and other fermentable liquids 1030 E. Daniel, Bape-aumetown, near Rouen, apparatus for indicating the water level in steam boilers 1031 F. Taylor, Manchester, improvements in the construction of paper collars 1032 A. Watkins, 435, Strand, and R. Cory Hanrott. 5, Gray'sinn-square, apparatus for winding and setting watches 1033 J. Edmondson, W. Edmonson, and F. W. Edmonson Manchester; improvements in machinery for etching or eugraving cylinders 1034 W. H. Carson and J. V. Toone, Warminster, improved automatic lamp-creep 1035 H. J. Kirkman. 3. Soho-square, improvements in the co struction of pianofortes 1036 G Baker, Bridge-street, Norwich, improvements in the manufacture of tacks 1037 T. Aveling, Rochester, improvements in the construction of agricultural, road, traction. and portable steam engines 1038 C. F. Andersen, Abbey-wood, an improved apparatus to be used in window cleaning 1039 A. Etienne, Charlotte-street, Fitzroy-square, construction of carriages, vehicles, and velocipedes Subscriptions to be forwarded to the EDITOR, at 31, Tavistock- cotton cans street, Covent-garden, W.C. J. L. T.-Write to the Secretary of the Institute of Surveyors, APPLICATIONS FOR LETTERS PATENT DURING THE 12, Great George-street, Westminster. W. R.-It is fruitless to kick against the pricks. J. B. We don't answer by post. PHRENOLOGY AND BIG HEADS.-"Saul Rymea " has sent us a long letter exposing the fallacies of T. D.'s" letter in our last number. The insertion of the letter would lead to a fruitless controversy; at all events we think our space may be better appropriated. Our experience teaches us big heads are no guarantees or even indications that their possessors are wise men. ་ C. V. No charge is made for queries. J. H.-Don't ask such silly questions. ALFRED ALLEN. We shall bye-and-bye have a halfpenny post for newspapers. The ENGLISH MECHANIC ought to reach von before Saturday by the ordinary trade channels. THE EARTH'S MOTION.-Mr. Beardsley says:-"Will you kindly alter the heading to my letters on the Figure and Motions of the Earth to The Earth-Its Reputed Figure and Motions?" I make this request as it is more in keeping with the spirit of the contents of those letters, and is in other ways also more applicable."-Mr. Beardsley is quite welcome to the change of title if if will do him or his cause any benefit. We think it right, however, to say that the reason why we have placed at his disposal a certain amount of space is that some one may have an opportunity of refuting his fallacies-fallacies which are being enunciated nightly by Parallaxes, enthusiasts, and charlatans. Perhaps Mr. J. Dyer, the author of the admirable little work "Spherical Form of the Earth," noticed by us a few weeks since, will reply to Mr. Beardsley? IGNORAMUSES.-Pitman's system, which is the best, can be learnt from his manuals, which are published at cheap rates. We give the preference to drawing, because a knowledge of that art is absolutely necesssary to the great majority of our readers, while shorthand oould only be useful to a few. We must advise you to become more perfect in spelling and composition before attempting phonography. LENA.-Search at the Patent Office. PLEBEIAN.-1. Prices of globes vary; inquire of the makers. 2. By tracing its position on a map or globe. 3. We do not know. J. BYNG.-It is a Parisian invention, and is patented in England, but whether manufactured or not, we cannot tell. Search at the Patent Office for the specification, and write to the inventor or his agent. We do not reply by letter. THE SIXPENNY SALE COLUMN is the only place in which can appear queries forwarded by A. E. Tucker, "One in the "Sussex" (2nd query). Dark," DERBY, A. O. Z.-Search at the Patent Office. GEORGE GASKELL-Both your queries have been answeredthe latter very recently. 95, VOL 4-Buy one of our cases. WEEK ENDING APRIL 12, 1870. 989 J. Winter, Wardour-street, Soho, apparatus for filling glass bottles and jars with soups, jellies, and other edibles 990 H. W. Hammond, Manchester, improvements in the manufacture of iron 991 H. A. Dufrené, 10, Rue de la Fidélité, Paris, improved machine for winding yarns or threads on bobbins-A communication 992 T. Smith, Leigh, looms for weaving 993 J. Pickup, Tong, York, improvements in machinery to be employed in drawing. spinning, and twisting fibres 994 A. M. Clark, Chancery-lane, improvements in apparatus for washing and treating pulps-A communication 995 J. Pickering, Glasgow, forming holes in iron castings 996 J. More, and W. L. G. Wright, Glasgow, apparatus for forcing and projecting liquids 907 T. Rose. Oxton, and R. Emerson Gibson, New Brighton, utilisation of a certain material obtained in treating cotton seed 998 C. J. Busk, Pancras-lane, London, treating cements for the purpose of rendering them applicable for the production of artificial stone-A communication 999 E. Green, Phoenix Works, Wakefield, apparatus for removing soot from the tubes of steam boilers closets 1000 J. Parker, Woodstock, improvements in dry earth 1001 E. Lever, Haughton, improvements in signals and name plates to be used with letter boxes Rochdale, steam boiler furnaces 1002 J. McNaught and W. McNaught, St. George's Foundry. 1003 D. M. Childs, 18, Mark-lane, London, improvements in sash fasteners-A communication 1004 T. Horridge, Bolton, meaus of communicating between the passengers and guard 1005 T. Ford. Birmingham, improvements in gas lamps 1006 I. Baggs, High Holborn, improvements in making carbonates of ammonia 1007 E. J. Hill, Victoria Railway Station, Pimlico, slipping and depositing parcels and packages or other objects 1008 A. H. Brandon, 13, Rue Gaillon, Paris, an improved strap fastener-A communication 1009 R. Jones, Botolph-lane, London, merchant, improvements in the preservation of animal and vegetable substances to be used as food 1010 J. Mayer, 59, Great Portland-street, improvements in specula for surgical purposes 1011 J.Sharrock, Rochdale, improvements applicable to winding engines 1012 F. J. Sweeting, Clyde Dry Dock, Rotherhithe, apparatus for indicating the distance travelled by vehicles 1013 G, H. James and J. James, 11, Newgate-street, improvements in cases for cigars 1014 W. Young, Magdalen-bridge, Midlothian, and P. Brash, Leith, manufacture of illuminating gas 1015 C. H. Wight, Baltimore, U.S., improved inkstand 1016 C. H. Wight, Baltimore. U.S., an improved stand for containing stationery, in combination with a thermometer 1017 W Henley and D. Spill, North Woolwich, non-explosive compounds forming the material for the manufacture of collodion 1018 A. B. Brown, Birkenhead, improvements in steering gear, and in machinery for starting, stopping, and reversing heavy steam engines 1019 M. J. Roberts, Pendarren, near Crickhowell, Brecon, propelling apparatus for ships and other vessels 1020 C. Crossley and R. Whipp. Manchester. and T. Crossley, Rochdale, improvements in the manufacture of size 1021 T. Adamns, 14, Little Tower-street, London, stationer, a spring clip file or binder-A communication 1022 T. Adams, 14. Little Tower-street, London, binding music, pamphlets, and other papers-A communication 1023 H. a. Bonneville, 18. Chaussée d'Antin, Paris, astronomical instrument called the Hellade"-A communication 1040 W. Cooper, Bradford, York, improvements in sliver or 1041 J. B. Blythe, St. Mary-axe, London, apparatus for seasoning, injecting, and preserving wood 1012 J. Fairclough, Warrington, an improved mill stone dress-A communication 1013 A.Craig, 12, May-terrace. Renfrew, improvements in mills 1044 C. F. Varley, Beckenham, improvements in electric telegraphs 1015 W. Nelson, Bolton, manufacture of quilts, toiletings, and other figured fabrics 1016 H. Mallet and C. Russell, New Basford, twist lace machines 1017 W, E. Newton, 66, Chancery-lane, improved machinery applicable for inland navigation-A communication 1048 A. H. Brandon, 13, Rue Gaillon, Paris, improvements in looms-A communication 1049 A. Mosley. Old Radford, improvements in the jacquard 1050 P. C. Thamsen, Copenhagen, improvements in finishing linen, cotton. and other fabrics-A communication 1051 J. Henderson, New York, an improvement in the manufacture of wrought iron and steel 1052 W. R. Lake, Southampton-bulldings, London, improvements in the construction of steam vessels-A communication 1053 A. Parkes, Birmingham, improvements in the manufacture of steel 1054 S. C. Lister, Bradford, improvements in looms for wearing 1055 L. Weber, 104, Rue Royale, Brussels, improvements in galvanic cells and batteries 1058 G. H. Ellis, 91, Gracechurch-street, improvements in rotary engines and pumps 1057 W. Higgins, 1. Great New-street, Fetter-lane, Middlesex, improvements in the manufacture of hackney carriage and other lamps 1968 A. Brown, Lanark, improvements in ornamenting wood' leather. and other materials 1050 J. B. Booth, Preston, improvements in apparatus for lubricating and covering spindles employed preparing, spinning. doubling, and winding fibrous materials 1080 R. Adams, 16, Gladstone-terrace, Battersea-park, improvements in spring hinges 1061 T. J. Smith, 168 Fleet-street, Improvements in treating excremental matters-A communication PATENTS SEALED. 2936 W. Kelsey, improvements in driving drums or pulleys 2037 D. Sowden and R. C. Stephenson, improvements in looms for weaving 2951 G. A. Middlemiss, Sunderland, apparatus for withdrawing water or other fluids in as pure a condition as possible from wells, cisterns, and other places 2950 E. A. Snuggs, improvements in cocks, taps, and valves 2950 R. L. Hattersley, improvements in looms for weaving 2962 J, B. Blyth, improvements in the mode of and apparatus for vaporising and burning liquid hydro-carbons for the production of heat in furnaces and for generating steam 2005 E. Farrington. improvements in breech-loading fire arms 2970 J. H. Selwyn, improvements in fire-arins, parts of which are applicable for use as a digging tool 2977 S. Osborn, improvements for reaping and mowing ma chines 2080 J. Hartley, apparatus for registering billiards or other games 2081 R. J. Ellis, improvements in apparatus for desiccating animal and vegetable matters 2991 J. Hudson, J. Hudson, and C. Hudson, improvements in machinery for the manufacture of paper 3079 W. J. Rivington, improvements in counting and registering apparatas 3080 C. D. Abel, a new or improved manufacture of metallic tiles or slates for roofing 3096 G.Ireland, improvements in nutcrackers 3255 J. Mason, an improvement or improvements in metallic pens 3557 W. Tranter. improvements in fire arms 178 C. A. Calvert, an improved apparatus for self-registering and checking the money taken for admissions to public entertainments 400 F. T. Ferguson, an improved jug or pitcher 2072 L. M. Casella, apparatus to be employed in lighting gas burners 2975 R. Scholefield, improvements in pumps or apparatus for raising or forcing water or other liquids or fluids 2982 W. J. Bonser, apparatus to be used for feeding and watering cattle in railway trucks 2989 L. A. Lesage, improvements in closing and securing vessels containing alimentary substances 3007 S. Barber, apparatus for the propulsion and steering of navigable vessels 3015 W. E. Gedge, an improved elastic horse shoe 3023 W. H. H. McNeight, venetian and other blinds 3057 J. F. Crease, an improved method of attaching cements to iron or other substances 3059 W. Firth, wheels of traction carriages for use on common roads and tramways 3071 F. Jenkin, improvements in bridges 3078 J. Rignall, improvements in reaping machines 3119 W. A. Ross, improvements in preserving the surface of iron, steel, copper, brass, and other metals 3156 R. Marsden, pulley blocks or apparatus for raising heavy weights 3159 A. Minton, improvements in electro coating iron and other metals 3100 E. de Lagillardaie, producing condensations and evaporations in vacuum 3217 J. P. Budd, improvements in the manufacture of iron 3768 R. Derham, an improved machine or apparatus for washing potatoes 3770 J. A. Johnson, improvements in the manufacture of iron and steel-A communication 153 J. H. Johnson, improvements in the treatment of acid tars obtained from boghead, mineral schist, or petroleum-A communication 202 H. M. Whitehead, improvements in preparing blocks of animal and vegetable materials for making soup or other liquid food 353 J. Hanson, improvements in breech-loading fire arms 401 W. R. Lake, improvements in looms for weaving-A communication 570 A. Wingard, an improved paddle-wheel for propelling vessels in the water The English Mechanic AND MIRROR OF SCIENCE AND ART. FRIDAY, APRIL 29, 1870. vious knowledge of them, of course failed to reap awakened interest in microscopy, and an inquiry the full benefit of the display; but those who as to the society represented, and other kindred were acquainted with the elements of natural ones in London. One thing should strike every history and microscopy, and who came to see and visitor to such a display as that of Wednesday not to be seen, found it possible to gain good re- night last-viz., the amount of freely offered sersults even in the heat, bustle, and jostling of the vice devoted to the getting up and successful crowd of fair and unfair visitors. The makers conduct of these soirées. Such service amply of microscopes were there, and had their tables proves the zeal of truly scientific men, and when richly garnished as aforetime, with burnished we learn that previous days of careful attention brass and glaring lamps. They showed, too, many are essential to the success of these exhibitions, THE ROYAL MICROSCOPICAL SOCIETY. highly attractive objects, but little or nothing we ought to be grateful to the officers and memnew to the advanced microscopist, though much bers of the Royal Microscopical Society, and to THE ANNUAL SOIREE. that was interesting to the passing gazer. But others on like occasions. May all these societies why should they make great efforts continually? find many new friends, ample funds, and a They have had their day, or their nights, and all thankful public to appreciate and applaud their the microscopic-loving world has admired their craft and landed their ingenuity. ON On this occasion, for the first time since its establishment, the Royal Microscopical Society attempted to inaugurate a new style of exhibition, Hitherto these displays have been of a very miscellaneous and heterogeneous character. The several makers of microscopes had seized the freely-accorded opportunity of showing their craft and skill to the great visiting public, and, in truth, the annual soirees have been theatres for the performances of Messrs. Ross, Smith and Beck, Powell and Lealand, Swift, Baker, Crouch, Murray and Heath, Stewart and Co., and other well-known makers. These soirees have really been manufacturers' bazaars, and greatly, it is understood, have they profited by them. During five or six of the latest of such displays the student will have observed many gradual improvements in the form and in the accessories of the instrument, and will have noted each step in advance in concurrence with the year of exhibition. Still this was not fulfilling the highest purposes - of Microscopic science. It showed what was profitable, but not always what was scientific. To obtain results in the simplest and cheapest form is the desideratum of the student; to show them in the costlier form is perhaps that of the maker, not that the makers are without merit, for they have met the spirit of discovery and research nor can they be blamed if they also look for a tangible profit. The Royal Microscopical Society has gradually gathered, by bequests and by purchase, a very considerable number of objects, chiefly indeed by gifts. The late Dr. Wallich, Mr. Richard Beck, and several others have given a most valuable series of objects to the Society, and the question has naturally arisen-bow, and when, shall these be exhibited? No occasion can be so good as the annual soirée. But, then, the instrument makers have nearly shut out the gentry of science. Well, let the gentry of science, for once, claim space with the makers; row such has really been the result. The Microscopical Society resolved to display its treasures, and never did they come to a worthier resolution. They printed a list of desirable objects, circulated it amongst the members, and thus contrived to offer a somewhat more systematic and really useful exhibition than aforetime. It was less showy to ladies, but far more instructive to men. For the first time, in fact, the soirée has been less miscellaneous, and more truly illustrative of particular classes of objects. There was, indeed, no time for a leisurely study of the various objects, and those who had no pre zeal! COLOURS, AND COLOUR BLINDNESS. IT is very evident to those who thoughtfully sidered the beautiful. Enter the woods, and the Dr. Carpenter was the lion of the evening, if the name of so large an animal is allowable' in ear is gratified by the songs of birds and the hum connexion with the smallest of creatures. On a of insects; the eye is pleased by the thousand raised platform at one end of the large room, he beauties of the landscape, and the variation of exhibited a very interesting series of objects from light and shade; all around is seen a tinted mass It is impossible to do any that speaks of the glory and goodness of the deep-sea dredgings. descriptive justice to them in a brief space-in fact, some considerable previous knowledge was Creator. And among the various examples of necessary to appreciate them at their true value. the care bestowed by Providence on man, one The wonder was not so much in the structure of of the most striking is the lovely mantle of colour a particular object as in its profound extraction. that is everywhere spread round about him; and To gaze at little spiudle-shaped "tests," or shell- yet what man has long and commonly enjoyed, like coverings, which were brought up from he often undervalues. To appreciate the full depths of 300, and 540, and 640 fathoms of sea-effect of this gorgeous robe of colour, it is neceswater, was no slight pleasure; while to examine sary to conceive a blind man suddenly restored them in connection with the useful little descrip- to sight. With what pleasure would he welcome tive catalogue printed by the Society, and also in this new sense! With what delight would he the clever enlarged drawings overhead, was full drink in this new source of enjoyment! With of instruction and entertainment. One object, a what interest would he survey the scene before small complete specimen of Orbitolites was most him, in its gay apparel! How long couldhe gaze attractive, for in it we studied the nucleus of the upon the far-reaching expanse of lively green disc formed by a spire of several turns, and the below him, and the calm deep azure above him approach to a cyclical arrangement, showing that without tiring of its loveliness. And after he had the whole subsequent growth takes its course on enjoyed the view of Nature in its marvellous a cyclical plan. Then there were a series of assemblage of tints and colours, with what Cristellaria, showing every gradation from the delight would he consider the details of the straight to the nautiloid form, which next to the seene, how tenderly he would touch the flowers, and, Globigerince and Orbuline are the most com- above all, how thankful would he be in the possesmon inhabitants of the abyssal waters. Beauti-sion of a sense which affords him such intense fully constructed are their finely-tubular shells, gratification! Very few value colour at its true while under another microscope was visible the animal itself of Cristellaria, which was obtained it, and consider other forms of beauty far preworth; and many often speak disparagingly of by dissolving the shell of a fresh specimen in ferable; and dilute acid. human creatures living in a white world, they would soon feel what they owe to colour. The fact is, that of all God's gifts to the sight of man, colour is the holiest, the most divine, the most solemn." many speak slightingly, because What could be a greater intellectual luxury sensitive to any kind of beauty. They really do not appreciate it, and are not "Such expresthan this bringing up, as it were, from the silent abyss of waters, some of its choicest and tiniest sions," says Mr. Ruskin, "are used for the most inhabitants, into the very heart of noisy and part in thoughtlessness, and if such disparagers populous London, and displaying them easily and of colour, would only take the pains to imagine pleasantly to the curious eye of every privileged what the world and their own existence would visitor to King's College on this Spring night? become if the blue were taken from the sky, and Here were some 1200 sightseers; many brought the gold from the sunshine, and the verdure from in commodious vehicles, all spared every kind of the leaves, and the crimson from the blood, drudgery and dredging labour, provided with fine which is the life of man, the flush from the cheek, instrumental aids to observation, in every respect the darkness from the eye, the radiance from the duly facilitated, and to crown all, with Dr. Car-hair-if they could but see for an instant white penter himself at hand, ready to answer any intelligent questioner, and sufficiently tolerant even of the bore and the bungler. In the upper rooms were the usual smaller displays, and relatively smaller, though by no means absolutely small, people of microscopic science. How pleasant on The investigation of the cause of colour has these occasions to meet old friends and ever to been attempted by several philosophers, though see old sights! On no account would we miss we can give here little more than the names of that amiable elderly enthusiast in polarised light, the more celebrated. Among the ancients, the who though literally one of the "nation of shop-hypotheses to account for the phenomenon of keepers," is a valued co-operator with the friends colour are sufficiently vague, and colour blindness, of his science. Ask him any question about or chromato-pseudopsis does not seem to have in polarised light, and you may count on a good and any way engaged their attention. With the useful reply. Long may we live in light! and Pythagorean school, colour was the superficies of and probably he would himself utter the prayer body; and Plato considered it as a flame issuing of one of the famous Homeric heroes, "Let me from bodies. Aristotle's notions were equally die in light,"-if we ventured to add one word to mysterious and inaccurate. After the long that prayer it would be "polarised." interval of the Dark Ages, when culture began to settle among the inhabitants of the West, modern philosophers promulgated their hypotheses. Des Cartes, the ingenious founder of the system of vortices, imagined colour to be a modification of light, and the difference of colour was produced by the rotatory motion of the particles that com To the great, tumultuous, busy, or idle world of London, such sights as we have attempted to describe are unknown. Even the scientific world in other branches of study, scarcely know of their occurrence. Let us hope that the attention we have directed to them will bear fruits in a newly cular colour, and to transmit or stifle, or as it is called in optics, absorb the others." most intense purity, followed by a blue, which, posed light. From this date all the students of White light can only STRENGTH OF MATERIALS.‡ HE table given last week shows us that iron |