vention described on page 268, No. 293, appears to be the same thing as Carre's large machine.-W. B. STANLEY. are replaced by fresh ones. When the fat is sufficiently impregnated, it is treated with alcohol as the other A. P. S. [5959.] DEFECTIVE ENGINE. -The piston is touching the bottom of cylinder.-J. P. C. [5963.]-OZOKERIT.-Little information has been [5926.]-MEDICAL ELECTRICITY.-Althaus's work is the most perfect on this subject, but is expensive. As a general rule, the positive pole of the coil should be [5895.]-BLUE DYE.-" Blue Dye "will find Nichol- placed nearest the source of the nervous current, and the son's aniline blue answer his purpose. It is the brightest negative pole further to the extremities. The exact and fastest blue. There are two shades, No. 1 and have always found that there is a great difference in positions depend wholly on the purpose intended. I No. 2; the last one is darker and redder. This dye is the sensation produced, when the current is passing Published as to the electrical properties of this on used in boiling water, slightly alkaline. The colour will then appear to be only a sky-blue, but when the. dyed material is worked and passed through an acidu lated cold water, it will change into a beautiful blue.RIEUX. [5900.]-ATMOSPHERE.-The dynamic theory of light and heat requires and admits the existence of an "ether" or invisible fluid of no ascertained specific gravity, or combining proportion. The gases it temporarily accompanies rise by expansion and it itself evidences degrees of intensity and great diffusive expansibility. I would suggest to experimentalists the possibility of the spectrum tints being the result of atom "dust "vibration, each tint being produced by respective species of atom"dust"; the finest atom dust penetrating the pores as heat, whilst light is but vibration of it or other atom dust; and atom dust I suggest is quite possible to be produced by combustion and other friction, as we see in Prof. Tyndall's and other experiments. This atom dust, shot by solar combustion into the sphere of the earth's attraction, may reach the earth, pass through glass, &c., somewhat sifted of its coarser "grains," and give spectra-line tints of the respective elements the several species proceed from and represent. To maintain the dynamical theory, we must hold that each consuming element has its respective lines of radiation, which diverge as rays. Sir D. Brewster found 2,000 dark lines in a spectrum which he delineated, and an account of them is given at page 48 of Hunt's "Researches on Light," 1854. The hottest rays are the least refrangible, says Dr. Herschel. The heat rays may be invisible, but the dark lines are from the actinic or chemical rays which act in photography, &c.-J. BARWICK, [5901.]-MEDALLET.-Probably a counter made in England, and referring to the Empress Maria Theresa. -BERNARDIN. [5906.]-COPPER EXTRACTION FROM ORES BY THE PRECIPITATING PROCESS.-I have worked Mason's Huelva pyrites, after burning for vitriol making, to some extent, as follows:-I first grind the pyrites between millstones or rollers to a very fine powder. I roast this in a long furnace heated below and above by flues. The roasting leaves the pyrites in the state of a mixture of sulphate of copper, oxide of iron, and sulphate of iron. I wash out the sulphates with hot water, and precipitate the copper on old hoop-iron. The oxide of iron sinks to the bottom of the washing vat. It is sold as "fettling," for puddling farnaces, at from 128. to 188. per ton.-ASSOCIATE. [5908.]-THERMOMETER.-It has been either placed in the sun's rays or in a very strong light; either would bleach it.-A MOKE. [5908.]-THERMOMETER.-Has " F. G. S." proved that the colouring matter has not sank to the base of bulb? Has he not tried inverting his thermometer for a day or a week, or even shaken it well up? He should test this before seeking any other reason.-J. B. [5910.]-LITHOGRAPHY.-The varnish is used for thinning the printing ink. It must be well worked up with the ink on the printing tablet with a palette knife, and as little used as is compatible with making the ink work properly, less is required than would at first be supposed. "Pater's" fault may be in using too much varnish, or it may be perhaps in not making his etching preparation strong enough. If the work is inclined to get smutty, a little vinegar, or stale beer, should be put into the water that is used to damp the stone.-CORNIX. [5915.]-ARTIFICIAL IVORY.-Make isinglass and brandy into a paste, with powdered egg-shell, very finely ground. You may give it what colour you like, but cast warm into the mould, which you previously oil over; leave the figure in the mould till dry, and you will find on taking it out that it bears a strong resemblance to ivory.-A POOR STUDENT. [5917.]-GREEN BLACK INK.-I believe the ink in question is the "Alizarine Ink," of which I gave in an earlier number the recipe. I will repeat it for the benefit of our new readers. Take 15 parts bruised gallnuts, and 200 parts of water, boil for about an hour, strain, and then add to the liquor 5 parts sulphate of iron, 4 parts fine iron shavings, and a solution of pint of indigo (powder) in 3 parts of Nordhausen sulphuric acid. Proportions are to be well observed. This ink writes green but turns black after a few days; it flows very well from the pen. I found the recipe in a German author.-BERNARDIN. [5919.]-GAUZE BATTERY.-" S. S." probably refers to the form described by me, p. 117 of last volume, some serious objections to which I have since stated. Plated gauze answers excellently for a battery for short and occasional use, but the porosity of the silver unfits it for being left in the liquid out of action. A gauze made of silver wire would be very satisfactory but expensive, and have to be made on purpose.-SIGMA. [5919.]-GAUZE BATTERY.-" S. S." may refer to p. 117, Vol. XI, p. 110 and (5137) p. 118, Vol. XII., for in formation respecting the above, and M. Bonquillon's, battery. Silver gauze would be the most perfect of negative plates, but for the expense. Were it not for the difficulty of obtaining it in the required form, the substitution of aluminum would present many advantages. It is nearly equal to silver in conductivity, its value by weight less than silver, (about 6s. an ounce, in wire 108.), while its low specific gravity, compared with silver (26 just where it should; a dull but not painful ache is observed, quite distinct from the ordinary sensation of the shock itself. Indeed, this is produced when the shock is barely perceptible, and it cesses on the slightest variation in the position of the conductors.-SIGMA. [5927.]-THE SPECTROSCOPE.-This instrument has not afforded the slightest indication that the elements are really compounds; its evidence is wholly the other way. That our elements are composed of simpler forms is merely a probable guess; of evidence that they are, there is not one single particle in any of the facts yet known to man, nor is there even the smallest proof that any element as known to us is capable of any alteration into any other elementary form.-SIGMA. [5939.]-SPHERICAL BOILERS.-This query has been repeatedly answered through our columus at different times to my own knowledge. Firstly, in Vol V. No. 117, page 227: secondly, Vol. VII. No 161, page 105: and thirdly, Vol. VII. No. 175, page 414, where it is very minutely described by myself; but if "J. G. D." has not access to any of those numbers, I shall be very glad to give him the information over again if he will publish his address in the Sixpenny Sale Column.-BOILER MAKER No. 1. [5940]-STAINS IN DOESKIN.-Try clean water with a few drops of nitric acid in it, and when the stain is gone, wash with weak ammonia.-T. F. [5941.]-PRESERVING EGGS.-A "Chip" will find the following recipe to answer his purpose well: 1 gal. of water, llb. of salt, 1 tablespoonful of lime, 1 oz. of saltpetre. Of course the fresher the eggs are put in the solution the better.-A. B. [5916.]-TUBING LOCOMOTIVE BOILERS.-There are two ways by which "R. W. L." may accomplish this; first, by driving inside, at each end, a taper ferrule. This plan is greatly in use by a great number of firms; but this method reduces the area of the tube ends, which some of our engineer's don't like. The next plan is to let the tube end project outside the tube plate about 8-16in., then flange the tube end over the tube plate, and caulk with suitable tools; not a caulking tool such as we use for caulking the edge of the boiler plate, but something like the segment of a circle at the point of the chisel, and ground a little bevel. "R. W. L." will see by the last method that no ferrules are required; besides, the area at the tube openings is not lessened. The firm which I work for will have them done no other way.-BOILER MAKER No. 1. [5949.]-COPPER WIRE.-The best mode of testing conductivity is by the Wheatstone's bridge, described P. 290. A complete description of the processes will very soon be given: and I have in preparation a table giving in the fullest manner all the available information as to the properties of copper wire specially.-SIGMA. The stance, though no doubt Matthiessen tested them befor Probably it will patenting its use as an insulator. answer about the same as paraffine; but it is no ender because much longer in use than those made of the new to obtain, as paraffine candles are even more commos, material.-SIGMA. [5970.] KLOTZ AND HIS VIOLINS.- Mathing Klotz, a Tyrolean maker, was the best panil of Stainer. He worked from 1670 to 1698. Instruments of later die bearing his name were made by his sons, who did set put on their own names until the death of their father. The sons were called George, Sebastian, and Egitis.MILES JENNINGS. [5979.]-DYNAMO-MAGNETIC MACHINE.-Brow ing's instrument is a magnet formed as a circle instead of a horse-shoc. At one part a circle is ent ont to form the magnet poles, and in this space the armatare re volves; it is formed on Siemen's plan, just as th Wylde's machine. Of course a single or compound magnet may be used as in other cases.--SIGMA. [5981.1-BATTERY FOR BELLS.-For this purpose I should recommend the manganese battery, "H. H ́S.” can convert his Daniells into this without difitaly. There have been several descriptions given lately of this and the lead sulphate cell, and if the querist will obtain No. 281, he will find in it, p. 481 of last Vol, z description by me of the properties, &c.. of these two cells, and also the sulphate of mercury cell, with the several advantages. The Leclanché manganese cell costs 58., and has a higher force than the DaniellSIGMA. [5984.]-COTTON TEST.-Cotton yarn can be diz tinguished from woollen do, by burning some threads, and observing the aspect and sinell.-J. N. D♫C. [5984.]-COTTON TEST.-The microscope will afford a certain and easily applied test, as there is no mistakieg the flat, twisted cotton fibre. The smallest admixture will be easy of detection.-H. P. H. [5986.]-OLD BOOK.-Were this mine, I should sab mit it to the inspection of some well-known dealer is old books, as Mr. Lilley, of Garrick-street, or inquire et the British Museum. I have always met with grest courtesy when asking a similar favour.-MEUNIEL QUERIES. [5990.]-ENHARMONIC PITCH-PIPE.-Will any obe say what kind of a pitch-pipe is the one which Herlan Smith speaks of as the enharmonic pitch-pipe, in his letter 848, p. 281 ?--T. V. [5991.]-SOUNDBOARD FOR COTTAGE PIANOI beg to ask the "Harmonious Blacksmith" throuch your columns, for instructions to make a soundboard for cottage piano; say best wood; what thickness; whether less joints the better; which way for joints to run; what distance from the soundboard to the top bridge so as to take good sized wire and secure good fail tone for 6-octave instrument ?-AMATEUR. [5992.]-PROBLEM.-I wish for the simplest method of calculating the following:-Given a sphere 553, we. (decimal 553), in diameter-to find an oval with the same surface measure, i.e., sq. in. (5955.1-HEATING APPARATUS.-In working such [5956.]-REDUCING RUBBINGS OF BRASSES,- 123 128 1+ 3 + 5, &c., = n2, 2 + 4 + 6, &c., =12+ R. and the sum of Is it known who was the first to notice this?—B. [5993.)-HALF SECONDS PENDULUM.-Will some render (who has a copy of "Read on Clock and Weten Work") be so kind as to inform me from the table therein, the length for half seconds pendulum, and the painbers for the wheels and pinions for the same ?—Thus, TOMPION. [5994.J-BOXWOOD CHESSMEN.-Can any of your numerous subscribers oblige me with a plan for polishing boxwood chessmen; also how to stain them black and then polish ?-CHESS. [5956.]-REDUCING RUBBINGS OF BRASSES.[5995.]-DIAGONAL STAFF.-W 1 Mr. Sommerville, Your best plan, as you cannot employ photography, and or another reader of this journal, give me instructions I presume have no pautograph, will be-1st, rule out a sheet of tracing paper into squares of in. 2nd. Fixing (without using the cross on the top of the stam, and to make a diagonal staff, such as issed in land survey a "rubbing" to a drawing-board, with the ruled paper the best kind of wood to make it of? An illustration above. 3rd. Rule out the paper on which you desire to will be of great utility.-ADAGIO. copy the said "rubbing" into squares, also of whatever size you wish to reduce to. 4th. Now with your hand copy carefully from 2; the squares will guide you where to insert the lines, &c., of the "rubbing." By this means you can either reduce or enlarge drawing or plan to any required scale.-CHIPS. [5958.]-PERFUME.--The perfume of such flowers AS cassia, bitter orange, violet, and sometimes the rose, and the like are extracted by infusion in the following manner. The infusion is a mixture of mutton suet and lard, properly refined and free from all impurities; this is melted in a steam pan, enamelled or tinned interiorily, and fitted with a tight cover, and the flowers or leaves are immersed in it and left for a day or two, stirring occasionally. When the flowers are exhausted of their perfume, the whole is remelted, strained, and pressed. The spent flowers are replaced by fresh ones, and so renewed until the fat has absorbed a quantity of perfume. The fat is then treated flowers by the fat is dissolved out. The liquors thus obtained are simple extracts of superior quality, and more delicate odour than the essences or solutions of volatile oil in alcohol. Some flowers cannot bear the little heat of the preceding operation. Jessamine, migno. nette, tuberose, and similar flowers belong to this category. The process for these is the following. The fat is spread, about the tenth of an inch thick, on sheets of glass; on this the flowers are sprinkled, and another glass coated with fat placed upon it. They are allowed to remain in this condition a day or two, then the flowers [5996.] -WATER OF THE TRENT. - Perhaps "Aroma" will kindly state what peculiar quality is there in the water of the Trent river which makes the bitter ale brewed there superior to what is brewed elsewhere. -T. O'BRIEN. [5997.]-LARGEST STATIONARY STEAM-ENGINE. -Will some reader inform me the power of the largest stationary steam-engine in England, and where I could see it ?-J. J. MCCORTEY. [5998.]-ENLARGED TONSILS.-One who has to use his throat a great deal would be much obliged to any one who can suggest care for enlarged tonsils ? He is told that constant burning them down with caustic is the only remedy. Is this true?--J. B. T. [5999.] - VINEGAR MANUFACTORY. Does any reader know what machinery is required in the process of making vinegar on the "stove principle," and toa name of an engineering firm in London who makes suca by the excise laws and regulations, if any? A reply will oblige.-R. C. and 10-58), renders it bulk for bulk about 1-5th as costly with alcohol. In this way the aroma absorbed from the apparatus; also, what is the smallest size plant allowed W. H. COFFIN. [5929.]-SMEE'S BATTERY.-The answer to No. 5919 replies to this also, as exactly the same action occurs; but for occasional use, a well-plated copper plate, prepared as described, is very efficient, but it has no economy if a sufficient plating is used.-SIGMA. [5925.]-VALUE OF COIN.-" Dixi" is in error in calling his coin a shilling of Elizabeth, with the date 1563. No shillings of Elizabeth were ever dated; the coin in question is a sixpence; value about 1s. 6d. or 25. -HENRY W. HENFREY, M.N. S., &c. kindly inform me of the uses to which "human hair is (6000.]—HUMAN HAIR.-Will some brother reader, pat to, and if it is possible to dissolve it with any acid and what are its component parts ?-B. E. LODDY. [6001.]-THE PREPARATION OF OXYGEN.—I am sure many others besides myself would be glad to know of MM. Tessie du Motay and Marechal's mode af preper ing oxygen. If any one would give particulars they would greatly oblige-P. B. [6002.]-TAXIDERMY.-Would any of your readers be so kind as to inform me what is the best method of clearing the blood and dirt from the feathers of a bird I wish to preserve as a specimen ?-G. T. [6003.]-DRAINS.-Will any of your agricultural readers tell me to what depth drains should be dug to, and oblige ?-A. PLANT. [6004.)-POULTRY FEEDING.-I have a poultry run some distance from my house, and now that the days are so short find it difficult to get to the run to feed them before they roost. I am told that some ingenious American has contrived a kind of box for containing the food, the lid of which opens when the bird alights on a kind of perch, and closes when it leaves the perch, after satisfying itself. If any of your readers would kindly describe the article and give a rough sketch, I have no doubt it would be welcomed by many poultry keepers.-F. WELLS. [6005.]-INJECTION OF MILK INTO THE VEINS. -Will some brother reader kindly explain the following passage from Buffon, on venomous serpents:-" Milk is One of the most mild and nourishing of all fluids, and seemingly the most friendly to the human constitution, yet if milk be injected into a vein, it will quickly become fatal and kill with more certain destruction than even the venom of the viper." Why does milk produce such fatal efects when injected into the blood ?-SCHOOLBOY II. [6006.]-CARBOLATES. -I am obliged to Mr. George E. Davis and "Urban" for their replies to my query (5577) respecting the action of carbolates. I am aware that phenol is a disinfectant and antiseptic, but not certain of its being a deodorizer, and it was in reference to this latter property that my query ought to have been more properly directed. I have been accustomed for some years to use McDougald's, Calout's, and other carbolates (McDougald's being, however, something more than a carbolate) in sewerage operations, and have found in practice that immediately the powder or fluid has come into contact with sewage the fetid odour has disappeared, and from which circumstance I have inferred that the carbolic acid has formed non-volatile, compounds with the volatile gases of decomposing organic matter, and all odour has ceased other than a faint one due to the phenol. In preparing carbolate of lime I assume that caustic lime is combined with carbolic acid, and that on exposure to atmospheric air carbonic anhydryde is absorbed by the lime, an equivalent of carbolic acid volatilising by virtue of the superior anity of lime and carbonic anhydride, indeed much after the manner of hypochlorite of lime. Query, is this 80? Bleaching powder contains a maximum of about 36 per cent. available chlorine, and for determining the value of commercial samples there are various suitable methods; for these powders rapidly deteriorate on exposure to air-chlorine being given off; and this I believe is likewise the case with carbolates. Now I desire to ask your correspondents to point out the maximum available phenol in commercial carbolate of lime, and also some practicable mode of determining its quantity in different samples, presuming a practical method is known; or at all events to be good enough to mention a come-at-able work from which can be gleaned the necessary details.-W. R; [6007.]-COCOA FOOD FOR HORSES AND CATTLE. -Will any of your numerous readers inform me how to manufacture the above?-JUSTITIA. the weight short or long as required. If so, what is the [6016.]-CREOSOTE.-Is it possible to inject 101b. of 335 inform me how to make a small alembic to aistil in small E. BLACK. water per hour will be required to drive a water-engine, [6033.]-WATER ENGINE. -How many gallons of volutions per minute; water pressure, 90lb. on square two cylinders, each 2in. diameter, 4in. stroke, fifty reinch.-H. [6034.]-BILLIARD BALLS.-Could any one oblige BEN. G. me with a recipe for colouring billiard balls red ? of the best clay, and how to make it hard similar to some fine but hard moulds, would any reader informa me [6035.]-HARD SETTING CLAY.-I want to make what is used in tobacco pipes. The above information will greatly oblige—AN AMATEUR. lowing questions?" Of what material and how must a readers of the ENGLISH MECHANIC answer me the fol[6036.]-SCREENS. Will any of the numerous in. and 3 in. slides be used in a 3in. lantern? What screen be made to show the pictures through? Can number of slides will be required to occupy about two hours to exhibit ?"-JOHN JACKSON. objectionable to use with shingle of proportionate part of MATISM. the surface of land which indicates where fire-brick clay found, and what are those indications or signs?-O. S. kind as to inform me if I apply a condenser to his [6037.]-MEDICAL COIL-Would "Sigma" be so medical coil will it give more power, if so, where must the connections be made from the condenser to the coil? "E. L. G." [6038.)-SHOOTING THE MOON.-Let. 771, p. 202.him to explain; my own knowledge of astronomy is deThe letter of" E. L. G.," on the above subject contains a statement which, with your permission, I would ask rived from popular works on the subject, and therefore I may only be exposing my own ignorance. writes thus: "the place of equal attraction between us thrown one 590th of the way, which is but three-quarters much as the sun has something like 5902 times the (earth and moon), is fully beyond eight-ninths of the way earth's mass, a body to reach him need only be to her, or say at her nearest 200,000 miles. But inasof the above distance." towards the sun?-M. PARIS. is it that the moon gravitates towards the earth and not tween the sun and earth is within the moon's orbit, how Now if the neutral point be to Mr. Davis if he will have the kindness to answer the kindly inform an "Old Sailor" if there are any means I am con dent tell me if it is necessary to have a reflector behind [6040.]-MAGIC LANTERN.-Will some correspon the lamp in a magic lantern? whether the reflector should be made of tin? what is best for it if tin is lens, if not, what proportion should the reflector bear to not best for it? if the diameter should be the same as the lens?-Jos. J. HARTLEY. 1 [6008.)-BRAMAH PUMP.-Would some kind reader of your journal inform me what a bramah pump is for forcing liquids under pressure, such as are used in soda-water engines, and if not asking too much, give drawing of such pump, to scale having a 3in. piston ? after his plan, and find it much more convenient to manage Platt's self-acting mule headstock, with particulars of [6010.] WILKINSON'S PRINTING PRESS. should like to ask Mr. Wilkinson a few questions concerning his printing press, as I am thinking of making one from the description on page 273. His replies will doubtless be interesting to many other correspondents besides myself. First of all, what does he mean by saying, "get the bearers tapped, and four screws to alter the pressure"? I only see two screws in the drawing. What are they to screw down, and where are they to be fixed in the bearers? 2nd. Is the chase to be screwed on to the iron-cast table, and is it necessary [6034.]-ORGANIC ANALYSIS, ETC.-TO "URBAN." STOCK.-If some of our cotton operatives or mechani[6041.] PLATT'S SELF-ACTING MULE HEADcal correspondents would forward a good drawing of self in the cotton branch as to their mules and their drawing, it would enlighten a good many besides myconstruction.-W. H. J. and understood the great necessity of winding the wire thank Mr. Tonkes for his letter (924). I fully appreciated [6042.] - ELECTRO-MAGNETS, ETC. I have to in one way continuously, and hitherto have done so, but makes the wire to cross and wound each leg with an equal length of wire, finishing off with the ends where I always commenced from the part where Mr. Tonkes commenced, instead of at the poles as he recommends. plan is objectionable? and if it would be of any greater Would Mr. Tonkes be so good as to say whether this clock ?-UN ECOSSE. best size of wire to use for a magnet to drive an electric service to have more coils near the poles? and also the WHILE HARDENING.-Will some one tell me how to [6043.]-PREVENTING STEEL FROM SPLITTING for the latter to be planed quite true? 3rd. The tympan, versed the truck. One party says that it would weigh keep steel from splitting or cracking when hardening?— I presume, is fastened to the chase and not to the table itself. What is it made of? The drawing shows it as a flat plate and not a frame. If made of iron, how is the sheet to be fastened to it with pins? Surely this fastening process must waste a deal of time. 4th. What does he mean by fixing the tapes on the roller, "two one way and one the other"? This part of the description is quite unintelligible to me, as Mr. W. does not say what the tapes are to connect to the roller. 5. With what sort of cotton is the tympan to be covered, raw thread or cloth, and which side of the frame (if the tympan is a frame) is it to be put? 6. What is the method of proceeding to fix the type in the chase by means of "bevelled woods"? 7. How is the type to be inked so as to insure an equal colour at all parts? If Mr. Wilkinson will kindly reply to the above questions, he will very greatly oblige many of your readers, and especially your correspondent-VERTUMNUS. two parties about the weighing of a boiler upon a truck. VULCAN. finished and polished to the last degree of nicety, and [6044.]-POLARISCOPE.-I have sixteen small plates of the best white glass, each 1-16in. thick; they are informed how to arrange them as a polariscope, with only the addition of a plane mirror. are from Chance's of Birmingham. I should like to be further than the Newtonian rings, which are a detriunable to get any other remarkable effect from them ment. I have tried all angles. polariscope, this is all that is required; yet I have been In Le Count's ENGLISH MECHANIC will supply me with detailed information, I should be greatly obliged.-GEORGE BELL. If any reader of the out of work, with a wife and large family, wishes to [6011.)-SKELETON "Jack of all Trades" or any other ingenious friend oblige ROLLER SKATES. Will by sending descriptive sketch of the best form of skele ton roller skates to take any size (can a swivel roller be used for turning) ?- AN OLD SUB. [6012.]-FROSTING METAL SURFACES. any reader inform me of a process for frosting or metal-ceive the filtered water?-J. HUGHES. - Could lic watering by acids on brass or other metals?-J. A. [6013.]-HOROLOGICAL.-Is the motive power of a clock increased when the weight end of the chain is long? I am aware that this will obtain, to the extent of the additional weight of chain thus acquired, and know how to correct it, but is it so, irrespective of that. Will the fact that the weight is, say 6ft. from the pulley it drives, make that pulley go quicker? I am led to the inquiry, because I find that this is the case with my I can adjust its movement by keeping [6029.]-ANIMAL CHARCOAL AND FILTER.-Will soine reader kindly inform me how to make, or where to obtain animal charcoal, similar to that employed in the construction of " the poor man's filter;" also a composition for the inside of a wooden vessel which is to re kitebe [6030.]-ANEROID BAROMETER.-Can any one in- and Geo. Fox for answering my query, and, with your [6045.]-HARDENING ritan give a few hints on the setting of saws?-R. S. knitting machine, showing how the stitches are formed, MECHANIC'S APPRENTICE. [6049.] ROYAL COLLEGE OF SURGEONS (LONDON)-Would any reader supply me with a copy of the questions asked at the above college in their examination (classical) ?-MEDICAL STUDENT. [6050]-QUINSEY.-Having been troubled with the quinsey for a considerable number of years, I shall be glad if some of the friends of the ENGLISH MECHANIC will give me a recipe for a cure or prevention.-SUB SCRIBER FROM THE VERY FIRST NUMBER. [6051.]-LIGHT AND HEAT.-On reading an essay on "Temperature," by Samuel Parkes, F.L.S., published in 1815, I alighted on the following paragraph: "In regard to climate, it is not necessary to enter into the disquisition, whether the matter of heat be transmitted to us from an immense globe of fire which we call the sun; or whether it may be more probable that the necessary quantity of caloric for the wants of the world and its inhabitants, was made inherent in the world at the time of its formation, and that this sun is an inhabited world, with a phosphorescent atmosphere that perpetually sends forth rays of light, and that these elicit, and, as it were, put in motion the matter of heat belonging to his as well as to the other planets." Has the italicised proposition ever been verified or refuted ?-E. H. A. A. [6052.]-THE GUN LICENSE.-Will some reader inform me, through the medium of your paper, to which I am a subscriber, whether a gun license licenses the holder to carry and use an air-gun, as it does not state particulars on the license ?-E. L. ROWLEY. of [6053.]-CORRECTING PRESSURE.-Will any your readers give me the formula and method of correcting the pressure and temperature of the atmosphere to sea level, the height of barometer above the same being 90ft.; and also the method of correcting the volume of gases by temperature and pressure ?-T. H. SOMER VILLE. [6054.]-PRESERVING SHELLS, BONES, ETC.I am making a collection of native shells, and I find it impossible to free them from an unpleasant fishy odour, due, I should imagine, to a certain amount of cartilage which remains and slowly decays. Perhaps some brother reader could tell me of an effectual way to purify them? I should also like to know how bones are prepared for a museum.-F.R.G.S.I. (6055.]-SLIDE-REST FOR ORNAMENTAL TURNING.--Would it be too much to ask our esteemed correspondent, "J. K. P.," to give us a few particulars, and if possible a drawing, of a modern slide-rest for ornamental turning, with the measurements of the principal parts? Notwithstanding our friend, I believe, rather ignores ornamental work, I think if he can and will oblige, many of your readers would take it as a great boon.-J. A. L. [6056.]-WATCH REPAIRING.-Can any of your readers inform me whether it is right to oil the escapewheel teeth of a chronometer, and if so, whether the same rule applies to both steel and jewelled rollers ?T. G. SMITH. [6057.]-BELGIAN BEER.-When visiting Louvain I had an opportunity of tasting the celebrated Peterman beer, as brewed for exportation, and very good beer I consider it to be. Will any of our Belgian friends favour us with the process of brewing it? It occurs to me that if introduced here its good body and aromatic flavour would suit the British palate.-ESURIENS. 1 [6058.] POLISHES. Rosewood, birdseye maple, walnut and mahogany veeners. Can any of your readers tell me what polish to use for the above, and how to begin to lay it on ?-ALEPH. [6059-]-PREVENTING BRASS TARNISHING.-Is there anything that can be put on polished brass exposed to the weather that will keep it from tarnishing? Will lacquer or any varnish; but it must not show on it, and must let it keep a good polish? Also, how am I to cut a round cast-iron spout that carries the water from the roof of the house without taking it down? I want about 6in. off the bottom for a better fall.-WELBY. [6060.]-ORGAN AND HARMONIUM COMBINED.Will" A. L. D." have the kindness to state whether he resides in London? I ask this because I am an amateur in the same line, having built a twelve-stop harmonium, and anxious to try my hand at an organ. I must also take this opportunity to thank Mr. Hermann Smith for his articles on "Harmonium Construction," for it was by these alone that I was enabled to construct one. Would Mr. Hermann Smith like to examine it? if so he has my permission; and then perhaps if his criticism was published it might induce others to try.-THOS. HARDING. [6061.]-MAGIC LANTERN.-Will some one be so good as to give a diagram of the arrangement and foci of magic lantern condenser to show an 8in. or 10ft. circle? And also the best way to intensify and tone dry-plate transparencies ?-SHOPMATE. [6062.]-WATCHMAKING.-Will you kindly insert following questions on watch-jobbing? 1. What are the circles for on each side of a mainspring gauge 14 to 26 ? 2. How are watch wheels fixed in turns while drilling hole for new pivot? 8. How do jobbers put watch mainsprings in barrel with winder? An early answer from Horologer," or "Nobody," would greatly assist your old subscriber. -POOR JACK. 16063.]-SWASHPLATE TURNING.-Would "J. K. P." or some one well up in the subject kindly explain the best apparatus to attach to my lathe (sliding mandrel) for swashplate turning in wood and ivory? A drawing would be most acceptable. I have looked through all the Vols. of the MECHANIC, and cannot find any allusion to it.-J. P. G. [6064.]-DOOR-PLATE ENGRAVING.-Would any correspondent kindly oblige me by describing the process of filling in the wax of door-plate engraving, and the most effective way of arranging an address? ENGRAVER. [6065.]-BOOTH'S VELOCIPEDE.-Will your correspondent, A. Booth, kindly give dimensions of the frame of his tricycle, distance of seat from driving-wheel, and guiding-wheels, as well as the stirrup? Is the end of the frame over the guide-wheels made wide to gave a steady bearing, otherwise what prevents the frame and drivingwheel from rocking ?-C. T. [6066.]-HEATING BY HOT WATER.-Will you, or some of your correspondents, inform me, fer the information of myself and the churchwardens of this parish, whether the man who is appointed to attend to the seen from Carnwath, is described as having passed from north-east to south-west, nearly overhead, and as having been followed by a rumbling sound after an interval of ninety seconds. In the immediate neighbourhood of Glasgow there was, on that night, a haze so thick as s conceal the stars; but the glare of light produced by the meteor was distinctly seen at thirty seconds before nine, Greenwich time. It lasted three or four seconds, and, judging by the distinctness with which it illumin ated terrestrial objects, was considerably brighter than the light of the full moon. From the appearance of the sky in the quarter in which the light vanished, the luminous object seemed to disappear in a southerly [6067.]-AREA OF HEATING SURFACE.-Will any direction, at an altitude less than 30. A rumbling sound followed, after an interval which was not friends give the area of heating surface in a locomo tive boiler for a given amount of h.p.; also particulars accurately ascertained, but it is believed to have been of the number, length and diameter of the tubes; to-between three and five minutes, corresponding to gether with dimensions of fire-box, and should be glad distance of between thirty-six and sixty miles." GRAPHITE.-Graphite, or plumbago, has been found to be informed whether the fire-box or the tubes raises n gneiss, mica slates, clay slates, limestones, and a most steam for the same area of heating surface? Also what area is reckoned of heating surface per variety of other rocks of different geological periods Its origin has long been a matter of conjecture, and h.p. in the Field boiler?-YOUNG ENGINEER. scientific men have not been able to agree upon i [6068.]-GUARANA.-Can any reader give any par- Professor Wagner ascribes it to the decomposition of ticulars about this ?-SERGIUS. cyanogen and of the cyanides. The black mass which sometimes separates from hydrocyanic acid, on being washed in nitric acid and dried, is found to consist d scales of graphite. Dr. Wagner infers from this the the artificial graphite that is formed on the cooling of many varieties of iron has its origin in the same source, namely, cyanogen. It is not the carbon which is held in solution in the melted iron, but the cyanogen compounds, that give rise to the graphite. In the manu facture of soda by Le Blanc's process there is always a quantity of graphite formed which is derived from the decomposed cyanogen compounds, and, in some of the large establishments of Bohemia, practical applicatio is made of this incidental product in the manufacture of lead pencils. This theory of the origin of blackled is worthy of attention, as it may lead to cheap methods for the artificial production of that valuable substance, and at the same time help to explain many dific geological questions. [6069.]-DRIVING WHEELS.-Which will take most power, a 6ft. driving wheel gearing into a 8ft. wheel, or a 8ft. driving wheel gearing into a 6ft.?-SERGIUS. USEFUL AND SCIENTIFIC NOTES. LEVANDER'S IMPROVED UNIVERSAL EQUA THE ECLIPSE EXPEDITION.-An accident a happened to the Sicilian expedition (Mr. Norman Loelyer's party) for the observation of the forthcoming eclipse. The Psyche in her voyage from Naples struct on a sunken rock six miles north of Catania, Sie the crew were saved. The instruments have been set into Catania. Commander Fellowes hopes to save s if assistance comes at once from Malta, where be bu telegraphed. UNNOTICED QUERIES. IN future, if any query remains unanswered for four Since our last "Clockmaker" has answered 9, "Ben. G.," 5062; "G. L.," 5113; "J. M.," 5148; "Esuries" 5192; "No. 170," 5218, 5262; "M. P.," 5248; "God Laboratory," 5293, 5807, 5869, 5401; "Sergius," ; "Iota," 5306; T. Harding, 5307, 5869, 5421, 52, 54, W. Purkiss, 5422; "A. S. C.," 5423. 5410 Concertina Tuning, p. 166. 5416 District Surveyors' Examination, 166. 5428 5430 5431 bringing the instrument into the meridian, and an 5445 5449 5460 5494 5508 Pitch of Trinidad, 166. Curvilinear Perspective, 167. Bagatelle Table, 168. MONEYS COINED.-The annual return from the 5463 Royal Mint shows that the following moneys of the realm 5465 were coined in this kingdom in 1869:-6,441,822 sove-5473 reigns, 1,861,764 half-sovereigns, 297,000 florins, 786,560 5475 shillings, 388,080 sixpences, 4,158 fourpenny and 4,488 5476 threepenny pieces, 4,752 silver twopences, 7,920 silver 5484 pence, 2,580,480 copper pennies, 3,225,600 halfpence, and 5489 3,225,600 farthings. There was an unusually small 5491 quantity of silver coinage. No crowns or halfcrowns 5492 have been coined for several years. The value of the pieces coined in 1869 was as follows:-Gold, £7,372,205; 5495 silver bullion was £135,083. Worn silver coin of the silver, £76,421; copper, £20,832. The amount paid for weight of 325,977 oz. ; and the nominal value of £105,000. 5514 was purchased for re-coinage; the Mint value, at 5s. 6d. 5515 per oz., was £89,644; and the loss by re-coinage, 5518 £15,356. The amount paid for copper bullion and old 5519 copper coin was £8,356. The amount of seignorage 5520 paid into the Exchequer in the year was £12,845. In the ten years 1860-69 there were coined at the Royal Mint 46,187,360 sovereigns, 12,140,516 half-sovereigns, 5531 Reflectors. To Mr. Browning, 191. 8,981,280 florins, 26,227,080 shillings, 17,028,000 sixpences, 5532 A Wreck, 192. 41,580 fourpences, 15,995,760 threepences, 151,420,416 pence, 157,696,000 halfpence, 51,085,108 farthings. INDELIBLE INK.-The following recipe is from the Deutsche Industriezeitung: Dissolve four parts of aniline black in 16 parts by weight of alcohol, with 60 drops strong hydrochloric acid, and dilute the dark-blue 80lution with 90 parts by weight of water, in which six parts of gum arabic have been previously dissolved. This ink does not act upon steel pens, or suffer any alteration by alkalies or acids. 5529 5536 Reversing Motion, 192. 5538 Turbine Power, 192. 5589 Acetate of Soda Manufacture, 192. 5547 Sheepskins for Organ Bellows, 192. 5548 Silk Paper, 192. 5551 Malleable Cast-iron, 192. 5555 Pedal Harmoniums, 192. 5556 Telescopical, &c., 192. 5558 Link Motion, 192. 5560 Humours of the Eye, 192. 5561 Lens for Spectroscope, 192. 5569 METEOR.-Professor Rankine has written to the 5562 5570 Oil Varnish for Silk Hats, 192. The English Mechanic AND to work. Some appeared to be well up on their MICRO-POLARISCOPY. THE microscope is at once the most sociable seratched their heads with their pen-holders, to Tand the most unsociable of instruments. To WORLD OF SCIENCE AND ART. at the stroke of the hour, and the filled-in papers FRIDAY, DECEMBER 30, 1870. ORIGINAL ARTICLES. GOING IN FOR THE WHITWORTH rub up by friction the electricity of thought. At 10, sometimes 11 p.m., according to the nature of the queries and directions attached, all stopped were placed at once in a bag sealed up and sent off to head-quarters by next post. This was the modus operandi in nearly all schools of design or science in the kingdom during, for the candidates, that busy month of May. I had almost forgotten to mention that there were three grades of questions in these papers, and two classes in each grade. The grades were honours-advanced and elementary, only one of which grades was allowed to be answered. Nothing more was heard of the subject by any of the students until the month of August, when lists of the successful candidates on AVING seen so much in the engineering the various subjects were forwarded to those compapers relative to the Whitworth scholar-petitors who had obtained the requisite number ships, and inquiries having also been frequently of marks on the theoretical papers to enable them made on the subject by numerous friends, I con- to go up to the final examination. A notice sider that a short description of the mode of pro- shortly followed requiring these to make their cedure, as having been experienced by an actual appearance at Sir Joseph Whitworth's works at student, will not be unacceptable to our numerous Manchester, at half-past eight on Tuesday, the readers, more especially to those younger friends 30th of August, to compete in the practical or who, being gifted with a love of mechanics, hope handicraft examination. To my surprise when at some future time to share in Sir Joseph Whit- the list was exposed to our view, thirty-three only worth's munificence. had reached the requisite number of marks out of upwards of 4,000 who had attempted the task. Eighteen of these, of whom only seventeen showed up, were to commence on this the first day for the workmen's examination, the remaining fifteen came on the 1st Sept., they only going in for students' test in the use of tools. HA It will doubtless be known to most of those who peruse our pages, that Sir J. Whitworth is endeavouring to promote engineering and mechanical industry, by placing thirty scholarships of the annual value of £100 each for competition by any of her Majesty's subjects, whether of the United Kingdom, India, or the Colonies, who shall not have completed their 26th year on the 1st of May during the year of competition. Ten scholarships have been competed for this year, each scholarship of the annual value of £100, being tenable for two or three years as experience may suggest. I knew very little more than this about the subject some eight months since, but on inquiry at the nearest school of design I was shown a prospectus and informed that by sending to the secretary of the Science and Art Department at South Kensington I would have a copy of the most recent edition forwarded to me. I did so at once, and shortly had the leading_conditions and requisites at my fingers' ends. I found the first thing to be done was to enrol my name amongst the candidates, of whom there appeared to be a good supply, and send my address to the nearest school of design. This soon done, and I thought no more of the matter until a printed form with the imposing words "On Her Majesty's Service" was forwarded to my address, informing me that the theoretical examinations would come off during the month of May at the institute of the nearest town. Next came to hand a rather lengthy list of the subjects for examination, which was certainly a very varied assortment, the principal and most essential being a knowledge of mechanics, theoretical and applied; mathematics; drawing, both freehand and mechanical; chemistry and metallurgy. The hours of examination were between 7 and 10 p.m., with locked doors, no student being allowed to re-enter the room after having once left it under any pretext; and the evenings during which examinations were held extended through the whole of the month of May. I had not specially prepared for any of the subjects, but thought I would just stand the test principally that I might have an idea of what the ordeal would be likely to be on a future occasion, and chose about six subjects in which I considered I was best up in. Behold me then at the nearest institute where the students of the science school were at the same time being examined. The door opened at a quarter to seven, we enter and are told off to our places by numbers, each competitor having inkstand, pen, and just the requisite quantity of paper allowed him to answer the questions upon. Of course, when the subject was mechanical drawing or a sketch was required, the student was allowed, and in fact requested, to provide himself with drawing-board and instruments. All the candidates being seated, the secretary for the institute opened the sealed bag containing the examination-papers, which had been simultaneously forwarded from the central department at Kensington to all the science schools and institutes in the United Kingdom. At five minutes to seven the same individual read the rules from which the pupils were not allowed to deviate on pain of immediate expulsion. The papers of questions were distributed by the examiners at seven, with instructions at the foot of each paper, and we went At a quarter to nine on the morning of the 30th, sixteen of the eighteen workmen were assembled, and were conducted out of the office at five minutes to nine into the workshop, in which their practical abilities were to be put to the proof. The greater number of these had to go to the fitting test at the vice, which was a very good one. A turned piece of steel was required to be squared to gauge for a certain distance, and a bored hole in a cast-iron boss had to be squared out to fit this accurately, so that it might be just pressed in by hand. The turning required was to bore two cast-iron bevel-wheels accurately to gauge, turn two wrought-iron mandrels to fit them, then finish and scrape up the whole surface of the wheels. The pattern making was no less easy, the task being to make a pattern of a bracket or support with a cored hole, drawing supplied. The time allowed for each of these operations was eight hours. The students' examination was slightly easier, the time allowed for each subject being two hours. The vice tests were two, one of the hammer and chisel, the other of the file. The former test was to take a chipping off a 6in. face of cast-iron, leaving it as smooth and true a surface as possible from the chisel. The proof of the student's capability in filing was to file up a cube to gauge, and also an hexagonal nut. Besides this there were four other tests-1st, the lathe, at which the candidate was required to turn up a bearing and small portion of shaft from a short section of bar iron; the forge, at which a drill and chisel were to be drawn out from bar steel and hardened, and also to forge a pair of callipers; the axe, where a piece of timber had to be squared to pattern, and an axe handle required to pattern, a spokeshave being allowed to finish with; lastly, the saw and plane, at which the candidate was required to make two straight-edges, each 2ft. long, width to gauge, thickness to measure, and to saw out of a plank, and square two pieces of timber to a certain thickness and length. Some of the students and even the workmen who were allowed to engage in some of these latter tests, in lieu of the other, went away with blistered hands especially at the forge, and all appeared to be glad when it was over. the diffident lover, anxious to become on friendly " of the matron As I have observed in former papers, the requisites of micro-polariscopy are neither numerous nor expensive. The Nicol prism, as polarizer and analyzer, is upon the whole the most effective, but the possessor of the prism introduced into microscopy by the lamented Mr. Reade will find that its use as polarizer will enable him to get the beautiful effects, to obtain which a somewhat elaborate arrangement was devised by Mr. Furze. To save recapitulation of what I have previously written, I will assume that my reader possesses a microscope fitted with a Nicol polarizer, and with an analyzer capable of rotation. He has also a set of selenites, giving red, yellow, blue, as primaries, with of course their complementaries, when the prisms are altered in relative position. Besides the selenites, he has a slide or two of mica films, giving violet, crimson, &c. These he can easily make for himself from a piece of mica, such as is commonly sold by gasfitters as a "smoke consumer." He must split off a film; the colour he can ascertain by placing the film in his polarizer, and looking at it through the analyzer, the whole being turned towards a good light. If the colour please him he can mount the film between a slip, and then cover with Canada balsam, as a cementing agent. So much for the machinery; now for the "pretty things." Warm a glass slip with a square cover placed thereon in the centre. From a lighted" composite" candle drop a little melted "tallow" or composition" (it is neither) on the edge of the thin cover, and allow the slide to remain warm long enough for the "fat" to run under the cover by what we call capillary attraction. So soon as the slide has become cold, clean off the surplus fat and remove the slip to the stage of the microscope, where it is to be viewed with the aid of a blue or a yellow selenite. The vivid displays of colour presented will defy description. There are few more beautiful objects than this slide of "fat-acids." A pinch of most of the washing-powders used in the kitchen or laundry department of our domiciles, dissolved in hot water and allowed to recrystallize in a thin stratum on a slip, and then mounted in balsam forms a splendid object, preferred by many to even the gorgeous salicines Sir J. Whitworth generally looked round at of Mr. Barnett. An immense number of delileast once a day, and seemed to take much inte- cately beautiful feathery stars are seen on a dark rest in the endeavours of the earnest competitors, ground when the object is viewed without a selesome of whom will, I trust, show themselves nite. With a selenite, which should not be a red worthy of the liberality so bountifully showered one, the stars are less beautiful, but the blue or amongst them. Those students who took interest purple ground, from which they seem to stand enough in these things to ask permission were boldly out, give them a singular attractiveness to kindly conducted round the works only to admire many. The washing powder folk must not comsome of the most beautiful and perfect machinery in England. May we have many such men, as the owner has proved himself to be, who are willing to help those who endeavour to help themselves, is the desire of one who hopes to be enabled to leave the world by his exertions in some way better than he found it. VERITAS. plain if I give the slide a name. It may be labelled "Anhydrous Carbonate of Soda." A slide of honey mounted in distilled water forms another very beautiful homely object, and should be viewed with the aid of a blue or a red selenite. These are a few of the things which may be prepared off-hand by any one microscopically impecunious. Amongst other "polariscope slides" that should find a place in every cabinet are slides of salicine, which, if well prepared, are most gorgeous; of iodo-quinine, and of chlorate of potash amongst chemicals. Others of no less, perhaps greater, beauty may be found mentioned in the lists of our professional mounters, and it is hardly worth while here to enumerate them. A good section of the horn of rhinoceros viewed by aid of a red selenite (some prefer blue, but I write as I think) forms a beautiful object, and is interesting into the bargain. It should be added to any cabinet from which it is absent. Sections of many woods, longitudinal almost always, transverse sometimes, are very beautiful, and for this class of objects the violet mica is most admirably adapted, but requires more care in the setting of the prisms than can always be given to it when a person is "exhibiting." Mr. Walter White sent me the other day a section of Salix alba, which he thinks the perfection of polariscope objects, so far as woods are concerned. Without indersing his opinion to the full, I have no hesitation in affirming that it is, when cut as well as his, as beautiful as any. A section of stem of fern cut longitudinally is also exceedingly beautiful. But to my mind a transverse section of Aristolochia, of Chamorops, or of Clematis vitalba, viewed by aid of a violet mica, will hold its own against all comers. The latter will most certainly please the ladies. If you take a raw potato, mash it in cold water and secure the starch, you may proceed to mount it in balsam, or other like medium. As little heat as possible must be used. The resulting slide, viewed either with or without a selenite, forms a remarkably beautiful object; but I need not remark is of little scientific value. Other starches mounted in the same fashion will give slightly different effects, but for show purposes those of potato and of canna (tous les mois) are the best. A slide of any of the homeopathic (save the mark!) cocoas will also amuse a party with the additional advantage that its appearance may lead Paterfamilias to ponder the reasonableness of paying eighteenpence per pound for a starch he might purchase by itself for 4d. Paterfamilias may mount his first grey hair, following the example of a friend of my own, and exhibit it triumphantly. But on mo account should his specimen be taken from the head of Materfamilias, or if so be that that is his only source let him be careful how he label it. All white or grey hairs polarize beautifully,-the hair of the white bear perhaps more beautifully than any. "How like a map!" Such is a section of granite when "polarized." This is perhaps one of the most effective slides, since the section itself is so terribly uninteresting to the tyro. The philosopher of the family may accompany its exhibition by a learned discourse upon granite in general, and upon the elective interferences of its various crystals. I, forsooth, am not the philosopher of this ENGLISH MECHANIC family, and for this week at any rate leave this question open, and also postpone a wee disquisition upon "Starches, their Nature and Origin," I have it in mind to inflict, to use a Dorset phrase, somewhen. I have said nothing about the "stars." Those of Deutzia scabra, of Eleagnus, Hippophaë, and the like. These are easily mounted, easily obtainable (I could supply a few score readers with raw material), and if well mounted are very beautiful. "But what things are not beautiful; when rightly viewed?" Truly none. But so far as regards polariscopy all things are not beautiful, enough are so to enable any one to speedily fill a good-sized cabinet, and I hope that I have pointed out a source from which much pleasure may be derived. Stray notes upon the use of the polariscope may possibly follow shortly. H. P. H. PRACTICAL INSTRUCTIONS IN THE ART BY SABLE. THE *The right of reproduction is reserved. venience of the operator, and it can be securely | it does; also other undesirable effects too nume clamped in position by pressing down the sliding-rous to mention, unless the utmost caution be bar B. I made my easel of good white deal; it used; therefore I advise beginners to abstau has served my purpose for nearly twelve years, from its practice. When working to order it a and is as good as ever. A is a flat piece of board absolutely unavoidable sometimes, for customer in. thick, with stays at the back to prevent like old Time, wait no one's leisure; but great warping; it is attached to the under side of the nicety and judgment are necessary to practice à immovable foot-board A by two hinges of with success; to the advanced artist only cal leather, and is covered with white paper forming recommend it. However, by all means harda a backing to the drawing, enabling the artist to your outlines. After standing about thirty hous see the faintest tint he lays on the glass. The pare and improve them with the penknife, if ne standards c c are 18in. high, 24in. wide, of in. sary, as before directed, and then place them i stuff. The entire width of the easel is 17 in.; a tin box having the lid perforated with a number depth of foot-board A, 6in; width of sliding- of small holes; this can be stood in the fender bar B, 24in.; both of in. stuff. The splines e e or placed in an exhausted oven for a few hours, are in. wide, 1-10in. thick; they should be after which the box and its contents must be fastened with glue and three small brass screws, allowed to cool very gradually. The outlinel leaving a ledge 1-10in. on which to rest the edge glass should stand against the sides of the bas, of the view, as in the figure. Fig. 2 shows the as plates on the dresser shelf; a little ingenuity top ends of the standards c c, and the way in will easily accomplish what is required for this: which the sliding-bar B is held by the pieces d d When treated thus the outlines will not work which play on the angular edges of c c. The in colouring unless very roughly handled. desk is attached to a frame by two hinges, and can be readily adjusted to the requisite height by the support f. Take one of the outlines (say Fig. 3), secure it as before directed on the easel, get a good light on the white grounding A, and examine your subject carefully. The beginner will be sure to find some of his lines too thick, others ragged and uneven. With the penknife (Fig. 2, p. 194) these must be pared thin and smooth, especially those in the lights. Having done this very accurately, next remove all dust and atoms with a large soft brush provided for the purpose. The proper colours are lakes (crimson and yellow), sienna, and umber (burnt), Vandyke brown, French ultramarine, Prussian blue, indigo, and lampblack. These must be prepared in oil, and the purpose for which they are required ought to be explained to the vendor; they should be obtained from some eminent artists' colourman, as they must be very finely and perfectly ground. Colours prepared expressly for this branch of art are to be had at a slightly advanced price. There are also other colours which produce beautiful effects-i.e., the madders, Italian pink, and verdigris-but they are very unmanageable in the hands of the amateur, the former requiring embarassing media, and the verdigris having a tendency to opacity; they should, therefore, be avoided until considerable experience has been gained. The student should next provide himself with a dozen good sable-hair pencils mounted in duck and crow-quills (six of each), have handles fitted to them, and select them with the utmost care; they will cost about 6d. each. I tried to get off with French camel hair and Siberian hair, but it ended in vexation. There must be no stray hairs; and with the aid of a magnifying glass cut off the extreme points, as shown in Fig. 3, but leave the points of two of the crow as purchased. A moderately fine etchingpoint, a bottle of the finest pale drying oil, and some clean white rags free from lint will complete the list. In painting for the trade it is usual to place the slides in an oven after each manipulation to accelerate the drying and harden the colours; this is said to produce greater transparency. So Get a small wide-mouthed bottle, holding abou half an ounce, fitted with a sound cork; fill a three parts with pure mastic varnish, add half s teaspoonful of rectified turps and ten drops d pale drying oil, stir with a thin stick and stand i in a gentle heat for a few minutes. This mast be kept well corked when not in actual use. Label this mixture "Medium No. 2." Place on the glass palette a very little burnt sienna and crimsonlake; dip a "duck" pencil into the medium, and mix small portions of the colours until a taway flesh tint is produced; smear a little on a trial piece of glass to determine the proper depth, the fill the brush moderately, and commence laying the tint, beginning at the forehead and working downwards quickly and evenly, leaving the white of the eyes untouched: do not hurry the operation. You will not succeed the first time; bat with patience and perseverance you will conquer all obstacles, as I have done before you, if your heart is in the work. The brush should lead, or rather entice the colour over the surface of the glass, scarcely touching the glass itself; coax the colour thus to the shady side of the face, and having carefully wiped the brush, rapidly take up any surplus, if you have well judged the quantity of the colour with reference to the surface to be covered there will be no surplus whatever. In laying flat tints be careful not to carry the colom over the parts already covered. Should any parts appear uneven draw the brush between the thumb and finger until moderately dry, this will flatten it, causing the point to spread and assume the shape of Fig. 4, with this "stroke" the uneven parts in various directions, as in "cross hatching;" the breadth of the pencil point must be regulated for the surface to be "stroked," the touch must be light, the hairs of the brush should gently scratch the surface of the colour without penetrating to the glass. The lines caused by this operation are very soon obliterated by the colour gradually coming into them. It will, therefore, be seen that to insure success surfaces met be "stroked" before the varnish begins to set. The addition of the oil to the medium retards the setting of the colour and causes it to work with greater softness and freedom. Stroking and dabbing are the foundation of all softness and |