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THE FLUTE AND FLUTE PLAYING. [186] SIR,-I am pleased to find the old flute has found a friend to speak in its favour. I have had twenty years' practice on the old instrument-one of Rudall's-and agree with Mr. H. Chapman that the fault generally speaking is with the performer rather than with the flute. When playing, I have heard the remark, "Well, I cannot bring such a tone as that. I do not know how it is, I cannot do it." But I knew, and the secret lies in this, that a great mistake is made in endeavouring to blow as loud as possible. This is not the way to bring sweet sounds from your instrument: quite the contrary. I have no doubt all find a difficulty in learning, no matter what flute they possess; and if you do not sometimes make fingerings, possibly you may find it awkward in some passages to play as you would wish; for instance, C sharp in alt. to natural, and many other instances. The best scales I know are James's, published at sixpence each.

I have spent many a delightful hour with Nicholson's Beauties, the Fantasias of Tulou, Kuhlau, Berbiguier, Dressler, Fürstenau, Devienne, Vern; but I think the most difficult of all is Dronet's music. Yet all these flautists performed upon the old flute, and found, I should suppose, no particular difficulty in playing the music they wrote. No doubt the instrument is imperfect, and many of them very much so; but I can play with violins, violoncellos, and pianos without playing ont of tune, and if one can do it there is no reason why another should not. I can go from D below the line to upper B in alt. in a moment, and in some of Berbiguier's music it is a case of necessity to do so, and that perhaps for sixteen bars following each other. I think it a great mistake to have the lower C keys at all. By the bye could any of your readers give me the name of the author of a flute instruction book which has at the end of its preface, numbering 32 pages, full music size, the following quotation:

Qui variare cupit rem prodigialiter unam, Delphinum silvis appingit, fluctibus aprum. Hor., De Arte Poetica, 29. It has chapters on sound, tone, fingering, tongueing, time, double-tongueing, staccato, &c., shakes, &c.,objects of practice, musical expression, modulation, variations, and examples in each.

T. CRIDLAND.

[187] SIR,-As an amateur flautist, I have perused with much pleasure the letters upon this subject from several of your correspondents.

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EXTRACTS FROM CORRESPONDENCE. worth more than a shilling above the value of the metal.

PRE-ADAMITE OR PRE-HISTORIC MAN.-J. Sargent says, "Your correspondent T. S. Conisbee' is rather too hasty in pronouncing me a sceptic without knowing my reasons for making the remark I did upon this subject. I merely wished to see a few arguments for and against it, in order to see the view generally adopted by scientific men, which the letter of 'H. P.', Hull, appears to show."

A CURIOUS SENTENCE.-"Mus" says:-Your" correspondent's letter on the above, that appeared July 22, was very strange. It is such a curious sentence, that when I went to school I don't recollect the word Arepo,' nor can I find it in the dictionary; and last, though not least, I never recollect seeing an imperative in o'before. If Reg. Pilkington' can give me a proof that I'm wrong, of course I'll give in. True, it's some time since I left school, but I think I remember enough to know he's wrong."

REPLIES TO QUERIES.

* IN their answers, Correspondents are respectfully requested to mention in each instance the title and number of the query asked.

[2662.]-WATER METERS-are all constructed on the principle that "a given quantity of flowing water performs a given quantity of work." The water flows from the supply pipe, through a filter into a drum, which is caused to revolve by the passage of the water. This drum is fitted with a spindle, which sets in motion a train of wheels that register the amount in gallons on a dial plate. The meter of "Fidus Achates" is doubtless out of order, or possibly the water is supplied at different pressures, which would make a difference, but not to such an extent as he has experienced.-H.U.

[2672.]-DRAUGHT WANTED.-H. Gregorieff should make a flue to the chimney, he will get a good draught as wanted. If the boiler stands above the ground he must make the flue slope down at a gentle angle, and make the flue large enough, for it requires a large flue to make a good draught. I know several as far from the chimney as that one will require to be, with good results; arch it over in the usual way.-HEATHER JACK. [3812.]-CONDENSING ENGINE.-Condensing engines do not make a noise. The valves in the hot well and on the bucket make the noise. If they are fitted with India rubber valves there is very little noise and very pleasant working.-HEATHER JACK.

[3828.]-PRESERVING KID BOOTS.-If" Old Scrub" will rub her kid boots with a little cream, and polish gently with the palm of the hand till dry, it will keep the kid soft and good. Sour milk will spoil the kid. HOUSEWIFE.

[3842.]-STEEL WIRE.-" J. R. Y." can obtain steel wire of any gauge he may require at most of the London tool shops. I would, however, suggest to him the great superiority of the English gongs, which are made on a totally different principle, and of different wire to those used in American clocks. Doubtless it is to the American gongs that " The Harmonious Blacksmith" refers, when he reminds "J. R. Y." that "wire gongs have a very disagreeable tone." Those made in England which have come under my notice have anything but "a disagreeable tone," the imitation of the church bells being excellent-ROGO.

I should not have troubled you with this note, had not the letter in your last issue from Mr. H. Chapman appeared to me to "hit the nail upon the head," and it goes a long way to settle the different opinions as to the merits of patent and ordinary instruments. For several years I used the old fashioned eight-keyed flute, and when by practice I had obtained sufficient knowledge of the instrument to blow it in tune, I yet found it imperfect in the lower notes-viz., from G to lower C; the latter I could not at all depend upon producing. I then got hold of a "Siccama" and with the indifferent practice my profession allows me, find the lower register most powerful and easily produced; the only difficulty I find is, that, being a self-taught player, there must be some systems of fingering upon the "Siccama" and the old eight-keyed that I am ignorant of. Will Mr. Chapman kindly inform me if there is a scale for the "Siccama," and if so, where I can procure it ? A great advantage of the "Siccama is, that it varies little or nothing in playing. When using the eight-keyed with a string band I was frequently obliged to flatten it (by the tube), as it sharpened half a note, or more. My Siccama," I find, alters nothing with an hour's steady playing, and I can with imperfect practice depend upon my flute being in tune. A friend of mine possesses a Carte Boehm, in silver, and although he can execute passages more brilliantly than I can, inasmuch as the fingering in the upper and lower octaves is the same (at least he says so), yet his tone is not equal to mine upon the "Siccama," and I believe, had I the time to practice he enjoys, my instrument is far superior to his. In conclusion, I can heartily endorse Mr. Chapman's opinion that, "practice makes perfect," and that if your flate-playing readers cannot, like myself, devote sufficient time to practice, there is no instrument like the "Siccama" in price and efficiency.

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DOWS."Pitman" should get a spring barrel like
[3912.]-REVOLVING FRAME FOR SHOP WIN-
those in eight-day clocks. With a few wheels and pinions
properly arranged he can make a frame that will
revolve one way all day long.-H. U.

[3918.]-ENAMEL.-A dead white enamel is made by
calcining together two parts of tin and one of lead. Of
this combined oxide one part is melted with two parts
of fine crystal and a very little manganese, all previ-
ously ground together. When the fusion is complete,
the vitreous matter is poured into water, and the "frit"
is dried and melted anew. The pouring into water and
fusion are sometimes repeated four times, in order to
secure a perfect combination. The crucible should be
carefully screened from smoke and flame. The smallest
portions of oxide of iron or copper will destroy the value

of this enamel.-H. U.

[3975.]-VALUE OF COIN.-An Oriental one; not -HENRY W. HENFREY, M.N.S., &c.

[3982.]-WORKS ON SOAP MAKING.-I think that among the French manuals of the "Collection Roret" there is a "Manuel du Fabricant de Savon." Apply to a French bookseller.-BERNARDIN.

[4002.]-MUSLIN.-I know of nothing to restore the colour to muslin or cotton when faded; but if "Beta" will boil the muslin dress with plenty of black soap and soda for an hour or two, and afterwards bleach in the open air, it will become pure white. I have done this often. -HOUSEWIFE.

[4005.]-CLEANING INSIDE OF GUN BARRELS. -I should recommend the following process for cleaning the inside of gun barrels:-"Turn an ashen rod a few inches longer than the barrel, and so nearly of the size of the bore as to allow of the following process: Let one end of the rod be cut lengthways, so as to make a slit of 6in. in length, into which slit enter as much of fine emery paper as will completely fill up the bore of the barrel, taking care, in folding the paper tightly. round the wood, that the emery surface is outward. Force it into the barrel by screwing it downwards from the top to the bottom, and repeat the process till the barrel is as clean and polished as when it left the maker's hands. No sand or coarse stuff of any kind should be used." Extracted from "Blakey's Shooting," Routledge.-MUZZLE LOADER.

[4007.]-TO CURE HERRINGS FOR DOMESTIC USE.-Draw out the gills and gut without splitting the herring, lay in a tub and sprinkle with coarse salt, and leave them for twenty-four hours to bleed; then have a good barrel and put in a layer of herrings and a layer of coarse salt, alternately, till the barrel is firmly packed full; press down with a weight till the salt is melted to brine, and cover them; remove weight, and cover to exclude air, and they will keep for a year.-HOUSEWIFE.

[4009.]-HEATING BOILERS WITH GAS.-" Corn Factor" will find but little economy in heating boilers with gas indeed, it stands to reason it must be far more costly. Nothing is more certain than that the perfect combustion of a given weight of fuel produces a constant amount of heat. Gas consists of only a portion of the combustible elements of the coal from which it is distilled, and this portion costs at least as much as the it is more economical than coal, it must be because a total weight of coal from which it is extracted. If, then, greater proportion of the heat generated is utilized. There may be some difference in favour of gas in this particular, but nothing like such an advantage as will make good the difference in cost per heat-unit. The object of all boiler-furnace makers nowadays is to thoroughly utilize the fuel and obtain all the heat possible from it. As regards supplying boilers with hot water, there can be no question of its advantage; in fact, where economy is studied it is always done, or attempted to be done, as the numerous "feed-water heaters" illustrated in "our" MECHANIC show. It is only from the fact that gas can be instantaneously kindled and extinguished, added to the fact that the majority of our cooking stoves waste half the heat that might be generated, that there is any economy in the use of gas as opposed to coal. Gas is, of course, much cleaner and more convenient.-S. A.

[4011.]

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ORGANS.-I believe that barrels of musical boxes, organs, &c., are pricked off by fastening a sheet of paper round them with the dots printed on it to act as a template for drilling the holes.-G. W. A.

[4014.]-MEDICAL ELECTRICITY. To the first question it is disputed whether a secondary current is any use or not. Halse contends that the secondary current is no use. Dr. Althus uses both currents. Coils are so constructed that either the first or secondary current can be used at discretion. Dr. Althus also uses the continuous current without the coil, which requires a large number of cells, and which is different in its effect and superior in some diseases to a current got by means of a battery and coil. O'Bec may study the whole subject if he is willing to purchase Dr. Althus' book, which is published by Longmans, Green & Co., and costs 15s. To the second question: Yes; but the coil he describes is not made that way. Wires are branched from various lengths of the wire, No. 0 giving a very short part of the coil, the second giving an additional part, No. 16 giving the whole length, which is the highest power. Such a coil is troublesome to make, and were the first current to be used as well as the second, two set of studs would be required; one for the primary coil, and one for the second; and which would be a very complicated coil indeed. The best way is to get a coil made with two connections for the first current, and two for the second, and a brass tube to draw out for the regulation of the power of the current.-M. D. should try to make soda water, &c., by the process [4096.]-SODA WATER.-If any of your readers given by "Joe" in the number for July 15th, they will most likely fail in the attempt, as a very small quantity of carbonic acid is contained in unslaked lime. What "Joe" probably intended was "unburnt limestone,' which is a carbonate of lime, and would therefore be capable of giving off a considerable quantity of carbonic Chalk is the material most commonly used acid gas. for the purpose. There should be a washing vessel between the generator and that containing the water to be aerated, and it is necessary that all the vessels should be capable of standing a very considerable pressure,

[3926.]-FORCING WATER.-It will require more power to force the same quantity of water at the same speed and to the same level through a pipe 180ft. long than through one of only 30ft. in length, because there is the friction of the water in the pipos to be overcome. This depends on the velocity of the water; and assuming, in the case in point, a velocity of 3ft. per second (a very usual one) the extra power required would be equal to raising the water 9in. higher. As the friction increases as the square of the velocity, a velocity of 6ft. per second would be equal to an extra head of Sft., and so in any other ratio.-Q. Q. R.

[188] SIR,-In reply to J. R. Rendle, I would say that I did not presume to direct professionals, but only to assist amateurs who cannot give time to acquire perfect mastery of the flute. I could always make better music in the way I have described, being able to give more attention to the blowing, as the fingering mentioned in the Times some weeks ago in an article required less. If any one tries the method, and find about an ex-officer of the British navy settling there. It otherwise the beverage produced will be of a very tame

he cannot blow in tune, he has only to give it up, and no harm done. The upper octaves of the flute have the same distances between their notes as the lower, which is theoretically wrong; yet, in practice, the lower notes, with an increased pressure of wind, give their octaves with sufficient truth.

The players on keyed brass instruments have separate joints to alter the pitch, the intervals of their valves remaining as before. I do not see why flute players should not try for a similar accommodation. I believe the best way would be to have two flutes, one voiced in D and the other in D flat, by construction, using either as the occasion required. I am sure the relief to all but extraordinary players would be great, and the expense of the pair need be but a fraction of what is charged for first-class instruments.

T. S. G.

[3949.]-REPUBLIC OF GUYANA.-This Republic was

seems to be in the north of South America, I think near
Venezuela.-BERNARDIN.

[3961.]-BISULPHIDE OF CARBON PRISM.-The
best cement for putting together glass prisms, to be
filled with bisulphide of carbon, is a mixture of common
glue and West India molasses. Make a tolerably liquid
glue, and add about one-eighth the quantity of common
molasses. Lay the metal or glass form, ground to a
suitable angle, with its face up; then place the glass
with a brush, and allow it to flow by capillary attraction
plate upon it, and apply the cement on the under side
between the glass and the form; repeat this operation
several times if necessary. This is better than to wet
the edge of the glass at the outset before attaching it to
prism. The stopper to the prism can be cemented in
the same way, and in filling with the bisulphide of car-
bon, always leave a small space for the expansion of the
liquid. The prisms should be kept in a cool, dark place,
and ought not to be agitated previous to using, as the
light is in that case unequally refracted.-S. J. P.

character.-F. C. S.

[4118.]-ANNUITY QUESTION.-Will you allow me out = 15-6834 years; 2nd, that the arithmetical printo state that the result of a vigorous computation comes ciples stated by "R. M." (p. 404), lead to the correct year; but inasmuch as the time is not proportional to the amount to be paid, the fraction of the 16th year is not truly found by his method; 3rd, that the principles stated in page 357 lead up to 63 years, which is too long refer to two similar questions in "Morrison's Mercantile a period. In corroboration of these statements I beg to Arithmetic;" also, to one similar, but rather more complex in "Todhunter's Algebra."-M. L.

[4118.]-PROBLEM.-As "Gimel" did not cor

rectly answer the problem, I submit the following short method:-Put a = 1,05, b = 2000, c = 187, and T = have T = log. time, then by log. arithmetic we

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log a = 15-68352 years, the time required.

The preceding appears to me to be a very natural solution as the question is worded, but if it be considered as to find in what time a given annuity (e) | at a given (a) rate of interest will be equal in present value to a given sum (b), the equation will be a T-1 a-1

C a T

X

207 B.C.

Antoninus Pius; who reigned from A.D. 188 to A.D. 161. The other coin I am not able to identify from the engraving.-HENRY W. HENFREY, M.N.S., &c. [4306.]-SILVER COIN.-"Giles's" coin is cne of the earliest Roman silver. It is believed to have been coined by the Romans, in Campania, about the year Obverse, a double head, like that of Janus. Reverse, Jupiter in a quadriga (four-horsed chariot), same as that above, and proves the truth of the preced- sceptre; behind him, a small figure of Victory. It is a gallopping to the right; holding a thunderbolt and a double denarius or small medallion. Value, about 158.HENRY W. HENFREY, M.N.S., &c. [4306.]-SILVER COIN.-A Roman family denarius; I think, Furia.-BERNARDIN.

=b, as is well-known, which comes to the

ing method.-F. L. H.

[4128.]-DE-MAGNETIZING STEEL.-There is no liquid that I am aware of that will de-magnetize steel; the idea savours much of the days of the alchemists; but the balance and other steel parts of the watch mentioned can be de-magnetized, either by heating them (though that would most probably spoil them), or by reversing their magnetism just to such an extent as to neutralize it. It might be rather a tedious operation, but could be done somewhat in the folllowing manner: -Suspend the balance wheel by a fine thread or hair, and notice which are the north and south points of the wheel. Then touch the wheel with a small horseshoe magnet, placing the similar poles together, i. e., the north to the north, and the south to the south. With a little care I think the wheel may be successfully demagnetized.-Q. Q. R.

[4219.]-TIGHTENING PIANO PINS.-The plan "Man of Necessity" suggests-viz., that of driving wooden wedges between the wrest pins and the wood plank of his piano, for the purpose of tightening the said pins in their respective holes, is an impossibility. The only remedy is to put in a larger set of pins which will well fill the holes. I only recommend this plan to him because he is evidently an amateur. My own mode of proceeding would be to rebore the plank for pins from two to three sizes larger than the existing ones, for the purpose of thoroughly clearing the holes of canker and rust, which, if left, often creates what is technically known in the trade as "jumpers," i. e. the pins won't turn smoothly in their holes, but move with a succession of jumps, and then good bye to all comfort in tuning. If he prefers my first plan, let him take one of the present pins to Mr. Meek, music smith, Windmill-street, Tottenham Court-road, and order a set of pins to pattern, but one size larger. If he prefers the second and better plan, let him order them two or three sizes larger. But I must warn him that this presupposes a nicety and steadiness of hand in reboring, and the ability to shape and fit his boring-bit to his pins, which he knows best whether he possesses. The pins (extra in number for a grand), will cost him 3s. 6d. or 4s.; boring bit, to be had at Buck's, in Tottenham Court-road, 44d. If, now, he gets into a mess, it will not be the fault of your correspondent,-W. T., Pianoforte Tuner and Repairer.

[4253.]-TODHUNTER.-Let me thank the "Fellow of the Royal Astronomical Society" and Mr. Proctor, Mr. Rendall, and also "Anon" and "Bernardin" for their responses. I know all about the decimals, and the two right angles, and so forth. I only quarrel with the word "invariably," and I am pertinacious enough to still think the word objectionable, because calculated to confuse beginners. Query-If a lesser luminary than "Todhunter" used it would it not be condemned? Is it not of a piece with the resemblance of the two niggers, "Cæsar and Pompey are exactly alike, 'specially Pompey?" Such is the "invariably." It would, I think, have been more correct if "Todhunter" had stated that the symbol denotes the ratio, &c., and also it is (disadvantageously) employed to denote another aspect of the same. This is the reverse of "invariably." As well say that the pound sterling value is invariably represented by the golden sovereign, whereas it may be by two half-sovereigns, four crowns, eight half-crowns, ten florins, twenty shillings, forty sixpences, 240 pence, &c. If I was a great man I would make "Todhunter "right by keeping for the ration, and using a different symbol for the circular measure, say the same inverted, ", or the Sanskrit p, which is ; anything would be better than using an "invariable" system for different purIs it not best to admit that Todhunter is wrong, and that the usage of the scientific world wants mend ing, as much as our weights and measures; like as even Newton used to speak of "his mistake" in using "Algebra" (see Preface to Pott's Euclid). By the way, can you spare me space to express that I bow most cheerfully to your stopping my tilt against the Algebra windmills? You are our captain, Mr. Editor, and we bow to your behests. In fact, it may tend to show how serviceable and convenient is the ENGLISH MECHANIC when I mention that the bare fact of so many persons more ready than able to immolate me as an algebra heretic quite answered my main object. Yes, our paper is an "institution" by which we can not only teach and inquire, but also feel the pulse of our own aims and crotchets; nor will you, it seems, let any of us go too far.

poses.

-GIMEL.

[4262.]-CORNISH ENGINES.-ERRATA.-I have to apologize for two blunders in my note on the above. In line 28, page 458, for D E K read D and H, and in line 42, for the centre of piston cross-head" read E. I should have observed at this point that when the beam is placed at the half stroke, above or below the horizontal, the piston rod must be got quite upright, or plumb, before striking the arcs of circles for finding the fixed centre of radius rod.-J. K. P.

[4283.]-WARPED CABINET LID.-Let "J. B." damp his carpet about 9in. wide and the length of the lid, and place the same with the hollow side on to the carpet or floor, as either would do, and let it remain so (say) twelve hours; it will bring the top quite straight if it is not bound at the end by clamps or mouldings.

-CABINET MAKER.

J. C. S.

[4290.]-FOOD.-If "Tau Tau," p. 406, obtains "Hints to Dyspeptics," written by Dr. Grindrod, Malvern, I think he will find it answer his purpose. It is a small work, and may be had direct from the Dr., as above. [4304.]-NAPKIN RINGS.-The plan I have adopted as to marking napkin rings has been as follows:-I have first traced the letter with a pen or pencil upon the ivory or box rings, and when to my satisfaction, I have gone over it with a solution of three parts nitric acid and one part turpentine, and have never found it fail.-Z. BARNARD. first -The

coin

of

[4307.]-HORIZONTAL v. VERTICAL ENGINES.Horizontal engines are generally preferred to vertical, as they can be driven at a greater speed on account of being more securely fixed to their foundations. They are also more compact, and more cheaply made than the vertical.-CUTHBERT.

[4309.]" BARTON'S SELF-ACTING FEED-WATER HEATER."-The float is a copper ball, diameter in accordance with size of cock required to supply the heater with water.-S. CROMPTON.

[4913.] - SILKWORMS' EGGS. In answer to "C. H. B.," the eggs of the common silkworm do turn brown soon after they are laid, which colour they keep until they are hatched in the spring. May I ask if there are any of your correspondents who have had any experience this year with the Japanese and North American species-Bombyx, Pernyi, Yama-Micii, and The failures last year were the Ailanthus worm? How must it be this year?attributed to the heat. GEORGE E. DAVIS. [4313.]-SILKWORMS' EGGS.-They ought to turn If they do of a dark colour a few days after being laid. not they are certainly unfertile.-A. S. C. [4318.]-SILKWORMS' EGGS when laid are of a bright yellow colour, but usually change in a few days to a blue or slate.-HARRY G. NEWTON. [4314.)-RULE WANTED.-Assuming the weight to be in cast iron the following will perhaps be intelligible. A cubic foot of cast iron = 450lb., therefore the cubic contents of the weight :

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..1333 90622

=1833 cubic feet.

9in.

and 14 in. are equal respectively to '75ft. and 1-2083 ft. 75 x 1-2083 = -90622 14715ft. thickness of required weight, which may be brought to inches thus-14715 x 12 = 1-76580, so that the weight will be rather more than 1in. thick.-HARRY G. NEWTON. [4314.]-RULE WANTED.-Multiply the length, breadth, and thickness together, and when the dimensions are in inches, multiply the product by 26 or 100 for cast iron, by-28 or 28 for wrought iron, and by

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for cast brass, which will give the weight in lbs. conversely. Divide the given weight by the fraction for the metal as given above, which will give the number of cubic inches required. Then multiply the known length by the breadth, and on dividing the number of cubic inches in the given weight by this last product, the thickness of the weight will be given in inches.-Q. Q. R. [4316.]-A DIFFICULT QUESTION.-As I read this question it seems to me that there are three rings, tubes, or hoops spoken of. The first tube has an extreme diameter of 12in. Its " covering hoop" is to have a ten sion of 4 tons per square inch, and it ("this second hoop") is to have a diameter of 18in. This, again, is to be covered with a "third hoop" the diameter of which is to be found. The ambiguity seems to arise from the mixed use of the words "tube and hoops," when "tube" would have been the best word to use.-Q. Q. R.

[4320.]-BREAM FISHING.-There is no better method to entice bream to the hook than to bait the river over night with grains, throw about a bucketful in the part you intend to fish (a wide and deep part is the best) and get up with the sun and begin operations; bait with wasp grub or gentles, use a fine but strong line, keep as far from the river side as possible; bream are very shy fish, therefore you must fish cautiously; they bite best when there is a light breeze; if they will not take grubs or gentles try well scoured worms; a running line will be required. Two or three rods and lines may be used at the same time.-A YOUNG TYKE.

[4321.]-WATERPROOF.-A short time ago I had a waterproof coat which had been laying by some time, and was very hard, and a friend of mine (who had been in India) restored it to its original state by dissolving a handful of best grey lime in half a pailful of water, and wipping the coat at the parts that were hardened, doing so twice, at about three hours interval.-J. P. K. [4322.]-SEWING MACHINES.-I had a sewing machine, and found it leave loops, loose ends, and catches, and a succession of loops on the hooker; but I found, after trying it different ways, that by altering the hooker so as to drop a little later, or the needle and feeding bar a little sooner, it would go all right.-J. G. for instruction on furnaces, I should say if the old one [4828.]-GLASS BURNING.-In answer to "Kemp," has done well get another like it; but I can give him the

wing, and he can judge of their respective merits. Build of brick, between 30in. and 40in square, an aperture 6in. from bottom for fuel, then some bars are placed across the furnace like a flooring, above which is another aperture to receive the trial pieces of glass. Over the flooring is placed an earthen pan, at the bottom of which is placed two or three layers of quicklime, with pieces of glass between them. The use of the lime is to give a regular heat to the painted glass, the first stratum of which is placed upon the uppermost layer of lime, and all the pieces to be burnt at once are in like manner disposed horizontally, with a layer of lime between them, and the last stratum of glass to be covered with the lime. The furnace is then covered with tiles and luted close, with the exception of four or five small apertures to serve as chimneys. Of course it will heat gently for the first two hours, and then raised gradually to the heat required for the fusion of colours. This point must be ascertained by occasionally examining the trial pieces in the small apertures.-D. F. ASHTON,

[4805.] SILVER COINS. "N. T. B. M." is a silver denarius of the Roman Emperor [4325.]-PLANTING-What does "M. N." mean by

"slitting" and planting house plants? Geraniums, larias, verbenas, and such-like plants are "track the year round in "houses" and frames; but genesin the autumn. The best time for striking fuch in the spring, when the young shoots are about an and a half long, and before the wood has become -SAUL RYMEA.

[4325.]-HOUSE PLANTS.-Take cuttings of t which I suppose are fuchsias, calceolarias

geraniums, now and next month. Cut them or and plant them the next. This is important, the, wound may have time to dry. Strike the first two glass; geraniums in the open border, in full sat potting them before the first frost. Morse, of Dave Gloucestershire, sends for two stamps a catal cuttings every January. They are supplied in ga condition, and with ordinary care a stock of good may be raised at a small expense.-AMATEUR

[4328.] - MOUNTING MICROSCOPIC OBJECTSshould recommend "C. R. H." to obtain "Dav the Preparation and Mounting of Microscopic Obje published by Hardwicke at 28. 6d., by careful att to which, together with the exercise of a little the he will be able to mount any object he may come I should advise him on no account to commens such objects as whole crickets, but to take pan sects, as legs, eyes, heads, spiracles, gizzards, & will be found much easier by a beginner, and nish him with more interesting slides than va the insect entire.-J. SARGENT, Jun.

[4328.]-MOUNTING MICROSCOPIC OLPetals of flowers are rarely capable of presen their colour is not sufficiently persistent. of pelargonium petals may be stripped off, glass slip; and mounted in Balsam-potass wud! them. Thick objects require a cell, which m glass, wood, vulcanite, or of almost anything. Fer objects cells cut from thick card answer the A common gunwad punch serves admirably. them out. I have of late used Pumphrey's vake cells for all purposes; they are cheap and efor Wings of insects rarely require any medium. Wins Lepidoptera should be mounted dry; “opaques” olim tera, Neuroptera, and Hymenoptera are also usually "transparents."-H. P.

[4328.]-MOUNTING MICROSCOPIC OBJECTSfear Mr. Sutton's reply to Query 4328 savours a little more of theory than of practice. He appears to speak of the process of soaking in liquor potass as simply to render the object transparent and to soften it so that it may be pressed flat. In my ides, the real object of soaking in liquor potass is to dissolve away the whole of the fleshy parts, so that nothing but skin and muscle remains. I should not advise C. R. H.," or any other plicated as a cricket. To begin, let him take a flea; amateur, to attempt at first any object so large and comput it alive into a vessel containing liquor potasse (it will sink to the bottom in a day or two); let it remain for & week! or ten days, when it should be taken out with a camel's hair pencil and put into a saucer of clear cold water; have ready a stout glass slide 3in. x lin., an another piece of same glass lin. square,; place the insect (still in the water) on glass slide, and the lin. sqm on top; by pressure the whole inside will come It will then require very careful washing with cas hair pencil in at least two waters; float it on tee glass slide; cover with thin glass, and tie cotton. Put it aside for a day or two to dry; where it may remain for a week, or rather less it tied as it is into a vessel containing w paraffin lamp, over which I have contrived will be ready to mount. In mounting, I use hot plate." I first heat the balsam by the fire quite fluid; then place it handy on my hot p another part of which I have a small stocks slides. With a camel's hair pencil-which I slap in my balsam-put a drop, according to size of o bemounted, on to heated slide. With a needs > object off the slide where it was tied to soak in and place it wet with turpentine into middle of balsam; then take up a clean glass; cover in heat it over lamp, and place over object. Se whole by small brass clip, and place near fire for re the day, after which lay aside in secure place for 15 when it may be cleaned and covered.-A. A. F.

[4329.]-THE MICROSCOPE.-In answer to the microscope I should propose for his purpose be a Student's from one of the London make Swift, Collins, or Crouch-from either of these b paid to a shopkeeper for an inferior foreign artic procure a good microscope for about the same the bye, I saw at the Workmen's Exhibition a microscopes, by the first of these makers, the examine, as from the description given there of of which I would specially recommend "Sab

Student's I should think it the article to suit (pres all there stated to be correct). A few hints may The stand should be firm and sufficiently heavy out of place as to the best construction for such vent vibration, and so well balanced that it show indications of falling over when placed at an The bar or coarse adjustment should move steady, out shake, and with the same amount of tension a length. The stage to be of sufficient size to allost plate to move over this, allowing motion in all directes use of a frog plate, zoophyte trough, &c., with a secr The aperture in the stage should be perfectly ce stage apparatus; for the fine adjustment choose one th with the optical tube, and with a tube fitting for all we is known as the lever arrangement, that is to say, the cylinder into which the objective is screwed is ra and depressed by a lever and fine thread screw; this the only reliable form, and the only one I know that a central lift. The points wherein to test such an strument in its mechanical parts will be for the bar of by the mirror, care being taken that the light is coarse motion. Apply the fin, objective and illuminst oblique; to insure this place the lamp in front and the same plane as the mirror, and incline the mirror an angle of 45°, the light will then be thrown through the object-a diatom is about the best-and with the c milled head carefully focus, and note if, by raising depressing, the object vanishes in a direct line and from the edge of the field. The same test should be used for the fine adjustment; this should focus quick a field of view it occupied in the first instance. Such sharp without the object moving from the part of th

instrument with a lin. and fin. object glasses, a live box, stage plate, and thin glass covers will be all "Sabbas" requires for a commencement.-C. C. S.

[4329.]-THE MICROSCOPE.-" Sabbas" has asked his question of another correspondent, and it is almost a breach of courtesy for me to reply thereto. A few words may be excused perhaps. The universal microscope of Smith & Beck, the Student" of Messrs. Wheeler, Barker, Dancer, &c., &c., ad lib., will be cheap and fairly good. Field's Society of Arts is a fair instrument and very cheap (£3 88.) But I think the cheapest, and for its price the best, is one made by Winspear, of Hull, lin., fin., and fin.; good objectives and a useful stand for £5. An application through the Sixpenny Column would find either of these gentlemen.-H. P.

[4984.]-ECLIPSE OF THE MOON.-I hope, for the sake of the querist, that abler pens than mine will also give an explanation of the interesting phenomenon to which he calls attention. The reason, I believe, that we see that part of the moon at all which is immersed in the shadow of the earth is that the sun's light is refracted or bent by the earth's atmosphere in such a way that part of it falls on the moon, although the earth is between it and the sun. "Lunar" will see that this light arises from an entirely different cause from that seen on the shaded portion of a nearly new moon, which is simply due to reflection from the earth's surface. The red colour is caused by the sun's rays passing obliquely through the various strata of the earth's atmosphere in the same way that we have red tints at sunset and sunrise. The earth, on the 12th, must have represented a singular appearance from the moon. It would have appeared as a black globe (of course entirely hiding the sun) surrounded by a luminous red ring.—ÁLGOL.

[4335.]—IRISH MOSS.-It is used for jellies, feeding cattle, sizing yarn or paper pulp; in Bavaria for clarifying beer.-BERNARDIN.

[4336.]-TONGA BEAN WOOD-or better, Tonquin bean wood, does not come from the same tree which produces the Tonquin bean, as its common name might lead anyone to suppose; but from a straggling sea-side shrub of Tasmania. Its odour is similar to that of the Tonquin bean, hence the name. The botanical name is Alyxia buxifolia, Dogbane order, or Apocynem. Samples were exhibited in 1862, in the Tasmania court. At the last Paris exhibition Cochin China presented samples of bark of Alyxia odorata, quoted by Mr. Eug. Rimmel in his "Book of Perfumes." Among the novel odorous products it may be the same plant.-BERNARDIN.

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CE2500 = 50.

BE 160- 80 = 180

(Euc. 1. 47) B C2 = B E2 + CE2 =
= 1802 +502 =8900 + 2500 = 16900.

B C 16900 140 (nearly).

P.S.-If I mistake not the above questions are proposed by a private student preparing for the London Matriculation Examination, and are taken from Newth's 1st Book. Pray allow me to inform "Amicus" that he cannot hope to pass the above-mentioned examination by working from this book. Better get Newth's larger work, or better still, Warmell's "Mechanics' Hydrostatics, &c.," published by Groombridge. "Todhunter" is excellent, but requires a knowledge of trigonometry.C. H. W. B.

[4361.]-METHYLATED SPIRIT.-Methylated spirit is made by mixing one part of turpentine with nine parts of alcohol (plain spirit distilled from any grain). The only reason of mixing the turpentine with the spirit is to prevent its being drunk as a beverage, whereby the revenue would be affected. It is allowed to be used in preparing tinctures, and for any purpose connected with medicine, art, or science.-T. L. H.

[4363.]-LIMEWASH ON MASONRY.-The lime being an alkali, any acid should dissolve it. The cheapest and strongest acid for the purpose is the brown oil of vitriol of commerce, spec. grav. 1-712, price three-farthings per pound. Probably llb. of the acid to a pail of water would do the work required, the wash to be applied with a brush. J. L. H.

[4369.]-EMIGRATION.-The Government have pub-" lished a small pamphlet on Emigration to Australia, price 2d. It contains a mass of valuable information. Let "Jobber " get it. Any bookseller can obtain it for him, or Messrs. Longmans & Co., Paternoster-row, will send it direct.-F. R. G. S.

[4370.]-PROBLEM.-I suppose "Sunbeam" wants the two parts of the pole and the base to form a triangle. If so, the pole must be cut 45-5ft. from bottom to touch the required point in the base.-W. FELTON. [4970.]-PROBLEM.-54.5ft.-BEACON LOUGH.

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A

B

502 866, E C = 100

[4342.1-READINGS FROM THE GLOBES.-" Keith on the Use of the Globes" is a most excellent authority as in fig. 1, angle B A D = 60. I conclude that "if in a on the subject. The last edition, as given in Messrs. Long-right-angled triangle one angle = 80°, the opposite side = man's catalogue, corrected to January, 1870, is enlarged half the hypothenuse," hence (problem A) resultant of two and improved by Professor Taylor, Le Mesurier, B.A., and forces of 100, meeting at an angle of 150 (v. fig. 2), I Jacob Middleton, price 6s 6d. The variation of the com- have A E 50, B E = √1002 pass is about 20 to the west. In the year 1865, wishing BE, A C2 = A E2 + E C2, hence AC 5176. Analato know the exact variation of the compass, I addressed gous solution for the second problem (v. fig. 3).—BERa note to the Astronomer Royal, and he very politely NARDIN. answered it. If "St. E." would do the same, giving his locality, he would no doubt be similarly treated. Mr. Proctor and F.R.A.S. have also given the varia

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[4344.]-WEIGHTS OF CHEMICAL SOLUTIONS.I really cannot undertake to work out calculations except when they relate to matters with which I am myself dealing. Like our friend "F.R.A.S." I have a very strong abhorence for "doing sums." It is easy to extract from chemical books, such as Storer's "Dictionary of Solubilities," tables showing the amount of each salt present in solution at varying temperature, and, in some cases, also formulæ for calculating the quantity at any density or temperature; but these even would not give such information as is asked, because they relate to pure substances, while soda ash is a commercial body of irregular composition. Thus, 50° Twaddel is sp.g. 1.250. A solution of caustic soda at ordinary temperature of this density would contain some 16 per cent., of carbonate of soda about 26 per cent.; but a solution of soda ash of this strength would give very different products, according to its own composition." Alkali" would do well to experiment on the subject, for information so gained is far more valuable and enduring than cut and dried statements.-SIGMA.

[4347.]-TUNING BY EQUAL TEMPERAMENT.I have heard of French, Latin, and German "without a master," but I never heard of tuning ditto. Who can explain such a thing concisely and explicitly? And who, among your readers, except "A Would-be Tuner," would wade through it, even if you, Mr. Editor, would grant the requisite space. Let a "Would-be Tuner" pick up any old square at a broker's, or auction room, and take lessons in tuning of some competent tuner for a twelvemonth. Both instruments and tuners swarm in London; so he can have no difficulty in that respect. Let him practise five or six hours a day; then let him article himself as an improver for two or three years, at a nominal salary; or, failing the latter, at no salary at all; when if his ears have no constitutional defect, he will be able to go out into the world and take his chance of a crust with the rest of us. I know no other mode of obtaining his wish, unless he has the advantage which I possessed in my youth of having the run of a large factory with over 100 pianos in it in various stages of progress, among which I could tune, under my father's superintendence. "Would-be Tuner" knows best the facilities he possesses in this respect. I have supposed he has literally none, and have, therefore, given him the best advice in my power under such circumstances. W. T., Pianoforte Tuner and Repairer, [4348.]-PROBLEM. — Draw the parallelogram A B C D, having the angle A B C = 150°, and the sides A B, B C, equal, each representing in magnitude and direction a force of 100lb. Then the diagonal B D= the resultant of these two forces.

B 100 E

[4353.] ROAD MEASURING.-In answer to "J.T. S." relative to the above, I can inform him that the machine usually used by the Metropolitan Police for such purposes (as in case of disputes with cabmen, &c.) is a single wheel mounted in a light frame, with a handle to push and guide it with, and a connecting rod in gear, with a few wheels which are under a dial marked with the miles, furlongs, and 10 yards; two wheel. I believe the pedometer is only used by amateur hands or pointers show the distance traversed by the walkers, and requires to be regulated according to the step of the wearer, and even then is not entirely to be depended upon for any degree of accuracy.-TOMETER.

[4355.]-ART DEGREES AND MATRICULATION EXAMINATIONS.-Having had much to do with regard to the Matriculation Examination, London, I feel competent to answer "Beriro." The subjects required are, algebra (i. quadratics), arithmetic, geometry (Euclid i.v.), mechanics, optics, hydrostatics, chemistry (non-metallic elements, &c.), Latin, French, Greek, English, also history of Greece, England, Roman Empire, &c., but by application to Dr. Carpenter, 13, Saville-row, "Beriro" would get a syllabus, with requisite information. The fee is £2, times of examination, January and June. I know of no degree that can be obtained in England without matriculating. A German M.A., Ph. D., &c. &c., may be obtained any day, by any. body, by payment of from £10 to £20. Valuable hints on matriculation will be found in the "Assistant Masters' Journal" No. II., Allman, 463, Oxford-street, price 6d. H. W. B.

[4358.]-COPAL VARNISH.-"A Youth" might add a quarter of a pint of japanners' gold size; if stiff, a little turps; but at the same time cannot understand good varnish not drying under 60 hours. Think he must have got some linseed oil in, if so it never will be good.-ONE IN THE TRADE.

[4358.]-COPAL VARNISH.-Your varnish is none the worse for drying so slowly, but much more liable to stand well. If you wish it to dry quicker put in a little liquid dryers (terebine), this will hasten its drying, and not destroy the gloss.-H. C. C.

[4359.1-AMBER BEADS.-I do not know of any way to polish amber beads; but to distinguish real from false ones, take a piece of silk, and after warming it, rub the bead with it for a short time, and then place a few small pieces of paper or feathers on the table, and bring the excited bead near them; if it be real amber, and the process quickly performed, the feathers or paper will be attracted. It is best to hold the bead with a piece of glass tubing or sealing wax.-F. WALKER.

[4359.]-AMBER BEADS.-"L.'s" beads are most likely only imitation ones, for the great majority of beads sold for clouded amber are but a mixture of gums, which are soft and also easily amalgamated with fatty matters and become dull and dirty on the surface as well as scratched. The false amber is easily shown. Scrape a small portion of the suspected material to powder, and if it dissolves in turpentine, whether hot or cold, it is not amber. Real amber has a smooth clean feel, and does not scratch readily. Putty powder will restore the polish to real amber.-Q. YORKE.

[4861.] METHYLATED SPIRIT.-This is made from spirits of wine spoiled by a portion of naphtha, which, of course, prevents it from being used for tinctures.-H. C. C.

[4370.]-"PROBLEM." -If I understand "Sun Beam's" question aright, the following is the solution he requires:-Let a b represent the pole 100ft. long, and C a point 30ft. distant from a; o is the point at which the pole is to be cut; let z be the length of the part cue off. Then by "Euclid, Book 1, proposition 47," we have x2 = a c2 + a 02 100-x. Thus we have

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[4375.[-RED BRONZING.-This is done by the same process as green bronzing, but using red lacquer.H. C. C.

[4976.]-COD LIVER OIL.-"A Mechanic" should try milk, and drink a good quantity of it in the day. If he finds that it makes his head ache, as probably it will, commence with a wineglassfull or even less, until his system becomes used to it and increase the quantity daily.-W. H. C.

[4376.] COD LIVER OIL.-Let me assure "A Mechanic " that there can be no better substitute than Devonshire cream. A Kentish friend of mine, a tradesman, a fine tall (unmarried) man, of the name Braund, told me that he seemed quite to be sinking in consumption-weak, hectic, spitting blood, &c. He was ordered to take cod liver oil, but his system nauseated it utterly. He then was recommended to try Devonshire cream, and it thoroughly re-established him. At the time he stated this to me he was not stout, but fairly fleshy, vigorous, and full of work. I advise "A Mechanic" to eat it out of a "slop basin," with a dessert spoon. The in London, more; almost all good dairymen keep it or price of the cream now in Devonshire is 1s. 6d. a pound; can get it. I think I remember a place for it on the west side of Berners-street, Oxford-street, London. In the country, in a general way, it is the same price as fresh butter. It is the best lubricator for the wheels of existence.-GIMEL.

[4876.]-COD LIVER OIL.-The only substitute for cod liver oil that I have ever heard of is cream, either scalded or raw. This is vastly more palatable than cod liver oil, but not in any way so efficacious.-Q. YORKE

[4376.]-CODLIVER OIL.-The following is a good substitute, and very palatable:-A bottle of port wine, 2oz. of isinglass, and 2oz. of sugar candy. Put these ingredients into a jug, and let them remain 12 hours, then set the jug in a saucepan of boiling water for an hour. When the isinglass is dissolved all is ready. It may be taken warm or cold.—J. L. H.

[4377.]-TEMPERING BRACE-BITS.-Let "A Mechanic" get his brace-bits a little hotter than a blood heat in a slow fire, and plunge them in a pail of cold water; take them out and rub with a Turkey stone slip on one part of the bit just to brighten, and then hold the shank of the bit over or on a very hot piece of iron. When he sees the bits let down to a deep gold, an eighth of an inch from the cutting part, plunge in cold water again.-W. REED.

[4377.]-TEMPERING BRACE-BITS.-"Mechanics" brace-bits may be re-hardened by heating them to a blood red and plunging into water, and drawing the temper to a deep straw colour. I see so many questions relative to tempering steel that a short article from a correspondent able to do it properly would, I am sure, be acceptable. There are very often two or three queries in a number relative to this simple process in

practical mechanics.-G. W. A.

[4378.]-HOW LL.D.'s ARE MADE.-I doubt rather an "Ambitious One's query being bona fide. If it is, I can but say that he must exert himself and gain a position worthy of the honour if he wishes to become a D.C.L., which is purely an honorary degree conferred on distinguished persons. To become an LL.D., he must go through the usual academical course and examinations.-Q. YORKE.

[4379.] BORING CYLINDERS FOR MODEL ENGINE.-I should have thought that if" Sabbas" had been able to bore his cylinder to his satisfaction he would certainly have been able to form the steam passages in it. I drill a hole in the face of the flange and meet it by one from the valve face; sometimes I drill two holes side by side, and drill a series of holes in the valve face converging upon the two passages beneath between the holes to form the port. He says he has no (of course for an oblong port), and chip out the metal tools and knows nothing of the work. I should give it to a workman to do under the circumstances.— G. W. A.

[4388.]-WEAK EYES.-A very efficacious way of strengthening weak eyes is to daily pour into them

478

while open, a tumbler of cold water. For sores about the eyes, one of the best remedies is the sulphate of zinc ointment sold in the chemist's shops.-J. L. H. [4389.]-LATHE.-"Young Amateur" should buy "The Lathe some elementary work on turning, say and its Uses," then he would not find himself so lost. To make a quantity of backgammon men or such like work, let him first turn a cylinder of the proper diameter, then with a parting tool cut into the required number of pieces, which should be wide enough, or rather, thick enough, to allow for finish. To chuck these, use a spring boxwood chuck with binding ring of a suitable size, which he must learn how to make, as being an essential addition to his stock of chucks, first turning the discs on one face then on the other. Or, a plain boxwood chuck some 5in. or 6in. long, with the cut of a coarse saw through it longitudinally, carried as near to

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If this pressure be applied through a vertical space of
lin., the weight of 100lb. will be raised 12in.-T. W. P.
[4407.]-MAMMOTH.-"Naturalist" will find, I think,
a nearly perfect skeleton of the Elephas primigenius in
the British Museum.-F. WALKER.

[4410.]-TURNING SPHERES.-J. D. L." had better

[4422.]- REVERSING ENGINES.-Can a pair engines (steam) be reversed by two excentrics answer through your columus will oblige an o scriber.-FIELDUS WESSON.

[4423.]-TO "MUS"-Would "Mus" give me the following information:-My prints, when finished, by a brown leathery appearance instead of that plead black which we have with professional prints. I fel Jabez Hughes' instructions, and all goes well until above result. P.S.-What good account can old ni of silver baths be turned to ?-J. B.

[4424.]-COFFEY'S APPARATUS FOR DIST LATION.-Could any reader give me any informat lation? There is mention made of it in the Lane 4 about Mr. John A. Coffey's patent apparatus for di June 11th, 1870, page 844, which represents it as a paraffin oil which can be heated to 1100 Fair. with

the end when it is screwed on the lathe as may be safe try to turn his billiard balls by hand; first with practice little or no expansion and no evaporation. Huit eve

hole made with a bit. Make an opening on the face of this chuck slightly too small for the discs to be turned, open the jaws with a wrench, and snap the work in. The spring of the wood is quite sufficient to hold anything of the diameter of backgammon men.-Q. YORKE [4891.]-SCREW TAPS, ETC.-Bichromate of potash will case-harden iron screws of small diameter; sufficiently so that they will cut a steel die (carefully softened) if they are used with a light hand. Shape the screws first like a tap, and when very red hot, apply plenty of the potash, and plunge into cold water. If they get too brittle, they must be tempered.-Q. YORKE.

[4393.]-STEAM-TIGHT JOINT.-If W. Reed would mix a little red and white lead together, get some hemp, twist it loosely together in the shape of cord, or the size he wants, work the lead well into it, lay it on the manhole door joint, then screw it in its place, he will find it steam-tight.-J. G.

[4393.)-STEAM-TIGHT JOINTS TO MANHOLE IN BOILER.-If W. Reed would get a piece of fin. lead pipe, or in., according to size of boiler, then solder the two ends together, then flatten out the pipe and make it fit round the lid of boiler; afterwards place some good red and white lead on both sides of level collar, then bolt it down and screw up tight, which will prevent any further escape of steam.-J. W. H.

[4398.]-MELTING SPELTER FOR BRAZING.even with this "Deeside " may find a difficulty in brazing Borax is commonly used as a flux in brazing, though brass to wrought iron. The brass pipes have to be specially made for the purpose I believe.-Q. Q. R. [4397.]-SCREW TOOLS FOR SCREW PLATES.If" Faber" wants to make a set of small taps for his screw plate, let him forge some 6in. square saw files, or let him get some cast-steel about a 32nd part of an inch fuller than the holes in his plate, soften them (by making them red-hot and burying in dry ashes), and then screw them about 14 in. in length with his plate. After screwing, file them tapering square of an inch, just leaving the notches of the thread on the angles, and harden and temper the same, as in answer to "Mechanic" (4377), only let them down to a very pale straw colour.-W. REED.

The [4399.] INTERNALLY-GEARED LATHE.circles of holes on the outside of the internal wheel are intended for a dividing plate for wheel cutting or ornamental turning, exactly the same as any ordinary single-geared lathe would have, and are used in conjunction with the spring index. Upon examination, the internal wheel of my lathe appears to have had the teeth cast in it (most probably from a metal pattern), and the bottoms of them have been cleaned out with a flat-bottomed drill to form the circular bottoms of the teeth (they are represented square in the drawing by mistake, and as the wheels stand I have 14 teeth instead of 12 as explained), and the points have been "topped" by the turning tool. "Deeside" will see that it is impossible to cut this wheel with a revolving cutter, because there is no "thoroughfare;" therefore, I would suggest a plan by which I think he will be able to do it. Let him make a turned pattern to the dimensions of the drawing (or reduced proportionally), the recess in it to be equal to the diametrical distance from point to opposite point of the wheel (allowing for turning out) which will be 6 7-16th in. Let him turn up the casting, and by means of the dividing plate drill a series of sixty holes on the circumference of a circle whose diameter is 6 11-16th in., just a larger than the pitch line 6gin.; these holes form the bottoms of the teeth and the metal between the edge of the hole, and the circumference of the recess is then to be chipped away neatly and so forms the tooth. He can "slot-drill" the teeth if he likes, and then only the corners will have to be rounded with the chisel. size of the drill is 3-16th of an inch. I think the above is a practical way of going about this job, and is the method I should pursue if I had it in hand. If any other correspondent can suggest a better I am sure "Deeside" will be obliged to him.-G. W. A.

shade

The

[4400.]-MICROSCOPIC OBJECTS, DIATOMS, ETC. -Diatoms are everywhere. Perhaps Weymouth would answer "Hunter's" purpose as well as most places. Seaton, in Devonshire is also a good microscopic ground. There are chalk cliffs, plenty of seaweeds, corralines, sponges, and sometimes a cuttle. Exeter is close at hand, with Budleigh (where there are plenty of diatoms), and the Exe mead at Woodbury. Dorchester is hard by Weymouth, and its chalk affords an abundance of very fine Foraminifera. At Portland, "Hunter" can secure fossil wood; and in the marshes, away towards Poole, plenty of microscopic mosses and lower algae. Where does "Hunter" live? Where would he like to go?-H. P.

[4403]-MECHANICS.-I am really in as great a fog as "Alyssum" upon this question. It may be possible, but I have been always taught the contrary. No simple machine will perform the necessary work.-C. H. W. B. [4403.]-MECHANICS.-" Alyssum's" question might have been put a little more definitely, although, perhaps, his real error lies in his fear of encroaching on your valuable space. However, for the sake of illustrating the mechanical principle he seems to have in view, we may suppose the small weight to act on the short arm of a lever, and the larger weight on the long arm. ratio of these arms would have to be as 1 to 12. Suppose the short arm to be 1ft., then the long arm would be 12ft. Let a weight of 1lb. act at the end of the short arm, and a weight of 1001b. at the end of the long arm.

The

a template. They can be done so easily
anyway, they must be chucked in boxwood, and when
they are nearly finished, in a chuck to fit the exact
hemisphere; in which chuck let there be a good rubbing
of chalk to make them hold. Presupposing that the ivory
is free from scratches, polish with whiting and water of
the consistency of cream, used with a soft rag; dry, and
then use dry whiting; and for the last, to complete the
gloss, rub with a faint touch of clean oil on a fresh rag.
-Q. YORKE.

QUERIES.

[4412.]-WRITING INK.-Could some reader kindly
inform me what may be done to prevent writing ink
from turning bad this hot weather-if there is anything
that may be put in it ?-J. G. M.
[4413.]-FEED-WATER HEATER.-Seeing a descrip-
tion of feed-water heater by "One Eye," in your journal
of July 22nd, I beg to remind him of the great liability
to back pressure in heaters of this construction. In
good faith, and with every desire for mutual information,
I would kindly ask "One Eye" has he ever taken dia-
grams in order to ascertain the amount of back-pressure
since using the heater? If he has not, I would strongly
advise him to do so, as I am afraid what he is gaining
thankful to "One Eye" for his testimony in confirma-
in one direction he may lose in another. I am also
tion of the practicability of raising feed-water (by ex-
haust steam) to 212°. At the same time I cannot help
doubting the economical efficiency of his contrivance,
until supplied with a diagram taken when the feed-water
is being admitted into the heater. Would "One Eye"
kindly send me one?-S. CROMPTON.

[4414.]-HEIGHT OF OBJECT.-How can we ascer-
tain the height of an object, say twenty yards on the
opposite side of the river, the width of which river we
The simplest way, without having
do not know?
recourse to instruments or algebraic formule would
oblige.-ENQUIRER.

[4415.]-CURIOUS PROBLEM.-In the ENGLISH
MECHANIC for July 22nd, p. 415, Prof. Balfour Stewart
asks what becomes of the energy of the cannon ball
after it has struck the target? He says it is stopped by
percussion. But what would be the result if an "irresist-
ible" force came into contact with an "immovable"
body?-SAUL RYMEA.

what success? Any information would be of pa service to me, as I cannot find any one who know thing about it. J. T. T.

[4425.]-MALLEABLE CAST IRON.-Thanks to

sociate of the Royal School of Mines" for the infus tion given through your valuable journal last questions:-Where can I get Dr. Percy's work, Va Will he, or any other kind friend, answer the fe And if I can get the specifications of patents tak under the above head without applying personaly if Cumberland hematite pig iron, or any oth first refined in a small cupola with charcoal, r into small pigs, and afterwards melted in or pot furnace, makes good malleable castings) Vd this be cheaper than using fluoric acid? anily spar or limestone would do as a flux in the amis coal cupolas ?-A YOUNG CASTER.

[4426.] STEAMING BONES PREVIOUS! GRINDING.-Where can a good apparatus be be and what price, second-hand? Is there a better pris than steaming them? What books are published one of T the composition of artificial manures ?-FARMER. [4427.)-CASE-HARDENING.-Will practical correspondents inform me how to case-baris the inside sliding cylinder of a poppet head withes scaling? I have turned it bright and smooth and an afraid of spoiling it at the last moment.-W. H. B.

[4428.]-COIL.-Could any reader tell me the proper proportions of primary and secondary wire suitable for a 5lb. coil, and the proper gauge?-T. BUTLER.

[4429.]-TINNING AND BRAZING.-Can any one inform me if there is a work published on "Tinning and tinning of copper goods?-A SUBSCRIBER. Brazing," as I wish for some information respecting the

[4430.]-PUTTING THE SHOT.-Will any brother reader kindly inform me what size the patterns must be in wood for 181b. and 201b. shot? A plain answer will suit.-ROUND SHOT.

[4431.]-MENDING EBONITE BATH.-I have an ebonite bath 15in. by 12in., and having had the misfortune to place my foot through one side, would be glad if any of your readers will tell me how to repair the same. I have the broken parts.-J. B. CLARKSON. [4432.]

-"ISOMETRICAL."-" Isometros" conten his best thanks to "J. K. P.," and is sorry he has understood his query. What he wanted was the pr tion the major and minor axes of ellipse bear to ad [4416.]-PHOTOGRAPHICAL.-Could any of the other, and to the diameter of the circle to k readers of the ENGLISH MECHANIC tell me, through the sented. N.B.-I do not wish the lines of orig medium of this paper, the cause of silver prints becoming to be reduced to "isometrical proportio a ing such a foxy red? I find such a difficulty in exciting the isometric representation of original the paper. If I float, say a dozen sheets, the silver bath ISOMETROS. becomes discoloured; in printing the prints become a foxy red; and in toning they get brown instead of black. I have likewise in my working negative bath had such a quantity of brown negatives, and nothing I can do to it makes the negatives black. If any one of our readers can help me, they will be conferring a favour on many more, who have no doubt experienced similar difficulties.-JOHN.

[4433.]-MARKING COTTON CLOTH.correspondent inform me as to what is the nature of the acid or other substance in use at and bleaching works for marking the disting number or mark on the (cotton) cloth before proce to bleach it; the mark being put on so as to res the party to whom the cloth belongs? The sab used will resist the effect of boiling in time, then sta [4417.]-SAFETY VALVE FOR KITCHEN BOILERS. ing in spirits of salts, then boiling in soda ash, t -I saw noticed somewhere, some time ago, a safety valve steeping in a solution of bleaching powder, then s for kitchen boilers. Can any of your readers kindly telling in spirits of salt again, and sundry washings thro me the maker, and whether this safety-valve answers the hot and cold water, and will yet retain its proper purpose of making the boiler absolutely safe? Mine is a resisting any dyeing process to which it may after cast iron one. Is there any possibility of expansion pipes be subjected, leaving the number showing out plaish white ground.-B. D. F. becoming closed, except by frost ?-OSMOND DOBREE. [4418.]-SILVER COIN.-Perhaps readers of the ENGLISH MECHANIC will kindly inform

some of

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the

[4494.]-TAPS AND D IES.-Can any reader t taps and dies for right-handed work? If so, plen if I can make left-handed taps and dies out of ast scribe the modus operandi.-W. REED.

[4435.]-CHANGING RED CORAL TO PINK any one tell me if I can weaken the colour of res so as to make it pink? If so, how ?-W. REED. [4436.]-BEE KEEPING.-Have any improverci been made in Woodbury's frame hive since the described in Payne's Bee Keeping ?-J. R. W.

[4437.]-FLUORIC ACID.-Can any reader inform whether fluoric acid is chemically made in Amed and if so what is about the price of it; and if not whethe fluor spar can be got there, or rather is it found the

me what the coin is, a sketch of which I enclose. It is of silver, and rather thick.-A YOUNG BEGINNER. [4419.]-WATER GLASS.-Will any of your chemical subscribers be kind enough to give a form for making-J. K. H. water glass?-JOHNSON.

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[4438.] COTTON SPINNING. An "Inquirer would feel obliged if your cotton spinning friends wi give their opinions as to the following questions:-In single engine, 48in. on the wire, cylinder being 45in, di meter, and running 140 revolutions per minute, what speed ought a 24in. doffer to run, also a 6in. car ding rolle when the engine is carding 4001b. of middling America per week? Also, what speed ought a 9in. licker-in of taker-in to run in the same engine?-INQUIRER.

[4420.]-VACUUM IN CONDENSING ENGINE.-I have a 30-horse condensing engine, and by the indicator On Saturday we took out I have only 10lb. vacuum. the air-pump piston, and found the springs to be a metal ring that goes inside the brass one; and the only way to extend the brass ring is to hammer the metal ring larger, and I think it would soon go back to its original size. So we took out the springs and put laggs in their places, but were pressed for time, and the joiner had only deal wood by him, and that not very dry. The laggs are 3jin. long, 1 in. thick, and the piston is 18in. diameter, and it was a good fit. But to our surprise we have only 91b. vacuum-1lb. less than the old pistonwhen working a fin. less than the cylinder. Can any [4440.]-WHEELS AND PINIONS OF WATCHES, brother reader tell me the cause? The air pump is in No. 1.-Would "Horologer" kindly inform me ha the centre of the condenser, and the injection pipe is many teeth each wheel, and how many leaves each at right angles to the eduction pipe, and nearly meets.pinion of a watch should have; and if a watch lin

J. B.

[4421.]-MAKING FLANNEL ADHERE TO BRASS. -Any correspondent who will kindly inform me how flannel adhere to brass will oblige.to make A SUBSCRIBER.

[4499.]-MATHER AND PLATT'S PATENT PISTON -I am working one of "Mather and Platt's" patent pistons, and should feel obliged if any brother enginee: could inform me how to take it to pieces for cleaning, and how to put it together again.-C. S. A.

8-10th, 8 size, should have as many as a watch lin. 9-10th, 20 size? Where are the seven jewels in watches placed! In which size watch is a scape wheel with eleven teeth placed = a fifteen teeth and thirteen teeth wheel? An answer will greatly oblige.-B. E. LODDY.

as I am thoroughly conversant with that myself.-OLD
DIP.

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[4456.]-PLUMBAGO BOTTLE BATTERY.-I will thank your able and scientific correspondent "Sigms" to have the goodness to inform me where the plumbago bottles for battery purposes can be got, and the probable cost of each, or with the zinc and binding screws com

[4441.]-WATER BAROMETER.-I would feel ob-
zed to "Cornubia" if he would favour me, and I am
are many more, with a fuller description of his water
arometer.
I have been experimenting with that
ind of instrument for the past eight or nine years, and
ould be glad to give a description of mine, in which
ercury is used, if you thought proper. Meantime, I
ould like to know what provision he makes for correct-plete.-ELECTRO-MAGNET.
g the influence of temperature on his barometric tube.
ithout this it cannot be known to what extent the rise
fall is due to that or density. I would also wish that
ie card was shown on a larger scale, as it is too con-
ned in its divisions, and so to explain all its parts and
slations that one might venture to make a similar one?

-JUNIUS.

[4442.3-CROQUET.-Will some reader give me the articulars for making a set of croquet. I wish to know he length and thickness of the mallet head, the length nd thickness of the mallet handle (the thickness at ach end of the handle), the number of hoops required, ind the size of the opening in them, what sort of wood hould the different articles be made of, the simplest dan for turning a wooden ball perfectly round, the size nd colour of the balls, and in what order are the colours ainted on the starting posts? I also wish to know what le clips are ?-WOODMAN.

[4448.]-MOTIVE POWER FOR VELOCIPEDE.-I ive been expecting to see some account in your paper of small high-pressure engine applied to a velocipede. he boiler could be heated with asbestos (instead of bal) and oil lamps. It would not take above -horsewer to move a four wheeler, with india rubber tires, to Weight of carriage to be Bcwt. arry two passengers. less. Will any of your correspondents kindly suggest ze of copper boiler, cylinders, size of tank, probable ost, and whether practicable without danger? All bicycle nd' velocipede riding is attended with great labour, hich tells seriously on hilly roads. If some small com act contrivance can be used as a motive power, and ree from danger, there would be a ready sale, which would amply repay the ingenuity of the fortunate inventor. Awaiting information on the above subject.

THOS. STANHOPE.

[4444.]-JELLY-FISH IN STONE.-The slabs used for paving London Bridge are spotted with greenishyellow marks, of varying shapes and sizes. A friend tells me these spots are the petrified bodies of jelly-like fish imprisoned during the formation of the rock from which these slabs were cut. Is this really so? I wish some of our correspondents would tell me something about them.-MEDUSA.

[4445.]-ASPHALTE FOR GARDEN PATHS.-Can any one tell me if I can use asphalte for garden paths; what would it cost; and how do you lay it down?SABBAS.

[4446.] MOUNTING MICROSCOPE OBJECTS, Erc. What is the best method of mounting the Rotiferæ, or Wheelbearers? Has any one tried the small rubber rings as cells for mounting in liquid? How do they answer ?-H. U.

in

[4447.]-BOGIE ENGINES.-Some of these have been Are they any use on the North London line. advantage; and do they save anything ?-SLEEPER. [4448.]-TRUE MERIDIAN.-Will some of my fellowreaders explain the best way to find the True Meridian," and also let me know how much difference is there between thepresent magnetic meridian and that in 1860 ?-YOUNG SURVEYOR.

[4449.]-RESTORING FRESHNESS TO FILTERED WATER-I have a most excellent animal charcoal filter, which gives a good supply of perfectly pure and transparent water, but it drinks "flat," something like water which has been boiled. I shall feel greatly obliged to any of your scientific correspondents if they will inform me of the best means of restoring freshness to the water, by passing it through a strata of some other material after it has been filtered.-F. P. S.

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[4457.]-STEAM BOILER.-I have a steam boiler about 20-horse power. I require two distinct classes of steam off it-viz., one class at 50lb. per inch, the other at 201b. per inch. Would some brother reader kindly say how I may obtain it? Is there such a thing as a reducing valve to be had which would have this effect? -OLD DIP.

[4458.]-LIQUID HARNESS BLACKING. Would
some of your kind readers give me a good receipt for
making the above ?-R. S., Handsworth.
[4459.]-WHITE FURNITURE CREAM. Recipe
wanted for making the above.-R. S., Handsworth.
[4460.]-SLIDE VALVE, ETC.-TO MR. BASKER-
VILLE.-On reading Mr. B.'s letter in a back number on
the lead of the slide valve, I met with several difficulties.
In the first place I wanted an accurate description of the
slide valve itself. Secondly, I was at a loss because I
had never heard the words "lead," "lap," and "travel,"
accurately defined. Questions like the following
occurred to my mind. Where is the "travel" measured
What is
from? Is it the "throw" of the excentric?
What is the
the distance between the port holes?
"lap"? "Where is the lead measured from?" All these,
and numerous others still remain unanswered to my
mind, though I have spent some time in studying the
subject; and as I am unable to procure a good work on
the steam engine, I appeal to Mr. Baskerville to put me
right. At the same time I would thank him to give me
a sketch of a pair of excentrics and link motion slide
valve and cylinder (33-16th in. diameter, and 6in. stroke),
What I want most
for a 2-horse power road steamer.
are the eccentrics, link motion, and slide valve; about
the cylinder I am not particular.-THOS. WATSON.
[4461.]-SCREW CUTTING.-Will "J. K. P." please
reply to the following questions:-I have a 44in centre
lathe, which I am fitting for screw cutting. What
of wheels would you say are the best for it; 14 or
pitch; and how many threads to the inch for the leading
screw ?-H.WILLIAMS.

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USEFUL AND SCIENTIFIC NOTES.

NEW USE FOR YEAST.-In some localities large quantities of beer yeast are run off into sewers and wasted. It contains from 7 to 11 per cent. of nitrogen. M. Bernier mixes about 100 kilogrammes of the yeast with about 30 kilogrammes of quicklime and 10 of gypsum, and thus obtains a manure which may be used instead of guano.

ECONOMICAL PAINT.-Skim milk, two quarts; fresh slacked me, 8oz.; linseed oil, 6oz.; white Burgundy pitch, 2oz.; Spanish white, 3lb. The lime to be slacked in water, exposed to the air, mixed in one-fourth of the milk; the oil in which the pitch is previously dissolved, to be added a little at a time; then the rest of the milk, and afterwards the Spanish white. This quantity is sufficient for 27 square yards, two coats.

RENEWING RIBBONS.-Old ribbons will look quite renewed if washed in cool suds made of fine soap, and ironed when damp. Cover the ribbon with a clean cloth and pass the iron over that. If you wish to stiffen the ribbon, dip it, while drying, into gum arabic water. White silk gloves wash well, and should be dried on the hands.

TO MAKE OLD KID GLOVES NEW.-Make a thick mucilage by boiling a handful of flax seed; add a little dissolved soap; then when the mixture cools, with a piece of white flannel wipe the gloves, previously fitted to the hand. Use only enough of the cleaner to take off the dirt, without wetting through the glove.

DYEING HORN BLACK.-According to C. Burnitz, of Stuttgart, horn may be dyed black by a cold process in the following way:-The horn is first to be soaked in a solution of caustic potash or soda until the surface is a little dissolved, and feels greasy. Then the article is to be washed and treated with aniline black, after which it is to be slowly dried and again washed. By exercising a little care, we read that combs with fine teeth may be dyed in this way. The articles look of a dark brown colour by transmitted light, but seen by reflected light they are deep black.

Gladstone
THE WEALTH OF ENGLAND.-Mr.
12d at a meeting at the Mansion House on Tuesday,
July 12tn, the annual increase in the wealth of the
country amounts to £100,000,000 a year, of which
£20,000,000 are made in the city of London. Lord Stanley,
the present Earl of Derby, some few years since, calcu
lated the increase of our national wealth at the rate of
£50,000,000 per annum.

[4462.]—STRANGE PHENOMENON.-Observing in
the ENGLISH MECHANIC an article headed the "Leaf as
a Worker," I write an account of a strange phenomenon
that has come under my own observation. About two
TRACTION.-The resistance to draught on dirt or
years ago, while taking a walk after dark, I happened to gravel roads is about 148lb. to the ton. On a well-con-
be standing near to a thorn hedge, when I observed, in
structed macadamized road it is not far from 661b. to the
looking amongst the leaves, a flickering light. Struck
ton.
On a good pavement, say granite or Belgian, it is
with this appearance, I closely observed it night after about 331b. to the ton, while on an iron rail track it is
night. I saw the same appearance on every green plant-lb. to the ton. These facts show that a horse
I found the saine on every stone wall; indeed, everything will draw about three times as much on a macadamized
that I looked upon disclosed the same flickering waves rond as on a common road, four and one-half times as
of light. I conjectured what it might be; sometimes I much on a pavement, and eighteen times as much on
thought it might be light absorbed by the plants through
an iron rail. This conclusion, of course, implies that
the day, and leaving them at night. I also attributed it the horse has the same secure foothold in each given
to electricity, also to a delusion in my own eyes. I tried
to show it to some of my acquaintances, some of them
could see it and others could not. Since then I have
observed it regularly, but cannot come to any definite
opinion regarding what it is. I hope some of the readers
of the ENGLISH MECHANIC will give it a fair trial and
give their opinions. I see it best by looking steadily at
the leaves from a distance of 5in. or 6in. upwards, and at
present after ten o'clock at night.-GLOWWORM.

[4463.] ROTATORY MOTION.-Can cold compressed air be made to produce rotatory motion without heating in any way? If so, to what pressure must it be condensed?-YOUNG ENGINEER.

UNNOTICED QUERIES.

[4450.]-TO "SIGMA."-Will "Sigma please give me a little information respecting the Smee and Bichromate batteries? I have noticed that in the former there are two large zinc plates, with a platinised silver plate between, for the negative; while in the Bichromate there are two large carbon plates, with a small zine between-the two batteries appearing to me to be IN future, if any query remains unanswered for four quite reversed. Now what I wish to know is-Firstly-weeks, we shall insert the number and subject of the Are the conditions altered because the plates are reversed, and do the two batteries resemble each other in working? Secondly-Which is the most powerful, and naintains its power the longest, and how long? ThirdlyWhich is the most economical in working? Fourthlyre there any advantages in either over the other? and astly, ought the zinc to be amalgamated with mercury or the Bichromate ?-M. R. C. S.-A NEW SUBSCRIBER. [4451.]-MOULDS OF COINS.-Can any corresponent inform me with what substance I can make small oulds or impressions of coins, so as to plate them with opper with a battery ?-F. WALKER. [4452.]

query in this list, where it will remain for two weeks, if
not previously replied to. We trust our readers will
look over the list, and send what information they can
for the benefit of their fellow-contributors.

Since our last "Heather Jack" has answered 2672,
3812; "Housewife," 3828, 4002; Muzzle Loader," 4005;
M. 'D.," 4014; H. W. Henfrey, 3975; Bernardin, 3982;
3926; Rogo," 3842; "G. W. A.," 4011; “S. A.," 4009.
"S. J. P.," 3961; "H. U.," 2662, 3912, 3918; “Q. Q. R.,'

- LIGHTNING CONDUCTOR.-I shall be
nuch obliged if one of your kind contributors will 4029 Fixing Colours in Cotton Material, 310.
favour me with particulars of a lightning conductor; 4036 Botanical-Chemical, 310.
what kind of material is most suitable for the purpose; 4042 Magnet, 310.
and the best way to fix it, &c.—IRON.

4044

Air Gun, 311.

4046

Harmonium, 311.

4049

Polishing Copper, 311.

4050

4052

Iron Moulding Boxes, 311. Enlarging Cartes de Visite, 311. 4060 Vulcanizer, 311.

Parsons' White Brass, 311.
The Lathe, 311.

[4453.]-FLATTED OIL BACKGROUND FOR PHOTOGRAPHERS USE.-Will any of your readers inform me how to prepare a background in flatted oil for photographic purposes, to roll upon a stick? I have one on a stretcher, 7ft. by 6ft., which I prepared in the fol- 4059 Soldering, 311. lowing manner: 1st, by tacking the canvas to the stretcher; 2nd, giving it a coating of common size; and 4069 3rd, painting it with two coats of ordinary slate colour 4070 "paint. But the difficulty I experience is this--in the lamp weather the canvas slackens, and in the dry wea her it tightens, which I think is quite the reverse with he canvas without the paint.-TYPO-PHOTO. [4454.]-BLACK JAPAN COACH-WORK.-Perhaps 4093 one of our readers can inform me how to make black apan for coach-work? If they can I shall be grateful. 4102 J. WILLIAMS.

Harmonium Query. To "Eleve," 311.
Refuse Lime, 311.

[blocks in formation]

Natural Selection, 311.

4081

The Shiptonian Velocipede, 311.

[blocks in formation]

case.

TEST FOR LOGWOOD IN WINE.-Lapeyrère has discovered that that the hematite contained in logwood yields a sky-blue colour with salts of copper. Thus, if strips of good filtering paper, Swedish being preferred, are placed in an aqueous solution of neutral acetate of copper, and then dried, they can be used for testing wine. When a strip has been dipped into the wine and removed again, the adhering drop must be made to run backwards and forwards over the paper, which is then quickly, but carefully dried. If the wine be free from logwood, the colour exhibited after the strip is dried will be grey, or rose-red greyish, but if logwood is present the tinge will be distinctly sky-blue.

ANTIFLAMINE.-A material has recently been introduced at Paris under the name of "Antiflamine," for the purpose of extinguishing fire in the case of accident; it consists of aluminous and magnesian silicates reduced to fine powder and dried at 212 Fahr., 700 parts by weight; chloride of magnesium in crystals, 200 parts; sulphate of soda, 50 parts; chloride of lime, 50 parts; and tartaric acid, 1 part 1,001. The article is supplied in a pulverulent form, and is perfectly soluble in water. It is proposed to mix it with the water in the fire-engines, the effect of which, it is claimed, is to lower the temperature and to surround the burning material with gases which will not support combustion.

NEW NAVAL LIGHT.-A French paper says that it is intended to supply several vessels of the fleet with an apparatus intended to light up the line of the horizon in dull weather, or any point of the sea-coast at which it may be expedient to disembark at night. This apparatus, placed in the fore part of the ship, is composed of an electric light and a powerful reflector. The light is produced by the combustion of two cones of coal, in communication with a magneto-electric machine. This is itself put in motion by a small steam-engine connected with the ship's engines. The reflector, on Fresnel's system, is analogous to that employed in lighthouses. This apparatus possesses such great illuminating power that, when directed upon a point of any coast, it is clearly visible at a distance of about two miles, without its being possible for the enemy on the coast to distinguish the ship bearing the light. The ironclad frigate Heroine carries one of these lights, which has been useful in gloomy weather to the transatlantic packets. The Russian Government has ordered several of them from the French inventor, and proposes placing them in the port of Cronstadt. Speaking of this system, the Austrian Admiral Tegethoff, the victor of Lissa, used to say that if he had had the assistance of such lights he should have annihilated the Italian squadron while anchored in the roads of Ancona. It is, in fact, known that one night, very shortly before the battle of Lissa, the Austrian fleet approached within reach of the cannon of the port of Ancona. Admiral Tegethoff thought he could distinguish through the darkness a thick smoke, showing that the Italian vessels were getting up their steam, and were about to weigh anchor. Such a reflector as that recently invented would have permitted him to see that he was mistaken, and that the fires of the hostile squadron were not lighted. The fate of those motionless vessels would have been decided.

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