cess after the sketch of B, the machine will do its work as well as ever, and in many cases better.-JACK OF ALL TRADES. [5082.]-NORTH POLAR STAR AND ALCAR.-The earth's pole describes a circle in about 25,000 years, which has for ages been bringing it nearer to the a of Ursa Minor, and some time in next century it will be within, I believe, half a degree; but Mr. Proctor can doubtless tell the exact minimum, and in what year it will occur. Till then our pole star is more and more useful; but to the ancients it could hardly be called a pole star; and our hemisphere has not the advantage of one so bright or so near the axis in one century out of fifty. The last that at all resembled it was a Draconis, about Moses's time, and that neither so bright nor so polar. With regard to "Jack by the middle horse," or Alcar, I never was aware of his existence till, at 18 years old, I was struck by his appearance immediately after crossing the Strait of Dover, and in France used to see him constantly. star-gazer, I have never once, with the naked eye, made In this country, though a frequent him out. By the way, the conversion of the tail stars into horses of the wain or plough, seems very odd treatment of Ursa Major, as it makes them constantly dragged backwards thereby instead of dragging it. E. L. G. [5105.]-PROBLEM-METRICAL WEIGHTS.-Mr. with four of the right weights he must weigh further than with his five; and with 12 he must, instead of 4005, weigh 265720.E. L. G. Lines decides a great deal too fast. [5105.] PROBLEM METRICAL "Comus" is quite right.-E. L. G. WEIGHTS. [5106.]-PROBLEM GLOBE CONSTRUCTION. The meaning of being "built of pieces all similar and the shortest possible," was meant to be that it could not be built of shorter ones all similar. "O. F." is right as to their number, but the 120 from the dodecahedron that he says "will not be so short," are identically the same pieces. He does not, however, give "the angular measures of one," that is, the means of constructing itthe working drawing-which, I should have added, must be obtained in one diagram of not more than a dozen lines and arcs. A workman can make nothing of the mere statement that the three angles on the sphere will be 90°, 60°, and 36. He must have the pattern of each plane face.-E. L. G. In [5114.]-GLANDERS.-The symptoms of glanders are -1st. A discharge of glairy matter from the nostrils, and more frequently from the left than the right. 2nd. A swelling of the glands under the jaw, and generally on the side corresponding with the affected nostril. other respects, the animal is generally in good health, and also in good condition. Sometimes the glanders is accompanied by a disorder of the skin named farcy, and then the horse's health is generally affected. Glanders has been divided into two stages, named the acute and chronic, or the first and second stage. The first stage is generally attended with cancerous ulceration on the face, the lips, or the neck, with painful swelling on dif ferent parts; the swelling sometimes appearing like a corded vein. The acute glanders destroys the animal in a short time, or else makes him such a pitiable object that the owner is generally induced to have him poleaxed. The second stage of glanders is marked by ulceration within the nostrils; the matter is in larger quantity, and more glutinous and sticking about the margin of the nostrils, and also about the upper lip, and zenerally obstructing the passage of air, so that the horse makes a snuffling noise in breathing, and sometimes the matter is streaked with blood, and the animal also bleeds from the nostrils when working. The chronic glanders is generally very mild at first, and some horses, when taken care of, will last in working order for years.— KING. handle to lift it by, together with a proportionate Don't Know," I think if he follows the advice of "George spondents-viz., J. Moseley and "Amateur Workshop," [5195.] ZOETROPE. -Depth of cylinder 7-125in., mode of turning it with a model engine: turn a through a series of quartzose rocks, with here and there [5204.]-INDIAN COINS.-A "chuckrum "is a coin with Newman's photographic varnish, then paint as you to assist "Cuthbert" in his persevering attempts to [5238.]-ANASTATIC PRINTING.-With every desire achieve success in this art, I must express an opinion that the result, however excellent, will not be worth [5140.]-MECHANICS.-I strongly recommend to Sons (now Vincent Brooks) some large anatomical plates the time and trouble. I have seen at Messrs. Day and "C. G. W." Tait's "Mechanical Philosophy" (Long- (6ft. in length) printed from zine; but they were done by mans, 10s. 6d.).—OSA. [5151.]-SOFTENING TONE OF HARMONIUM.-drawn on the zinc with lithographic ink and finely what is called, I think, " zincography." The subject is "R.E. G." can soften the tone of his harmonium by having powdered rosin dusted over the plate. The superfluous the reeds filed a shade thinner, afterwards retuned. The cheapest way would be to put a layer of wadding action of sulphuric acid, until the lines of the picture, rosin being brushed off, the plate is submitted to the below the keys, along the top of the touch-springs. The which are protected by the rosin, stand up sufficiently more wadding the softer the tone. tone would be the sweetest by the former method.-production of a picture is required, is to lay the engravThe quality of high to print from. Another method, when an exact reORGANIST. ing to be copied on a board and sponge it over with dilute nitric acid. When the acid is absorbed an inked the lines of the engraving. The picture is then laid on rolled is passed over, which only deposits "colour" on the zinc plate and submitted to pressure for the purpose of transferring the ink. When this is accomplished submitted to the action of sulphuric acid till the parts the zinc is covered with powdered rosiu as before, and not wanted are eaten away. As a general rule the plates tions not required. I do not imagine zincography is are gone overwith a graver afterwards to remove the pormuch used nowadays, as engravings and lithographs effects by the photo-lithographic process, excellent can now be reproduced inore readily and with better specimens of which may be seen in recent numbers of Strasburg Cathedrals, &c.-SAUL RYMEA. the Building News, e. g., Trajan's Arch, Antwerp and [5162.]-CONDENSING ENGINE.-In "Novice," he would gain no advantage by converting answer to his high-pressure cylinder into a low-pressure one, inasmuch as the cylinder which he is now working is fin. less than the old one he has taken out; if it was a 10horse-power nominal, therefore to put a condenser to it could not in any way assist him to economize the power or water. It appears that his chief object is to economize water. To do this effectually he must aim at saving steam. If he can't put his engine to work more expansively, he must put in a bigger cylinder to the present engine, and cut the steam off sooner. This will enable him to work the steam up better in the cylinder, by propelling the machinery to its last impelling force. The chief object must be to reduce the terminal pressure in the cylinder, then he will not only save steam but water.-E. MALBON. [5241.]-GILDING SILVER CHAIN.-Probably the [5242.]-SILKWORMS.-Being unable to give "Silk- [5168.]-TINNING.-The scoured sheets are dipped, into a solution of oz. of sal-ammoniac to 3lb. of water after which they are plunged quickly and frequently into the bath of tinning composition already prepared in the cauldron, care being taken to scrape the places not perfectly tinned. After these precautions, the sheets are drained and dried, having been previously shaken for the purpose of cleaning off the superabundant composition which would otherwise cling to the edges and ends of the sheets or pipes. The above composition is of tried solidity, and may be easily extended over surfaces of any length. The length of the iron sheets intended for tinning may be 7ft., and the width in any proportion. [5243.]—RUPTURED FEED PIPE.-Let" E. N." take With regard to pipes of the same length in a single a piece of sheet-iron and bend it to his pipe. Spread piece, they may be soldered with copper, a far more solid soldering than brass, and which does not make some red and white lead mixed upon any thickness or ridge. Also tinning tacks, nails, &c.some calico or canvas, and pass it be. The workman, having previously made the surfaces of tween the sheet-iron and pipe. Make the articles clean from rust or other oxide, by pickling two, three, or more according to the rupture, of ring cramps around it, bolt up, them or putting them into sulphuric, muriatic, or nitric and all will go right.-JACK OF ALL TRADES. acid diluted with water, as usual, and washing them well afterwards in water, puts them int› a gallon bottle, having an oval body, a narrow neck, and a stone ΩΠ [5245.] - POWER FOR CIRCULAR SAW.-A two horse- [5245.]-POWER FOR CIRCULAR SAW.-I cannot do better than give Frank Chessell the result of my experience with small circular saws, viz.-I have found Sin. circular saw may be driven capable of cutting short that with a well-constructed foot-treadle machine, an lengths of timber about 2in. in thickness. A saw of 12in. or 15in. diameter will require the power of two men applied by means of a hand-wheel of about 6ft. diameter, from which a band is taken to small pulley on the saw spindle. This arrangement is equal to sawing hardwood scantling about 3in. thickness. I have found a saw 18in. diameter with this power will cut about 7in. in thickness. A BA easily driven by means of a 24 h. p. steam engine, and 24in. diameter requires about 4 h.p. steam engine and will cut about 9in. thickness. I have had all the above in further particulars if required.-B. B. operation from time to time and shall be happy to give [5250.]-THE VIOLIN.-If "R. T." has time and acoustics. Let a cord, say four or five feet of catgut, be ments, he will obtain, a clear idea of the meaning of opportunity to prosecute the following simple experithe term nodal line, a term belonging to the science of tightly stretched, in a horizontal position, across two supports so that it may be free to vibrate. If a violin bow be then drawn across the portion between the supports, (which portion only will be referred to when the word cord is used hereafter), or it be sharply plucked, it will vibrate throughout its whole length, (Fig. 1). Now let a "bridge" be placed against a point, FIG.I Both parts will be thrown into vibration thus: FIG. 2 the situation of the bridge,and the portion a b of the string termed (c d), separated by a point, e, which is at rest. This being divided into two ventral segments, as they are point is called a node, and its existence may be shown by placing three bent pieces of paper astride at the points d, e, and exciting; those at c and d will at once be jerked off, while that ate will remain unmoved. By moving the bridge one-fourth of the way along the cord, and exciting, the whole length will be divided into four segments, thus: the points a, b, being the nodes or FIG. 3 and c being the situation of the bridge. When plates of points of rest, which may be made manifest as before. strings, so that in some parts we find nodal lines, or vibrations interfere with one another, as in the case of glass or metal are thrown into vibration, we find that the curves, where the vibration seems altogether unfelt, plate of glass or metal should be fixed horizontally by its while other parts correspond to ventral segments. A evenly over the plate, and it should then be excited by centre to a stand. Fine sand should then be scattered drawing a violin bow across its edge. The sand will be others in lines, these lines crossing each other, and shaken off certain portions, and will accumulate on curving, and forming often beautiful and complicated the lines on which the sand accumulates are nodal figures. The portions left bare are the ventral segments, lines where there is no vibration; and, I presume, a forming a certain determinate shape. It is this which is referred to in the extract from Savart.-A. J. SMART. nodal system is a number of these lines together, [5252.]-WATER POWER.-Everything else being the therefore the one to be preferred for economy to an same, an overshot wheel is twice as powerful, and is undershot wheel. The stream mentioned will be equal the rate of 3ft. per second. But this would be a very to 55 or 56 h p., if an overshot-wheel be used, moving at large size indeed. The shaft should be an 8 or 10in. one. G. W. D. G. and, I am nearly certain, not an Anglo-Gallic. "Delta's" [5253.]-SILVER COIN.-It is not an English coin description is very clear; and I think that it must be Beginner," p. 120, of the last number.-HENRY W.Hɛxsome Continental sterling, like those of "The Baldred FREY, M.N.S., &c., &c. [5254.]-PARCHMENT SIZE.-"Robinson Crusoe" will find the following method answer his purpose:After making the size allow it to cool; then take a little plaster of Paris, and mix it thin, and run it on the top time, and easily broken into at any time.-M. P. to form a light crast. It will keep for any length of limate and a few drops either of carbolic acid or of any of inferior tenacity; try a first-rate dealer's strings [5260.]-PLANING SCALEBOARD.-"Brother Chip," I presume, wishes a description of cutting scale board by a scale board machine, which is mostly used by steam or horse-wheel power. To describe it fully would require drawing, which I have not time to give. It is simply an inverted plane about 10ft. long by 2ft. wide, with an iron 16in. wide, and placed at half-pitch, or 45 degrees; the same bed or plane made to move backwards or forwards by a chain-and-clutch motion on a very strong frame about 4ft. high, to allow the leaf or brand when cut to come out in curl, and received by the man attending the machine. By purchasing a few leaves you could see one at work. There are but few scaleboard cutters now, and they are mostly in Southwark. The best I knew was Attens in Cumberland-street, Curtain-road.-CABINETMAKER. [5268.)-DANIELL'S BATTERY."Jacobus " сяц make his Daniell's cells answer by cutting his cells down to 4in.; he will then be able to get porous cells to suit his cylinders of copper. The zincs I should advise to be supported by discs of wood turned with a shoulder to fit the porous cells, and well varnished with shellac or sealing-wax varnish. The following sketch will assist in rendering the matter clearer: A them three times, and he hoped he might live till the [5274.]-POROUS porous cells by rolling a piece of card round and glueing [5274.]-POROUS CELLS.-" Robinson Crusoe" may [5275.]-LAND SURVEYING.-Fig. 1 is merely an illustration of the way a line in the shape of the letter S is measured, and is accomplished by running offsets or short lines of different lengths at right angles to a straight line, the places where offsets are taken being measured. The figures in the field book of 5183 -A the disc of varnished wood, B the zinc rod fixed with thick varnish or cement irto the centre of A. Cardboard may be used as a porous cell, but brown paper is better. Leather may be used. Plaster of Paris makes the best home-made porous cells, but requires a nicely. made mould and plug to work properly. Worsted is a somewhat better insulator than cotton, but if it is only wound on the coil side of the wire, stand as 52 0; this means that at 49 links a rightit will be found wanting. The fourth question is asked on the assumption of the sizes being given. There is no statement of gauges; the primary should be No. 16 or 12; the secondary, No. 36 copper, covered with silk. The quantities given will do.-THOS. HARDING. [5263.]-DANIELL'S BATTERY.-The copper cylinders are too small; it is a mistake to narrow them, for really the larger the better in many respects. 2. Cardboard or brown paper will answer for porous diaphragms, but would be wretchedly bad economy. Nothing is so good or so cheap in the end as good porous earthenware. 8. Worsted is a very bad insulating material, because it occupies too much space. 4. The wires would make at best only a poor coil, for the proper construction of which directions have been given times out of number.-SIGMA. [5266.] POLISHING MOTHER-OF-PEARL. Go over it with pumice stone finely powdered (first washed to separate the impurities and dirt) with which you may polish it very smooth; then apply putty-powder and water by means of a rubber made of hat, which will prodace a fine gloss and good colour. Copied from a recipe by G. S. CHAPERTIN. [5268.] - POLISHING SMALL BRASSWORK.-It needs nothing to polish it in a shaking barrel, but if the sand or any grit get in, if it is only whiting it will keep them black.-JACK OF ALL TRADES. [5268.]-POLISHING SMALL BRASSWORK.-The articles to be polished should be shaken by themselves for a short time; then some greasy parings of leather, called "mosings," should be put in the band with them. After they have been shaken smooth, the greasy "mosings" should be removed and clean ones put in, and the shaking continued until they are sufficiently bright. I know of no plan of preserving the colour except lacquering. This is easily done, but great care must be taken that they are perfectly free from grease.-D. CLARKE. it (sec. 5), are placed as 549 520, when they should 549 angle is measured at the left of the straight line, and at [5276.]-SILVER COINS.-No. 1, I believe, of William [5276.]-SILVER COINS.-In reply to "The Baldred Beginner." No. 1 is a silver penny or sterling of Guido, Bishop of Cambray, from 1997 to 1306 A.D. It has observe: Full face bust, GVIDO EPISCOPVS. Reverse: A cross, with three pellets in each angle. Legend: CAMERACENSIS. Rare. No. 2 is a coin of some Duke of Brabant of about the same period. The obverse inscription appears to be MONETA ANDWER. That on the reverse, DVX BRABANTIE.-HENRY W. HENFREY. [5277.)-MODEL YACHT.-Dissolve the best black sealing wax in methylated spirit, and paint with it. JACK OF ALL TRADES. [5277.]-MODEL YACHT. -Before varnishing the spar, dip in or paint with Brunswick black; may be bought at any chemists.-B. G. [5280.]-MEASURING," Erc.-1. To strike out the oval given, divide its height into eight parts; strike the upper semicircle with a radius of three. From its two extremities as centres, strike the sides with radii of six; lastly, the lower curve with radius 1, which will touch them. The area I have found to be 36-1633 of the squares of the above units, or 1-220th more than the square of the width. 2. The true content of "Country Gabie's" ballast heap is eighteen'cube yards and two [5272.]-OLD COIN.-In reply to "Pierre," p. 120, his coin is what is called a St. Patrick's farthing. Obverse, under a crown, David playing on a harp. Legend: FLOREAT REX (May the king flourish). Reverse, a figure of St. Patrick, standing, mitred, with a double or metropolitan cross in his left hand, and stretching out his right over a cockatrice, and other venomous animals; behind him, a church. Legend: QVIESCAT PLEBS (May the people remain quiet). This farthing and a somewhat similar halfpenny, both called St. Patrick's, are supposed to have been struck in Ireland, during the reign of Charles I., by the rebels, who pretended to act under the king's authority. The crown on the obverse is of brass. On the reverse, St. Patrick is said to be re-thirds. The defective mode of measurement described presented as if driving the venomous creatures out of the church, alluding to the Protestants, called in an act of the rebels, the Puritanical-the malignant party. Not common; worth several shillings.-HENRY W. HENFREY, M.N.S., &c. [5272.1-OLD COIN.-It is called a St. Patrick's farthing, and was struck by order of the General Assembly (of rebels) at Kilkenny in 1612, "in honour of St. Patrick and of their new order of Knighthood." It is thus described by Simon, in his essay on Irish Coins: "The farthing has likewise on one side a king crowned and playing upon a harp; a crown of copper or brass over it, and round Floreat Rex.' Rev.: St. Patrick mitred, holding in his left hand a double or metropolitan cross, a church behind him, and stretching out his right hand over a parcel of serpents and other venomous creatures, as if driving them out of the church, and alluding to the Protestants, called in the before-mentioned act the Puritanical-the malignant party. Inscription: Quiescat Plebs."-D. T. BATTY. (H. G. Plant and "Bernardin" have also answered this query.] [5213.]-COINS.-No. 1 is a gold solidus of the Roman Emperor Constantins II., the son of Constantine the Great and Fausta. He was sole emperor from 350 A.D. to 361 A.D. The coin has-obverse: bust to right, diademed; legend, FL. IVL. CONSTANTIVS. PERP. AVG. (Flavius Julius Constantius Perpetuus Augustus); reverse: two figures seated, holding a shield, on which is inscribed VOT.XXX. MVLT. XXXX. This refers to the vows made by the emperors every ten years: and the inscription is supposed to mean that he had made gives 18 and one-third. The four corner-pieces forming [5281.)-HYDROGEN GAS.-If quite pure it displaces [5281.]-HYDROGEN GAS.-In reply to Mr. Hutchinson, the quantity of pure hydrogen gas required to float a body in the air, 1261b. weight, would be 1,458 cube ft. Of course the weight of the balloon would be included in the 1261b. One cubic foot of air, the temperature being 60 degrees Fahr., and the barometer at 30in., weighs 535 grains; and one cubic foot of hydrogen weighs only 37-153 grains, being 14:4 times lighter than air.-JOSEPH BUTCHER. [5281.]-HYDROGEN GAS. 1 == Weight of 1 cubic foot of air = 536.958 grains. [5286.]-FIXING LEAD TUBE TO GLASS DITTO.If the outside diaraster of his two tubes is alike, he could solder a short brass socket to his lead pipe, and fix the glass tube in the socket by means of white lead.PHILOS. [5287.]-IMMERSION LENSES.-The first half of this query has already been answered at least twice within the last few weeks. The immersion lens differs from the dry lens in use by requiring the immersion of its front lens in film of water covering the object. In construction these lenses differ in their corrections been so arranged as to require the refractions of the wall film. The front lens is very thin in the case of an immersion, a fact which those who borrow them may profitably bear in mind. A full answer to H. W. Curtis's second query, "how they are made," would require a treatise. -H. P. Catherine II. No. 2, Danish coin of Christiern V., read [5291.]-COPPER COINS.-No. 1, Russian coin of "Christian V., D. G. DAN.;" No. 3, Danish coin of Frederick VI. No. 4, medal (modern) of the Pope Gregory III. None of any value, except perhaps, the last one, if of a renowned engraver, and in good state of preservation.-BERNARDIN. [5295.]-THE MICROSCOPE.-The neutral tint reflector at 7s. 6d., to which I refer on p. 100, will be more serviceable than the much more expensive lucida. A Kelner's eyepiece is useful with low powers, giving as it does a large flat field, but its definition is far from good. Any microscopist may make his own "neutral tint" by aid of a neutral-tinted piece of glass and a pillbox. The sketch on p. 100 (the reflector is out of position there to show the front) will give an idea as to the mode of fixing the reflector. The angle is about 45". Perhaps a "Poor Microscopist" will repeat his queries respecting the Kelner, if this reply does not meet his wants; the previous questions have escaped my notice. I question whether he will be able to make a good Kelner.-H. P. [5296.]-SULPHATE OF LEAD BATTERY.-The cups are tinned all over. I have tried sheet tin but it does not answer, except for a very short time.-SIGMA. [5297.]-STICKING PAPER TO BRASS.-Use a solution of equal parts of powdered gum dragon and gum arabic in water, to which is added a very small portion of glycerine-about three drops to each ounce of solution.-W. W. [5801.]-SCREW-CUTTING. -"Engineer" should buy Greenwood's book, see advertisement,bottom of first column, p. viii., No. 292. It is generally correct, but there are several mistakes on pp. 67, 68, and 69. As you will probably not have a leading screw either of 2 or 3 threads to the inch, this will not hurt you. I should advise a 2in. screw, but I do not expect you to take my advice.-J. K. P. [5312.]-SCREW-CUTTING LATHE.-I suppose the centre would be about 10 to 11in. apart in "Ignorant's " lathe. The screw would go about half way down the bed in front probably. Perhaps lower if there is not room otherwise over the screw and under the saddle, for the upper half of the nut to rise a sufficient distance. The wheels should be of No. 10 gauge, or 18 teeth per inch diameter.-J. K. P. [5314.]-WENHAM'S BINOCULAR.--The sketch given herewith, will, I hope, enable Hydatid" to fix his prism. He had better place it by some arrangement Fig. 1.-A Field Lens. B Objective. C Prism. D Half [5326.]-FLIGHT OF BIRDS.-" J. R." cannot do [5929.] CHUCK FOR CYLINDER. - Drive your chuck on to a mandrel, or arbor, centred at the ends. You can file some flat places on the projecting ends of the mandrel, for chucking it by on the face-plate, if you have one, but I do not quite understand what you mean by " divide the piece of metal, &."-J. K. P. [5353.]-TRACING PAPER.-Mix together by a gentle heat, loz. of Canada balsam and pint of spirits of tur pentine; with a soft brush spread it over one side of good tissue paper. It dries quickly, is very transparent, and is not greasy, therefore does not stain the object on which it may be placed. From "Enquire Within."A. J. W. (5855.]-MECHANICAL MANIPULATION.-Holtzapffel's "Turning and Mechanical Manipulation: " only 3 volumes published. Vol 1. materials: their differences, choice and preparation; various modes of working them, generally without cutting tools; second thousand, 1846, price 1 guinea. Vol. 2: the principles of construction, action and application of cutting tools used by hand; and also of machines derived from the hand tools; 1846, price (I think) 258. Vol. 3: abrasive and miscellaneous processes which cannot be accomplished with hand tools; 1850, price (I think) 1 guinea. J. K. P. [5366.] CHURCH BELLS.-The three heaviest church bells in England are at Westminster, York, and Oxford. Weight respectively 13 tons 10jcwt., 10 tons 15cwt., and 7 tons 12cwt.-R. E. WAY. [5367.]-BULLET MOULD.-TO "FABER."-The recesses in bullet moulds are "ground" out with a tool called a "cherry," made to the requisite form, the hollows having been first drilled and chipped or filed, as necessary, as near the mark as possible before. hand. For a spherical bullet the cherry is forged as a ball on the end of a slender stem, which usually has at the opposite end a taper square to fit the ordinary hand brace, which is the best thing that gunmakers use for all purposes such as tapping, rimming, and with what they call a "brace chisel" for forming with suitable tools called "grinders " both the shaft and also the heads of all the serew pins and screw nails that they use, and also for turning them into their places when made. The forging of the cherry is first roughed down as near the required size as may be, and is finished to form with a tool made as a ring of steel turned out conical inside to the proper diameter, and with a notch on one side to admit the slender shaft of the cherry, which is worked round and round in the sharp end of the tool till it just drops through. It is then ready for filing with sharp edged grooves over its whole surface, and its application when made is simple enough, the hole for pouring in the melted lead serving for the shaft to work through. When the sides of the mould very nearly meet, the cherry is worked by hand alone, in each half of the mould to destroy ringiness. Other shapes are produced in a similar manner, all depending on the perfection of the tool used.-J. K. P. [5868.]-NUTS FOR MODELS.-TO "FABER."Get from Stanton's, Shoe-laue, some brass wire drawn to the hexagonal form and, drill and tap it, when cut, to the short lengths you require: one of the so-called American three-jaw chucks would be just right for this job.-J. K. P. [5968.]-MODEL ENGINE.-"Faber" may make his nuts in this manner-the way I always make mine. Saw off sections from a piece of brass wire or rod, and drill and tap each piece. Next set up on your lathe a small piece of steel rod, and turn down a short portion (from in. to gin.; according to size of nuts), to form a "nose" upon which he can screw each nut. Face up one side of each piece, and having done that reverse it all, and face up the other side, taking care to get the slide of the rest at the end of its travel, to ensure the same thickness of all. Next saw down a piece of steel between the centres and tap, a length sufficient to screw four or six pieces upon. Having screwed them on, turn the whole as one piece. Throw off the band and place the index into the 60th hole of your 360 circle and by working the top slide the edge of the tool will scribe a line along them. Repeat the operation with the index in the 120, 180, 240 and 300 holes of the circle; then all that remains to be done is to file down carefully to the lines which will give you a true hexagon. All the pieces will have to be returned to the "nose" mentioned above to be bevelled on one side to the ordinary shape. I always use this plan for nuts up to gin. in the tap. I am at present engaged on a locomotive 14in. to the foot, and have had to make a large number of nuts.-G. W. A. [5376.] ELEMENTARY VEGETABLE PHYSIOLOGY.-Professor Balfour's "Oulines of Botany," or Prof. Oliver's little work published by Macmillan, would probably answer "Botanist's " purpose. Probably many readers would like to see a short series on this subject in the MECHANIC, if some botanical friend and the editor could find it convenient.-H. P. [5880.]-LOGARITHMS.-If "T. W. S." gets Wormell's "Arithmetic," 2s. or 3s., Murby and Chambers' "Tables," 3s. 6d., he will find therein full information relating to logarithms.-C. H. W. B. [5389.]-MOULDY BREAD.-"Mould" is a species of fungus, and Mr. Whitham's description of the one he observed, shows conclusively enough that he has lighted upon one of the many varieties of fungi accompanying the decomposition of vegetable substances.H. P. [5402.]-KEEPING WALNUTS.-Put them in a stoneware jar with lid fitting inside the neck. Proved.-T. W. WEBB. QUERIES. [5410.]-CONCERTINA TUNING-I was greatly pleased to see "Amateur Tuner's" able reply to "Concertinist" (4476, p. 66), as I have been looking for infor mation on that subject a long time. Would "Amateur Tuner "help me in following difficulties? I have tuned á patent piano concertina twice, "scale from lowest treble G to top G," following the instructions of a work called "Tuning by Equal Temperament," i. e., the fifths diminished, fourths augmented major, thirds also, and octaves tuned perfect, commencing at middle C. I get all keys in fair tune, till I come to keys of E flat and E major (4 sharps) when the chords become unbearable; also the fifth D A, and one or two other chords in keys of B flat and A major. The work I go by, says the only fifth that will be rather harsh, is A flat, E flat, but I find to my sorrow, after going through the 72 reeds, that there are several fifths bad. If you can give me a scheme for tuning eight keys perfect I shall be grateful. I should (if possible) like the imperfect keys to be four and five flats, ditto sharps, as I seldom use those keys. 2. What sort of metal must I ask for to make reeds yielding a full mellow tone; where procured; and will same metal do for higher as for lower notes ?-J. TAYLOR. [5411.]-NITRATE OF SILVER.-If I dissolve an ounce of silver in nitric acid, how much of the nitrate will it make, and which is the best way to do it ?VIATOR. [5412.]-MAGNETO ELECTRIC MACHINE. TO "SIGMA."-Will "Sigma" kindly be more explicit? What size of wire, and length and diameter of coil will I require for my magneto-electric machine? I have not been able to show any current with my galvanometer when attached to the machine. I have seen a machine no larger than mine lift a few ounces when attached to an electro-magnet. I am afraid it is in the adjustment that I err.-A. SUTHERLAND. [5426.]-CARDBOARD GLOBE.-I wish to construct a globe, 8in. in diameter, of 24 pieces of cardboard, so that each piece shall be equal to 15° of longitude. Can any of my fellow readers tell me how to strike the requisite curve; also, if I divide a hemisphere into 18 equal parts of 5 each, from the equator towards the pole, by what means can I find the exact diameters of each part? An answer will kindly oblige.-HY. J. B. [5427.)-OZOKERIT.-What mineral is ozokerit; where is it found; are the ozokerit candles really made with that mineral?-O. Z. K. [5428.]-PITCH OF TRINIDAD.-Is the pitch of the "Pitch Lake" of Trinidad employed in industry somewhere?-GOLIATII. (5429.]-FLATTING FOR VARNISHED WORK. The panelling in front of the gallery of an old chapel is grained wainscot and varnished; as the woodwork is old, every knot and unevenness shows very badly, [5413.]--ORGAN BUILDING.--Will Mr. Taylor,or some from the cross-light from the upper windows, and from of our organ building friends be kind enough to the light of the gas. Will any of your numerous correlet me know the smallest possible size for a C C C Bour-spondents inform me of a flatting coat over the varnish don? If a block, 4in. by 5in., would do, and how high to make the graining look dead and rich, instead of the moulds should be cut up; or if the block could be glossy, without showing the unevenness of the old I want a flatting that will not go off. I made smaller to speak the C C C note; and also how a har- woodwork? In an octave coupler have seen graining flatted that continued to look rich monic flute stop is constructed? I have had some work done by a how is the C C sharp connected with the tenor C sharp, after some years. the C C sharp being on the roller board ?-T. JONES. painter, but it soon went off glossy.-E. O. S. [5430.]-CALCINED TARTAR.-What is calcined tartar ?-VULCAN. [5414.]-CUTTING CIRCULAR BARS.-Would any brother reader kindly inform me the best means of cutting circular bars for ash pans ?-CHESTER. [5415.]-BANBURY CAKE.-Can any one oblige me with a recipe for a Banbury cake and a sweet biscuit, something similar to the Osborne made by Huntley & Palmer? I do not want to make them to sell.-INQUIRER. [5431.]-BLEACHING WOOLLEN RAGS.-I shall to cost not more than 2d. per lb., by other means than feel obliged by a recipe for bleaching old woollen rags, stoving.-TYRO. dimensions. This flue has been tried for two different [5432.]-STOVE FLUE.-I have a brick flue running [5416.]—DISTRICT SURVEYOR'S EXAMINATION. dimensions, 44in. by 9in. in height, and about 6ft. in from a cellar nearly horizontally (i.e. slightly rising); -Will somebody inform me what are the subjects of ex-length; at the end of which the flue turns at right angles amination issued by the Society of British Architects for the office of district surveyor in London, and if how obtainable and oblige?-SUB-SILENTIO. any honours are obtainable from the above society, and [5417.]-STORM GLASS.-Will some kind reader answer me the following? How to make a storm glass (camphor), with full particulars both of working and making.-SUB-SILENTIO. upwards, to a perpendicular height of 33ft., of the same descriptions of downward-flue stoves, placed in the hall above the cellar, without success; for unless the wind not draw at all. was strong, and in the proper direction, the stoves would I wish to ask the courtesy of some correspondent to inform me, 1st, whether by placing a hot-water apparatus in the hall, heated by a hot-water stove in the cellar beneath, the fine is likely to answer; that is, would the stove draw sufficiently well with the wind in any direction, or in the absence of wind? What description of hot-water apparatus would be best ? 3rd Why did not the downward-flue stoves answer? → HIGHFIELD. [5433.]-ETCHING ON ZINC.-I wish to etch on zine with a galvanic battery. Can "Sigma' or another of your correspondents inform me what solution to use in the vessel wherein is suspended the zine plate to be -F. THOMAS. 2nd. [5418.]-LAMP.-Will some kind reader aid me in the following? I saw an account some time ago in a book, but cannot now lay my hand upon it. "How to make a small lamp producing light enough to tell the time by a watch at night. All that I remember is that spirits of wine was drawn up by a small cotton wick to a piece of platinum which was kept red hot somehow." If someone would help me in this I should be greatly obliged, as I do not want to waste all these dark winter evenings in bed when I might be studying.-INVITA MINERVA. [5419.]-INDIA-RUBBER TIRES FOR BICYCLE.-etched, and what metal to use in the same as an anode? "K. S. N." had a vulcanized india-rubber tire placed on the driving wheel of his bicycle, two flanges of sheet-iron retaining it in its place. At first there was just sufficient room for the wheel to rotate under the fork of the support, but after use for a very short time, the tire began to rub against the fork, and at last it rucked up and jammed the wheel fast, stopping and upsetting the bicycle. K. S. N." desires to know whether this is the invariable result of using india-rubber tires, or whether it is due to the use of one which was too large from the first, or that was improperly fastened to the wheel. He would be glad to know what sized india-rubber tire should be put on a 38in. wheel, and how it should be secured in its place? also if there is any way of contracting a vulcanized india-rubber tire ?-K. S. N. [5434] STRIKING CUTTINGS.-In a treatise on "Optics" I find the following: "In the practice of planting cuttings, the use of blue glass screens is highly advantageous, as the light and heat rays are partly absorbed, whilst the actinic rays pass through and accelerate the development of roots." Is this last assertion correct? Has any correspondent tried it?-SAUL RYMEA. [5435.]-STEREOTYPING.-Will "Leeds" still further mentions? What sort of brush is used; and what are the proportions of size, whiting, and paste? Many querists have asked for information on this subject, but have hitherto failed to obtain satisfactory replies.-SAUL RYMEA. explain this subject by diagrams of the apparatus he [5420.]-TARNISHED SILVER LEAF.-I have some silver leaf which I wish to use on canvas, what I have used tarnishes; can I prevent it, if so, how must I pro--The above sketch represents a train of wheels, the [5436.]-APPLYING AND CONTROLLING POWER. ceed? I have used gold size to put it on.-ONE IN A pinion B making about 500 revolutions to one of A. The Fix. power is applied at A, by means of a spring, and I wish A B [5421.]-MICROSCOPE.-I have a microscope: I believe, it is called the "School of Arts Prize Microscope," price 18s. 6d. I want to know-1st. What are its magnifying powers with the different lenses? 2nd. What is the focal length of the different glasses? 3rd. What glasses should I procure to increase its magnifiying power? 4th. Its condenser is attached to the stage by a movable arm, and as the tube has to be brought very near the object it obstructs the light. How could this be obviated? Could any of your correspondents inform me where I can get a catalogue of mineral collections (priced), and also the names of a few works on minerals, &c., and oblige ?-A SCIENTIFIC NOVICE. [5422.]-SPECULUM GRINDING.-Would Mr. Parkiss kindly inform me if glass discs could be procured of different sizes up to 12in., finished on edge and back, similar to those of Mr. Browning's? I have purchased discs from two different parties, none of which were finished neatly, which I think is essential if the specalum is mounted in an iron cell, especially if the telescope is used as an equatorial.-ANTARES. [5433.]-TURNER'S CEMENT.-Can any of your readers kindly inform me where I can procure a particular sort of cement, suitable to attaching work to a chuck on the lathe, made of a mixture of gutta-percha with other substances? I bought some a few years ago, which was the strongest and most tenacious cement for the purpose I ever met with, from Mr. Kennan, in Dublin, but he does not recollect where he got it.-G. C. C. the speed so that B shall make about 100 revolutions per to know the most simple way of controlling and regulating wheels and a fan, as in the striking portion of a clock, minute. I know this could be done by means of additional but it would, I fancy, be at a great loss of power at B, and this I wish to avoid as much as possible. If you or any of your readers could give me a hint I shall be glad. P. R. W. [5137.)-INTENSITY COIL-Will "Sigma" or any other brother reader kindly let me know what battery power I can use with my intensity coil, so that there may is constructed as follows: The primary wire consists of be no danger, of injuring the secondary wire? The coil 1lb. of No. 16 cotton covered, wound in four layers over a solid iron core, 4in. diameter, which is enclosed in a wooden tube 1-16in. thick. The secondary wire is composed of 8oz. of No. 39 silk-covered wire, wound on in twelve layers, each layer being insulated by one cover of silk well warnished with shellac, and one cover of varnished paper. The wire is also well varnished with shellac. It is the bichromate battery I intend to use; and if the battery power could be given in square inches, that is, the number of square inches of zinc to be exposed to the action of the acid, I would prefer it. I suppose the two carbon plates should be connected together.T. J. O'C. [5424.]-TO" SIGMA."-Should the zines of the manganese battery be amalgamated?-ELECTRON. [5425.]-CURIOUS OCCURRENCE. In the shop where I work are two saws, hanging kindly give me the dimensions of a reel for an intensity [5438.)-REEL FOR COIL.-Will "Inductorium against the wall, as seen in the manner coil, according to his principle, that would hold about. shown by sketch. When they are s in motion-that is, made to sway back-lb. of No. 36; also the size of the iron core and quantity wards and forwards-they keep swaying make the reel, mahogany will do? How is the wire t of primary wire? I suppose if I cannot get ebonite to for a long time. But what is most strange is that, when apparently they would be on the point of stopping, they would instantly renew the swinging, as if some invisible band impelled them onwards They kept up the motion thus, alter nately appearing to stop and renew for upwards of an hour. My fellow workmen and I were so much surprised that I determined to seek a solution to the mys tery through your journal.-GILFS FARRE. be wound in the divisions? Is it to be wound, as when making an ordinary coil, one layer over another, or is the wire to be wound on just as it may chance to go, until the space between the wires composing the core, with the division is filled ? Would it do any harm to fill up shellac varnish, in order to prevent oxidation.-THOMAS J. O'CONNOR. [5439.]-DRYING INDIA RUBBER. I have disolved some india-rubber in coal-tar naphtha, and mixed it with some boiled oil, and I have put it on some canvas. I have also tried india-rubber alone, but they take such a long time to dry. Would some kind reader inform me what to mix with it to make it dry quicker?IN A GREAT FIx. [5440.]-WHEEL CUTTING.-Can any of the readers of the MECHANIC give a description how small oval or elliptical wheels are cut? I have been cutting some for an elliptical cutting frame, but through them not being ent correct the teeth break out when running at a great speed. With one pair oval wheels, and the others round wheels, making two to one, or two and a half to one, or three to one, some very curious figures are produced, differing from any arrangement of round wheels, oither in the elliptical cutting frame, or geometric chuck. All the loops are different and very pleasing to look at.-J. LANE. - (5441.) CABINET-MAKER'S TOOL CHEST.Would "Cabinet-Maker," or some brother reader, kindly give me directions, with your permission, Mr. Editor, through our paper, the way to proceed to make a cabinetmaker's complete tool chest ?-G. S. CHAPERLIN. [5142.-VACUUM.-I wish to obtain a good work on vacuum, and the laws relating thereto, &c. Possibly some of the numerous readers of the MECHANIC may be able to inform me of one. Or a few articles relating to the above placed in your journal may confer as much benefit to other readers as to your humble servant. ONE IN IGNORANCE. [5443.]-AN ECONOMICAL BRICK KILN.-I find your paper of great use to me out here, and get many useful and practical hints from it. May it go on and improve others, while those connected with it prosper in all they undertake. May I beg from some of your masy kind readers and correspondents a plan for a brick and lime kiln, on the most economical principles-the fuel wood, the lime made of oystershells? I have kilns of wood now, but they take so much wood, and wood is very expensive here. It costs me at the rate of 10s. per thousand to burn the bricks. I want something cheap, such as the natives can manage and build.-J. H. A., Lagos, West Africa, September 19, 1870. [5444.]-WROUGHT-IRON BEAMS.-The ends have the marks of a circular saw; they appear to have been cut through while red hot. I should be glad if your correspondents would inform me how the circular saws are kept cool, and what they are made of?—J. M. E. [5445.]-BRASS MELTING. I should be much obliged if Thos. Fletcher would inform me whether old fragments of brass require zinc or lead to be added when re-melted, or a flux of any kind; and also if he would give me a hint as to making moulds to pour the brass into. Would plaster of Paris do for a mould now brass has become unsaleable in small quantities? This information would be valuable to many.-J. M. E. [5146.]-SURFACE CONDENATION.-Could any of the readers of the ENGLISH MECHANIC tell me how much cooling surface is required in a surface condenser for an engine 18in. diameter and 4ft. stroke, making fifteen revolutions per minute, with steam 301b. above atmospheric pressure?-S. C. [5447.] - MUSIC PLATES.-Can any render give information respecting music printing from zinc plates; also of the preparation of the plates ?-ZINC. (5448.)-CARPENTER'S BENCH.-I am about making a bench for carpentry and cabinet work, and shall feel obliged if any reader can inform me whether there are any improvements on the ordinary old fashioned bench I can add.-ALPHA. [5449.]-LATHE QUERY.-I have a Slin. table lathe with drill and centre chucks and wish to know what are not so readily acted on by change of temperature as without success? Yet, moreover, some time ago, I obtained the following information from the French Academy of Science,-viz., "You must first precipitate sulphate of iron with carbonate of ammonia, and then dissolve the precipitate in sulphuric acid, and take care to have a perfect neutral solution." I am at a loss to decipher the above, as it does. not mention quantities, nor how applied. If "Sigma," or any other of your scientific correspondents could plainly instruct me in the above, I should feel extremely obliged; and it would be of infinite value to many more of your correspondents.-J. T. SPENCER. [5472.]-AURORA BOREALIS.-Some of our savants have been trying to prove that the two phenomena-sunspots and the aurora-are connected. I thought that aurora were in one particular like storms-that at one time they appeared on one part of the earth and at other times in other parts of the earth, and more particularly [5458.]-TO "BRIDGETON."-What is meant by placing a prism "parallel to the source of light?" Will in northern latitudes. If they even depended on the number or size of spots on the sun at any particular "Bridgeton" kindly explain this ?-B. A. time, would not the whole globe be affected simultaneously?-STAR-GAZER. [5459.]-CURIOUS CATERPILLAR.- Many thanks to "A. S. C." for his reply to my query. I would now ask him, or any other entomologist amongst our readers, if he can tell me the name of the caterpillar I now attempt to describe. It is fully 3in. long, is covered with a beautiful very soft black fur, which is from in. to 8-16in. or in. long; the fur is greatly like the chenille which used to be in fashion some time ago for ladies' hair-nets. The head is black; there are two tawny-yellow spots on the second segment. These tawny spots are continued along the sides, though, as they get farther down to the tail, they become gradually blended into one another and form a bar of yellow, which extends from the back more than half way down to the belly. This yellow is very remarkable when the caterpillar is curled up; when walking it is not so observable. I have looked over all the books I could find-" Newman's Moths," Wood and Coleman, but can find nothing at all resembling it. It was found feeding on silver-wood, and on this it has for now four weeks boen almost exclusively fed, and seems to be in very good health. A second one I have is not so large; only 2in. or 24in. long. Any one giving the name will greatly oblige.-DERF ERRAC. I am [5460.]-SLIDE-REST.-TO "J. K. P."--Might I ask our most obliging correspondent and authority en lathe construction of a slide-re t for a foot-lathe? I know work, "J. K. P.," if he would some time describe the making drawings is troublesome work, but I am very much tempted to ask him if he would do so. anxious to make a slide-rest for my lathe, but as I live in the country, far from any town where there is a good lathemaker, I cannot see one to examine it. This is my plea for making so large a demand on "J. K. P.'s" good nature. I am not a bad filer. I have a good supply of screw-tools, dies and taps, so that making screws or striking any thread by hand in the lathe would give me no trouble. Also, I can use the hammer and tongs perhaps as well as most amateurs; so that if I had the ground plan to work on, I would not fear of being able to carry it out. My lathe has no leading screw, so it is a simple slide-rest I want.-DERF ERRAC. - [5461.] BULBS. Can any of our horticultural friends inform us how to retard the growth of hyacinths, tulips, and other bulbs, so as to have a long-continued succession, and also how to hasten the growth in order the bulbs in a dormant state for a year, or numbers of to have very early blooms? Also, is it possible to keep years? Any information on the culture of these splendid flowers will be thankfully received by numbers of our readers at this period of the year.-LIEBE. the most useful accessories I can make to it of a simple account of the effects of morphia, and its chief salts, in [5462.]-MORPHIA.-Will any one kindly give me an nature that will not require much time. I am well acquainted with turning, and any hints will oblige.scription of the effects of the other narcotics would also relation to its power of producing sleep? A short deoblige.-CACODYLE. ALPHA. [5450.]-CARBO-OXYGEN LAMP.-Can any one tell me whether the new artificial light (Philipp carbooxygen lamp) is to be seen or heard of anywhere in England?-A. H. (5151.] METAL PICKLE-BOTTLE COVERS. Could any brother mechanic tell me what is the name of the white metal used for covering pickling bottles; how it is put on; price; and where it is to be got?-OLD BOTTLE. (5452.]-LONDON UNIVERSITY DEGREES.-Will some obliging reader answer the following questions? 1. In order to be examined for a B. Sc. or B.A. degree at the London University it is necessary to matricnlate. The only qualification mentioned in the calendar is that the candidate shall be over 16 years of age. I wish to know if 30 or 35 years is any disqualification; or if it is unusual for candidates of that age to attend? 2. Will you give the classical subjects for next year (1871) for the matriculation examination?-R. T. [5453.] PRECIPITATE OF AMALGAMATED ZINC. Is it possible to throw down a precipitate of amalgamated zine? If it is, would not such a composition do better than silver for specula ?-B. A. [5454.]-CONIC SECTIONS.-In conic sections the line between the focus of a parabola and the point in which the tangent cuts the axis, the line called the focus at the point," and the line between the focus and the point in which a line perpendicular to the tangent cuts the axis, are proved to be equal to each other; and yet by actual measurement on the diagrams the last-mentioned line is found to be less than the other two. How is this? Similarly, the subnormal is not equal to half the latus rectum. Will Mr. Proctor kindly explain ?-B. A. [5455.]-LATHE-Will you kindly insert the follow. I have a small 5in. foot-lathe, and I want to apply face-plate, driving through a carrier another wheel on ing ? a slide-rest. I also want to drive it from a wheel on the the screw. Can any reader tell me what wheels I shall require; and also the threads per inch I shall want in the screw, so as to be able to cut screws from in. to jin. in diameter, Whitworth's pitch? I think that an ordinary V-thread for the screw would do for a small slide-rest. A sketch would be of great use to me at present.-ToM BROWN. [5456.]-WATCH BALANCE.-Perhaps your intelligent correpondent "Seconds Practical Watchmaker" will inform your subscribers if it is possible to place a ompensation balance in a watch to be nearly as dective as the present expensive balance. Wood is [5463.]-PROBLEM.-1. Find the sum of the areas of the two triangles which satisfy the conditions of the ambiguous case. 2. In the ambiguous case the area of one of the triangles is n times that of the other; show that if b be the greater of the given sides, and a the n + 1 less is greater than 1 and less than - See n-1 Todhunter's larger "Trigonometry" Chaptor b a Nos. 8 and 10.-THOMAS. XIV., [5464.]-PRINTING TELEGRAPH.-Will any reader inform me whether there is any telegraph worked by a single line that prints the messages in ordinary type; and full particulars respecting the same; when patented, &c., &c. ?-R. M. [5465.]-HARMONIUM.-What is the meaning of 3in. wind or din. wind, as applied to the pressure of a harmonium or organ bellows; also, how is this pressure ascertained when a spring is used; and also, what is the ordinary pressure of wind for a harmonium with one row of 8ft. reeds?-VALVE. [5466.]-AMERICAN MOTH TRAP.-Can any correspondent furnish me with a description of the same, and hints how to make one?-SPHINX. [5467.]-GLASS LENS.-With what fluid shall I fill a hollow glass lens, so that it shall be achromatic? What liquid or solution is there that has a less dispersive power than water?-B. WATSON. [5468.]-ANALYSIS OF WHEAT, ETC.-Would any reader oblige by giving a complete analysis of wheat grain; also, of bran and sharps? - B. WATSON. [5469.]-PROOF COINAGE.-Will any of our numismatic friends kindly inform where the proof pattern gold, silver, and copper coinage of the present and and from what source do they obtain them? Hum former reigns are procurable, excepting through dealers, phreys, in his "Coin Collector's Manual," states that same may be obtained on application at the Royal Mint. Is such the case? To whom must application be made; and what are the scale of charges?-BLACK RAVEN. [5470.]-CATARACT.-Will some friend kindly explain fully for me the construction, action, and use of the cataract, as applied to Watt's single-acting pumping engine.-PUNCH. [5471.-ELECTROTYPING.-Could "Sigma," or any other of your correspondents, inform me how I could ob tain an electro-deposit of iron from a copper-plate engraving, as I have spent much time and study on it, but any kind could be fired off at the rate of sixty times a [5473.] RAPID FIRING.-If a breech-loading rifle of minute, would it be likely to burst or get red hot by such rapid firing; or if an outer casing of iron or brass the depth of about in., would the water keep the barrel was to allow the barrel to be surrounded by water to cool ?-A. F. [5474.)-LIME-LIGHT.-Can any one inform me the cheapest and best way to make an oxy-hydrogen lamp for the purpose of making a lime-light, and the best plan for manufacturing the gases ?-EPSILO. [5475.]-OVENS FOR BAKING AND ROASTING.-I am a suppliant to your intelligent readers, who will perhaps kindly communicate the degree of heat necessary for the above? There is a cooking-pot advertised which is said to roast a leg of mutton by aid of the steam from a saucepan of boiling water. A large baker also professes that the ovens are heated by hot water, and the bread baked by it. How the brown on the mutton, and the crisp crust of the bread, can be produced by such a process is a mystery to-A GOURMET. [5476.]-MALT KILNS.-Wil any reader kindly infor me of the best mode of constructing and fitting up a first-class malt kiln on the latest and most improved principle; likewise how the floor should be constructed? -YOUNG MALTSTER. [5477.] JUPITER.- What is the breath of the apparent disc which Jupiter presents to the inhabitants of his 1st, 2nd, 3rd, and 4th satellites: and centre of its primary planet ?-W. CROWFOOT. what distance is each of those attendent orbs from the [5478.]-A NOVEL LANTERN.-If a room is entirely darkened, and a hole made in the window-shutter, through which is pointed a fin. plate lens, with a camera attached to it, then in the carrier of the dark slide place a lantern transparency. Now, if daylight is allowed to pass through the picture and lens into the room would the picture be reflected on a screen in the room, magic lantern fashion; or, in other words, can daylight be thus used to show a lantern without a condenser ?-PYRO. numerous readers refer me to a good work on the weight [5479.]-WORK ON METALS.-Can any of your the same; if so, will they oblige me with full particulars of metals, and with the rules or formula for obtaining in your next? I want the price and the publishers.R. W. [5480.]-HARMONIUM. Will Mr. Hermann Smith, Sourdine stop is made to act in a harmonium?-ARTEMUS or some other competent person, please tell me how the WARD. [5481.]-SUGAR CUTTING MACHINE.-I should be obliged if some one of your kind readers would give a drawing and short description of a loaf-sugar cutting machine, or a loaf-sugar saw mill," in the ENGLISH MECHANIC? Also can any body tell me if such mills are cheaply made ?-E. V. M. B. [5482.]-LONDON AND BIRMINGHAM RAILWAY. — What is the difference between the present line of road, and the one originally proposed previous to the commencement, about 1836, and abandoned on account of the opposition offered by the great landowners on the thirty miles between Camden Town and the Tring Summit Station ? Perhaps some among your engineer How different it would be were that line about to be readers may know where the early plans are deposited. carried out at the present time!-H. B. M. [5483.]-CAMERA LUCIDA.-A camera lucida, invented by Amici, and perfected by Chevalier, in Paris, is I have read, superior to Wollaston's camera. Is it to be obtained in England ?—A. C. G. [5484.]-CURVILINEAR PERSPECTIVE.-Can any one tell me of a book on curvilinear perspective, besides that by W. G. Herdman (1858)? I should be glad if "E. L. G." (to whom I already owe thanks) or some other talented contributor, would say a few words on this subject of curvilinear perspective.-A. C. G. [5485.]-COLOUR OF BRASS.-Having read "Cuthbert's "instructions for constracting a simple furnace for melting brass, I should be glad if some fellow reader would inform me how to get the brass castings a good copper colour, as I am obliged to use a quantity of old brass, which causes a very weak colour upon articles that are moulded ?-MAINWARING. [5486.]-ARMATURE.-Will "Sigma" kindly tell me whether cast-iron will do for the arinature of a inagnetoguson's "Electricity" that the armature of Wilde's maelectric machine, because I find it stated in FerI had thought that soft iron was chine is made of it? necessary. Also, is Wilde's the best form of machine ?E. C. L. [5487.]-FIREWORKS.-Will "Pierre" kindly give me some instructions as to the following fireworks, &c., viz., tourbillions, pigeons, and Italian streamers; also, whether it is not dangerous to ram iron borings and meal powder together, as is done in gerbs;" and can any reader tell me how much gunpowder any one is allowed to keep on the premises for private use without a license?-PYRO. [5138.]-WINTER SPLATE MACHINE.-In Pepper's "Cyclopædia of Science," p. 224, is a drawing of this machine. Will some one give size of brass ball for prime conductor, and diameter and thickness of tall wooden and iron ring condenser; and explain how wood and iron are united suitable for a 2in. plate?SOLICITOR. [5489.]-LAMPETER COLLEGE.-Will any of your readers kindly inform me what degrees are obtained at this college; what is the course of study; what are the fees; and whether residence is required. Any other information will greatly oblige.-STEEL PEN. [5490.]-PENDULUM.-Why must a pendulum which vibrates seconds be shorter at the equator than at the poles ?-F. MARCHANT. [5491.]-SHELLS.-Are petrified shells susceptible of a polish; and how may it be effected ?-F. MARCHANT. [5492.]-BAGATELLE TABLE.-I wish to make one. Will any kind friend say what are the proper proportions for the table, the exact positions of the holes and pockets, the cost of the balls anfi cups, and where they can be purchased ?-L. J. [5493.]-GENEVA.-Can any reader inform me where I can purchase a directory of Geneva and the watchmaking districts of Switzerland ?-SUNK SECONDS. [5494.]-WHEEL BAROMETER.-I have the case of a wheel barometer containing the dial, hands. &c., but it has got no tube. Would some kind reader tell me how to put in a new tube, which I am going to order, and which I intend to put in myself; how to adjust the float, &c.; and also will I have to give any special order concerning what bore, &c., of tube, and any other information necessary ?-WHEEL BAROMETER. [5495.]-PIANOFORTE SOUNDBOARDS.-Will the "Harmonious Blacksmith" or "W. T." be kind enough to explain why some of the best pianoforte makers cut away the top base corner of the soundboard of cottage pianofortes; and yet leave untouched the corresponding corner of the soundboard in the grand pianoforte ?— WEST YORKSHIRE MAN. [5496.]-SCALE OF BOURDON OCTAVE.-I should feel obliged if the "Harmonious Blacksmith," Mr. Hermann Smith, or Mr. Kemble, would inform me whether this scale of a Bourdon octave of pipes is a good one, viz., the C C C inside measure, Sin. by 7in.; the C C 4in. by 3in.? Also what thickness of pine is best to make them out of: and what height the mouth of the CCC pipe ought to be cut to for 2in. pressure of wind; and what is the composition of spotted metal for organ pipes ? -GILDER. [5497.]-BRASS LACQUER FOR TIN.-If any subscriber would tell me how to make and use a lacquer to make tin have the appearance of brass, it would be esteemed a favour by-A BRAZEN TINKER. [5498.]-FASTENING INDIA-RUBBER TO IRON.Can any of your readers inform me if there is any cement, or liquid preparation, that will attach vulcanized india-rubber to iron? I wish to fasten a rubber band in the grooved tire of a bicycle wheel to prevent its springing out when turning a corner.-C. TowNLEY. [5499.]-LAMPLIG HTER'S STAFF.-Will someone explain the arrange ment of the light at the end of the staff used by our street lamplighters? What is the substance used for burning ?-R. W. T. [5500.]-THE AURORA BOREALIS.-Will Mr. Proctor, "F.R.A.S.," or some other brother subscriber, explain the theory of the aurora borealis as now accepted? The brilliant displays of the present week have re-awakened an interest in them, which reflection and refraction theories do not satisfy. Will someone also explain the quickest and best method of liquidising indian ink.BENENOKE. [5503.]-VETERINARY.-One of my horses being seized with inflammation of the lungs, I called in a farrier, who applied a very strong blister to his side. This probably saved the horse's life; but the worst of it is, that the blister took off the flesh as well as skin, and the wound is not yet healed, though it is now five months since it was done. The horse is always kept in the stable. Will some one kindly tell me what to apply to it ?-G. THOMAS. [5504.]-TO MILLERS.-Can any of your numerous correspondents inform me what "horse-power" does it require to drive five pairs of French millstones, of 44ft. diameter, grinding Indian corn into fine meal, at 180 or 190 revolutions per minute; and is this the usual speed? -BENSON. [5505.]-GREASE IN BATH.-Can any correspondent tell me how to get off easily the grease that invariably collects on the light-coloured paint in the inside of a bath? I find that soap and soda are useless; turpentine removes the paint; and rough towelling is too great a labour.-F. V. [5506.]-COPAL.-Will some kind reader inform me by what means I can bring gum copal to the consistency of honey, in the mean time to preserve its natural transparency; would any kind of spirit do?-R. JONES. [5507.]-HORIZONTAL WINDMILL.-1 was much pleased with the plan given by "Jack of all Trades," in yours of Oct. 21, of a cheap motive power-a horizontal windmill. Would "Jack" be good enough to mention what size the wings of the windmill should be made to work a small chaffcutter ? By doing so he will oblige.R. H. S. [5508.]-SILVER CASTINGS.-What is the material used in making moulds for casting silver articles?— FRED. ROE. [5509.]-FOCUS OF LENS.-I have a concavo-convex lens, 3in. diam., 4in. focus. What should be the focus of a double convex lens to make in conjunction with the one I have a good condenser for the lantern, and how should the lenses be mounted in the tube ?-OXYHYDROGEN LIGHT. [5510.]-TO "SIGMA."-I am making a galvanic chain as a wearable source of electricity, but should like amalgamate the zinc plates with it. If so, will you to know if the system would absorb the mercury if I kindly name a substitute and method of using it? I may add it is only the common commercial sheet zinc, about No. 12. Perhaps it will not require amalgamating, as I shall excite the chain with only vinegar or salt-water. I wish to know also how to purify zinc of the above gauge.-THEOREM. [5511.]-WEIGHTS AND MEASURES.-Is apothecaries' weight, as ordinarily given in arithmetics, used now? What measures are now in use for ale and beer; also for wine and spirit? I only want those actually in use.-WILHELM M. B. quires a perfectly calm atmosphere for its proper action; this may be secured by building a small cromlech of flat stones, which are always at hand in hilly countries, and with the help of a large handkerchief, as a further protection against the wind, no difficulty will be found in securing efficient performance; other contrivances will suggest themselves where stones are not procurable. Although it would seem that alcohol is consumed to a disadvantage without a wick, yet practically the "Etna boils water with a smaller consumption of spirit than any contrivance yet tried, a good argand lamp quiring at least half an ounce to do the same work as the "Etna." re NEW CRUCIBLES.-A new material for the manufacture of crucibles is described by M. J. Desnoyers. The substance known as gaize, or pierre morte, is a mineral largely met with in the departments of the Ardennes, where it forms a deposit of some 100 metres thickness. Its specific gravity is 1:48. It is on being dug up quite soft, so that it can be cut with a knife, but becomes hard on drying and very hard when exposed to red-heat, whereby its specific gravity is reduced to 1-44. This material, says the Quarterly Journal of Science, is essentially a substance capable of withstanding high temperatures; and the author exhibits crucibles made from the gaize which have been used successfully for melting iron. Dr. La Salvelat, the celebrated chemist of the Imperial Procelain Works at Sèvres, states that layers of similar material exist in the central parts of France, and that these minerals are of great value for the construction of blast and other furnaces. GLUE WHICH STANDS MOISTURE WITHOUT SOFTENING.-In about 8 fluid ounces of strong methylated s pirit dissolve oz. of sandaric and mastic, and add joz. of turpentine. Add this to a hot, thick solu tion of glue with which isinglass has been previously mixed, and filter, while hot, through cloth or a good sieve. EXPLANATION OF STEAM-BOILER EXPLOSIONS. -A writer in Dingler's Polytechnisches Journal calls attention to the fact that hitherto no account has been taken of the possibility, which he proves to exist, that that these explosions are occasioned sometimes by the and the gases generated by the combustion of the fuel formation of an explosive mixture of atmospheric air collected in the flues and tubes of steam-boilers. The [5512.]-BATTERIES.-Will "Sigma" kindly tell me how many square inches of zinc in a bichromate battery would give a current equal to 55 square inches of a Callan's battery ?-THOS. J. O'CONNOR." [5513.]-BICHROMATE BATTERY.-Will Mr. Wil-author gives instances of explosions which could be disliam Tonkes kindly tell me if there would be any necessity of attaching the carbon plates in the manner he describes at page 106 to the conducting wires for batteries that are only used occasionally, probably not more than one hour at a time ?-T. J. O'C. USEFUL AND SCIENTIFIC NOTES. EVOLUTION OF LIGHT.-A simple discovery of the evolution of light has been lately inade by Andrew Pritchard, the author of a "History of Infusoria." He found that on tearing a piece of new calico in the dark a line of light was observable along the torn edges. Whether this arises from electricity or phosphorescence is not yet ascertained; but that it is produced from the dressing is certain, inasmuch as, after being washed, the phenomenon is not observed. Mr. Pritchard has sent us a piece of stout twilled new calico to experiment upon. tinctly referred to this cause.-Chemical News. SNAKE-POISON AND ITS ANTIDOTE.-The American Journal of Pharmacy prints a paper on this subject, the gist of which is, that the virus of snakes, and all animal poisons, have their specific antidote in the gall of the animal or reptile in which these poisons exist. The pure gall is mixed with alcohol (95 per cent.; 200 drops of that liquid are thoroughly mixed with 20 drops of the gall, and 5 drops given at a time in half a tumblerful of water. UNNOTICED QUERIES. IN future, if any query remains unanswered for four weeks, we shall insert the number and subject of the query in this list, where it will remain for two weeks, if not previously replied to. We trust our readers will look over the list, and send what information they can for the benefit of their fellow-contributors. Since our last "Sergius" has answered 4605, 4660; "Jack of all Trades," 4657, 4658, 4660, 4695, 4383, 4719 4743, 4754, 4763, 4778; W. G. Williams, 4635, 4719. 4791 4793 Horizontal Oscillating Cylinder, p. 622. Iron Ship, 622. 4801 Greenhouse, 622. 4802 Water Power Wanted, 622. 4803 Faure's Battery, 622. 4809 Celestial Globe, 622. 4814 Water Supply, 622. 4815 Good Reed-Organ Pipe, 622. THE COAL FIELDS OF INDIA.-From the report of Dr. Oldham, the chief of the Geological Survey of India, it appears that what is known as the Damuda series of coal-beds contains many seams very irregular, and varying in thickness from a few inches to 20ft. and more. Numerous coal seams are much injured by trap dykes, which have ramified through them, and rendered the coal useless. There is also a general tendency to ignition in the seams, owing, it is thought, to the presence of iron pyrites, which give rise to spontaneous combustion. Dr. Oldham calculates that in the Jherria coalfield, which contains the series Talchir and Damuda, there is an available quantity of coal of about 465,000,000 cubic yards, or about the same number of tous. Coal of excellent quality has also been found in Assam, near the river Bra hmapootra. LOCALITY OF THE SENSE OF TASTE.-Dr. 4820 Camerer gives in a recent number of the Zeitschrift 4822 fur Biologie, the results of his experiments on the locality of the sense of taste. He finds that the sensiessentially on the presence and number of the fungiform 4834 tiveness of different parts of the tongue depends 4827 papillæ. These are most abundant near the apex of the tongue; they are less numerous at the edges of the 4836 organ, and disappear near the circumvallate papillæ. There are no papilla on the under surface of the tongue. The mode in which Dr. Camerer conducted his experiments was to press a tube of about fin. in diameter over different parts of the tongue and adjoining mucous membrane, and then to pour in a solution of the sapid substance to about the height of a fin. Nine persons were experimented on, and the subject of the experiment 4868 did not in any instance know beforehand the nature of the solution the taste of which he was called upon to determine. The substances employed were common salt, sulphate of quinine, sugar, and sulphuric acid. From his experiments it appears, says the Lancet, that the parts of the tongue that are free from papillæ possess no sensibility; also, he finds that a weak solution of a salt is more readily perceived after pure water has been tasted than after a strong solution has been tasted during the previous twenty-four hours. By touching 4885 the fungiform papilla with a fine spiculum of salt crystal he was able to show that the gustatory sensibility resided in the fungiform papillæ themselves, and not in the adjoining mucous membrane. WATER-BOILING APPARATUS.-Mr. W. T. Suffolk has experimented during a pedestrian tour on the most advantageous methods of boiling water, and has come to the conclusion that the very best arrangement is an" Etna" of French construction, made of very thin copper, electro-plated, and weighing, with a store of 6oz. of spirit, 141b. The time occupied in boiling half a pint of water is from seven to ten minutes, and the consumption of spirit about two fluid drachms. The apparatus re 4871 4878 Lead Burning, 622. Link Motion, 623. Sponges, 623. 4818 Hydraulic Apparatus, 623. 4953 Gearing for Bucket, 623. 4857 Model Windmill. To John James, 623. Australian Nugget, 623. Trumpet Stop, 623. Transparent Size, 22. Portable Windmill, 22. Stiffness of Finger, 22. To Millers, 23. Discoloration of Leather, 23. 4886 Dyeing, 23. 4890 The Painter of Seville, 23. 4883 Stereotyping, 23. 4893 Bronzing Card, 23. 4880 |