length and breadth at widest place of the radius plate "B. If Mr. Plant will kindly give these measurements at the earliest leisure, he will much oblige, T. J. W. the service of the public, and not an engine to be em- (4984.)-FURNACE (Unnoticed Query). - - Ове о! ployed for the fiscal requirements of the Finance Gita's oil lan ps or small gas furnaces would answer. Minister. At present, he has a surplus of £1,416,922, The former works with light parathine oils, and would which, if called upon to give up, he will propose to com- melt 5lb. of cast-iroa. Price 31s. 6d. One of the gas pensate by additional income tax, or, perhaps, by poll- furnaces was described by" Sigma" on p. 23.-ETHYL. tax. Let, therefore, this surplus be settled as a permanent charge on the Post-office revenues of £1,500,000 perix 60z. of spirits of salts, and 4oz. salt of lemons to[4985.]-SPOTS ON MAHOGANY (Unnoticed Query). annum, but in any future increase of revenue let him not participate, but let it be applied strictly to the legiti-gether, drop a little on the stains and rub with a cork till the stains disappear. Then wash off immediately mate purposes of postal accommodation." with cold water.-AU REVOIR. INDIAN COIN. Henry W. Henfrey says: -"In letter 720, J. Van L. N. says that I am wrong in naming the foar numerals, 1, 2, 4, 7, eck, doo, chicar, hift. I beg to mention that I did not give these names on the authority of Mr. Marsden, but from a very useful little work, which details all the foreign alphabets, etc., viz. : Typographia,' by J. Johnson, published 1821. Indian and Persian terms given by J. Van L. N.,' are perfectly correct, according to Duncan Forbes and others, but I submit the question whether eck, doo, chicar hift, may not be different ways of spelling the same words MR. TONKES AND TODHUNTER. [858] SIR,-It would be much the best if contributors would restrict their effusions to those subjects with which they are acquainted. I am one who be lieves in Wm. Tonkes's abilities, but my belief received a desperate shock in reading his note upon algebraic tables (see page 209). Evidently the subject is Greek to him, or he would speak less at random. I do not pretend to be an adept in algebraic science, but I do know this, that as a rule, and taken altogether, Mr. Todhunter's works are the best published. The usage 3. 32 is perfectly correct, and it would be very difficult to know how it could be avoided in the given case. I am not speaking of the dot which represents multiplication; that is a minor matter in the case, where a work by ayak, doo, chahar, haft !". man of acknowledged excellence is written down by another who by his own words has never seen it. Neither can the words of a man be taken as worth mach when speaking of mathematics, who has never heard of a mathematician who has few equals, and is not excelled by half a dozen men in the whole universe. C. H. W. B. VINE CULTURE. [859] SIR,-I have beens axionsly expecting to see a reply to No. 849, page 593, Vol. XI., by "In Vino Veritas." Would the accompanying paragraph from the Chamber of Agriculture Journal induce some one to reply? "A boxwood merchant invited us to see his grapes, cut of course, and very delighted we were with them; for seldom have we seen finer fruit come out of the most costly grapery; yet these had been gathered from what are termed ground vineries-little unheated frames on the span-roof or letter A principle, some 16in. in height and 2ft. 8in. in width at the base, which rests on bricks to allow the admission of air. The vine is planted at one end, and is led along inside on a slate bottom. It is managed, as regards pruning, in the usual way; and would it be believed, from a vine thus circumstanced have been cut branches of fruit, black as sloes, covered with a beautiful bloom, and weighing from lb. to 24lb? These little ground vineries are made in 7ft. lengths. Mr. Wells has several of them in operation at Southend, and from each of them he usually cuts from nine to a dozen bunches of grapes, all fit for presentation on any gentleman's table." E. L. EXTRACTS FROM CORRESPONDENCE. REMEDY FOR NEURALGIA.-A medical correspondent of the Lancet says:-"A few years ago, when in China, I became acquainted, with the fact of the natives when suffering with facial neuralgia, using oil of peppermint, which they lightly applied to the seat of pain with a camel-hair pencil. Since then, in my own practice, I in the same way frequently employ oil of peppermint as a local anesthetic, not only in neuralgia, but also in gout, with remarkably good results; indeed, the relief from pain I have found to be almost instantaneous." MUSICAL STRINGS.-" Stepanfetchit" says:-" In the ENGLISH MECHANIC (the most practicalof men) page 197, for 18th Nov., 1870, I find the words, placing the hammer so as to strike the wire about on e-seventh to one-ninth of the whole length,' &c. Try two-fifteenths and one hair's breadth more." OBSERVING JUPITER.-Fearing my last letter must have miscarried, I again write in reply to "H. A. C." (4593) to inform him that he has done nothing remarkable. With my 8 reflector, using a 6in. stop, on Sept. 22nd, I saw Jupiter's 1st, 2nd, and 3rd satellite at 7.13.m., the sun rising here at 5.53 on that day; and I saw with 8in. aperture, the 1st and 2nd at 8.7 a.m.; and I could, I believe, have followed them until the planet set. The distance between the sun and the planet was 94°, or thereabouts. I should be glad to know what others have done in this way. For "H. A. C.'s" information, I may tell him that I used a power of 300'. ALFRED CUNNINGTON, Southgate House, Devizes. The LOOSE RUNNING CARRIAGE WHEELS.-S. F. Ekciwnuh says:-"Your correspondent, Wm. Tonkes, p. 131, let. 660, has misunderstood the purpose of my drawing on p. 84, let. 539. It was intended to show that the conical form of railway wheels makes the difficulty of passing round a curve greater, if anything, than if they were of a cylindrical forms. For if the wheels were detached from the carriage, placed on a plane surface parallel to one another, one wheel of each pair being made larger than the other to represent the action on a curve, then set rolling independently of one another, instead of one pair following the other, after a few revolutions they would be in totally different positions. "J.," p. 112, let. 616, informs me that the axles of the Brixton cars are divided, and therefore the above does not refer to them. INDIA-RUBBER SOLES.-A correspondent of the Scientific American says:-"Some years ago I applied soles to a number of pairs of boots that wore entirely out without the rubber separating at any point. The following is the method I adopted: Get some dissolved rubber; scrape the sole clean, and coat it with the dissolved rubber, and set it away to dry; the next day add another coat of rubber, and continue so to add until the rubber will remain on the surface like varnish. It will take three or four coats. In the mean time, scrape or sand-paper the rubber sole, and give that one coat of the dissolved rubber, and allow it to stand a day or two; now give the sole of the boat a good coat and apply the the air all out with a round stick, in the same way that rubber, having both sole and boot blood warm. Work shoemakers finish the bottoms of boots." REPLIES TO QUERIES. In their answers, Correspondents are respectfully requested to mention in each instance the title and number of the query asked. [4825.] -ELLIPTICAL CUTTING FRAME. TO "J. K. P."-I must and do apologize to this gentleman for having misquoted his letter of Sept. 30 (page 45). I really did not notice that it was part of a rose-cutting frame he had made, but I must add that the letter was uselessly and severely depreciatory of two very clever and ingenious instruments, besides being slightly ambiguous in itself. "Elliptical" is a proper term to use rhetorically, "elliptic" in geometry and mechanics. -WAHSROF. [4842.]-LAND QUESTION.-In the graphical solution, p. 168, the reader will please to move the middle y drawn equal, as described.-E. L. G. to the next point toward his right, X Y, Yy, yy, yB, were [4872.]-PRESERVING MUSHROOMS (Unnoticed Query).-Button mushrooms must be rubbed with a bit of flannel and salt; throw a little salt over them, put them in a stew-pan with some mace and pepper; as the liquor comes out shake them well, and keep them over a slow fire until all the liquor is dried into them again; then put as much vinegar into the pan as will cover them, give it one warm and turn all into a glass or stone jar (secured from air). They will keep good for two years and are excellent.-W. P. [4876.]-COD LIVER OIL (Unnoticed Query).-This has probably not deteriorated if the bottles were full, the oil well secured from the air, and not smelling rancid.-ETHYL. [4958.]-DISCOLOURED COIN (Unnoticed Query). -Rub with ammonia. I believe it to be impossible to restore it to its original colour.-AU REVOIR. SPOTS ON JUPITER.-"Io" says:-"Some of our readers may like to know that on Thursday, the 17th ult., there were four black spots to be seen on the planet" Jupiter about 2 a.m; three on the dusky belt below the equator, and nearly equidistant from each other, a line connecting them; and the planets' limb would be about two-thirds of its diameter. Also, one and two hours previously, two spots on the dusky belt above the equator, and nearly close to the planet's limb." INDUCTION COIL.-To "Nil Desperandum."-(C89) From what I understand from the description, enamelled cardboard, an inferior insulator, has been substituted for the ebonite tube. The secondary current would, therefore, escape through the primary or core, and a few discs would give the same effect as the whole number. It is very objectionable to turn the primary half a turn back, as it is of importance to keep the secondary close to the core; beyond what is absolutely necessary for the insulation. Valuable space has thus been wasted. The wire might have been brought back underneath the stand. Perhaps the ebonite discs may not tit closely. It is, however, difficult to discover a fault of this kind without inspecting the apparatus.-S. T. PRESTON. POSTAL REFORM.-Mr. Hyde Clark says:-"One simple step towards postal reform is to stop the Postoffice from becoming a further temptation to the Chancellor of the Exchequer, which causes its legitimate unctions to be tampered with. The Post-office is for [1960.]-AMATEUR CLOCKMAKING.-TO "IGNORAMUS" (Unnoticed Query).-Perhaps E. B. Denison's Clock and Watchwork," Blackie & Sons, might answer your first query, but I think it would be uscless, not being sufficiently detailed. 2nd. Since you possess a lathe, you will find it very useful, unless it is too large, and will not require many tools besides. Clock, as well as watchmakers, buy their tools as they want them; when they find a tool is needed for a particular purpose, begin, and you will keep going. Wouldn't it be a good knowing what they want, they straightway procure itiden to buy a 1s. 6d. “clock” at a bazaar (one of those that go so vigorously), or a second-hand one at a marine stores, and copy it the same size or on a much larger scale? Of course you would use better materials. You could calculate a train to make fewer beats and have a longer pendulum. A working model would be a great help to the book; for, after all, all clocks are similar, and I don't think you could get on very well without a model. At all events you must make a plan (front and side elevation), or in some way see clearly how to go about it-this is the only way to succeed.-NOBODY. [4966.]-VARNISH FOR SKATES (Unnoticed Query) -A good varnish for skates is shellac dissolved in spirits of wine. (Tried.)-C. H. H. [4976.] SCRATCHES ON PLATE GLASS (Unnoticed Query).-Wash with sulphuric or muriatic acid diluted with water and mixed with coarse sand.-AU REVOIR. [4986.]-SPOTS ON MAHOGANY (Unnoticed Query) The spots described may generally be removed by carefully repolishing with "finish." Rub softly in a rubber. Be careful not to rub hard enough to take the circular direction with some "finish" on a soft linen polish altogether off.-A. S. C. [4988.)-SPOTS ON MAHOGANY (Unnoticed Query). Stains and spots may be taken out of mahogany with a little aquafortis or oxalic acid and water, rubbing the part by means of a cork, till the colour is restored; observing afterwards to wash the wood well with water, and to dry and polish as usual. From "Enquire Withis." -SERGIUS. [4991.]-BITTER ALE (Unnoticed Query).- Bitter ale or Indian pale ale is brewed from the best malt and hops only. The peculiarities of manufacture are, a much larger proportion of hops-attenuation carried to a greater extent than in other ales-temperature of wort during fermentation never to exceed 65 Fahr. Pale ale properly brewed never requires fining. The quantity of hops per quarter of malt rauges from 181b. to 241b.; the ordinary strength of wort when passed inte the gyle tun 24lb. per barrel, or specific gravity 1066; it is attenuated down to about 4lb. of extract, or specific gravity 1011-1012. Quantity of ale produced about four barrels per quarter of malt. Forty years ago pale ale was very little known in London, except to those engaged in the Indian trade. The house with which I was connected snipped large quantities, receiving in return consignments of East Indian produce. About 1839, a ship, the Crusader, bound for one of our Indian ports, foundered, and the salvage, comprising a large quantity of export bitter ale, was sold for the benefit of the underwriters. An enterprising publican or restaurant keeper in Liverpool purchased a portion of the beer, and, I believe, laid the foundation of the home trade and introduced it to his customers; the novelty pleased, now so extensively carried on. -MEUNIER. [4991.]-BITTER ALE (Unnoticed Query).-In answer to T. O'Brien I may state to commence with that bitter malt, and best Farnham, East Kent, and other hops ale is made from nothing but water, the best pale according to judgment of the brewer. As regards the processes it goes through:-1st. The malt is ground between smooth rollers set close enough to break every kernel (no more); the next proceeding is called mashing, i. c., to mix the ground malt (grist) with water at or about 160°, according to temperature of atmosphere or quantity brewed, using about two or three barrels of water per quarter of malt. The mashing part is carried on by means of revolving machinery inside or outside the mash tun, or if small quantities by means of oars or rakes; it is then allowed to stand a short time and a few barrels are run under near the mash tun at a temperature of 180 or 190° according to circumstances; it is then allowed to remain two or three hours for the diastase to act upon the starch, converting it into sugar; at the end of that time the taps are set, slowly allowing the wort to run bright into the copper, where the hops are generally added as soon as possible. If two boilings are made some of the hops are kept back for the second wort: in some breweries a second mash is made for the second wort, but not in all. After the wort has boiled from one to two and a half hours it is then turned into the coolers in at one end and the cold water at the other, the wort ard from these run into a refrigerator, the hot wort going ontside and the water inside copper pipes, or vice versa, so that when the the wort enters the relrigerator it is about 2002, and when it leaves the other end it is about 56. It runs from these into the fermenting vessels, where the yeast is added to start the fermentation, and now comes the most critical part of the process, for as much yeast must be added as will attenuate a given quantity brewed of a gravity varying from 171b, to 21lb. per of beer down to a certain point. As bitter ale is generally 4lb. per barrel,-the sugar attenuated being converted barrel, the attenuation ought to be carried down to about by the action of the yeast into alcohol and carbonic acid gas. After the beer has done working and become days, it is run into casks, and about 1lb. fresh new hops somewhat clear, which it will do in about six or eight Added to give a fine flavour, and also to keep the air from getting at the beer whilst it is on draught and turing it acid. I might add that when fermentation commences the heat rises, for two or three days, in all about 12° or 149, when it is checked by means of cold water being run through copper pipes in the fermenting tuns. For bitter ale of a gravity of 18lb. per barrel from 161b. to 2016. of hops are used, generally half new and half yearlings, besides 11b. used for hopping down in the casks,as before mentioned. A quarter of maltwill yield about five barrels of ale at 181b. gravity. India pale ale is generally of a gravity of from 2016. to 241b., hops used about 18lb. to 24lb. per quarter. A. K. (keeping ale), gravity 18lb., hops 121b. to 171b. per quarter. I shall be glad to give further information.-AROMA Query).-Let a "Collier Lad" get Roscoe's" Elementary [4997.]-ANALYSES OF MINERALS (Unnoticed Chemistry," price 33 Gd., and study it carefully through. When he has mastered its contents it will be time enough for him to think of such analyses as he describes.-ETHYL. [5048.]-MAGIC LANTERNS (Unnoticed Query).The magnifying lens ought to be at the place where the condensed beam is reduced to its smallest, that is, where the condensers would form an image of the flame or other source of light. I say "condensors" because their work cannot be well done by a single lens, or even less than three. To intercept and utilize a good part of the therefrom an angle of at least 150. The amount of lamp's supply, the first lens, a meniscus, ought to subtend bending in the extreme rays will then be 75+ the angle they are ultimately to form with the axis when diverging from the lantern to the screen, which may be conveniently 15 or 202. Now a bending of 900 cr 95 can hardly be effected by less than three lenses. These, then may condense the light into the least space (or a 1 [5305.]-BOOKS ON CLOCK AND WATCHMAKING. rough red-bordered image of the source of light) at from [5062.]-PUMP (Unnoticed Query).-If "Brewer and Maltster" will let me know his present working arrangements, I will give him a plan to alter them as he requires.-BEN. G. [5838.1-STEEL BOILERS.-TO "BOILER-MAKER NO. 1."-Thanks to "Boiler-Maker No. 1." for his able answers to my queries, and I quite agree with him that there are a great many boilers made of the commonest plate that can be produced with not a particle of scrap in them; and yet there are manufacturers who have the [5092.] ELECTRO-MAGNETIC BATTERY (Un- audacity to brand such rubbish "best scrap;" and it noticed Query).-I must again apologize to "Beriro" is not to be wondered at when there is such a demand for delay in answering. Having been very busy I had for a cheap article, but which in the end is not cheap, overlooked his query. I fear I cannot assist him, as as such boilers are not long at work until they require from his sketch it would appear that he requires a repairing, and then there is no end of cost. I am quite of current which will overleap a space of several inches of "Boiler-Maker No. 1's" opinion, that a punched hole air. No battery however powerful will do this. A very is good enough if men will take the trouble to keep large induction coil, or a frictional electrical machine, their punch and die in good order-that is, as soon as can send a spark across such a space; but if employed, they get blunt (which they will do after punching a I don't think either would answer "Beriro's" purpose, quantity of holes) just to take them out and set them up as, if I am not mistaken, he wants the current to pass a little, and they will be as good as ever. After punchthrough some liquid contained in the bottle. If a sparking I have examined several holes with a good raagniwere sent from a coil between the pillars as sketched, fying glass, and have failed to detect any flaw from the it would pass round, not through the bottle. Would it edge of the holes, as some writers would have us do to have platinum plates connected with the poles of believe. I will take "Boiler-Maker No. 1's" advice a battery, and dipping in the liquid, so that the current and keep a sharp look out; and I hope, with Mr. should pass from one plate to the other through the Editor's permission, the gentleman signing himself as liquid? If so, that conld be easily managed, providing above will give us a good practical paper on boiler and the liquid be a conducting one.-IGNORANT IRISHMAN. girder making, as I feel confident such a paper will be [5095.]-POISONOUS FRUITS (Unnoticed Query).-interesting as well as instructive to a great number of In the Midland Counties, the fruits attacked by the your subscribers, and might be the means of swelling wasps are reputed the finest, as the birds peck the ripest the number of readers of our valuable journal. I have heard there is a work on smithwork published cherries. In France the same belief obtains. I never heard anything about the wasp avoiding poisonous in Liverpool, and by a Mr. Bowdon, at one time foreman at Messrs. McKiever's shipbuilding yard, Liverpool. Perhaps some of our correspondents in that district could inform me where it is to be had, and at what price.-VULCAN. fraits.-MEUNIER. [5126.]-PRESSURE OF AIR.-The pressure of air corresponding to given velocities, or vice versa, may be found by slide-rule thus, using the C and D lines :Pounds per square foot 10 or 40 Velocity in miles per hour 90 005 1-97 0603 8.70 178 315 444 1 20 3.5 42 6 8 95 Ex. C DI Ex. Ex. 45 23 Pounds per square foot 2100 Velocity in feet per minute C0003 1:43 -001 15.85 228 33.5 513 006355 DI 10 1500 40 5000 600 7260 900 100 Pounds per square foot 8.5 DI 1 2-09 6:61 20-9 661 209 &c. [5153.]-DEAFNESS.-As "Saxon" has not responded to R. J. Peters, perhaps a Celt's opinion may be accepted, unless R. J. Peters's motto be "No Irish need apply." I have one ear as deaf as R. J. Peters (convenient sometimes), and have expended a good deal of money on it. I recommend R. J. Peters to read Dr. Yearsley, who stands at the head of English aurists ("Yearsley on Deafness;" John Churchill & Sons, New Burlington-street; price 6s.). There is a chapter in this book on ear-trumpets, and another on incurable, besides many on curable deafness, which I think should interest R. J. Peters very much.-PADDY. [5358.]-OIL FOR MAGIC-LANTERN, ETC.--"Zetetic" will find the fountain solar lamp the best for the magiclantern, as it gives a powerful light of small diameter (an important matter for magic-lantern purposes) and the supply of oil is uniform to the last. I have used colza oil for some years, and find it answer very well, though some recommend camphorated sperm oil.-J. MOODY. [5380.]-LOGARITHMS.-Although "C. H. W. B." has referred " T. W. S." to certain works on logarithms, perhaps it would assist others of your readers who are desirous of working with logarithms if an example or two were given, premising that one of the best tables for the purpose is that prepared for the S. D. U. K., and published by Walton & Maberley. It may be obtained for about 1s. 6d. Logarithmic operations, which are performed by addition and subtraction, furnish the results of multiplication and division. The principal care to be exercised is that of properly placing the "index," which is always one less than the number of digits. Thus to multiply 438 by 97 we say :— The index to the quotient is 8, indicating that it is a [5253.]-SILVER COIN.-I compared the description given by "Delta" with that of several coins and found parts of it on some Flemish denarii. Let me propose a few suggestions. Might it not be IPRA instead of JRRA? The denarii of Ypres are rather common. Might the letter A with the pellets, with the M+M, which I believe is III+III, not represent a temple? the words BO. NO... not form parts of BONUS DENARIUS? Enricus be the name of a moneyer, or of Henry the First, King of France? The temple, with the words BO. DEN occurs, among others, on some coins of Baldwin IV., Count of Flanders (989-1008). Those coins are very rare, and, what is more curious, of all the denarii In the first instance the product is the square, and in coined in Flanders before 1055 none have been found the second the cube of 2. The nature of the reversc there; all the specimens come from Denmark or operation, division or the extraction of roots, is obvious. Norway; several found in Denmark among a great For example, the logarithm of 4 divided by 2 gives the quantity of Anglo-Saxon coins are at the Museum of Co-square root of 4, and the logarithm of 8 divided by 3 penhagen. The extensive commercial relations which at gives the cube root of 8.—W. R. BIRT. that epoch existed between Flanders and England introduced the Flemish coins into the latter country, and then, in one or other incursions of the Normans, they formed part of their booty. It is not impossible, then, that some specimens inay also be found in England. If the coin described is one of those, it is very rare.BERNARDIN. easily with a Sin. object glass, may rest satisfied that BIRT. [5886.]-GLASS MARBLES are made from rods technically termed "cane," of various colours, cut into lengths, softened and rolled. The threads, &c., which I suppose to be what is meant by" ornament" in the query, are produced thus: The body or ground aaid which these appear in the finished article, is drawn from the melting pot, rolled on the marver; thin threads or strips of different colours are then united to it, the mass is warmed up, coated with a layer of flint or colourless The converting glass, and then drawn out into cane. these rods or canes into spheres is frequently done at the glass-worker's lamp.-ENGRAVER. [5387.1-NORTH POLAR STAR.-The position of Alpha Urs Minoris, the pole star, as regards the trac north pole, is only relative, and depends upon its hour angle. At its upper transit it is seen on the southern meridian, at its lower on the northern. From its lower to its upper transit, it is enst; and from its upper to its lower it is west of the meridian. It is slowly approaching the pole, and will arrive at its least distance, half a degree, in A.D. 2100.-W. R. BIRT. [5402.-KEEPING WALNUTS.-I have found the following method answer very well:-Place layers of sawdust and walnuts alternately in a box, taking care to have the first and last layers of sawdust 2in. or 3in. deep.-A COUNTRY ORGAN. (5411.]-NITRATE OF SILVER.-In answer to "Viator"; loz. of silver would give loz., 4 drms., 86 grains of the nitrate. It is easily made by digesting the silver with equal volumes of strong nitric acid and water, evaporating to dryness, dissolving in water, and recrystallizing twice.-GEORGE E. DAVIS. [5419.]-TO "K. S. N."-INDIA-RUBBER TIRES FOR BICYCLES may be fastened by driling holes in the iron tire at every 2in. Stretch on the rubber tire, in which bore holes, as above, then taking care your screws fit well, put them in, first placing a drop of oil under and on the head, the rubber will then close up. lin. screw will be long enough, as gin. may enter the felloe; and in. the tire, leaving in. to keep on the rubber. The above is a Birmingham maker's plan, and I intend fixing a tire on the above principle.-BEN. G. 66 .... [5126.]-CARDBOARD GLOBE.-In description of Fig. 2. p. 213, for "divide the quadrant on A B into any number of parts," read, “. . . . equal parts." I omitted the word "equal," thinking it would be understood, but the engraver having made them so extremely unequal, the word becomes necessary.-E. L. G. [5427.)-OZOKERIT.-Ozokerite, the mineral from which Messrs. Fields' candles are made, is a tough When and flexible hydrocarbon, soluble in oil of turpentine. [5439.]-GENEVA.-There is a directory for every town of note, which can be obtained through any foreign bookseller, such as L. Hachette & Co., King Williamstreet, Strand, W.C., or Marion & Co., Soho-square, London. It is now about eight years since I was there, and as they were planning out the ground outside the fortifications, and otherwise greatly altering the town when I left, I could not be of much service. The principal watchmaking districts are Locle, Canton de Neuchatel; La Vallée, near Lausanne, Canton de Vaud; and Geneva.-NOBODY. We [5444.]-WROUGHT IRON BEAMS.-" J. M. E." is quite right in thinking that the beams are sawn. have the same process here in Sheffield for cutting railway bars all one length. In rolling rails of course there are raw ends to them, and as they are wanted still red hot to the sawing apparatus, which consists of with the ends square and nice they are carried while two circular saws, with peg teeth, of about 30in. diameter and in. thick. These saws revolve at a high speed and are placed at the distance of the length required apart from one another, they are set on the floor of the mill and between them is a movable frame for the support of the rails, which can be advanced up to the saws by the man in attendance. When a rail is put on the frame the man causes it to travel up to the saws and amid a shower of sparks off go the ends. As they cannot be rolled off as fast as can be sawn the saws do not get so hot as to do them much injury.-A SHEFFIELDER. [5448.]-CARPENTER'S BENCH.-As no one else has answered "Alpha " perhaps I may just say that no other improvement is needed to the old carpenter's bench. Everything needed is there when you have a bench (12ft. long, 3ft. 9in. boards wide, and 2ft. 10in. high), runners for cutting stuff on, tool box in the top, box at each end, vertical and horizontal screw, bench-pin, holes, &c. Mind and have the three boards at top perfectly level, and out of wind.-VELOCE. [5384.)-RESPECTIVE MERITS OF TELESCOPES. -SOLOMONS' £5 TELESCOPE.-"B." says with a "power of over 100 definition is out of the question." I should like him to have seen, as I did on Nov. 12 and 13, Jupiter's belts and all the minute details of the moon's surface with powers of 250 and 800. This, too, was when there was a great deal of dew, and it had so condensed on the object-glass that it looked like ground [5461.]-BULBS.-Bulbs may be retarded, if kept in glass, the dew-cap not being used. With these powers and this state of the object-glass I could see everything as pots of light soil, dry and cold, and in comparatively sharply defined as when I commenced observing with a dim light, water being seldom given. An early set of power of 20 and a clear dry object-glass. I also saw yacinths, &c., may be secured, if kept in waterthe doubles of Orion's belt when their primaries could glasses in warm rooms; and when these fade, the bulbs hardly be distinguished with the naked eye on account treated as above, being taken out of the soil, the roots of the mists of the horizon being at a low altitude.well washed, and the bulbs placed in water-glasses, will [5302.]-PNEUMATIC QUESTION.-" M. P." having given a reply to this question, as regards the case of a corked bottle containing water, contradictory to mine, I must rejoin. Water corked into a bettle must convey the pressure of the atmosphere at the time it was corked to the sides of the bottle. Hence, when placed under the receiver of an air-pump, the sides of the bottle must be subject to the original internal pressure and to a diminished external pressure. Whether that pressure can break the bottle is another question; for, the water scarcely expanding at all, the expansion of the glass [5381]-RESPECTIVE MERITS OF TELESCOPES. would probably be sufficient to make compensation audF.R.A.S.," in his paper on the moon (ENGLISH relieve the pressure. Let some possessor of an air-MECHANIC, No. 211, Nov. 23, 1859, p. 245), speaking of pump try the experiment and tell us the result.-O. F. Stadius," says, "an observer who can make it out [5462.]-MORPHIA.-Sulphate of morphia crystallizes in prisms, which dissolve in twice their weight of distilled water. They are composed of Nitrate of morphia yields needle-formed crystals in stars, which are soluble in one and a half times their weight of distilled water. Muriate of morphia is soluble in ten and a half times its weight of distilled water. The acetate crystallizes in needles, the tartrate in prisms, and the carbornate in short prisms. Tincture of galls is said to be a good test of morphia, free or combined. Subacetate of lead throws down all the animal matters with which acetate of morphia may come to be associated in the stomach, without acting on that vegetable salt. The excess of lead may be separated from the clear liquor by a few bubbles of sulphuretted hydrogen; and the morphia may be recognized by crystallization in vacuo, and by the red colour which nitric acid imparts to it. No morphia is found in the blood of animais killed with it. Morphia acts with great energy on the animal economy. A grain and a half, taken at three different times, produced such violent symptoms upon three young men of seventeen years each that Sertürner was alarmed lest the consequences should have proved fatal.-BEN. G. [5474.]-LIME LIGHT.-Mr. Trinder, p. 214, rightly observes that making hydrogen is quite needless, common coal-gas answering at least as well; but his advice to make oxygen in an iron retort will involve great waste both of oxygen and iron. The retort should be of clay or glass, according as the fire or a lamp is used. In any case, however, the heating chlorate of potash alone, as "Ben. G." directs, is most dangerous. I once narrowly escaped setting a house on fire by so doing. It must be mixed with some oxide for safety, and that of manganese has been usual. As this is black, however, it might contain soot or other combustible matter, which would make the mixture more dangerous than even the chlorate alone. I therefore suggest either red lead, red precipitate, or polisher's rouge (crocus powder). Whatever be used, no oxygen is given out, I believe, but by the chlorate. Red lead might pass into the higher purple oxide, after which it would serve any number of times unchanged, by merely washing away the soluble chloride of potassium left when the chlorate is spent.-E. L. G. [5478.]-A NOVEL LANTERN.-Diffused daylight, i.e., sky or cloud light, cannot be applied to form images, magic-lantern fashion, though sunlight is the best of any for that purpose, if directed by a heliostat, or mirror driven by a clock, turning it first into a direction parallel with the earth's axis, whence a fixed mirror can turn it into whatever direction is best for use. Every country school-house ought to have a tube for this purpose, fixed through its roof, with the heliostat mirror on its top, which might be constantly driven by the cord of the ordinary clock weight passing over a pulley on its axis. Whenever the sun shines, a lucernal power would then be at hand, on merely darkening the room, superior to all the most costly ever contrived for metropolitan theatres or shows. All the "educational purposes" described by Mr. Highley, pp. 151, 173, would thus be practicable in the poorest village school, by an original outlay not necessarily more than doubling that of their necessary clock.-E. L. G. [5481.]-SUGAR CUTTING AND CHOPPING MACHINES." E. V. M. B." requests information on these machines; being unusually well acquainted with most of the contrivances for cutting or chopping sugar I reply. There have been many machines designed for this purpose; one of the first, if not the earliest-excepting the old hand chopper and the common nippers-had a frame of saws (just like a deal saw frame) and cut the loaf of sugar into slabs, which were afterwards divided by a system of knives into cubical pieces, so nearly alike in weight that a dozen taken indiscriminately from one heap usually balanced another dozen taken from another heap. The chief defect of this machine-now over forty years old, in the design of which my late father was assisted by a clever mechanic-was, that in common with all machines which I have had experience of in which saws are employed, the sugar adhered to them. The next which came under my notice was the design of a Mr. Molyneaux. This had a circular saw about 2ft. diameter, which cut off a slab, which slab, by the action of two rotating systems of knives, was broken into pieces very far from eubical in form. To my sorrow it was a decided failure, and combined with my former experience caused me to feel a strong prejudice against any further attempts to saw sugar for table use, although a French apparatus for that purpose was to a considerable extent a commercial success. This contrivance consisted of a frame, carrying three or five saws, worked by hand, and the thin slabs it produced were afterwards cut-it would be an abuse of language to write choppedby a knife moved by a screw. It became very popular in Paris and on the Continent, but although adopted by a few English families, for private use, was too slow in its operations to be suitable for the trade of a retail grocer, who must needs have a quickly-acting apparatus to keep time with that wonderful "go-aheadishness" which so distinguishes his class, that, to judge by their habitual practice, cannot afford time to put a pair of scales out of hand on the counter without making a row. I beg their pardon, I mean a noise. The first attempt to chop sugar-using the word chop in its usual sensewas fixing a large pair of nippers on a stout board. The late Mr. Symes improved on this idea by employing a lever of the second order to which one or more knives SUGAR CUTTING AND CHOPPING MACHINE (5481). fast, so he generally prefers a machine which can be [5504.]-TO MILLERS.-I have had so little ex- [5504.]-TO MILLERS.-You will require a 25 horse engine to drive five pairs French stones, grinding Indian corn. Should prefer running them at about 140 revolutions per minute.-C. J. of the Edict of Nantes from returning to France, he [5517.]RECRYSTALLIZATION.-"W. C. C." can recrystallize the salts he names by saturating the mother liquors when further evaporated yield another solutions at boiling point, and allowing to cool. The crop of crystals, though less pure than the first.GEORGE E. DAVIS. [5521.]-SPECULA.-In reply to "B. H." I should say that 6ft. 6in. was the most convenient focal length for a Newtonian 6in. reflector; but for a speculum which is to be mounted on the Herschelian principle the focal length should be much greater. If B. H." is about to construct a reflecting telescope I should most strongly advise him not to adopt the front view system, as the atmospheric disturbance caused by the head of the observer, must quite counterbalance any advantage that were affixed. He counterbalanced the lever by a spring, may be gained in light-gathering power. In conclusion and when well proportioned it is an effective apparatus. I must thank "B. H." for his kind and encouraging reMany thousands of well-made machines on this plan marks, but I must beg him not to term my letters "inwere sold during the term of his patent, and I am sorry [5516.]-WHO MADE THE OLDEST STEAM LOCO. structions," for since the appearance of Mr. Purkiss's to add many more of very ill-made ones after its expira- MOTIVE KNOWN?-I enclose a few particulars con- excellent letters, to which I owe so much, it would intion. It is a common but lamentable fact that many cerning the invention of steam engines. The first perdeed be impertinent to try and "instruct." Moreover my things which are well made during the so-called son who considered the properties of steam philo-object in writing is to show how much any one may exmonopoly of the patentee are very ill made when their sophically was M. Pafin, a physician, born at Blois, pect to do, without machinery, which no doubt gives manufacture is in the power of those who are erroneously who visited England in 1680, and became curator of the more excellent results, but is not within every one's said to have no character to lose, but of whom it might Royal Society. The "Digester," which he constructed reach.-F. M. NEWTON. more truly be said that to lose their characters would be a next year, exemplified the enormous elastic force that great gain to them. Hand-lever sugar chopping machines, steam acquires when heated and confined. As a source although comparatively rapid in their action, bardly of power he proposed atmospheric pressure, by forming suffice for modern retail trades. Your retail grocer, if a vacuum, either by the inflammation of gunpowder or not exactly a "fast" man, wants to chop his sugar pretty the condensation of steam. Precluded by the Revocation [5522.]-COOKING WITH GAS.-Your first difficulty lies in the gauze being too coarse. Decrease the aperture a little (20th of an inch quite safe) and it will prevent the flame passing through, from the fact that it conducts away the heat with such rapidity that the gas is cooled below the temperature necessary for com- [5522.]-COOKING WITH GAS.-The principle of consuming air with gas is now brought into practical use in the manufacture of cooking stoves at so cheap a rate that I should recommend a "Young Baker" to purchase one. A good one may be had for 1s. 6d. If, however, he prefers to make his own, a small cylinder, say 3in. long by 14in. diameter, covered at top with very fine wire gauze, and fitted with a common burner inside close to the bottom, with plenty of air-passage round it, will answer his purpose up to (say) 1 pints of water. Should this be too small, a larger burner and cylinder may be used; this is more economical and more easily regulated than any burner. In lighting up, the light must of course be applied to the top of the gauze, and not to the burner itself. The gauze on his present stove must be too coarse, or the flame could not get undermeath it,any more than the flame of a Davy lamp can ignite the gas that may be outside, always provided that the stove is lit on the top of the gauze.-P. J. M. [5522.]--COOKING WITH GAS.--The fault is in having too large a surface of gauze. I use a gauze about 24in. or Sin. diameter, and not too fine. If you will do the same, you will have no trouble.-T. F. [5523.]-MELTING GOLD. Cut your silver and copper in very small pieces, and give it a good melting heat for ten minutes or quarter of an hour after it has begun to run down. Use borax as a flux. If it still cracks, use sal ammoniac. I do not get one cracky ingot in fifty by this way.-T. F. [5533.]-CLAY RETORTS.-There are several methods INITIO. [5535.]-NEW BINOCULAR MICROSCOPE.-Though it has been a marvel to me for years past, to see the absurd form figured on p. 165, and no appearance of any being constructed to give the immense advantage, for which alone a doubling of tubes was worth having, I am assured by a microscopic observer that these, as described on p. 125, have existed for these ten years. Instead of "a clean vertical section," I should rather describe what is wanted as a doubling of the whole instrument, except, perhaps, the object glass, which, if small, may receive its two beams through two pin holes, distant apart about a third of its focal length; and after passing through it they might be turned aside by two prisms like that on p. 125, which would send them up the axes of the two tubes. Each pin hole, and indeed the aperture of object-glass in any microscope, ought never to be wider than a twelfth or tenth of the object's distance therefrom. When it is greater it may easily be proved that the brilliant effects seen can be nothing but optical illusions.-E. L. G. [5587.1-YEAST.-Boil, say on Monday morning' 2oz.; of the best hops in 4 quarts of water for half an hour strain it and let the liquor cool to new milk warmth; then put in a small handful of salt and lb. of sugar; beat up 1lb. of the best flour with some of the liquor, and then mix well altogether. On Wednesday add 3lb. of potatoes boiled, and then mashed, to stand till Thursday; then strain it and put it into bottles, and it is ready for use. It must be stirred frequently while making, and kept near the fire. Before using shake the bottle up well. It will keep in a cool place for two months, and is best is that it ferments spontaneously, not requiring the aid at the latter part of the time. The beauty of this yeast of other yeast; and if care be taken to let it ferment well in the earthen bowl in which it is made, you may cork it up tight when bottled. The quantity above given will fill four seltzer-water bottles. I have heard of many recipes, but I believe this to be the best.-AU REVOIR. 15587.]-YEAST.-"Won't Rise" will find the following a very good recipe for making yeast:-1 quart of malt, loz. of hops, 1 gallon of water, llb. of flour. Boil the malt and hops for an hour, strain them through a sieve and mix with the flour, which must first be mixed poured on it, stirring well all the time. When it is with a little warm water before the boiling liquid is lukewarm add the quickening. It may be boiled next day, and is fit for use, having it in the mean time covered up, and kept moderately warm. 1 quart and 1 gill of the above is sufficient for 1 stone of flour. Lay the bread in sponge over-night, and bake in good time in the morning.-SPARKS. [5526.]-NAPKIN PRESS.-I send a sketch of a homemade napkin press, which answers very well; it is made altogether of beech. a, board, 2in. thick and required size; bb, uprights, 3in. square; c, cross bar, 3in. by 4in.; d. screw, 24in. diameter, four threads to inch, passing through c; handle; f, board under which napkins are put, lin. thick; g, board screwed on ƒ for the end of d, which is plain, to run in; it is 2in.thick and 4in. broad. The uprights, &c., are all dovetailed.-C. H. H. [5527.] SPRINGING. - TO "STUD-PIN."- The trouble you experience arises most probably from the balance being out of poise, or, still worse, from its being heaviest on the wrong side. A "horizontal" balance ought to be in poise, or inclining to be the heaviest on the side which, when the watch is held up by the pendant, is the lowest while in beat and at rest. By making this side heavier you can always make the watch gain in this position, also the reverse for the opposite effect. It should be done carefully, for the least thing in the world is sufficient. A horizontal watch ought to gain in hanging up, though not more than one second in two or three hours, while going right or inclining to lose in laying flat. There are other causes of irregular going, the bottom of the wheel touching the upper edge of the notch in the cylinder, or the lower plug; the safety-pin not being in its proper place, a very common fault, or the notch not cut deep enough, and consequently the bottom of the notch touches the wheel at each vibration. Cheap watches give a deal of trouble by the endstones being loose, and allowing the pivot to pass too much through the hole, thus working on the shoulders instead of the ends. The above faults cannot be too closely sought out, as some[5540.]-CEMENT FOR LINING WOODEN VESSELS. times they are not easy to be seen, but they can always-I, like" Electro," at first had a great deal of trouble be heard if the watch be placed to the ear, which I should in keeping wooden vessels from leaking, as the sulphate advise always to be done, and any noise heard fully ac- of copper solution is so penetrating. I, like him, tried several things, but rested at last in pitch, but that failed until I adopted the following plan:-Let your wooden vessels be dovetailed at the corners, and the bottoms well screwed on; do not use any glue or white lead in the joints, and the wood ought to be very dry, well seasoned; then make a fire inside of it with shavings or paper, until the wood is quite hot and almost singed; [5587.]-YEAST.-Letters and recipes for yeast and bread-making in Vol. XI., pp. 15, 43, 63, 65, 479, 551. Consalt also " Enquire Within for a collection of different methods. The baker's patent yeast is made from 9 gallons of water, in which 10 oz. of hops are boiled and poured on a full half peck of malt. This is a very powerful ferment, and requires great care in making the bread. Dried German yeast may be bought at most corn-chandlers' shops, with directions for use, and demands less attention. The lightness of bread depends more upon a proper heat in oven and good kneading than on the yeast.-H. B. M. then have the pitch ready, and pour into it, moving it about until it is covered all over about the thickness of a penny, then take a box iron, with a red-hot heater inside, and iron it well over, carrying the corners of the iron well up into all the angles. This drives the pitch well into the wood and into every crevice. One of my cisterns is lined with stout sheet glass, and the angles done over with pitch burnt well in with a hot iron. But if " Electro" lines with glass his wood-work and glass must be quite flat. Some of my friends in the trade have slate cisterns, and no doubt they are the best, for the solution will come through earthenware though it be well glazed.-H. P. [5540.]-CEMENT FOR LINING WOODEN VESSELS. I have had a wooden box in use for a good while (holding solution of sulphate of copper) made from pitch pine. The sides and bottom were grooved and put together with stiff white lead; the box then received four coats of good varnish, such as is used by grainers, each coat being put on when the preceding one was dry. though I never empty it except to clean or renew the The screws were copper. It has never leaked a drop, solution.-ETHYL. [5540.]-CEMENT FOR LINING WOODEN VESSEL. Electro" will find the following cement answer for the purpose he requires:-Beeswax, 1lb.; resin, 5lb.; red ochre, 1lb.; plaster of Paris, two tablespoonfulls melt altogether in an iron ladle, and apply whilst hot. I have also lined wooden cells for a Daniell's battery with shellac varnish, with which I mix sufficient lampblack to give it a black appearance.-INDICATOR. [5541.]-MENDING EBONY.-The strongest way is to get a piece of silver or brass tube and fit it over the rod and then glue it in neatly.-GE. Ss. rule, just the size of your ramrod; reduce the broken [5543.]-THE VIOLIN.-If "George" carefully inserts the blade of a knife (a thin one, such as is used by artists for mixing paints, is best) between the belly and side of his instrument he can separate them; he should not scrape the glue away, as this would prevent them fitting together again. When he is ready to join them, let him have a number of small clamps, shaped like a capital E, but without the centre bar; they may be all easily made to the requisite size out of a wide piece of deal, which is then split into the required number. Warm the timber before joining it, but be careful not to allow it to warp whilst doing so; use the finest of glue. "George" may procure it at some pianoforte manufactory. Cramp on the belly quickly, and tighten the clamps with small wedges. The glue should be spread neatly both on the belly and sides, so that an assistant is needful.-E. B FENNESSY. [5544.] BENDING MAHOGANY MOULDING."T. B." must take two pieces of deal, one to fit the inside, the other the outside of the moulding (the deal of course cut to the curves he requires); soak the moulding in boiling water for ten minutes; then put it between the pieces of deal; then cramp them together, slowly bending the moulding; let it stand for three days, and it will be fit for use.-G. E. MILLER. [5545.]-WHITE POLISH FOR LIGHT WOOD.White (bleached) shellac, 8oz.; white gum benzoine, loz.; gum sandarach, Joz.; methylated spirit of wine, or naphtha, 1 pint; dissolve.-BASIL. [5519.]-CAM.-Draw the line A B and cross it at right angles with the line C D, and from M the centre draw the circle E F G, and divide it into any number of equal parts, say sixteen. Draw lines from the centre through these divisions and extend them beyond the circumference; then make O B equal to the required travel, and R S equal to the required curve of the bobbin; GREATEST B divide these curves into the same number of equal parts as EF G, or eight each. Then draw straight lines from these divisions across the line BO, and take the distance from M, the centre, to the first of these divisions on the line O B, and lay it off on the first radius on each side of the centre line; do the same with the other divisions, and lay them off on the other radii, then draw the curved line AO through them and it will be the shape of the cam required.-VALVE. [5552.]-THE SLIDE-RULE is used for performing quickly a variety of arithmetical operations, also for gauging and mensuration of nearly every kind. Lloyd's sliding rule is explained in a little pamphlet sold for 6d., by J. T. Allen, bookseller, Frome.-T. W. BOORD. [5552.]-THE SLIDE-RULE.-The "uses" to which the slide in carpenters' rules can be put, and "the way of working it," are too many and various to answer in this place, for it will solve almost any arithmetical question. I recommend S. Shirtcliff strongly to study the instrument at once with a good work on the subject; it is not difficult to learn, and well repays the trouble. For books on the slide-rule I refer him to answer 5129, page 117 of the present volume; and in addition, Bayley's is the on and is full of useful matter, even if you do not use the rule at all.-Q. YORKE. [5557.]-CURVATURE OF THE RAINBOW.-Any given colour of the rainbow is caused by the impression made upon the eye of the observer by the rain-drops, which occupy a cone, brightest at its surface, having the eye as its apex, and which all appear of the colour in question. Hence the radius of curvature of the bow cannot properly be estimated except by angular measurement, and that is the semi-vertical angle of the cone of coloured light. Its extreme value for the red rays is 42 2; for the violet rays it is 40 17. The axis of the cone of coloured light is parallel to the direction of the sun's rays.-O. F. [5563.]-OX GALL:-The following recipe is given in Vol. IX., p. 387:-Take a gall fresh from the ox, put it in a basin, and let it stand all night to settle; pour it off from the sediment into a clean earthen vessel, and place in a saucepan of boiling water over the fire, taking care that no water gets in. When quite thick, pour it out in a plate and place before the fire to evaporate. When it is as dry as possible, put it into small pots and tie down. It will keep good for years. When wanted for use, dissolve a portion the size of a pea in a tablespoonful of water.-H. [5563.]-OX GALL.-The following is slightly altered from Fownes's "Chemistry," 10th edition:-Evaporate the ox gall to dryness in a water bath; treat with alcohol (pure if for medicinal, methylated if for manufacturing purposes); an insoluble jelly of mucus is precipitated. To deprive the alcoholic solution of the colouring matter, digest it with animal charcoal, or precipitate by means of baryta-water; filter and distil off the spirit, unless the latter be wanted mixed with the ox gall for any subsequent combinations. If G. Pemberton wishes for simply purified ox gall, the above process will suffice. Should he wish for pure bile, let him either apply to the above named work, or write again.-BASIL. [5563.]-OX GALL.-There is an article on this subject in an American paper, in which, for clarifying, the writer recommends as follows:-The ox gall is first boiled and carefully skimmed; to every pint add loz. finely powdered alum; boil until the mixture is perfect; then let it cool; then take the same quantity of ox gall boiled and skimmed as above, and add 1oz. common salt. It is then left to settle for two or three weeks, decanted, and the two preparations mixed together, which precipitates the cholesterine. It can then be used in painting for the finest miniatures and water-colours. H. G. [5564.] WATERPROOFING SOLES. -Make the soles perfectly clean and dry outside; then paint them well with the best Stockholm tar, medium consistency; when perfectly dry,repeat with another coat if the leather continues to absorb it freely. After wearing a short time, give another coat in the same manner over the parts most worn. This method also adds warmth and durability to the soles when carefully attended to while they are new, both for children and adults.-ANON. [5564.]-WATERPROOFING SOLES.-Let a "Leeds Subscriber" apply a coat of gum copal varnish on the soles of his shoes, and repeat it as it dries until the pores of the leather are filled, and the surface shines like polished mahogany, which he will find makes the soles perfectly waterproof, and also causes them to last three times as long as ordinary soles.-GEO. VALENTINE. [5564.]-WATERPROOFING SOLES.-I prefer a preparation of tar, called American fluid, and sold by Barclay and Sons, Farringdon-street. My country sporting friends use beef-suet and zent's-foot oil, well rubbed in and dried. There is a preparation "Dubbin," which is said to be good.-ENGRAVER. 5564.]-WATERPROOFING SOLES.-Take of neat'sfoot oil 8oz., paraffine oil 2oz.; mix, and apply with a sponge, the leather being previously well dried.Proved.-T. N. [5565.]-LEAD POISONING.-Use warm baths and a milk diet; shred white onions, and bake them gently in an earthen vessel till they are soft. Spread a thick plaster of this, and apply it to the benumbed parts. -T. N. [5565. [-LEAD POISONING.-M. Didier, a red lead manufacturer in France has discovered that the use of milk with their meals preserves his workmen from lead diseases. He compels each man to take a litre (nearly two pints) per day. Perhaps the constant use of milk would restore the workman mentioned by your correspondent T. O'Brien.-F. H. [5565.]-LEAD POISONING.-I have heard of a method of eliminating lead from the system, as practised by a medical man named Caplin, favourally spoken of. I understand that he has published a pamphlet detailing his method of procedure, which may be procured through any bookseller. In my time I have employed many polishers, and have invariably found that those who were scrupulously clean in their habits escaped, and that the dirty ones suffered more or less severely.MEUNIER. [5567.]-GORE'S FURNACE.-In reply to "Student," the inventor's address is 50, Islington-row, Birmingham. -BEN. G. [5584.]-PIANO-WIRE.-See letter on piano-strings, by "Harmonious Blacksmith." length of stroke, 14ft.; number of boilers, 4; furnaces for ditto, 40; horse-power, 1,000; diameter of paddle. wheels, 56ft. Screw-engines:-Number of cylinders, 4; weight of ditto (each) 30 tons; diameter of ditto, 84in.; length of stroke, 4ft.; number of boilers, 6; furnaces for ditto, 72; diameter of screw, 24ft.; number of blades to ditto, 4; length of screw-shaft, 150ft.; weight of ditto, about 60 tons; horse-power, 1,600; weight of ship, engines, &c., as at its launching, 12,000 tons; immersion of this weight, 15ft. 6in.; ordinary light draught, 20ft. Quantity of coal which can be carried for voyages, 11,379 tons; anchors, 10; weight of ditto, cables, &c., 253 tons.-G. MYERS. [5595.]-GREAT EASTERN.-Length 692ft.; breadth 831t. across paddle-boxes 144ft; depth 58ft.; burthen 25,000 tons; draught of water 30ft.; combined steam power 8,000 horses.-AB INITIO. [5597.]-POLARISCOPE.-" A. H." having procured his prisms, the price for which should not, I think, exceed 10s. or 11s., should fit one into a tube which should fit smoothly into a collar exactly fitting his stageaperture. He might most likely contrive that this collar should fit into the place of the diaphragm plate. This is the polarizer. A precisely similar fitting, excepting as regards size, will serve for the analyzer, and should be so arranged that the screw of its collar should go into the lower end of the microscope body, the lower end of the analyzer being provided with a female I have it in mind to forward a short article on screw to receive the male screw of the objective. the polariscope in relation to microscopes shortly. P.S.-As there appears to be another contributer with the same initials as myself, I will in future sign myself.-H. P., H. [5607.]-GUANO.-This manure was first brought to Europe by Humboldt in 1804. Its importation to this country began about 1841; by whom I know not.-H. U. [5611.]-STARCH.-The mark "Thomas" speaks of, is, in some form or other, common to all, or nearly all, starch, and distinguishes the Lilum" point. The precise nature of the markings, which are so commonly seen on starches, and are so seldom correctly given in engravings, is perhaps not yet known, and it is not easy to give anything like a short resume of present knowledge upon the subject. The starch granule or corpuscle may, I think, be regarded as a single vesicle or cell containing a semi-fluid mass of about the consistency of blanc mange. Probably the concentric markings around the hilum mark the boundary between successive inclements in the cell, or it is possible that they may be only plaits or folds in the membrane of the cell wall. If "Thomas" will mount a slide of starch-say maize (Brown & Polson of the trade)-in tolerably thick balsam, without the application of heat, and immediately observe it under a high power, he will gain a little information relative to the nature of the hilum. He may profitably follow this by a careful study of the appearances the same starch presents in water, glycerine, and glycerine jelly; whilst a slide mounted in weak spirit and water, with a little magenta dye, will enable him to trace the various concentric marks to his heart's content.-H. P. H. [5616.]-BLEACHING BONE.-Bones are generally bleached by first boiling in water and then exposing them to the sun (under glass). When the article is finished it is soaked in turpentine for a day, boiled for an hour in water, and polished with whiting and water on a woollen rag, or with slaked lime wetted to a paste, and applied with a woollen cloth.-H. U. [5627.]-FASTENING LEATHER BANDS.-Dissolve Nelson's patent opaque gelatine in strong acetic acid (over a fire) until about the consistency of honey. Paste it on to the splices with a table knife while quite hot. Lose no time in applying the parted surfaces to each other; rub them well together with the face of a hammer, so as to squeeze out the superfluous solution. If the thin edges have a tendency to turn up, put on a weight. In less than an hour the joint will be as strong as the solid leather. The splices should not be less than 5in. long, and carefully cut. For that purpose I have found a joiner's smoothing plane the most suitable. If the "band " is in a position where the "rubbing cannot be adopted, place the splice between two flat pieces of wood and put on a cramp hand-screw.-BROTHER TED. [5627.]-FASTENING LEATHER BANDS.-Let “A Novice" try shellac 1 oz., methylated spirit oz., digest in a warm place.-A. B. wide and either 11" or 7" long, i.e., from back to front. The slides should lie with their narrow ends towards the front of the drawer, and each rank should be divided from the other by a narrow strip of wood. Neither cedar or deal must on any account be allowed to form part of the cabinet; at any rate of its interior. The sketch given will show "Rhus Cotenus" how to construct a drawer. The size and shape of the "chest" are of secondary importance. A very good bed is that of a bookcase on a small scale, the drawers being shat in by either glass or wooden doors. If enough of our readers are interested in the matter, I shall be pleased to give a few notions on the arrangement of a cabinet.-H. P. H. QUERIES. [5646.]-JUPITER.-Having observed some peculiar dark markings upon the lower belt of Jupiter, as shown in diagrams, I have directed the attention of other amateur observers to them, but we cannot make out what they are, and why they should always appear in about the same position upon the planet's belt, he revolving on his axis once in about ten hours. Perhaps, through the medium of your valuable paper, some one would be kind enough to give us a little information as to what they are, and why they should always appear in about the same position, and what gives the faint chocolate colouring to the belts? I would just observe my observations were made with a Cook's 4in. equatorially mounted, and a Ray's 3ğin. altazimuth, both inverting eyepieces.-SERPENTIS. FIG. 2 Fig. 1. Time 9h. 35m., Nov. 10th, 1870, broad belt slightly coloured chocolate, O. G. 3gin., eyepiece 90 and 150 diameter. Fig. 2. Time 10h. 25m., Nov. 1st, 1870, broad belt chocolate colour, O. G. 4in., eyepiece 120 and 200. exerted by a 101b. weight falling from a height of 80ft.? [5647.)-RULE WANTED.-What is the force in pounds FRED ROE. [5648.)-RULE MARKING.-What is the best way to mark a foot rule (steel) with divisions of inches, subdivided by 50ths, 20ths and 10ths? The steel straight another of 50ths, and another of 100ths. I want each edges, sold by Lloyd, are divided into one inch of 10ths. inch divided in this manner.-FRED ROE. [5649.]-ELECTRIC SPARK.-Would some correspondent kindly inform me what length of a spark I ought to obtain from a coil 9in. long, diameter of core in., the primary coil containing 1lb. of No. 14 cottoncovered wire, the secondary 11b. 36 cotton-covered wire, worked with two Bunsen cells, 4in. high, the condenser to contain 1lb of foil. Would it work better with other sized cells and condenser, if so what size?-SCOTY. [5650.]-ORGAN BUILDING.-I am exceedingly glad to see Adept " again, and so is more than one about here (Longton). May I ask whether an organ builder would construct an organ as follows:-1. Wind chest, &c., for an organ of, say, seven stops, but with only two stops supplied; the others to be added from time to time as money is forthcoming. 2. Two manuals, and constructed so that a third might be added at any future time if required. 3. Swell, with wind chest, &c., for say five stops and only two supplied, as 1. 4. Pedals and one row of pipes. 5. Bellows sufficient for the organ when completed, and to be blown by water power. Organ to be kept in as little space as possible, and large be about the difference in the cost of an organ as above, pipes to lie on the ground out of the way. What would and one complete at once, excluding the water blower in not wasted on case? each case-workmanship of best quality, and money What would be the minimum distance from back to front?-JOHN KING. aquarium by giving the wood bottom (horoughly dried [5630.]-AQUARIUM.-"Neptune" will improve his first) five or six coats of gold size, allowing each coat to harden before applying the next; or, better still, procure a piece of strong crown or sheet-glass, cut to easily 15651.]-CHUCK FOR CYLINDER.-Many thanks to fit the bottom of his tank, and carefully fasten it with a "J. K. P." and "Tometer" for answer to query 5529, cement composed of white lead and red lead, an equal but I should have said it was a solid cylinder of metal, weight of each worked to the consistency of putty with and perhaps if I say how I go about turning it their a little gold size. This must be thoroughly dry before answers will help others as well as myself. In the first the water, &c., is put into the aquarium. The bottom of place, my lathe is a simple affair, without faceplate, an aquarium should be always made of slate, not less only used for turning small articles out of round steel than lin. in thickness. This is strong, does not warp or and iron, but occasionally I have to turn more cominjure the water, and is quite water-tight. The water in plicated articles. I screw a piece of wood on the mandrel at all; in fact, improves the longer it is kept in use. It a properly managed aquarium does not require changing head, and turn it true, then I bore a hole in it as large due regard is paid to the balance of animal and vege- it an iron ring, so as to hold it tight; then I turn it on as I wish, and saw it down so as to make a sort of dog chuck; then I put in the piece of metal and wedge over table life, each consumes the waste matter given off from the side and drills it &c., then I take it out and put it on the other, and lives and thrives thereby. For the proper kind of plants and their management "Neptune" is re- a piece of paper (on which I have made with rule and ferred to reply No. 4350, in No. 270 of this journal.compasses, if I want to turn it on four sides, a square, or three sides a triangle and so on), and mark it, then get the mark in the middle and turn it and drill it as before, and soon. The only objection I have is that it wears loose, and then I have to make another wooden chuck. If I knew what sort of iron chuck to make it would be useful for other things.-GE. Ss. T. G. [5593.]-OCTAVE COUPLER.- For this mechanism in the organ see the letters of "Adept " in Nos. 223 and 224, Vol. IX. I do not think it can be adapted to [5641.]-CABINET.-The best form of cabinet for an harmonium; in fact, I do not see its necessity or microscopic slides is that of a small chest of drawers. utility in such an instrument.-S. A. R. 121⁄2 OUTSIDE 34 [5652.]-BRICK MAKING.-Can any of your readers inform me if the brick-making machine, p. 56, has been tried for making tire bricks; if so, with what result?BEN. G. [5653.)-MARINE SOAP.-I would feel greatly obliged if any correspondent would favour me with directions for making marine soap.-F. C. S. [5595.]-GREAT EASTERN.-The following are the principal facts connected with this wonderful ship:Length over all, 692ft.; breadth, 83ft.; ditto across paddle-boxes, 120ft.; depth from deck to keel, 60ft; number of water-tight compartments, 12; ditto partial, 7; width of space between the two skins of ship, 21t. 10in.; length of forecastle, 1401t.; height of ditto, 8ft.; ditto saloon on lower deck, 13ft. 8in.; number of saloons, 5; height of saloons on upper deck, 12ft.; number of ditto, 5; length of upper saloons, 70ft.; ditto lower, 60; thickness of iron plates in keel, lin.; ditto inner and outer skins, in.; ditto bulkheads, in.; ditto iron deck, jin. Power of paddle-engines: Number of cylinders, 4; diameter of ditto, 74in.; weight of ditto (each) 26 tons; Each drawer should be about g" deep, 121" clear inside OTHERS.-I have a large organ with 14 steps in the great 13% INCHES 122 OUTSIDE [5654.] CHEAP AIR PUMP. Will some correspondent describe a cheap air pump, paying especial attention to the valves ?-C. H. H. [5655.]-OPEN PEDAL FIPES.-TO" ADEPT" AND |