[54187.]-Hock Wine.-I note P. Ward's reply on p. 472, and wish to add that, being as it were to the manner born, the addition of, say, a handful of good raisins to a hogshead of sour wine, will cause it to ferment, and by keeping the cask full to the bunghole, it will give off a lot of scummy matter, and will soon become good vinegar. -A., Liverpool. [54187.)-Hock Wine.-"No Sig." should proceed as follows:-Put aside a fourth part of the wine and add fresh slaked lime in small quantities to the bulk, stirring well until the acidity is gone, then gradually add the remaining wine until a very slight acidity is left. This is necessary, as, if the wine is rendered alkaline from the lime and left so, all its flavour will be gone and a disagreeable flavour remain. The lime will all subside, and the clear portion can be poured off. To this add sufficient port wine to freshen it up, about one bottle to eight or ten pints. Of course, its value as a genuine hock wine is gone, but this, or turning it into vinegar, is the only remedy.-J. C. L. [54190.1-Calculus.-Let F1, F2, F3, denote the three fixed points, and O the centre of inversion. Let R be any point on the curve; let fi, fs, fa, T, be the inverses of these points. Then since O T, F tube must be lowered from time to time to follow [54204.]-Turning off Gas by Electricity. [54204.]-Turning off Gas by Electricity.A simple, if not the simplest, method of doing the above is figured in accompanying sketch. A, A start at the wheel-bed and go on increasing till the wheel breaks, but if the axle had been tapered, its weakest point would have been the centre. Any flaw starting there can be easily discovered, and the axle can be removed before any damage is done. By tapering axles whenever possible, you do all in your power to force fracture to take place at the centre (that is, supposing fracture ever does begin), the part where it is most easily discovered; and I submit the tapering of axles is the one thing most desirable.-G. R. S. [54214.]-Portable Pipe Organ.-Thanks to "Gamma." Such case, then, abandoned for usual "Gamma or any other reader tell style, can how soundboard is placed in Cramer's drawing. room pipe organ? which stands only 5t. high, and is really charming, both in tone and in appearance. Is there any serious objection to soundboard standing in case on floor parallel with bellows instead of over it? It may save others from expense and sorrow to know that small Bourdons are not usable in small room; have tried various pressures, &c., but in any case player hears a puffing of wind, and the note is only heard to perfection at some corner of room. Can this be accounted for? So, disposing of large instrument, and not now having access to back volumes as formerly, advice as to what stops are best, scales, and forms of construction will oblige-BETA. 154217.]-Wheel Gearing.-I will suppose "J. L. E." has got his cogs fitted in the wheel rim and turned up; he must then strike his pitch circle in the centre of the cog; next pitch the cogs out, then with the pitch in his compasses strike out the tops of the cogs, as shown in sketch, figure ary OR = K = OP. Of a circle can be described around F, RTf, then the angle OT fi = angle OF, R-the triangles O Tfi, ÖR F, are similiar; then RFI 1= OR OR. OF, 0fi = Now RF, is p1 and call Tƒ1 r1; then P1 =OR. OF1.71 K OR.OF, T2, &c., are two electro-magnets coupled so that their poles are disposed in the manner shown, or all the reverse way, according as to which direction the current is sent to them from a commutator. B is a polarised armature through which a brass pin is fixed and Similarly f2 = screwed at one end as at F, the other end slides in the guide E. C is a cylinder of brass just fitting therefore, putting these values in the equation into the brass socket D, which has attached to its a p2+rp2 + Yp3=0 we get for the equation of lower end the gas in- and out- let G, G. These the inverse Curve a.OF1.2, +3.0 F2.2+y.sliding parts are to be lubricated by vaseline. It OF3.13 will be seen that by adjusting the cylinder C on the screw F, a variable amount of cut-off, or the reverse, can be obtained. I have used this method successfully 12 years ago; but not on so large a scale as "W. H. M." requires.--PAUL WARD. = 0.-H. H. HARRIS. [54192.]--Microscope.-Lacquer all parts that do not slide inside other parts, the inside tubes, &c., polish well before fitting into their places, and wipe perfectly dry; then every time after using wipe quite clear, and your instrument will always be fit to look at and work with. Don't oil any part excepting the inside bearings, such as rack, stage, and slow motion, and be very sparing with it in these places. Better use a grease made of beeswax and tallow.-W. J. LANCASTER. [54208.]-Paralysis Coil.-I should say prob- [54210.]-Locomotive Axles.-Second column, letter showing centre, and segment of circle struck from it; square over, and strike the other side, not altering the compasses till all are struck out. He may make the cog flanks, that is the portion below his eye, he can continue the arc down to the wheel pitch line, straight by the eye; or, if he can't trust rim, as shown at f 4. These latter lines will help him to keep the cog truly parallel on the flank. It "J. L. C." will follow the above instructions, his wheel will run, and run well, if the cogs be properly fitted and fastened. Books will be of little use to him, and may confuse and hinder him. To prevent error, I have purposely made my sketch as simple as possible.-TYKE. [54217.]-Wheel Gearing.-I send sketch of teeth as requested. It is 13in. below pitch line, 20% p. diam. [54193.] Abyssinian Pump. - The reply given by A., Liverpool," is evidently not founded on experience. The vacuum shows that the joints of the pipes are all sound, and is so far a satisfactory indication, moreover the putting down the small pipe would, by destroying the vacuum, render the tube well useless as such. The right way to [54210.]-Locomotive Axles.-The answer to proceed is to fill the tube quite full of water, and this query would take up too much space; but if tin. above ditto. The thickness is lin., and clearthen screw on the pump, which must be worked at querist can get the big edition of Unwin's "Machine ance space lin., the wood cogs being necessarily vigorously in short quick strokes. After some time Designing," he would be able to get all the informa- much thicker than the iron teeth. The radius for the water will probably be found to flow from the tion he requires. I would like to ask Mr. Gobert his striking the faces is 2in. taken from a striking pump spout, but in extremely small quantity at authority for the statement, or by what mode of line, in. below pitch line. The flanks below pitch first. When this occurs longer strokes may be reasoning he arrived at the conclusion, that the line converge to the centre of the wheel, and are taken now and then, but the main thing is to keep tapering of locomotive axles is "a useless refine strengthened by small radii of about an in. or up a continual jigging action till the mud and grit ment.' I had always imagined that, after making in., curving into the periphery of the rim. Your are got out of the perforations, and a cavity is formed the safe moment of resistance of the section at its wooden wheel may possibly have teeth of a different round the bottom of the tube. At first the water is least or weakest part equal to the bending moment length to those here figured; if so, the length of thick almost as porridge, but gradually becomes it was the one thing necessary. If you consider the iron teeth must be altered to correspond. But perfectly clear, then it often gets thick again, and the axle simply as a beam loaded at two points that will not affect your method of marking out. so on, till after a time no more mud can be brought equi-distant from the ends; then, undoubtedly, the First, set out your pitch upon the ends of the teeth up even by rapid and violent pumping, and the correct form is cylindrical and parallel; but expe- the p line, then the striking line in. below the a, a, then mark their breadth lin. equidistant from water then remains permanently clear and bright. rience has proved that axles never break in the Should no water be able to be got up after long middle, but always at the journals, wheel-bed, or line, from which mark the faces. Then draw the continued trial, it is probable the tube will be found just behind the wheel-bed; at these points, there- flanks with a straight edge, and strike the small to contain a lot of clay or dense mud, forced in fore, the stress is evidently greater than at others; curves at their roots. If you work the teeth during the process of driving down the tube, and the conclusion to be arrived at is that the cross in a box ("E. M.," Vol. XXXVII. p. 191), you this must be got rid of before the water will rise. sections at these points should be increased. If one will mark out a single tooth in the same way upon To do this a small bore tube (say, in.), must be of the wheels should meet a stone or other obstruc. the end of the box, and set and glue them upon the screwed on to the pump by means of a reducing tion, the stress generated will be greatest at the edge of the rim by a centre line drawn through the socket, and lowered down into the well tube, till it wheel-bed, and gradually decrease towards the pitch line upon their ends.-J. H. just reaches the top of the mud in it, then by continually pouring water down the well tube and pumping it up through the inner tube, the mud will be eventually got out. Of course, the small other wheel. Further, take a parallel axle and (54218.]-Holes in Circle.-Mr. Davies will suppose that it will not be subjected to any greater find his formula by far the simplest for marking a stress than that due to the load upon it, then who the holes. I have worked out by means of a dis can tell where that axle will break? A flaw may gram on paper the particular instance to which he refers, and succeeded in marking off the holes with only a very small error, much too small to be of any consequence. The compasses should be set to measure 4.299in.; I set mine to 4.25in. full, with the result above-named. As cylinder covers, &c., are made to fit on in only one position, the small variation so introduced is quite immaterial.J. M. G. (54220.]-Silver Plating.-I think in Vol. XXXIV. I wrote three or four papers on silver plating and the construction of batteries for same. I endeavoured to make them exhaustive, and would advise a reference thereto.-Os. [54220.]-Silver Plating. The usual cause of stripping is want of chemical cleanliness, that is, absence of grease or oxide. However, an unsuitable current is sometimes the cause. Leclanché cells are not suitable for the cold bath; but I find them very useful for silvering small articles in the hot bath, which I keep in a stoneware vessel, set in a sand bath over a gas-stove. The Leclanché cells are very handy, because they are always ready, and require no attention; but with a cold silver bath they are apt to evolve gas, and that causes a bad deposit. You could easily try whether it is the fault of the battery by making up a Daniell cell in a jam-pot with a roll of sheet copper (no doubt you know how to make one; if not, refer to back numbers). Daniell's gives a much steadier and more suitable current for working, and will work nearly up to its strength for days, whereas the Leclanché runs down in two or three hours on the close circuit.-J. E. A. found at the bottom in a brown mass or spongy lumps; but to be certain you have got away all copper and silver, add fresh acid. After you have carefully poured off the old, when red fumes cease, you may wash the residue several times in clear water. This is pure gold, and may be collected and melted into a button, if necessary. The other liquid may be dealt with thus. Put in some clean pieces of copper and the silver will be thrown down, and can also be washed and melted; the remaining solution of copper you may throw away. After being certain you have got all the silver from this, drop in it a few drops of hydrochloric acid, or a little common salt, and if any silver is left, it will fall to the bottom in a cloudy mass; this is chloride of silver.-SUTCLIFFE, Sheffield. [54231.]-Plaster of Paris Moulds.-Mixing [54248.]-Raising Water.-A ram, under the with solution of potash alum hardens the plaster; given conditions, would not send up more than 250 but I am not sure that this would answer for ca-t-gallons per day of 24 hours. If more were required, ing in, as it might give up its water of crystallisa- it would be necessary to use a pump driven by a tion. For the same reason, it would not be well to steam, gas, or hot-air engine, as might be most use ammonia alum, which decomposes at a lower convenient.-W. A. S. temperature than potash alum.-SIGMA. [54231.]-Plaster of Paris Moulds.-When plaster is perfectly dry it must fall to pieces. It will not hold together without a certain quantity of water. Try sand mixed with a little fireclay or pipeclay; well dry the moulds, and you can make them red-hot if you like. I once cast some large silver rings in this manner.-Os. [54234.]-Cutting Deal.-It would be nonsense to tackle the job with such a toy engine; anything less than, say 3 h.p., would be extremely unsatis[54220.]-Silver Plating.-I use the follow-factory, at least to yours truly.-A., Liverpool. ing receipt, and never found it fail. Take fine [54235.]-olian Harp.-Unless you conmake not (54250.]-Toning Solution. Your toning solution ought to retain its strength for a long time. Do you mean to say that toning made up to the formulæ you give, and kept for a few days without being used, will not tone; if so, you must have something in the water which precipitates the gold. Use rain water or distilled if you can get it. (?) The diaphragms should be cleaned and bronzed in a solution of nitrate of silver, 60 grains to the W. J. LANCASTER. ounce of distilled water, and then blackleaded.— [54252.]-Colouring Walls in Distemper.What does this querist mean by "usual way with silver in an old cup, and pour in the acid and water I made three at a former period, and the wife had soft soap to 121b. of whiting; so to talk about soap, and stand it beside the fire until the silver is dissolved; if any silver remains add a litle more acid. The red fumes, caused through chemical action, cease when the silver is dissolved, or the acid done its work. The nitrate of silver thus formed should be carefully poured into another cup and made hot until a pellicle forms on the surface, then stand on one side to crystallise. When this is done the crystals of nitrate of silver are put into a large jar (I use a gallypot) and pint and half of cold distilled, water added, stirred with a glass rod until the crystals are dissolved. Dissolve some carbonate of potash in distilled water, and add some to the nitrate of silver. As soon as the potash ceases to cause any precipitation the operation is complete. Allow it to stand a short time until the precipitate is settled, then pour off the liquor, taking care not to lose any of the precipitated silver; add fresh water and allow to settle as before, doing so several times to thoroughly wash the precipitate. Now dissolve some cyanide of potassium in het water, and add rather more than will dissolve the precipitate. Sufficient water is now added to make half-gallon of the solution. If the solution works too slowly, add a little more cyanide, but this must be done very carefully-best use as little cyanide as possible.-RAT. [54222.]-Cleaning Filagree Work.-A weak solution of hyposulphite of soda, and a fine tooth brush would, I have no doubt, enable you to clean your silver filagree.-W. J. LANCASTER. [54222.]-Cleaning Silver Filagree Work. Boil in cyanide of potassium in a copper pan, another way is to heat up the work cherry red, and dip in sulphuric acid, dilute with half water. DENS. [54222.]-Cleaning Filagree.-Heat with the blowpipe to a dull red, and throw into weak sulphuric acid and water; or else a boiling solution of alum, which should be kept at boiling point with the articles in for half a minute or so. Then rinse and dry in hot box sawdust.-J. E. A. [54224.]-Wire Blinds.-Brush them over with paraffin oil.-A., Liverpool. [54224.]-Wire Blinds.-If "D. W." will get a piece of fine gauze wire, same as his blinds are made with, and run his paint through it on to a piece of sheet iron or slate, and take up small quantities of paint at each dip and work it into his brush well before applying it to the blind, he will find it to answer. The brush must be clean, and short hair is best.-J. C. W. to hide the razors and clothes lines. But in order to satisfy yourself, purchase a ring of violin 1st string, and drive a tack into the top of your hall door, and another one near the bottom, in the with a deep V for the string to lie in, so that it centre of the edge. Now cut out two little bridges won't come in contact with the doorcase; tighten up the string on the tacks, and close the door gradually until it begins to play.-A., Liverpool. [54240.]-Florida.-Look on p. 500, last volume. Don't go orange growing in Florida unless you have an independent income to live upon, as it takes some years before a profit is reaped from an orange grove. There is very little "cultivation " needed, but gathering the harvest, when it came, would tax any one not robust.-S. R. &c., is to keep the information back that is needed to explain his failure. If he means that he prepared the walls with soap, as he says, no wonder he made a mess of the job.-CREPIDAM. Paraffin contains no sulphur, and gas does; there[54254.]-Paraffin, Gas, and Electricity.fore, although it consumes more air for equal light, it does not generate the same products, and especially some which act injuriously on plants. The water and carbonic acid produced do not injure the plants, because they are the food of vegetation. SIGMA. [54255.]-Tempering Spiral Springs.-The best way to make these, I have found, is to purchase the bright steel rods sold by watchmakers' tool suppliers. Bend the said steel rod around a Battery. The platinum may be deposited in either and you will, I opine, be satified with the spring. [54242.]-Replatinising Silver for Smee's mandrel, a little smaller than the required size (just as purchased, without any heating before or after), of the following ways:-After brushing the silver plate over with strong nitric acid, and then washing-A., Liverpool. well, place it in dilute sulphuric acid, to which a few drops of perchloride of platinum have been added, the platinum will be precipitated in a pulverulent form; or the silver may be roughened with sand paper, and then placed into the platinum solution made quite hot, when a similar deposit will take place.-H. J. S. [54242.]-Replatinising Silvers for Smee Battery.-Prepare in a vessel diluted sulphuric acid about 20 per cent., tie to the plate to be platinised a slip of zinc, place the zinc in a porous the dilute acid, the silver-plate in the same outside pot charged with liquid in the vessel charged with the porous pot; in the outer vessel drop in a little strong solution of platinic chloride and stir. As soon as coating forms add a little more platinic chloride to strengthen; remove, dip in water, and dry spontaneously. Chloride of platinum is about 24s. an ounce.-DRYSALTER. [54242.] Replatinising Silver for Smee's Battery.-The silver plate must be first brushed over with a little strong nitric acid, so that a frosted appearance is obtained. The silver plate is then washed, and placed in a vessel with diluted sulphuric acid, to which a few drops of nitro-muriate of platinum are added; a porous tube is then placed acid; into this the zinc is put. On contact being in the vessel, with a few drops of diluted sulphuric made, the platinum will, in a few seconds, be de metallic powder, and the plate is then ready for use. posited on the surface of the silver as a black Iron prepared in the same way answers as well as silver, besides the great saving in cost.-THOS. H. HALL. [54226.]-Coating Iron or Steel with Vulcanite. This cannot be effected without proper [54245.]-Obtaining. Gold from Alloy.tools and apparatus. The rubber is packed round Dissolve in nitro-muriatic acid with aid of heat; the metal in a soft (unvulcanised) condition; it is the silver will remain as solid chloride. The soluthen subjected to pressure and vulcanised. A tion will contain gold, copper, zinc, &c. ; evaporate "vulcaniser" is a steam-tight boiler, in which the to dry; redissolve with water and throw down the rubber is exposed to steam at a temperature which gold as a brown powder with protosulphate of iron may vary from 280° to 320°, according to the time-i.e., green vitriol.-SIGMA. of exposure. It can be cured by dry heat, but it is not so satisfactory as the moist heat. (Vide "Cantor Lectures "" a year or two since.)-Os. [54229.]-Elevating Liquid.-I note J. J. Elliott's letter on p. 473, and would like to ask Mons. Rabache "how he proposes to raise the wind' at all times, as this is a problem which has Add one-third silver to your mass of alloyed gold, [54245.]-Obtaining Gold from Alloys.melt same and granulate; put this in Florence flask, and add nitric acid one part, water one part; the grains should be allowed to digest several hours. To promote chemical action, place flask on a sand bath over fire or gas burner. The gold will be [54260.]-Dynamos. - The amounts of wire given by Mr. S. Bottone are right enough; it was only in their arrangement where he was at fault. If the two legs of the field magnet are connected in multiple arc, the respective resistances of F.M. and A. will be near enough correct. As the machine stands you would be able to run ten 10-candle lamps; 2,000 per minute is too fast, 1,500 would be plenty. You might run the machine for 8 or 10 hours at a stretch if the external R. is about three times that of the internal. Use an engine well up machine would run an arc light of 600 c.p.-W. H. to its work, say about 1h.p. nominal. E., Coventry. The [54261.]-Winding Armature.-The plan you have adopted is a very good one, but you must be careful that the brass rods are insulated from the iron of A. The F. M. as it stands is wound with too high R. for it to be used for a plating machine. Its R. with all the wires in series, is 78 ohm. I do not know how much wire your A will hold, but I suppose about 6lb. If you wound A with 6lb. of No. 12, its R. would be about of an ohm., which is too low. You had better wind it with 6lb. of No. 14, which will have a R. of 34 ohm., and, of course, between brushes of .085 ohm. Connect the the current by putting various resistances into the machine on a shunt. You will be able to regulate F.M. circuit.-W. H. E., Coventry. [54265.1-Cements.-Portland cem nt.-Os. [54265.]-Cements.-I would recommend Roman cement for this purpose.-A., Liverpool. [54265.]-Cements.-If you can keep the water from actually mixing with the cement, and washing it out before it has had time to just set, Portland will do, and give excellent results; but if the cement is wanted to practically set under water, you must have hydraulic cement-that is, Portland, but not the ordinary stuff known by that name. Therefore, go to a respectable firm of cement merchants, tell supply the proper quality.-NUN. DOR. them exactly what you want to do, and they will [54265.]-Cements.-Hydraulic cement is made from argillaceous limestone, the presence of alumina conferring the power of hardening under water. Here are some recipes to choose from: -1. A small mixture of ground burnt clay, smith's forge scales, or calcined bay salt (pozzolana) added to the lime at the time of burning. 2. Chalk 4 parts, and clay 1 part, ground in water, settled, moulded, dried, and calcined. 3. Gad's patent dried clay in powder 3 parts, and oxide of iron 1 part; make into paste with boiled oil. But "B. O. B." will find pozzolana (a natural cement formed of volcanic ashes from Italy) mixed with a little lime, the best, as it hardens very rapidly, even if applied under water. -THOS. H. HALL. [54268.]-Chainstitch Sewing Machine. -Evidently not adjusted properly: these machines are troublesome to adjust, the needle motion requires setting with the feed motion, so that the feed moves ou when the needle is out of cloth and as it gets to its highest point, and then the hook should be set so that it catches in the loop as the needle rises, and retains it until the needle descends again and passes through the loop, which is held open by the hook. The needle-point should be th of an inch lower than the edge of hook before the loop is liberated and as the needle is still descending. The end of arm to which lever of hook is fastened should be about in. or in. below bottom edge of cloth plate. See that the tension is moderately tight, and that the cotton is round the thread post, and that the little roller just presses and holds the cotton when it is passing.-J. I. S. even ones. UNANSWERED QUERIES. The numbers and titles of queries which remain unanneered for five weeks are inserted in this list, and if still unanswered are repeated four weeks afterwards. 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, "Glatton" has replied to 52573, 52614; "Finem Respice," 53644; "H. J. S.,” 63717. 53729. Fish Offal, p. 263. 53704. Organ Specification, 285. Breakwater, 357. Differential Calculus, 358. 53997. Cartridges for Breech-loading Fowling Pieces, 858. QUERIES. seems hardly feasible that two tons of cast iron, inclosed within thick walls, and carefully tended. should sensibly feel the effects of heat and cold, But it is so; and although the errors are small still they are errors, and have to be eliminated. The standard sidereal clock is one of the marvels of mechanical horology. It is fixed to the north wall of that part of the observatory known as the "magnetic basement," the temperature there varying only a few degrees throughout the year. It was made by Messrs. E. Dent and Co. in 1871, and is somewhat peculiar in its action. As far back as 1826, the late Astronomer Royal read a paper 53732. Portable Writing Desk, 285. "The Disturbances of Pendulums and Balances, 53740. Roofs, 265. before the Cambridge Philosophical Society on 53735. Flue Rings, 263. and on the Theory of Escapements." That of the 53712. Nut and Bolt Making, 265. clock under notice is of the same character. The 53746. Measuring Timber, 265. escapement is a detached one, having an affinity to The pendulum im- 53956. that of the chronometer. pulse takes place at each double vibration, so 53960. that the seconds-hand moves only once 53965. every two seconds, those seconds being the 53971, The pendulum is hung from a solid large brass casting firmly attached to one of 53999. Intestacy, 958. the basement walls. It has a zinc and steel com- 54004. Solar Photography, 358. Pensation and a leaden bob, and the driving weight tion did it move freely. The first zinc tube rests slides down a prepared "shoot" to avoid vibraon the rating nut, then a steel one goes over that [54270.1-Greenwich Observatory Clock.- resting at its upper end upon the zinc, and carrying In giving a reply to this query, I think I cannot do at its lower end the leaden bob. The weight of the better than quote from an article upon "The Time- bob is about twenty-six pounds. The rod is of work and Time-signals of the Greenwich Royal Ob- steel. Upon the crutch-axis, held by friction, are servatory," which appeared in the Watchmaker and two straight brass and steel compensating bars, Jeweller. My knowledge of the clocks at Green- carrying at each end a small compensating weight, wich has been gleaned from reading that article, whilst along the crutch-rod is a spindle, tapped and and as it may not have come within the province of nutted at the upper end, and carrying a square many of your readers to know how "Greenwich weight at the lower end. This spindle is for Time" is obtained, and what are the instruments enabling very small changes of rate to be made which give undeviatingly true time, I may be ex-without stopping the pendulum. The compencused if I quote from it largely. It must be under-sating tubes have holes and slots cut in them, the stood that "true time," as we understand the term, better to allow the temperature to circulate. The is not obtained by observation of one instrument driving weight is only about 5lb." (To be conalone, but by comparative readings of a number; tinued.)-ALFOJOE. one acting as a check against another, although [54271.]-Starch from Potatoes.-"Tinplate" there is a principal clock, to which the others are in does not say on what scale he wishes to manua manner subservient. "The real time makers at facture; but here is an outline:-The murphies are Greenwich are the transit instrument and the first thoroughly washed, and if the peel is removed standard sidereal clock. The 'transit' is a telescope in the operation so much the better. They are then 12ft. long, having an object-glass of 8in. The rasped, by a revolving cylinder fitted with bits of tube is of cast iron, braced and strengthened, is saw blades, into a pulp as fine as possible. This conical in the centre, and rests by means of its paste is washed on fine sieves, which allow the trunnions upon firmly built solid piers. Upon one starch granules to pass and retain the fibre. The of the trunnion-pivots there is fixed a finely starch and the water is run into a vat and allowed graduated circle of degrees, minutes, and seconds, to settle; the water is drawn off, and the starch with micrometers and vernier to read them off by. purified by other washings; it is then dried and The instrument is pivoted due east and west, there- sent to market.-NUN. DOR. [54282.] Hot Water. -Will some brother hotby giving an axis due north and south. Near to [54272.]-Flower Painting on Looking-water fitter give me his opinion on the following!-[ each end of it is a horizontal line of mercury, by glass.-Trace the outline on the glass with water have a schoolroom to heat two stories high, 45 by 15. I which to test the line of sight and ascertain if there colour, so that you can rub out for alteration if purpose pipes 4in. diameter, middle two floors, and reare many errors-errors of collimation, as they are required, and then paint with oil colour.-SKIBBO. turn grates on top, 4in. pipes, top room. zin. pipes are called. In taking observations, the moment single. Now, would room branch out of bottom pipes that the clock star is on each wire the observer to use a ram, and there are makers who advertise 3in. pipes round top room, plenty of boiler power![54284.]-Raising Water.-I would advise you near boiler? Will this be plenty, and would you have touches a telegraphic key, which is on the ENGINEER. tube of the telescope near in the scientific journals specialities in this departthe eyepiece. That touch causes a mark to be made upon ment, who would answer your questions at once.the chronograph in another room, which A., Liverpool. [54280.1-Scientific Dialogues on the TidesIV. (Letter 22656.)-Would Rev. J. Pearson, M.A.. ing the tides, kindly give some further explanations, rein his very interesting and instructive dialoques concernspecting the details of the graphic mode described by him for ascertaining the heights, viz.-In what way are the full and dotted lines erected, from the path of the moon and sun in the lower half of the diagram, measured so as to obtain the heights in the upper half of diagram ?-or, what is the unit of measure where degrees are marked in the lower half, are converted into feet in the upper part of diagram, and why are the heights taken from 12ft. datum. ! I note the explanation and erratum in next No. 22693. The diagram given only applying to the heights of tides, can one be drawn in a simi ar way for the exact times of high and low water! And would Rev. J. Pearson, M A., kiadly furnish one for that purpose in the E. M." 1-Socra AFRICA. set of straight and concave pedals to a large American [54281.]-Organ Pedals.-I am going to make a organ. Will some one kindly answer the following questions! (1) How long should pedals measure from front of organ to hinge of pedal (2) How are they hinged? (3) Are the springs made of iron or steel wire! (4) How much do they concave-i.e. How much lower is the middle pedal than the end ones? (5) There are to be 30 pedals, made out of birch lin. thick; how much should they measure across from C C to F. 1-APOLLO. [64283.1-Noises in Telephones.-Referring to the above, we have in our office a Blake transmitter and two telephones; one is an Ader telephone, and the other an ordinary Bell telephone. If the Ader telephone be placed with its face against the mouthpiece of the Blake transmitter, and the Bell telephone is taken off the switch-hook, a peculiar squealing noise is the result, this noise continues as long as the receiver is near.... Thave mark is entered in the transit book when convenient. The chronograph is a timekeeper itself, Colour-Blindness.-There is every reason to and consists of a brass cylinder 20in. long and 12in. believe that the new apparatus for combining in diameter. It has a train of wheelwork, driven colours, devised by Mr. Offert and by Lord Rayleigh, by a clock-barrel weight, and regulated by a coni- will lead to a thorough scientific investigation of cal pendulum, the lower or bob end of the pendulum colour-blindness. Considering how common Dalterminating in a kind of paddle-float, and revolving tonism is, and how essential it is that railway men in a flat basin filled with glycerine. The resistance and others working with coloured signals should be of the glycerine to the motion of the paddle-float free from it, or at least know the extent to which performs the same functions as the ordinary pen- they suffer from it, some simple means of investigatdulum bob. The chronograph cylinder revolves ing it is desirable. Lord Rayleigh's apparatus is based once in two minutes, and it is covered by a sheet of on double refraction, and the obtaining of two paper ruled in faint lines by itself. There are ar- over-lapping spectra, which the person under exraugements of magnets and prickers, by which, amination looks at, and describes as green, blue, or when the observer touches the key at the transit purple, or whatever it appears to his or her sight. instrument, a steel point pricks the paper. As the Lord Rayleigh has, we believe, tested the vision silereal standard clock, by means of one of its of numerous friends, and is willing to extend his wires, also makes punctures in the paper every observations further. So far, he has found that the second, the observer can tell, on examining these majority of persons tried require only half as much marks and the spaces between them on the revolv-red in the mixed spectra to turn a given yellow into ing cylinder, at what particular fraction of a second green as he himself does. People vary from each ich wire in the object-glass of the transit instru- other in matching colours, and there are grades of ment was crossed by the clock star. Six hours' "colour-blindness." Ordinary colour-blindness is observation work can be put upon each cylinder, blindness to red, but the father of Mr. Stanley, the and four observers can maik at the same time, pro- optician, was colour-blind to green. As an envided that no two of them touch the telescope key gineer, when engaged in colouring plans, he had to of their several instruments at the same electric single out his green pigments by their names. To moment, a very unlikely occurrence indeed. The him they appeared a kind of brown. first time-signal is sent out from Greenwich at ten leigh has not, we understand, noticed any striking o'clock every morning. The state of the sidereal differences between the two eyes of the same person; standard clock has to be ascertained; it has to be except what is due to fatigue of one eye and freshcompared with the solar clock, and ness of the other. Dr. Guthrie, who is colour-blind that clock has to be brought to time. To to red, believes himself more than usually sensitive effect these, the "trausit" from the chronograph to blue; and Lord Rayleigh has found persons abcylinder-paper is read off; certain corrections are normally sensitive to red, as well as abnormally made, and the true time of the star passing the insensitive to it. It would be interesting to meridian ascertained. But the transit instrument discover whether such persons can itself requires correction occasionally, notwith- down the red end of the spectrum than is usual. previous instructions have been given. Unfortunately, I standing the ingenuity with which it has been built Perhaps the modification of Lord Rayleigh's appar-began with Vol. XXXVI.—THETA. or strength and the foundations and the piers upon atus, by Mr. Glazebrook, for measuring the distance which it rests. Temperature acts upon it as it acts on the spectrum which any one can see, will answer upon the balance spring of a watch, although it I this part of the inquiry. mean Lord Ray see further two theories as to the cause. (1) The current passing between the carbon-button and the following spring forms an arc, the noise of which is amplified by the Ader telephone, and so produces the above noises in the Bell telephone. (2) The induction from the other lines is increased as in the first case. These noises can only be obtained with Ader telephones. I inclose rough sketch showing position of telephones, &c., as used. I feel sure an explanation of the above wou'd be of interest to others as well as-E. A. B. [54284.]-Spectroscope.-On p. 36, Vol. XXXVII., Mr. Lancaster kindly offered to give another correspondent particulars of how to make a direct vision spectroscope. I should much like to make one, and think I could manage it, prisms and all, if he would be pleased to give full instructions. I do not find 49344 gave him the information desired and the matter seems to have dropped. Though I infer from recent remarks that some [64285.]-Silvering Brass Clock Faces Can anyone tell me how the clock makers silver the parts of old brass faces. There is a way of doing it without a ery. What ingredients are used, and what quantity method of doing it? Anyone answering this will tly oblige more than one.-LOST. 1286.1-Book Worms.- In the Daily Telegraph of 19th, there appears a leading article upon these resting and comparatively little known insects. The er remarks that "Somebody has just found and cted for public information, the curious little ture which eats holes in our books. Everyone knows there are such things as book-worms, very few see them." I should be glad if any of our readers d give me particulars as to what form the informaby the "somebody" above referred to is published, where it is to be obtained, as it is particularly insting to me just now, for a day or so before the cle appeared, 1 discovered, in looking through an old of Gil Blas, one of these insects; it has the appearof a small white transparent maggot with six legs, a somewhat loosely fitting skin, with a good deal of atural Size 1 on it. I subjoin a sketch of the insect, showing it atural size, and also its appearance under the microPerhaps some of "ours" may be able to throw light upon the habits of this insect, and how it conits boring operations, which, no doubt, would be inting to many another-BIBLIOPHILE, Leeds. 287.] Pacinotti Dynamo. - Will the soft iron field-magnets, described by Mr. Bottone, retain ient magnetism, after the machine is stopped, to the dynamo again ?-MRW. 288.)-Storage Batteries.-I should be glad of nation how to make storage batteries of sufficient to work one or two incandescent lamps. I want onally to use the lamps a few miles away from my no, and should like to carry with the lamps the ed batteries. My dynamo would have time to do arging.-Mew. 89.]-Consumption of the Brain.-A case cy occurred lately, attributed to the above cause. are the first symptons of the approach of this e? And is there any cure !-BETA. 90.]-Pure Water.-Observing that Dr. Eds says that "pure water" is the only thing that hes thirst properly, can anyone tell me how to it, and keep it in good condition, i.e., pure ? Also, r. Ridge say how much alcohol will effectually typhoid, cholera, and other germs in a glass of If the 20,000th part, I think I will venture to e risk of being injured by alcohol, fearful as that to be.-AQUARIUS. 91.)-Unfermented Wine.-Will some of gentlemen, who understand this question from Hebrew to modern English, kindly tell me how to unfermented wine? I am a manufacturer of soteetotal drinks, but, between ourselves, I am d to put alcohol into them if they are intended to a sale. If they are to be sold off in a short time, is no trouble, but I am unable to prevent them iting if they are kept, unless alcohol is added. I aid viessional advice, and have been told ermented wine, in the ordinary meaning, is im la.-ALTHAUS. 2.]-Bushel-Box.-Will some of "ours" give size of box to ho.d one bushel, the box to be 1-CEMENT. 43.1-Analysis of Gases.-In the Students' t, of Nov. 10th, 1883, there appeared a reprint of ons set at a (then) recent primary examination Apothecaries' Hall, for the Licentiate; and in the try paper this one-"How would you proceed to e a mixture of gases? Illustrate the method of ling in an analysis of coal gas." Now, will some iend show, concisely, how that question should be ed?-MEDICINE. 4.-Estimation of Ozone.-I would be glad informed of a quant tive method of estimating in ozonised air. I use the Siemens ozone tube, e silent discharge to produce ozonised air. Are tot some simple chemical solutions from which, if a red quantity of ozonised air were passed into them ans of a glass tube, a definite amount of some le substance (an insoluble peroxide, for example) be precipitated, and which precipitate could be d, weighed, and the amount of actual ozone into the solution ascertained by calculation? In 01ds, if I ozonise a litre of air, how can I find out er cent. of ozone there is in it? I would like to he manipulation, and have an example worked chemical books furnished this information, the would not be sent.-S. P. [54296.]-Burning Porcelain.-I should like to erect a small furnace for burning porcelain, painted over the glaze. Would one of your correspondents kindly describe how such a furnace would be best constructed? and also, what fuel would be required?-T. N. M. [54297.]-Incandescent Lamps.-Given, a lamp as to which you have no information whatever. How can the description of electric supply which it requires be determined that is, how many ampères of current will it take for full illumination, and at a pressure of how many volts! It may be supposed that a tangent galvanometer, bridge resistance box, and standard Daniell cell, are available. What other apparatus would be necessary, whether the lamp happens to be a three candle toy, or one of the new patterns taking about 100 volts, and less than one ampère ?-Cou TRY STUDENT. [54298.]-Electric Lighting.-I wish to place a Setrin lamp in circuit with a shunt wound dynamo, which gives a current of 12:5 ampères and 50 volts E.M.F. through an external resistance of 4 ohms. Will any of your correspondents tell me what resistance to put in with lamp, as when simply coupled with machine, the E.M.F. comes down to 26 volts? I do not know resistance of lamp ?-S. [54299.]-Sulphate of Ammonia.-Will anyone tell me how much oil of vitriol must be added to carbonste of ammonia to convert it into the sulphate ?-J. C. GEORGE. turning down the microscope and putting on a camera made as directed at page 423, in No. 693 of "E. M.," i.e., a piece of thin glass inclined at an angle of 45, centre of eye-glass Sin. above the table, on looking through the thin glass reflector, the image of the micrometer lines is seen on the table; but less than 2in. apart. I wish to know how many diameters the microscope then magnifies, and a few general observations on the subject. I have the achromatic object-glass of a small telescope about 5in. focus, and in. diameter, which I find useful by placing it a short distance above the microscope objectglass having no eighth or good 1in. With the 1-16, it reduced the magnifying power to about 400 or 500, that of the in. to about 75; does not make much difference used with 2in. The definition is not much affected, but a plano-convex from the eyepiece of a small telescope, supposed to be made of crown glass, does not answer at all-shows colour. I shall be glad if some of our optical correspondents will say what would be the probable effect of achromatic pl-no-convex glasses of longer foci, say, 74, 14, and 36in., placed in that position. Also as a flint concave answers in that position as an amplifier, would flint plano-convex do instead of achromatic plano-convex ?-M. Y. C. 154311.]-Arc Lamp.-To MB. S. R. BOTTONE.-(1) What size carbons should be used for the small arc lamp described by you in last week's "E. M." (2) Would the lamp be an infringement of any patent? (3) Is the Siemens H-girder armature patented 1-I. K. [54312.]-Opera, Field, and Marine Glasses.I have glasses of the above description, which are wrong, and I am at a loss how to alter them. Between the two eye ends is a triangular bar, with knurled knob, so they can look through three sets of lenses with wordings as above. On looking through them for a few seconds, you observe the object double. What is the reason of this, and how can I alter it 1 OPTIC. [54300.]-Liquefaction of Gases.-Could anyone kindly tell the pressure at which nitrogen, oxygen, and hydrogen are liquefied, and at what temperature Fahrenheit? Also the calculated boiling point of the same gases, barometer standing at 30in. ?-BASKERVILLE. [54301.]-Peroxide of Chlorine.-Can any correspondent inform me where I can find a description of the investigations of Professor Dewar, made in 1878, into the "molecular instability of peroxide of chlorine, in the presence of light" I am anxious to know the exact formula for this substance, the manner of preparing it, whether it is a gas or a liquid, the formula for the resultants of the decomposition, and the rapidity with which the latter takes place. I shall also be much obliged for any information as to where, in books or papers of recent date, I can find an account of any other [54314.]-White Japan Enamel-To JAPANNERS. liquids or gases which are readily decomposed by the-Would some reader kindly inform me how to obtain action of light.-A. A. C. S. white paint or enamel that will stand the heat for the inside of hoppers for coffee mills! I have tried white lead powder mixed with copal varnish, but when the stove is the proper heat for the black Japan outside, it is too hot for the white inside, and turns its colour.-S. P. [54302.]-Fused Chloride of Silver for Batteries. Will any brother reader inform me how to prepare this from the metal, I want to do it at home? -EXPERIMENTER. [54303.]-Niaudet's Battery.-Will anyone give information about this, and objections, seeing that it has and is also constant?-EXPERIMENTER. a higher E.M.F. and less internal R. than Leclanche, [54304.J-Lathe Mandrel.-I contemplate making a mandrel for a 6in. centre amateur's lathe, and would be glad to know the best angle to turn the taper bearing to, also the length of the bearing; the back end of the mandrel being supported on a centre. Also the length and taper of bearings for a mandrel running in collars at each end as in a back-gear lathe.-EXCALIBER. 1 Can [54305.]-Oxychloride of Magnesium. anyone give me any information concerning oxychloride of magnesium, which I am told is used as a cement in the manufacture of emery wheels? It cannot be obtained at Hopkia and Williams, and I can find no information about it in Watt's Dictionary of Chemistry. It appears, therefore, to be a technical, and not a chemical term. -P. (54306.]-Dynamo.-To MR: BOTTONE. -Thanks for your reply to my query, though it came late. I should like to ask your advice. The 50-light dynamo (which is series wound) is only working 42 lights the night through. I have now need for other eight lamps, but am afraid to connect them, because the dynamo, after five or six hours' run, becomes very warm, and I am afraid that if it had the ful number of lamps to work the night through, it would become hot enough to destroy the insulation. Can you advise me how to keep the machine cool if I connect other eight lamps? If not, had I not better reduce the speed of the dynamo a little, so that I can set the brushes to take the full current and thus reduce their wear and tear !-R. WILBY. I [54807.]-Cotton Rope Belts.-Can any of "ours recommend what to put on cotton ropes to make them The ropes are gin, diameter, run at a speed of 3,500ft. per soft and pliable, and thus prevent them from wearing? minute, and have to pass over pulleys Sin. diameter. have tried several substances, and am at present smearing them with a mixture of blacklead and tallow, which answers the best of anything I have used, but not as well as I should like. If some of our brother readers could recommend me to something more satisfactory, should feel greatly obliged.-R. W. I [54308.1-Small Stars near Arcturus.-Will some one please say how many small stars are ranged around Arcturus, giving roughly the pos. angles and distances? Webb is silent on the subject.-J. C. L. [54309.]-Leg Irons for Ohild.-I have a child nearly two years old, with, what my doctor terms, a weak ankle, which has been apparent from its infancy, and, but for a jointed iron support which I have fixed to the boot to come above the ankle, he would walk quite upon the inside of the foot. The stay, however, prevents this, but still he turns the foot outward considerably, apparently from the knee and thigh, and when walking springs almost off the inside of the heel. I have tried bringing the support further up with a joint at the knee and strapping it to the thigh, but this has not the desired effect, owing, I think, to not being able to strap it tight 5.1-Guttapercha Cement for Leather. ld be glad if any of the readers of the E. Menough without giving pain; besides, being rather heavy, form me how to make the above cement to fasten it causes the leg to drag. And I should be most happy if on boots, &c. I was told that it was made by means for bringing the foot round to its proper position. readers would kindly suggest any other ng guttapercha in naphtha (mineral) in a water ke glue, which I tried, but it did not answer. And ain been told that it is a particular kind of guttabut never having heard of two kinds, I think it a mixture. As this is a very good cement for the I shall be glad to hear how it is made, not being here it can be bought, and understand it will not ng without being spoilt.-S. E. SIMPSON. some of your -PHONETIC. [54310.]-Microscopical-Camera Lucida.-On looking through a microscope with a fin. objective at a stage micrometer with one eye, and at a rule divided into inches and eighth parts of an inch, the one hundredth part of an inch on the micrometer appears on the rule as 2 in, therefore, the instrument magnifies 250 diameters. On [54313.]-Water Wheel-Having an abundant supply of water for a wheel, 25ft. in height, and 8ft. breast, would any reader be so good as to tell me the nominal horse-power of same, with number of revolutions per minute? Should be glad of the rule for future calculations.-SALOP. [54315.] Lifebuoy.-Can any of the numerous readers of the E. M." tell me the way to make a cheap lifebuoy, suitable for a river bathing place, to throw out about 15 yards ?-or a description of any other life saving apparatus will greatly oblige.-A. R. HALLETT. [54316.]-Slate Water Cisterns.-Can anyone tell me of a composition suitable for staunching cracks in these? Some years since there was only a small vein in the stone visible. From exposure to the sun and frosts, this now permits the water to weep through (having been tight until this summer) what has become a slight crack.-H. R. 66 [54317.1-Siemens Torsion Galvanometer.Will anybody kindly inform me where I can get a good description of Siemens' torsion galvanometer ?-B. of these, similar to the sketch by F. R. A. S.," on p. 37, [54318.]-Abney's Reflecting Level.-I have one Vol. XXXVIII., but I fancy it is wrongly made. The pivot on which the level turns is below the glass tubeI think that if there were no refraction, it should pass through centre of bubble, and that to allow for refraction it need only be dropped to, say, the bottom of bubble. The salesman says it is all right, but I think he does not know. Is it possible to allow for refraction in more than three positions?-GLATTON. [54319.]-Harmonium.-Will some correspondent kindly state how I can make harmonium reeds speak evenly. The reeds are all in tune, but when a chord, for example, is struck, all the notes do not answer with equal rapidity, so that at first I may have CEG, and the G may not come on for perhaps the tenth of a second. Do the tongues want bending or straightening? They appear quite clean and bright; in fact, it looks as if a fresh set had been put in. The tone is good, and the voicing appears all right, but the unevenness of speech is most TOGETHER. unpleasant, and I should like to alter it if possible.-ALL [54320.]-Piano Strings.-Some time ago I bought an old six-octave horizontal grand piano, 8ft. long, trichord throughout; the lowest twenty-one notes, viz., from C to A Hat, have been strung with brass wire. The bottoms of wires have been fastened to a strip of oak screwed to side and bottom of piano. As all the brass and two-thirds of steel strings are gone, could I not restring it entirely with steel wire. The lowest six strings in the bass are from 6ft. to 6ft. 4in. long, and the highest on the brass string bridge (A flat) 424in. The note above this, A natural, below tenor C, is 9in. longer, being 51 in., middle C 21, and pitch C 10 in. Shall be much obliged for information as to size of wire I should use, and how to get over the difficulty between the two bridges 1-PASTA. [54321.]-Ferrotype Photos. I am about to obtain a jin. plate Merveilleux. Will Mr. J. Lancaster, or any of "ours," inform me if ferrotypes can be successfully obtained by it? If not, which would be the cheapest and most suitable camera to obtain :-ANOTHER AMATEUR. [54322.]-Lining Zinc Cistern.-Will Mr. Davies kindly explain how to line a zinc cistern, as this is a subject which he has not yet treated, although he has lead. I should also esteem it a great favour if he would shown us, and very plainly too, how to line cisterns with show us how the new patent 8 traps are made.W. J. G. THE London Hydraulic Power Company has in contemplation the extension of its system of mains from the City to Westminster. ENGLISH MECHANIC AND WORLD OF SCIENCE: No. 1,010. ANSWERS TO CORRESPONDENTS. All communications should be addressed to the EDITOR of the ENGLISH MECHANIO, 21, Tavistock-street, Covent Garden, W.0. HINTS TO CORRESPONDENTS 1. Write on one side of the paper only, and put draw- Attention is especially drawn to hint No. 4. The BACK NUMBERS. We receive so many queries asking for directions how to make many instruments and appliances which have been fully described in back volumes that we have compiled a list, which we shall insert in this column at intervals, of those most frequently sent, and as the numbers are still in stock, new subscribers should consult the list before sending their questions. Batteries: Nos. 715, 718, 734, 741. Bellows camera: Nos. 894, 897. Bookbinding: Nos, 613, 770. Coils, induction: Nos, 832.885 Coils, medical: Nos. 844, 898. Copying processes: Nos. 750, 753, 761, 762. Lacquers: Nos. 622, 866. Magneto-electric machine: Nos. 783, 826. Telephones: Nos. 692, 695, 747, 751, 899, 828, 846, 953, Varnishes: 478, 619, 675, 691, 723, 775. The following are the initials, &c., of letters to hand up to Wednesday evening, July 30, and unacknowledged elsewhere BEITANNIA Co.-Charles Todd, Adelaide.-J. V. A.William Grey.-R. A.-Experimenter.--J. M. G.F. H. Wenham-Kensingtonian. G. W. Nicolls. Pernambuco.-John Ballot, Transvaal. - Progress.-A. Best.-Arefes.-J. J. E.-Lewis Wright.-J. W. W.H. G. C.-Royevrus.-M.-Odous -J. P.-Julia. J. McC. (See the indices, Vol. XXXV. pp. 459, 602; Vol. XXXIII. pp. 556, 578, and so on. Several processes have been patented.)-BATTERY. (See indices. Given many times. For instance, p. 391, Vol. XXXVI., under Electric Gas Lighting.")-READER. (There is no question as to the utility of such appliances; but whether they will do you good depends on what is the matter with you. Look up the indices for directions for making.)-BRIGHTON. (See "Hints," No. 4, above. Ask at the metal sho s whether such a thing is made.) -CHIPP. (See indices, or say what it is you mean. Bronzing and bronze painting are different things.)ANOTHER AMATEUR. (Plenty of manuals. Ask any bookseller.)-H. R. (There are several works on Campanology. Try Masters and Co., 78, New Bondetreet, W.)-PLUMASSIER. (See p. 683, Vol. XXXVII., for bleaching ostrich feathers.)-PROSERPINE. (Look to the references in previous volumes. those you mention have been described.)-EUNOMIA. We believe all (Bee the lists given in recent volumes.)-AJAX. (The Instrument named contains pipes. See many replies in back numbers. It is usual to place a board covered with swansdown over the pallets. Dampers cannot be added.)-J. BADGER. (We gave the name of the author and the source whence quoted. nothing more of it.)-ONE IN NEED. We know (Gordon and last p. 571, No. 830. W. R. (For Acne, see p. 64, Vol. XXXV., and pp. " on the wheel CHESS. Aug. 1 1884 ALL Communications for this department must be addressed to J. PIERCE, Llandwrog, Carnarvon. PROBLEM DCCCXCVIII.-By A. E. STUDD. Black, White. [10+4 White to play and mate in two moves. White. 1. Kt-Q B7 BOLUTION TO 896. Black, 1. K-Kt 5 3. Kt or B mates 2. K moves NOTICES to correspondents unavoidably deferred. a sponge or soft brush.)-CEMENT. (Mostly found in nature; but they are produced wherever iron is exposed to the atmosphere or to a high temperature in the presence of oxygen. nature of the ore from which the oxides are obtained, The colours vary with the but they are red and black.)-YORKSHIREMAN. (See the illustrated letter, "Drills and Chamfers, and How to Make Them," cn p. 251, Vol. XXXVI.)-J. MCCUL LOCH. (We believe not, but apply to the author, St. Thomas-place, St. Dunstan's, Canterbury.) T. H. HALL. (We should be glad of any abstracts of lectures on matters of interest to our readers, but coull not insert any part of the lecture for which you kindly forward ticket.)-J. J. Breathing (Leave the invalid alone. H. K. pure oxygen" means prompt death.)Lime-water 5oz.. oil of almonds 3oz. Add perfume nd a little glycerine if you like.)-W. L. (What do you mean by a steam hammer worked by a horse?) -GEORGE WILKINSON. (All in good time.)H. HowSE. (That would be merely for one person's benefit, and the object of inserting the query is to obtain information useful to many.)-STEAM UP. (They are not made deeper, because it is considered they are deep enough. The subject has been discussed many times. The flexible wheel base carriages were described in Vol. XXXII. p. 496.)-W. H. B. (It is distinctly stated in the question that the pressure in boiler is to be taken at 45lb. Nothing is said about gauge pressure.)-MIDLAND. know of.)-WOOLWICH. (I has been stated previously (None at all that we -about 20 minutes. course.)-H. C. B. (We cannot afford space for a Useless for depositing. 2. Of letter, the principal point in which is your willingness mann's Annalen, Herr J. Collert describes the results to write to some other correspondent)-AN EXPERIElectric Properties of Flames.-In Wiedementer. (Is there not sufficient information even in of investigations on this subject, of which the folrecent numbers, to say nothing of the last volume?)-lowing abstract appears in the Chemical Society's WILLIAMS. SELLS. (The only law is that referring to "nuisances." tinuation of Hankel's researches on the electrical (See replies in recent numbers.)-A. J. Journal for June:If the neighbours will not object, that settles it.) properties of the Bunsen and alcohol flames. The FERRUM. (It is because the point This investigation is a conwhich bears on the rail becomes so highly polished method of experiment was as follows:-A spiral of that friction is redused to a minimum. Galton s experiments on the Brighton line. 2. Fruit with its axis, and connected with one pole of a salt in Vol. XXXII. pp. 97, 121, 166.)-COUNTRY Hankel electrometer, the other pole being in conSee Cap. platinum was placed in the flame symmetrically APPRENTICE. (You should apply at likely places.)nection with the burner; the electrometer was also W. F. JAMES. (Simply an advertisement.)-DELTA. (Rather too late to ask for what has been given almost connected by a commutator with the poles of a years ago." methods have been given. See indices. 2. About 2oz. pal results of the investigation are as follow: -1. See the indices.)-W. M. B. to the pint.)-QUINT. (You should seek the assis ance The difference of potential is dependent on the ma(Several zinc-copper pile conducting to earth. of an ophthalmologist, as the eyes require to be examined. terial and the temperature of the mouth of the The princiNothing can be done without that examination.)L'AMI FRITZ. (Your experience must be singular, and of which the burners are is clearly not the fault of the machine, for many of our burner; an electro-potential series of the materials readers have experienced no difficulty.)-ON GUARD. arranged, of which iron is the most negative. II. (We will endeavour to find space; but make them as The difference of potential is also conditioned by short as possible without leaving out important points.) the position of the spiral; the point at which the constructed can be XXXVI., and p. 452, Vol. XXXII.)-AN ELEMENTARY probably with that of maximum temperature. TEACHER. (Better consult a solicitor, and put all the This latter result probably represents the sum of See p. 211, Vol. greatest electromotive force is produced coincides facts before him.)-PHONO, Ayrshire. (It can be overcome only by an effort of the will. Perhaps in your several conflicting causes-firstly, by the rise of case there is some special cause.)-E. A. BARBY. (Next temperature the platinum is positively electrified; anhydride. As regards the second of these points, secondly, by contact with the experiments of Deville tend to show that the tively electrified by contact with steam and carbonit carbonic oxide gas it is negatively electrified; and the hydrogen and higher the temperature, the greater proportion of thirdly, in the cooler parts of the flame it is posi free hydrogen and carbonic oxide present: whilst Grove has shown that platinum is negatively electrified when in contact with these gases. III. The of a platinum spiral in a results obtained by the author agree with those of the latter obtained the values 1-92 and 1-44 Daniell Daniell, in an alcohol flame = 1-43 Daniell, while Elster and Geitl; the former finds for the E.M.F. Bunsen flame = 1.95 respectively. Gotch, St. Bride-street, E.C., keep files of Australian method is to have a series of five or six boxes, one papers; but you would scarcely obtain a situation by above the other, each with cotton batting in the Clarifying Olive Oil.-The most common answering advertisements in them. 2. Could only be answered by a surgeon. 3. See the catalogues issued bottom the oil passing the sixth will be beautifully by the publishers-that of Crosby Lockwood and Co. clear and ready for market. Some use cylindrical for instance.)-WILLIAM. (See "Hints," No. 4, above.) tin vessels holding about three gallons each, one -PASSTOSE. (You can find several specimens in back fitting into the other, in tiers of three, with fine volumes. It is the ordinary type of four-wheel coupled wire sieves in the bottom of each. with leading bogie.)-A. WooDCOCK. (See p. 392, volume, and many notes in back volumes.)-SKIBEO. lay two or three layers of cotton batting. (See list of Back Numbers above.)-A., Liverpool. is passed from one tier to the other until clear. (We think not. On these sieves rest for the present, as both sides have been be bleached and made much lighter in colour, but The "canned foods" may as well Clarifying can be done by the suulight: also it can The oil heard.)-J. C. GEORGE. 2. Because there is risk of contamination.)-X. Y. Z. artificial heat is necessary in the process. (Southwark-street, 8.E. not without injuring it. (Add a little carbolic acid, oil of cloves, or oil of lavender. If you had mentioned the ingredients, we When it is adulterated, could have said what is the best thing to add.)-JAMES is liable to become rancid when exposed to the air. PASKER. once heated it loses a part of the nutty flavour, and (The remedy will depend on what is the It should be kept in an ordinarily cool place, not exWhen cause, and to ascertain that, personal examination is posed to sunlight or heat; neither should it be necessary. RECENT SUBSCRIBER. (A letter posted on handled any more than is absolutely necessary in July 2 could not possibly be answered until the issue the filtering and bottling, and should not be shaken of July 11, and on p. 428 you will find the answer. Do you not understand that it is simply impossible for after it is bottled. The mucilage contained in the us to insert all the queries which reach us ?)-STAB. oil will not separate for a long time after the oil is (Lotteries of the kind are not illegal, because they give ready for use; and, as it does not injure it, is not, each subscriber a fair return, at ordinary selling prices, therefore, objectionable. for his money, and the profits on the manufacture or in the bottle like globules of water-in films, settling production of the goods are divided in prizes. Where to the bottom as sediment, and when shaken will art lotteries are got up for the benefit of institutions It will sometimes form or charities in which the subscribers get nothing but the give it a muddy appearauce, which, with the comfew prizes drawn for, permission must be obtained mon prejudice against all table oils that are not from the Home Secretary.)-STUD.ISST.C.E. (Entirely perfectly clear, renders it unsaleable, as consumers depends on the office entered: but the principal work consult more the eye than the taste. would be tracing, making working drawings, and cal- better when new and fresh, and what is gained by culating quantities.)-GEORGE. (We do not remember it; but there are plenty of fret-cutting machines sold its appearance by its remaining a louger time in the by our advertisers, and plenty illustrated in back tank is more than lost in freshness and delicacy of The oil is volumes.)-NOVICE. (Read the general directions on flavour. seating Architects and Builders, and has the largest circulatias ING NEWS," published every FRIDAY, price Fourpens any similar paper, and can thus judge where work is likely to be THE BUILDING NEWS is the Principal Journal, repre The charge for Advertisements for Situations Is One Shilling for Twenty-four Words. and Sixpence for every Eight Words after nested to observe that the last number of the term for which their subscription is paid will be forwarded to them in a PINS NOTICE TO SUBSCRIBERS. Subscribers receiving their copies direct from the office are reWrapper, as an intimation that a fresh remittance is necessary, I it is desired to continue the Subscription. |