(2366]-COPPER BOILER.-To find the pressure have a piano or harmonium, they will find a perfect the boiler will bear before bursting in the direction of fountain of sweets, in "Calcott's Half Houre," some of which the Doctor enjoys with harmonium or flute, its length, we may assume the whole boiler to be a hollow tube of copper, and being capable of sustain-content with the incomplete harmony resulting from ing a certain weight hung to it, equivalent to the deficient cello and Violin. Cocks and Co., of Burlingpressure on one of its circular ends, tending to force ton-street, will furnish a list: some more are pub If they or blow it to a distance from the other end-ride, lished by Cramer, Novello, Addison, &c. "Circle of the Sciences" for further details. To find the cannot satisfy themselves in this repertory, I don't area of a circular ring, add the inside and outside know what to say. Novello's now publish Cassell's diameters together, this sum multiplied by their differ- Choral Music," which is chokefull of beauties; the concertina takes a flute or violin part well. If I can ence, and by 87054 gives the area in circular inches, or further assist them I well.-HENRY USSHER, B.A., in our case:M.B., Surgeon. (38 Messrs. Effingh am, Wilson, and Co., are the publishers of the best works on book-keeping and mercantile affairs generally.-A READER OF OLD BOOKS. 32 32 32 38 32 0.7854 0.31 cir. in. 32 32 1 circul. in. of sheet copper has a tenacity = 7620lb. = ? 0-31 cir. in. 76 20 "× 0:31 "= As the area of the end is 144 x 3-1416 4 2362-20lb. cir. in. or, 113 cir. in. the boiler would bear a pressure of more than 2016. per cir. in. before parting lengthwise. When uniform thin maierial is employed, a cylindrical vessel subjected to internal pressure (fluid) is almost exactly twice as strong lengthwise as it is circumferentially.-A. TOLHAUSEN. [2398.]-BOOK-KEEPING. [2373 AND 2392.]— STENCILLING ON GLASS- [2374.]—BREWING.-" New Subscriber" omits to state whether he wants information on private or public brewing; if the former " Donovan's Domestic Economy," 2 vols., 8vo, Longman, 128.; "Levesque's Practical Brewer and Maltster," 238., Leath; "Black's Brewing," 10s. 6d., Longman. For public brewing, Tizzard is the authority price 258., published by the author. A READER OF OLD BOOKS. [2375.]-LIFTING SACKS. - "Rusticus" would soon get over his difficulty, if he were to use Weston's differential pully blocks. Weston's Patent Sack Safety Lift is preferable. I cannot suggest a safer or better means for economising labour.-F. RUSSELL. (2377) GEOMETRY. Please see my answer to query 2435.-BERNARDIN. [2383.] INSULATING POWER OF GUTTA PERCHA-Take air as 100, gutta-percha = 24-8, Hooper's material 331, and pure india-rubber = about 40.-F. RUSSELL. [2390.]-INDUCTION COIL.-The power of the battery to be safely used with a coil of the dimensions given by T. J. O'Connor, will greatly depend on the perfection of the insulation, but if it has been made with ordinary care in this respect, he might use 3 pint batteries of bunsen. In one of my coils made with special care for using high battery power with about the same length of secondary wire, I have used as many as five cells, when I obtained a spark about in. long. I need scarcely remind T. J. O'Connor that he runs considerable risk in using so much, unless he is aware how his coil is constructed.-T. S. CONISLEE. [2391.]-GAS STOVE.-When some years ago I made use of gas only to heat my workshops, I found a perforated coil surrounded by small pieces of pumice stone the most effectual plan it answered well for working also, and I should think might be applied with advantage to heat the coil mentioned in this query. The only defect with me, was the apparent impossibility of preventing the men from wasting the gas, and thus increasing the company's bill, never at any time too tight.-H. B. M.-H. B. M." will oblige by sending the Editor his address.] [2393.]-NICOTINE. - "Maues" can thoroughly de-nicotinise tobacco by passing the smoke through a solution of tannin in water, by which an insoluble tannate of nicotine is formed.-R. G. BENNETT. [2396]-CHAMBER MUSIC.-" Ophelia and Alma" do not want better music than Kozeluch, or Reisseger's trios, some are very beautiful, and if they Lilly, of Garrick-street, Covent-garden, who deals in [2431]-WEDGWOOD PLAQUES.-The address of Messrs. Wedgwood is Etruria, Staffordshire Potteries; the agents in London are Messrs. Phillips, Oxford-street, next the Pantheon; and Mr. T. L. Brown, St. Martin's-lane, between New-street and the church. No estimate of prices can possibly be given; some of the old plaques are worth t heir weight in gold, and some of the new ones would be dear if put into the scale against copper-I mean as regards their artistic value. ENGRAVER. [2434.)-MEASURING LABOURERS' WORK.Any book on mensuration and practical geometry will give the information required, bnt as to field surveying, an hour or two passed in actual work with a land surveyor will teach more than several days' " "Bonnycastle was reading. When I was young the favourite authority, and is not, I believe, yet superseded. I was reading lately "Geodesy." by the late Butler Williams, and found it an excellent work. -H. B. M. [2435.]-PROJECTION.-I beg to propose the following solution of the problem :-A cube of lin, edge is to be represented by its plan and elevation when the planes of two faces are inclined at 50% and 70° to H. P. a.) Construct a plane P' Q R, inclined at 50° to Hor6.) From a point O O' of that plane, draw on it a per pendicular M N. Pl. [2402, 2405, 2406, 2412. ]-MANGANESE BATTERY. x2 + 4 x + 6 = 0, x = -2+√ BERNARDIN. [2417.)-FERNS.-There is a very good article on [2419]-GALVANIC BATTERY.-It is better in [2421.-MEDICAL WORKS.-Culpepper's London Dispensary, 1649, 4to.; Culpepper's Ephemeris, 1651, 8vo.; and Galen's Art of Physic, translated by N. C., 1652, 8vo, are all in the library of the British Museum, where they can he consulted. The only way of obtain ing copies is by applying to a bookseller such as M E c) Construct a plane passing through M N and inclined at 70 to H. P. This plane will be P'S R, and the intersection of the 2 pl. PQR, and P'S R will be an edge of the cube. d.) Take on that intersection a point A, and from that point draw perpendiculars on the traces of the 2 planes. A C, A H, &c. The cube can be drawn. (There are several solutions); the construction e might, perhaps, seem somewhat difficult, the exiquity of sketch not allowing me to draw it in extenso, I give it here after separately to construct a plane passing through a line MN, M' N', and inclined at a to H P. Take a point O, O'on the given line for vertex of a cone of a°, and I construct a plane tangent to that cone and passing by M N, M' N', this plane (or, better 2 planes N T M and N'S M) will satisfy the required conditions. (v. Fig. 2.) This solution may also serve with a slight modification as a reply to Query 2376.-BERNARDIN. NOTES AND QUERIES. [2437.]-SIZE AND PRICE OF BOAT.-I want to know the size of a boat to carry three persons, and I should like to the proper length of oars and sculls. know the various prices of a boat between a pleasure and racer, and the prices of oars and sculls outriggers ?-W. W. [2488.]-DIAMOND CEMENT.-Can any of your kind readers inform me how to make a diamond cement that will stand hot water ?-INQUISITOR. [2439.]-SLOT CUTTING.-A question was asked, may be, about two years ago, in the ENGLISH MECHANIC, for which 1 looked out some time for an answer in vain. It was required to designate a tool by means of which slots could be cut in wood with the help of the lathe. Probably some modification of the American twist drill might effect this, the instrument being entered as a drill, and the slot being then completed by lateral pressure? Cannot our obliging "J. K. P." assist us ?-F.R.C.S. [2440.]-TOBACCO PAPERS.-Does any brother reader know of a machine for wrapping up tobacco in oz. and 1oz. papers as retailed by shop keepers; also of a machine for packing powders into paper packages?-NEVILLE. [2441.]-LACTARINE.-How can I make the lactarine (from milk) into a dry state, so that it will keep similar to dry albumen?-T. E. [2442.]-MOUNTING LARGE CYLINDER.-Could any correspondent offer a hint as to how I can mount a very large electrical cylinder; should caps be metal or wood; and be put over or fixed as plugs in the axes? NIUM. TUNING HARMO[2444.7-BEARINGS FOR Will Mr. H. Smith kindly inform me the best method of laying the bearings for tuning the harmonium?-H. W. FENNELL. [2445.]-GALVANIC BANDS.-I would feel very thankful to "Suffolk Amateur" for the following information concerning his galvanic bands, viz. :Breadth of bands, what is meant by chipping joints with thread, the meaning of list, and the side to be worn next the skin ?-GALVANIC BAND. -MEAT [2446.] PRESERVING. - Would any brother reader kindly inform me the method of preserving meat, &c., in tins, for use during the voyage to Australia -JAMES SMITH. [2447.)-ARTIFICIAL PARCHMENT.-Can anyone inform me how to make artificial parchment ?D. JONES. new planet [2448.]-PLANET NEPTUNE.-The Neptune, was discovered simultaneously by Le Verrier (by calculation and observation), and by Adams (by calculation only). Has the process employed by Adams ever been published, either by himself, or in I should like to go any philosophical transactions? over his computations, and humbly to follow the footsteps of the discoverer.-GIMEL. [2449]-OLD COIN-Will some brother reader kindly give me some information respecting the coin, [2457]-TEA CHESTS-Of what wood are the chests made in which tea is imported from China ?-GROCER. 2458-PREPARING RHEA FIBRE.-A prize of £5000 is proposed for the best machine; would some one favour us with conditions, &e.-INVENTOR. [A reply to the above will be found in the present number.-ED. E. M.] [2459.]-BANKALWOOD. -I wish some some particulars about this wool? It comes from the Philippine Islands.-CHARLES D. S. [2460.]-METAL PENCIL FOR LATHE-Can any of your correspondents inform me of some softer metal than lead, which would do to use instead of a black lead pencil in taking figures from the nose of a chuck on paper, instea 1 of a tool on wood? It could be cast to shape, and be firm and true, which, however well-fitted, a black lead pencil never is. I might still act along with the spring holder.-WAHEROF. [2461.]-PREVENTING INHALATION OF IRON DUST.-Will one of our readers give me advice to prevent the inhaling of iron dust? I am a turner, and am chiefly on cast iron. What do the needle grinders use to prevent the steel dust from entering the lungs ? Is there any such thing as magnetised wire sold in London? Any advice that would be beneficial would be thankfully received.-A TURNER. [2462-GAS GENERATING APPARATUS.-At the fat cattle show at the Agricultural Hall, last Christmas, there was a stand with a number of gas jets burning in the window. The gas was generate in a round iron vessel, about 3ft. across and in. or so high. I should be very glad to know whether any of your subscribers know anything of it; whether it is safe; and whether the gas is liable to deteriorate after burning some time; what the substaLce is from which the gas is prepared?-C. E. F. [2463.]—TO MR. SAMUEL JAMES.-Having made a bicycle to drive by the back wheel, like Mr. Samuel James's, I find I cannot get it to go on the level road, it seems to me I must have got my swinging bar, or the bar that answers to his chains the wrong length, for he says he can go with no noticeable pressure on the treadle, while with me on the level ground it is such very hard work. My back wheel is 3ft. 2in., a full size sketch of which I append? It is made of front wheel 2ft. 10in., crank sin., the wheels are 1ft. what appears to be brass.-E. T. MOODY. [2450]-FASTENING PIN TO BROOCH.-Can any of your readers inform me how I am to fasten the wire into a jet brooch? I have tried bath-brick and resin, but it does not auswer. Any information will be thankfully received.-YORKSHIREBITE. [2451.]-DIAMETERS.-I have a 3in. telescope, of which I have only lately employed the day powers of 40 and 60 for solar observation. I find they show the sun of enormous size, but I wish to know whether I am correct in saying that the actual size of the sun, with thea bove powers is I am of opinion the diameter must greatly exceed these dimensions. The 60 power just fills the field.AMATEUR. [2452]-HAS VENUS A MOON?-When looking at Venus, in January last, with my 84in. silvered glass reflecting telescope, using a power of 240, I saw what I at once thought to be a moon belonging to that planet, it having a sensible disc, and disappearing entirely under a power of only 40. Its distance from its primary being, as near as I could judge, four to five times the diameter of Venus. I asked some one else to look at the planet, and they at once, without a word from me, said, "Oh! it's got a moon, I never knew it had one before." Will any of your readers inform me whether my supposition is at all likely to be correct, as I see in Mr. Webb's little book, that others have seen a somewhat like appearance before?-H. A. C. [2453.]-FLASK AND BULLETS. Will some brother reader kindly inform me how to bronze a small powder flask, and also what advantage is gained by greasing pistol bullets before loading ?-KEMPSTER. (2451-GLASS BURNING.-Will someone inform me what is the best material for muffle for burning glass after being stained and painted; and best construction of flue for the same, as I am about to replace my old one (which is iron) with a larger one? MUFFLE. (2455.]-FRET CUTTING ROLLED BRASS.-Is there any machine known for fret cutting rolled brass, Jin. thick. I have tried many, and all fail to cut more than a smooth file after a very short time, and are only fit for amateurs or toys. Is this owing to the perpendicular motion of the saw, as when used by hand it describes an arc; or is it to the machine saw curving inwards, thus losing the projection of teeth? Any practical information will be thankfully received. -CHIP. [2456.]-OLD COINS.-Can any of your readers in form me what this coin is? I have two of them, and they are both alike with the exception of the inscription round the edge. If Mr. Batty, or any other skilled numismatist would like me to submit the coin for his inspection, I shall be most happy to forward it. I have also a coin with a head on one side, and the inscription "Voce Populi"; on the other side, Britannia seated on a harp. Can anyone inform me what it is? And I have a medal of Admiral Vernon's, 1739; on one side there is a fleet of ships, and on the other side Admiral Veruon with a drawn sword. It is a brass medal, and in very fair condition. -SHAHAZADAH. apart. Is that the cause, or what can it be? Being a journeyman carpenter it is a consideration to me, and I want, if possible, to make it go, so as not to have my outlay for nothing.-E. H. PRESTON. [2464.]-TARNISHED SILVER-LEAF-Will any correspondent tell me how to keep work covered with silver-leaf from tarnishing? About six weeks ago I made a picture frame, decorated with an incised ornament silvered, and hoping to preserve it from tarnish varnished the metal with mastic varnish, but it has I had always supalready gone a very bad colour. posed that the discoloration was owing to the action of the air on the surface of the metal, but could the air attack it through the varnish? Mr. Furze, of Hanway-street, produces silvered work which never tarnishes, and has the appearance of being varnished, and I had hoped for a similar result. Perhaps I am wrong in using silver, and should use tinfoil, but shall be glad of any advice, as I want to send the work home, and it cannot go in its present condition. WORKING WOMAN. [2465.].--COIL.-I have made an induction coil with 21b. No. 39 silk covered wire secondary, and 2 layer No. 16 primary, and can only get a spark (with 4 Groves's cells) of about 1in.; is that what I may expect? Would it spoil the coil to add 21b. No. 30, as I wish to get a larger spark; and what would be the best battery to use for strength and freeness from noxious gas, which I feel in Groves's very much? If "T. S. C.," who replied to "Nemo," in No. 2, Vol. II. (or any other of the many scientific readers who seem to take a delight in kindly instructing ignorant young men like myself), would kindly answer the above, I should be greatly obliged.-INDUCTION. (2466.]-ON SHEATHING IRON SHIPS WITH COPPER.-Many years ago I designed a method of sheathing iron ships with wood, for the purpose of protecting them from corrosion and fouling by coppering the wood sheathing. This was communicated to the Times, I think about 1862, but, strange to say, not inserted. Being too much engaged in working other patents at that time, I did not patent this, which has since been adopted in the Royal Navy. Can you, Mr. Editor, or any of my fellow correspondents inform me the date of the first publication of this plan for preserving iron ships; and is it now practically superseded by sheating with zine? Does zinc rapidly become foul?-THE HARMONIOUS BLACKSMITH. [2467.]-DR. KITCHENER'S GRAND PIANO.-I see an inquiry, No. 2273, for the late Dr. Kitchener's telescopes. May I also inquire what became of his grand piano? This instrument, I was informed, had the harpsichord action in addition to hammers, and several other musical instruments combined with it, which were performed on by the manuals and pedals. I should also be glad to be informed what has become of Earl Stanhope's huge unichord grand piano; This instrument which was from 10 to 11ft. long, was thought an int resting production of acoustic science in its day. THE HARMONIOUS BLACKSMITH, [2468.]—ANATOMY.-Can any one recommend me a good book on surgical anatomy, suitable for a wouldbe medical student? Please say price and publisher. -BUSY BEE. [2469.]-WALKING TOUR-I think of making a walking tour in the south of Englaud, a few hints would be acceptable.-BUSY BEE. [2470]-HATCHING MACHINE-How can I make a compact hatching-machine? A rough sketch would be valued.— H. [2471.] SUMMER BEVERAGES. - Will some brother reader give a good recipe for making spruce and lemonade for summer drink?-S. R. DUSTON. [2472-DYE FOR SILK PLUSH.-Can any reader inform me as to the best method of dyeing black silk plush ?-J. LAMBERT. [2473.]-TURBINE.-Will one of your readers inform me if a turbine is suitable for driving a lathe and other amateur machinery, and, if so, what fall it would require to produce, say, h.p., and where the best are to be obtained?-T. W. Boord. [2474.]—APPOLD'S CENTRIFUGAL PUMP.—Will any brother reader be good enough to give the formulæ for calculating the quantity of water thrown by, and the h.p. required to drive, an Appold's centrifugal pump?-R. H. M. [2475] - PRINTING WITH COPPERPLATE. — Can any correspondent tell me the way to print with a copper plate?-TOM TIT. [2476.]-CLEANING SOFT WASTE. Will some kind reader inform me of a method for extracting the grease from the cotton that is swept off the floors of cotton mills, so that the soft cotton sweepings may be worked over again?-JOHN WILD. [2477)-AIR STOVE.-I wish to know the amount of gas saved by using an air stove (i.e., a stove in which the gas is mixed with air previous to combustion) instead of a common ring burner; or, in other words, when burning the same quantity of gas what is, approximately, the advantage in increased heating effect? -R. S. (2478.] PITCHING AND TRIMMING COG WHEELS.-Would Mr. Baskerville or some one kindly give us some information on the practical method of pitching and trimming cog wheels just as it is done by any regular millwright?-T. GRADY. [2479.]-MUSIC PUBLISHING.- Which would be the cheaper process of publishing some music, by music type or lithography? The music which I thus want reproduced is at present engraved; it would, therefore, be good copy to set up from, or, I suppose, (for I know but little of lithography) to get "transfers from.-CLERK. [2480.]-STAMPING.-I should be obliged if any of your numerous readers could tell me the chief compounds of a good stamping ink, such as that used at the Post-office, for it must be perfectly ineradicable? -CLERK. [2181]-IS GUANO INJURIOUS TO HEALTH.— Could any brother subscriber inform me if they ever knew Peruvian guano (Chineas) to affect the health in any way, and if so in what manner?-CAPE HORN. [2482.] FUEL FOR PORTABLE ENGINE. - I have a 5-h.p. portable engine. I wish to know whether the using coke for fuel destroys the fire-box more than coal; if so, what per cent? Coals cost here 23s. per ton; coke, 108. per ton.-SUBSCRIBER. [2483]-BUOYANCY-Supposing a tin tube exactly 6in square and 16ft. long, what weight would it take to sink it 4in. in the water; also, what is the weight required to sink a cubic foot of air just to the level of the top of the water?-ONE IN A FIX. (2484)-COMPRESSED COAL-I shall feel obliged if some of your correspondents will kindly give me the best and cheapest way of making small slack coal into blocks for using in engines, &c., by some process which is not a patent," and inform me where I could get the machine, or see the way it is made?-A SUBSCRIBE R. [2485.]-GALVANIC ENGINE.-Can any one oblige me by informing me where I can get any information of a galvanic engine, invented some years ago at St. Petersburg, for propelling vessels? I believe a model was shown at the Exhibition of 1851.-OLD SALT. [2486-RUBBINGS AND SQUEEZES.-Can any reader kindly tell me the best way to take rubbings and squeezes of inscriptions, and engravings of bells in a belfry? Where can long strips of suitable paper be bought, and what is the best way of fixing the same whilst taking the rubbing? What kind of clay is the proper to use, and how should I apply it ?-T. A. T. [2487.]-ASTRONOMICAL.-The 7-inch Newtonian belonging to a friend persists in showing Jupiter, Sirius, &c., with a glare of light round them; can "F.R.A.S." or some other gentleman explain why? Jupiter shows a clear neat disc, well defined; but after sunset a glare begins to form round it, and sometimes extinguishes his satellites. Sirius also shows a very minute dise, well defined; but also has a similar glare, or cloud of light, round it. The speculum is only partially silvered, and the telescope only used with a single plane convex lens for an eyepiece. I may remark that increasing the power from 60 to 400 did not either increase or decrease this glare of light, and which presents Jupiter as if he was in the centre of a bright nebula. Au answer would greatly oblige my friend, and being unable to give one myself, I appeal to "F.R.A.S.," Mr. Proctor, F.R.A.S., Mr. Fothergill, F.R.A.S., Mr. Denning, and our other correspondents, for one-a URSE MINORIS. [2488.]-ASPHALTE FLOORING.-" Guillaume appears to have ignored my question to him under the above heading, Qy. 2061. If he cannot answer my question, can he substantiate his own statement? If not, he ought to state his authority.-SERGIUS. of your numerous correspondents kindly inform me, [2489.]-VARNISH FOR PAPER-Will some one through the medium of your columns, how to make a cracking, bear heat and pressure without sticking, and varnish suitable for paper, that will fold without contain nothing injurious to bright steel goods; or I shall be glad to know where such varnish can be ob tained?-GEO. [2490.]-VELOCIPEDE WHEELS. I should be form me if there is any chance of tightening the spokes very greatly obliged if any of your readers could inof the wheel of a bicycle, loosened by the oil getting to them; and also as to the best manner of oiling such machines when the hind wheel runs loose on the axle? My plan of oiling has been with a hole drilled through the nave, and a brass tube inserted.-D. B. [2491.]-THE EYE.-Would Dr. Ussher tell me how I am to keep the patient's eye steady, while taking a mote or fire off the eyeball?-I. N. G. [2492.]-BENNETT'S CHUCK-Would "J. K. P." explain how the article caught is set true in this chuck, as I see the screw travels in the sliding piece (piece or pieces ?)-I. N. G. (2493)-WAXING ENGRAVED BRASS PLATES. - Would Engraver" tell me how to produce the beautiful gloss I see upon the wax of some newlyengraved plates? as it always comes dull off the stone and polishing-puff with me, and if I try heat I in- [2495-PAPER STAINING-I am a house painter, observed, destituse of odour, which plays so important rect by Mr. Carpenter and Mr. Hampden, snow the ceutral signal more than 5ft. above the line of the two extremes, these gentlemen coolly claim the victory, and threaten to bring an action against the Editor of the Field (who was appointed umpire by Mr. Hampden himself) for fraudently deciding against them! CHIPS. A CURIOUS new tube-dwelling Stentor is described croscopical Journal. In the same number Dr. Car and have at times found great difficulty in matching/ence between the two solutions amounting to 10 per and figured in the April number of the Monthly MiWould any brother reader, a paper stainer, be good of all the trials. A more correct judgment was given penter describes the structure of a very peculiar fish colours to paper hangings, for cornices of rooms, &c. enough to inform me, through your columns, what are the principal colours paper stainers use in the manufacture of paper hangings, viz., what whites, yellows, blues, &c. It would be great assistance to country painters to know.-HARMONY. [2496.]-TO "MUS.”—Would "Yus" be kind enough to help me out of a little difficulty? I started with every requisite for taking glass positives. My success was above my expectatious. The following week I got half plain glasses; the third almost plain. The nitrate bath I made up every week with a plain 50 grain solution, new developing and fixing solutions. J. B. [2497]-TO A THINKER."-Would "A Thinker," who describes his excellent velocipede on p. 65, No. 3. Vol. XI., of the ENGLISH MECHANIC, kindly give the dimensions as follows, and oblige one much interested in the construction of velocipedes, and doubtless many others-Width of frame at seat; width between the wheels; length of crank; distance of bar (on which the front levers work) from the seat; also height of said bar from the ground; length of levers?--CONSTANT SUBSCRIBER. [2498]-TELESCOPIC QUERIES.-Can any of your subscribers inform me where I can obtain Kamsden's eyepieces, and what is the probable cost? How can I deepen the colour of my sun-glass, which is red; or can it be coloured any different tint? In reference to "Jupiter," does he not find the two higher powers of his telescope unsuitable for the planets, especially the higher power of 275? I should think the maximum power which his telescope will bear in excellent weather, so as to ensure good definition for the planets, will be 130; and this power will have a limited field of view.-WILLIAM BAGULEY. [2499]-APPARENT ANOMALY.- Will any of your readers explain to me the anomaly there is in the following case:-In all calculations respecting cotton spinning, the avoirdupois lb. is the standard; and we are told that it contains 7000grs. only, and that 24grs. make ldwt., and 20dwts. loz., and 16ozs. llb.: now, 24 x 20 x 16 = 7680, which gives us 68 grs. too much in 1lb.! Will some one be so good as to explain this?EDWARD HABERGHAM. [2500.]-PAINT.-Will any of your numerous readers kindly inform me what are the ingredients necessary to form a good lasting paint; in what proportion should they be mixed; and if any difference is necessary between the first or priming coat, and the last or finishing coats; if so, what is it? The above is for painting pitch pine. What varnish is the best to stand on pitch pine grained oak? How can I detect any inferior or adulterated paints, or if petroleum or other oils are used?-SURVEYOR. [2501-INDUCTION COIL.-Will Sigma" kindly assist me out of a little difficulty? I have just com pleted an induction coil, but i cannot make contact between the point of the screw and the spring. The instrument is of the vertical kind; the bobbin rests on a little table, supported by four brass pillars. The points of contact are not platinised; the extremity of the screw is iron, which rests against the spring, which is steel. The hammer is a piece of soft iron soldered on the spring. I cannot see why it will not act, for if I place a piece of iron against the screw, and allow its extremity to touch the spring, it will immediately commence to work.-THOMAS J. O'CONNOR. [2502]-CIRCULAR DISC.-I am much obliged to "J. B." and "S. B." for answering my query according to their understanding of it. But it is not simply a question of proportional areas; and as I should feel thankful if "Bernardin" or some other able mathematical correspondent will notice it, I repeat my query: Required the size of a circular dise, to be fixed with its centre in the boundary or circumference of a circular orifice, lft. diameter, so that half the area of the orifice is covered by the part of the disc that projects over the orifice. I find E. V. V.," Louvain, submits a problem somewhat pertinent to my query (No. 2295), and which no one has yet noticed.-G. B. HORNER. USEFUL AND SCIENTIFIC NOTES. other substances. Our ASHWORTH'S PATENT LOOPED BINDER PORTFOLIO-We can very heartily recommend this binder (which has been sent us by Messrs. Ashworth, Brothers, of 1, Ashley-lane, Manchester) to readers. It is cheap, simple, cannot easily get out of order, holds every leaf securely, and yet can be opened at any part perfectly flat. Its principal advantage, however, is not only that a person can bind his own chases it, thus effectually preventing the loss of copies serial literature, but that he can bind it as he purand the consequent annoyance of procuring back Messrs. Ashworth prepare a binder especially for the ENGLISH MECHANIC (both old size and new), handsomely got up and lettered with the title numbers. outside. GUM TREES.-The planting of gum trees in Algeria bids fair to lead to a considerable trade in North African timber. The Eucalyptus, or gum tree, was introduced by M. Reinel from Australia in 1862, and thrives wonderfully in Algeria. It is a general rule of vegetable growth that the more rapid the increase the less dense the wood, but the opposite is the case with the Eucalyptus. It grows fast, but its wood is at least as hard as oak. A gum tree of eight years' growth will contain as many cubic feet of as solid timber as an oak of nine times that age. At present M. Trottier is actively promoting its cultivation, INDIGENOUS MEDICINAL PLANTS OF INDIA.-The Secretary of State has authorised Mr. Broughton, the Government Quinologist at Madras, to investigate the properties of the indigenous medicinal plants of India. This is a most interesting and important brauch of science-important to the people of India, whether regarded in a sanitary point of view, or as a means for developing the resources of the country,-and we are very glad to see the Madras Government has given it the attention it merits. Broughton appears to have carte blanche given him in all arrangements connected with the observations, and the results are to be embodied in an annual report to the India Office. Mr. WATERPROOF FACING FOR BRICK BUILDINGS.-This invention is intended to prevent the brickwork of houses absorbing moisture, and is to be used instead of slates or compo. It consists in moulding terra cotta, stoneware, or other plastic waterproof material, into slabs of convenient size and shape, and working these slabs in with the brickwork somewhat after the manner of working facing bricks. One slab is made of such a shape that its edge, when placed on that of another, shall rest against a projecting piece flush with the back of the slabs when superposed; by these means, any water that might accidentally enter at the joints of the slabs, is prevented from entering the brickwork. If desired the slabs may be glazed. TREATING AMMONIACAL GAS LIQUOR. The liquor is raised by injected steam to 2128 Fah. added. The ammoniacal gas passes off, and is arrested Hydrated oxide of irou, sulphate of iron, or lime are by the purifying substances used. If lime only is employed in the boiling, the liquor is purified by the addition of sulphate of iron, until no further precipitate is thrown down. The precipitate formed is available for a pigment; from 2 to 201b. of sulphate of iron may be required for 20 gallons of the liquor, according to its strength. The ammonia arising from the liquor is taken up by dilute sulphuric acid mixed with sawdust. spent tan, or shoddy. The iron is used for the purpose of removing the sulphuretted hydrogen. MR. HAMPDEN'S GOOD FAITH. -Both Mr. The following are the initials, &c., of letters to hand first post, Friday, April 8: RECEIVED. Breavington and Sons. J. M. P., T. Berry, P. A CRIMINAL LITERATURE.-J. H. T., W. F., Dr. U., Suburban letter. Music.-Replies would occupy more space than so elemen- CRUSADER-There is no "short and easy "method. Pit- ELECTRIC PIKE.-See back numbers. J. CHIPPENDALE.-You are alone in your expression of regret. W. T-Write to the Secretary of the Institution of Naval J. CREMER.-Order through a bookseller or newsagent if you Hampden and Mr. Carpenter assented to the details of the experiment recorded by us last week, as conclusive, although the Field regrets to say that Mr. Carpenter alleged his opinion was founded upon theory aloue, and that it had never, as far as he knew, been tried. Now, the fact really is, that in a little C. b. F.-We do not care about advertising booksellers for treatise published by "Parallax,' and which we nothing. We always give their addresses. Write them. THE SENSE OF TASTE.-The sense of taste has rarely been submitted to scientific examination, or at ter's name on the title-page, in his own handwriting, J. R. MASON.-The advertisement columns are open to you. (Field) have now in our possession, with Mr. Carpen-F. R. SMYTH.-Send the drawings of the prie dieu to us. J. P. (Post-office, Monkstown).-No stamps enclosed. all events has attracted far less attention than its an experiment similar in its nature is described as sister senses of sight and hearing, perhaps on account having been made on the very same piece of water as ARGENTE.-We cannot inform you. of the impossibility of treating it mathematically, that on which we were then occupied, with a result That it differs to a remarkable extent in different exactly the reverse of that which recently occurred. individuals is, however, as every culinary artist Mr. Carpenter was, in fact, engaged to decide a diswould acknowledge, a matter of fact; and it is also puted question, of which he and his principal professed well known that it is capable of extraordinary cultiva- to be practically ignorant, although it was in print on tion in some men, as shown by wine and tea-tasters the authority of the head of their sect, that it had obtaining lucrative posts from the delicacy of their already been tried in the same locality; and this must discrimination. Recently Dr. Keppler has published have been then known to Mr. Carpenter, and his since been a paper in Pflüger's "Archives of Physiology," in admitted by him in our presence. The good faith and perwhich he gives the details of a number of experiments fect fairness of Mr. Carpenter were not, therefore quite he performed with a view of determining the limits of of the nature we then believed them to be, and we gustatory discrimination for sapid substances in have no hesitation in affirming that he was a most various degrees of concentration. In these experi-improper person to be selected to act as referee in ments he first made a standard solution, and then such a matter. The deception was, to say the least of successively employed weaker or stronger solutions, it, "unscientific"; yet Mr. Carpenter and his master, which were tasted with due precautions, sometimes "Parallax," both profess to be ardent in the cause of before and sometimes after the standard solution, science; and that it has recoiled upon their heads can until no perception of flavour was distinguished. The cause no regret to anyone who values the truth. substances he selected were common salt, quinine, Although the diagrams of what was seen by the telesphosphoric acid, and glycerine, all of them, be it copes used at both ends, and acknowledged to be cor a URSE MINORIS.-We are glad to know that our efforts are so much appreciated, and so useful. J. R. SOFFE.-About half a score have written to us about Dr. Usher's advice. The Dr. did not send it as his own. See extract from his letter on next page. Quoting from memory, he made a mistake or two. C. FALLOW, of Bathgate, Edinburgh, says, "I am only expressing the sentiments of the majority of my brother readers when I say that I feel excedingly sorry to see from 'Adept's' letter that he is still suffering from bad health. I hope a short time will make him all right again, and that he will be able to resume his most interesting papers on Organ Construction, which for so long a tine have graced the pages of our journal." We need hardly say that we heartily endorse Mr. Fallow's expression of sorrow, and also his hope. VERITAS.-Thanks for good wishes. S., Post-office, Yeovil.-No stamps enclosed. DR. USSHER wishes to inform Henry Good, and, we may add, many others who have written on the subject, that his "advice is given in inverted commis, and therefore not his own. He quoted it, as he saw it printed on a slip 30 years ago, when he was a little boy." Dr. Ussber also raises his voice against many of the medical suggestions, as not only useless but in some instances mischievous. W. HARRIS asks us to send him by post a receipt to apply a peculiar polish to tin. We do not answer such queries by post, and he ought not even ask us to do so. JNEWTON. We could not inform you. PUZZLED. Our reporter says that according to the eleventh edition of the "Manual," page 50, paragraph 136, the positions of all grammalogues are, as a rule, determined by their vowels, whether long or short. THE SIXPENNY SALE COLUMN is the only place in which can appear queries forwarded by "A Druid." Neville (first and last query), Delineator, Geo. Marden, "C. C. C.," "Inquirer," J. F. Titchmarch. GAMMA-Only as in everything else, by hard work, patience, and a sharp eye for opportunities. A BLACKSMITH.-We cannot answer your queries ourselves; they require the experience of half-a-dozen emigrants. Letters have appeared in recent back numbers, from settlers in the United States, from which you will probably gain information. BUILDER. We have described three flooring cramps within the last six months, the last one only a few weeks back. Why not take the trouble to look before writing? G. H.-Yes, 2s. 6d., or you can purchase a case through your bookseller. THOMAS DINEEN.-Your letter, which you say many are expecting to see, is inserted to-day. C. H. W. B.- Please send the description. J. ESTOFF-We don't remember receiving the query. It should be borne in mind, that we do not insert all queries. AN EFFICIENT LATHE.-W. J. Evans, of 104, Wardourstreet, says, in a letter, that the lathe belonging to Titus Salt, and described last week, was almost exclusively made at his factory. The outlines of the designs of the lathie were made by Mr. John Smith, of Jersey, an able andi ngenious amateur. D. T. BATTY-Thanks for co-operation. H. ADAMS.-Cyanide of potassium will remove nitrate of silver from the hands. SUBSCRIBER FROM THE FIRST.-We can offer no opinion as to the qualifications of different makers' bicycles. R. S., of the Irish Constabulary, Dulup, Drogheda, complains that he is obliged to give 24d. for each weekly number of the ENGLISH MECHANIC. We can only say that a good percentage is offered to the trade. R. S. must see that it will cost more to carry a copy to his quarters, than, for instance, to an ordinary English market town. W. M. MILL denounces the system of trying to get subscribers to publications by offering to give away magnificent prizes "for nothing." He knows of au instance where a subscriber was sufficiently fortunate to get a prize. He was very much elated. But it turned out that the prize after all was not worth the carriage. This is just what might have been expected. When every other dodge has failed such baits are offered to catch the unwary. J. B. HALLET.-Consult back numbers for varnishes. SAMUEL WARD.-The alteration in the advertisement pages was made in obedience to continuous and repeated solicitations of subscribers. If the publication suffers, the subscribers will gain. APPLICATIONS FOR LETTERS PATENT DURING THE WEEK ENDING APRIL 5, 1870. 910 R. G. Rainforth, Kingston-upon-Hull, consuming smoke 911 W. McNabb, &, Cambridge-terrace, Clapton, improvements in bale-hoops 912 R. Saunders, Croydon, rendering water-tight dock gates, ships' ports, &c 913 F. J. Upton, 188, Long-lane. Bermondsey, hats 914 J. A. Lund. Cornhill, keys for watches. 915 A. W. R. Robinson, and F. Wilcock, Rochdale, apparatus for preparing cotton 916 J. Holding and J. Eccles, Manchester, and W. B. Cooper, Bowden, temples for looms 917 H. Hughes, Homerton, reducing metal rods 918 C. Cotton, Nottingham, knitted fabrics. 919 J. B. Passedoit and L. A. Ritterbandt, 40, Eastbourneterrace, Hyde Park, manufacture of peat charcoal 920 J. Fennell, Salford, privies, closets, and commodes 921 T. A. Hickley, Temple, and W. Utting, Palsgrave-place, Strand, steering ships 922 G. Clark, 10, Craven-building, Drury-lane. heating, cooling, or evaporating liquids 923 H. B. Preston, Liverpool, evaporating sugar 934 J. Cofield, 22. Ravenhurst-street, Birmingham, fastenings for braces, belts, bonds, and straps. 925 J. Tietjen, Upper Charles-street, Goswell-road, improved endorsing stamp 926 J. Lister, 45, Duke-street, Moor, Sheffield, knives 927 G. Flashman, Dover, mattresses 928 J. H. Johnson. 47, Lincoln's-inn-fields, artificial fuel.-A communication. 929 A. Stiefbold, and G. N. Cory, London-wall, concertinas and accordions. 930 C. Necker, Berlin, sewing machines. 931 W. Avery, Redditch, umbrellas and parasols 932 T. J. Smith, 166, Fleet-street, machines for reaping and mowing.-A communication. 933 J. Sellers, Freston, shaping, cutting, and boring wood 934 E. Funnell, 54, East-street, Brighton, signal alarum for railways 935 G. Parsons, Martock, feeding apparatus for carding engines 936 M. Knowles, and J. Conlong, of Blackburn, and W. Frankland, of Grindleton, looms for weaving. 937 J. Capper, Clifton-park, Birkenhead, chimney tops or сар 938 C. D. Austin, Newcastle-on-Tyne, lubricators 939 A. B. Reis. Lisbon, apparatus applicable to barrels, casks, or vessels for the preservation of fermented liquors tion of hats 940 F. Tocher, 81, Southampton-street, Camberwell, ventila-, 941 W. McCraw. f, West Catherine-place, Edinburgh, improyements in photography 942 W. R. Lake, Southampton-buildings, London, mechanism 943 J. H. Johnson, 47. Lincoln's-in-fields, preparation of oluble phosphates of lime for diminishing friction-A communicatio 944 R, Scott, Addiewell, treatment of mineral oils 945 J. M. Clark, Aberdeen, apparatus for soldering tin cases 946 J. N. Taylor, North Shields, clickouts or tools for draw ing nails, spikes, and bolts out of timber or other materials 947 W. B. Quelch, Stapleton, chairs and fastenings for rails 948 A. V. Newton, 66, Chancery-lane, preparing Iceland and Irish moss for use as a food.-A communication 949 G. A. Huddart. Brynkir, construction of railways 950 J. Bailey, Wandsworth-road, Surrey apparatus for registering figures or numbers 951 W. R. Mowbray, Drypool, and J. Martin. Kingston-uponHull. protecting goods, wares, or stock in vehicles, and buildings 952 R. Atkin, Burton-crescent, plait and fastenings or connections for jewellery Raworth, Manchester, 953 J. Drabble, Chesterfield, S. machines for doubling and spinning. 954 W. MacLean, Glasgow, improvements in printing, lithographing, and zincographing 955 F. A. Harrison, and C. Priestland. Birmingham, metallio adjusters applicable for adjusting braces, garters, &c 056 C. B. Parkinson, and J. Metcalf, of Preston, improvements in working check straps in looms 957 C. Newhouse, Heywood, hoists 958 J. L. De Negroni, Paris stoppers for bottles, jars, pots 950 H. J. Haddan, 21, Lupus-street, London, apparati for assisting in the pedo-locomotion of the human body 960 A. V. Newton, 66, Chancery-lane, improvement in sewing machines.-Alcommunication 931 F. Field, Upper Marsh, I ambeth, application of a new material to the production of illuminating oils and solid hydrocarbons 902 A. Ody, Bristol weighing machines. 963 J. Chrimes. Clare-villas, Merton, arrangements for the safety and convenience of railway passengers 904 J. Wadsworth, Manchester, an improved portable oven 965 H. Law. 15, Essex-street, Strand, meters for measuring fluids 966 H. Jackson, Park-square, Leeds, drying grain, malt roots, spent malt or hops, megass or spent sugar cane, wool, and other substances 967 H. Jackson, Park-square, Leeds, improveme ts in mills for crushing and grinding 968 A. Barlow and J. Taylor, Bury, apparatus to be employed in preparing cotton 969 TL. Livsey, Bury, apparatus employed for filling or starching woven fabrics 970 I. Summersfield and J. G. Sanderson, Manchester, impressing machine for tailors. 971 W. Smith, Manchester, railway switches and signals 972 W. Rowden, Whitstable, apparatus for reeting and stowing the sails of ships 973 W. E. Newton, 66, Chancery-lane, machinery for making horse-shoe and other malls-A communication. water. 974 J. R. Cadman, Christopher-street, Hatton-garden, constructing and fitting brackets for shop windows 975 E. Thornton, Bradford, heating by the circulation of hot 076 J. Shackleton, Bradford, improvenents in utilising exhaust steam 977 O. Wilson and John Peebles, Errol, improvements in equilibrium slide valves 978 H. J. T. Piercy, Birmingham, tube cutters and screw stocks 979 A. M. Hobson, Brixton, and E. C. Smith, Enfield, velocipedes. 980 W. Johnson, Wynd's Point, Little Malvern, sheet-metal Baddie-trees 981 G. Deadman, Hatfield Peverel, improvements in horseshoes 98 W. N. MacCartney, Glasgow, new process for dissolving crude or manufactured indian rubber 983 J. W. Baker, Bradford, G. Worsnop, of Little Horton, and J. Grainge, of Bradford, improvements in the construction of kilns 984 F. R. A. Glover, Brading, anchors 985 A. Whittaker and E. Stead, Bradford, machinery for spinning mottled yarn 9806 A. T. Anquetil, Paris, application of oleic and stearic acids for protecting metallic surfaces from oxidation and preserving wood and other materials 087 W. R. Lake, Southampton-buildings, London, an improved Hluminated night clock. A communication nss C. J. Eyre, Westbourne-grove, securing envelopes and their contents PATENTS BEING PROCEEDED WITH. 3310 K. Ogden deodorizing compound 3388 A. McNeill, a safe for ships carrying valuables 3300 W. Thomas, improvements in obtaining power 3891 J. Fogg, machinery for dressing Bags 3392, Cotton, machinery for preparing fibrous substances 3401 W. C. Mann, hats 3406 R. Goddard, improved machinery for pill mass mixing 3416 W. Pollitt, and W. J. Knowles, improvements in machinery for washing. 3417 D. Barker, varnish and varnish paints 3424 W. Perkins, fusees, matches, &c 3435 J. Pitt, J. Pitt. E. Pitt, and W. Pitt. of Cleckheaton apparatus for drill-cutting and shaping metals 3435 L. Pochet, dressing stone 3443 S. Perry, J. J. Perry, and L. H. Perry, boxes for holding Various articles 3460, J. and J. Wood, and W. H. Wood, ventilating hats 3494 P. A. S. Langlois, and Thomassin, manufacture of sulphuric acid 3510 H. M. Nicholls, apparatus for) cutting continuous paper into sheets 3563 J. F. Alexander, undulating propellers for steam ships 3612 W. McGee and W. McGee, machinery for doubling and winding fibrous materials 3857 G. W Honeyman, preparation for the removal and prevention of incrustation in steam boilers 3641 W Foulds, apparatus for heating feed water.-A com. munication 36581A. M. Clark, jacquard apparatus.-A communication 3605 J. Smiles, breech-loading fire-arms 3705 J. Bourne, apparatus for the production of heat ways.-A communication 3722 W. E. Newton. adjusting and packing the rails of rail 3723 W. E. Newton, improvements in forming the joints of t'e ermanent way of railways.-A communication. 48 W. Weild. machinery for winding yarn or thread 9. F. H. Knevitt, improvements in shutters and blinds for wit dows 122 H. A. Bonneville, warming and ventilating close carrias es and boat saloons 14. T. P. Bals, moulding and compressing substances for A ficial fuel 19 J. M. Plessner, apparatus for the treatment of liquid fuel 35 J. S. Dronsfield, apparatus for zrinding the card, covered Faces of portions of the carding engines employed in the Ireparation of cotton 430 Alfred Fryer. preparation and preservation of animal and Vegetable substances to be used as lood 48 W. Whieldon and J. Beck, cocks and valves 499 J. Hammond apparatus for washing and cleansing clothes 530 J. J. Aston, propelling vessels on the water 565 J. J. Holden, gas retorts 697 G. Fowler, smelting iron ore 717 J. Wallace, apparatus for distilling 767 P. W. Spencer, improvements in imekilns 806 J. H. Johnson, improvements in crimping machines. 827 R. F. Fairle, wheels for rail or tramway locomotive engines and carriages 87. W. R. Lake, improvements in wheels for railway engines and carriages 817 J. H. Johnson, improvements in locomotion and in the means to be employed therein 850 C. J. Eyre, apparatus for producing motive power 870 W. R. Lake, improvements in turbine water-wheels.-A communication 872 W. R. Lake, preparation of ammoniated sulphuric acid for the manufacture of manure 885 W. R. Lake, improvements in valves.-A communication 899 R. Smith, machinery for doubling and winding cotton Persons having an interest in opposing any one of such their objections to such application at the said Office of the applications are at liberty to leave particulars in writing of Commissioners before April 26, 1870. PATENTS SEALED. fields, improvements in stoves and fire-places 2857 G. S. and H. Whitechurch, Serle-street, Lincoln's-inn2858 J. Butcher, Southport, Lancaster, dentist, improvements in fountain pens and pen-holders 2865 E. D. Farcot, Boulevart Beaumarchais, Paris. an improved mode of propelling and constructing ships and boats and their accessories 2806 R. Broadbent, Islington, Birmingham, improvements in gas governors 2870 P. R. Hodge, Adam-street, Adelphi, C. Hengst, Fulhamroad, Chelsea, and N. Wilson, 144, High Holborn, certain improvements in the manufacture and cementation or welding of steel and iron, iron and iron, and steel and steel together, and in adapting such improvements to various useful purposes 2875 Sir C. T. Bright, Knight, Westminster Chainbers, Victoria-street, improvements in electric telegraphs 2876 C. Mather and W. Rosetter, improvements in warping or beaming machines 2878 F. F. Villepigue, Brewers-lane, Saint Martin's-in-theFields, an improved method of and apparatus for piercing or boring holes in rock, mineral, or other material of a similar nature, applicable in tunuel, mine, quarry, and other such work 2832 W. Horsfall, New York, improvements in machinery for forging bolts, screws, and spikes 2886 W. Morris, Triangle, Halifax, York, worsted spinner, and J. Teal, Sowerby, both in Yorkshire, improvements in machinery to be employed for combing wool 2900 J. Kircher, Caunstadt, E. Ebner, Stuttgard, both of Wurtemberg. an improved black printing ink capable of being removed from paper 2892 E. Smethurst. Stockport Cheshire, improvements in funnels or funnel measures for the measuring and pouring of liquids into vessels 2893 W. Richardson, Oldham, Lancaster, improvements in machinery for burring or cleaning wool, cotton, and other fibrous materials burner, improvements in puddling furnaces used in the manu2971 J. Halford, Brettel-lane, Kingswinford. Stafford, coke facture of iron and in other reverberatory furnaces 2993 W. Kloen, Birmingham, a new or improved method of water-colour printing 3017 H. M. Marsden, Sheffield. York, an improved method of manufacturing sheep shears and other articles of cutlery 3051 D. Jackson and J. Riley, both of Oldham, Lancaster, and G. R. hay, Dukinfield, Chester, improvements in machinery for cutting, shaping, and dressing stone 3072 A. M. Clark, Chancery-lane, Middlesex, improvements in hinges and hinge guards for railway carriage and other doors, part of which improvements is applicable for warming and ventilating railway carriages-A communication 2808 E. Wigzell, and J. Pollit, metallic pistons for eam engines 2901 E. R. H. Hammond, and E. Hammond, in breech-loading fire-arms railway carriage doors 2913 A. Coleman, latches or locks applicable especially to 2015 H. Schildberg, signalling apparatus for use in private or public buildings 2919 D. Parish, axle-boxes.-A communication 2031 W. J. Jones, hot-water boilers 2931 J. More, oils for painting or other purposes 2040 H. Reid, Portland and other cements 2011 W. N. Hartley, whitening or bleaching yarns 2943 E. H. C. Monckton, improvements in railways, in motive and locomotive power 2000 W. Lincolne, securing the joints of belts.-A communi cation 2991 C. L. Page, packing cases or boxes for containing bottles 3016 W. B. Robins, syringes 3089 T. Bevington and S. Courtauld, and J. A. Norberg, machinery for breaking stone and ore 3121 H. B. Barlow, improvements in knitting machines, —A communication 3455 J. Speight, apparatus for spinning, twisting, and roving Worsted 3003 H. E. Newton, improvements in net machines 196 J. Paton, P. Harris, and R. Harris, apparatus for generating carbonic acid gas for extinction and prevention of fire 255 J. E. Standfleld, four-wheeled carriages 294 W. R. Lake, sewing machine needles and needle arms.A communication 319 W. R. Lake, an improved friction clutch.-A communication 412 J. W. Dixon and J. Bates, machinery for filing 474 J. H. Johnson, apparatus for lighting, applicable also for signalling purposes 476 W. R. Lake, instrument for determining the altitude and zenith distance of celestial bodies PATENTS ON WHICH THE STAMP DUTY OF £50 HAS BEEN PAID. 931 W. B. Hilliard, improvements in skates 943 E. S. Jones, an improved mode of and apparatus for rowing boats on water 951 J. J. McComb, an improved mode of coupling telegraph and other wires.-A communication 941 R. Canham, improvements in means or apparatus employed in the cure of smoky chimneys 974 H. A. Bonneville, a new and improved means of readily igniting fuel and lighting fires.-A communication 962 F. J. Manceaux, improvements in fire-arms and in apparatus for charging the same 970 A. V. Newton, improvements in sewing machinery.-A communication 988 W. Clark, improvements in applying and fitting the tubes. of inultitubular boilers.-A communication 997 P. Spence, separating zinc from certain ores or minerals; and in recovering other substances found the rowh 1044 W. R. Lake, an improved mode of embanning or preserv ing dead bodies and carcasses.-A communication 1181 A. V. Newton, blowing and pumping engines.-A com munication The English Mechanic AND MIRROR OF SCIENCE AND ART. STRENGTH OF MATERIALS.* BY A. TOLHAUSEN, JUN. IN Originality is not assumed, for the materials are common property, and I have never hesitated to consult the best modern authorities on the subject. I may mention Professor Rankine, Gregory, Rühlmann, Zeuner, Baumgartner, &c. &c., when I thought I might obtain a more elementary demonstration and preciser results. I hope that I have duly, yet at the same time honourably, availed myself of the advantages which they supply, but still not so copiously as to diminish the utility of those volumes, or to make me an unfair borrower. On a previous occasion, one kind of attractionviz., that of gravitation, has been discussed and popularly treated, and pursuing the examination of the invisible, active, and real forces of nature, the attraction of cohesion will next engage our attention. The term cohesion is derived from the Latin cum=together, and hero I stick, or cleave, and may be defined as that force which tends to make the atoms or particles of the same kind of matter move towards each other, and to prevent them being separated or moved asunder. As examples of cohesion in daily life, we may cite : 1. The manufacture of glass vessels, the materials of which have been soft and liquid in the furnace, and on the removal of the excess of heat, have become hard and solid, in consequence of the attractive force of cohesion binding the particles together. 2. The surfaces of an apple torn asunder will not readily cohere, but if cut with a sharp knife cohesion easily occurs. with which the practical mechanic has to deal. All the possible strains to which materials We shall now investigate these properties in CHAPTER I. Tension is a strain acting in the direction of the fibres of a body, and tending to pull it asunder, as in the case of stretched ropes, bands, tie-rods, and chains. Every body subjected to tension may be conceived as having its particles arranged in longitudinal rows, each particle being held to the next by some force which, as already mentioned, is called the attraction of cohesion. Let us now suppose that the applied strain is not capable of breaking the body, but if increased by the least imaginable quantity, a breakage takes place; this strain is then said to represent the absolute tenacity of that body; or, supposing an iron pillar is capable of sustaining 16 tons and no more, without breaking, we should call the absolute tenacity of that pillar 16 tons. The absolute strength of the different metals is determined by ascertaining the weight required to break square bars measuring an inch each way, or having a square inch of sectional area; the bars are laid horizontally, and fastened firmly at one end, when at the other end a known strain which is increased, if necessary, till the bar acting in the direction of the bar is applied, breaks. That the bar is not placed vertically has also a reason, for then additions to its length would increase the weight, stretching its upper portion, because each portion of added length beof the bar has no influence whatever on the comes an added weight; and again, that the length breaking load is self evident; for if any one part of its length is capable of sustaining the strain, and the bar be of uniform quality, every other therefore the law that the tensive strength of a part will be able to sustain the same; we have body, uniform in all its parts, is directly proportionate to their trausverse area, whatever be their figure or length. 3. A wound produced by a jagged surface is difficult, and takes more time to heal than some of the most desperate sabre cuts, the cohesion of the surfaces of thus cut flesh being very rapid. 4. The art of plating copper with silver, which is afterwards gilt, and then drawn out into considerations must be taken into account, namely, When a piece of material is being tested, two flattened wire for the manufacture of gold lace and epaulets, commonly called bullion, is another sacrificed for the sake of ascertaining the strength whether the piece is to be afterwards used, or example of the wonderful cohesion of the prac-of the material. In the first case, it is self evitices of gold, of which a single grain may be ex-dent that the testing load must be so limited tended over the finest plate wire measuring 345ft. in length. Of course these examples might be carried on to any extent; but as they are only inserted to convey more readily the meaning of the term cohesion to the mind of the reader, we shall restrict ourselves to the above. The cohesive force existing more or less in all materials is not constant, but varies with the rature of the substance and the order of its atoms, as is best shown by the burning of argil, hardening of steel, &c, in which latter cases it becomes greatly increased. ex than the proof strength, which will lie between the last load and the last load but one in the series of experiments*. Materials used in machinery, and subjected to tensive strains, ought to resist the separation of their particles-fracture-as well as any material elongation; therefore, in practice, where durability and adequate strength are required, it is necessary to give the materials we employ considerably greater dimensions than such as would merely preserve them from breaking, or to load them with considerably less weight than those which would tear them asunder. Again, materials subjected to considerable strains for long periods of time gradually lose their tenacity, which must be provided against when permanence and stability are required. To obviate these degradations of quality, it is found expedient not to load iron or wood beyond one-third, copper, brass, or lead beyond one-third. or even sometimes one-fourth, of their breaking strain (ultimate strength). The following table contains the result of experiments on the cohesive strength of various materials. The numbers are given roundly, and may be safely used in calculation, as they have been reduced to one-third or one-fourth of their breaking strength. ON CHEMICAL SYMBOLS. SYMBOLS AS APPLIED TO MOLECULAR IV OST of the elements differ from each other in their degree of chemical force, and this force or power of the element was for some time termed its atomicity, but now that term has been completely superseded by the term equivalency. that thereby the strength of the material is not in any way impaired, that is, it must not ceed the proof strength. Care should also be taken to avoid vibrations and shocks when the In the latter case, the load ought to be increased testing load approaches near to the proof strength. by degrees until the piece breaks. To obtain a sufficiently correct result, the load, when the breaking point is being approached, has to be augM mented by small weights. One method of approximately arriving at the proof strength of materials is to apply a moderate load, and remove When the particles of a body become separated it, then applying the same load again, and removthrough the action of external forces, and the co-ing it two or three times in succession, noticing at hesive force is not able to unite these again, the each time of application of the load the strain or alteration of figure of the piece when loaded, by body breaks, causing those particles giving way tension, compression, bending, distortion, or either to move towards or from each other. The greatest or least force required to effect the twisting, as the case may be. If that alteration above is termed the tenacity, strength, or cohesion of the same load, the load is within the limit of does not sensibly increase by repeated application of that body; the object of the present chapter is therefore the determination of this force in its proof strength. The effects of a greater and a various appearances, especially in those materials greater load being successively tested in the same way, a load will at length be reached whose successive application produces increasing disfigurement of the piece; and this load wll be gre.ter The right of reproduction is reserved by the Author. The equivalency of an element, then, is that power which it possesses of combining with other elements to become saturated; thus a tetrad will only partly satisfied, but if the force is completely always exhibit some degree of chemical force if neutralised by combination with other atoms, then a saturated and comparatively inactive body, taken as regards its chemical force, is formed. Hydrogen Professor Rankine's "Engineering." |