[5607.]-GUANO.-"H. U." is correct in the time that the first was imported in 1841, by W. J. Myers, Esq., of Exchange-alley, North Liverpool. In the previous year one of the masters employed by the above. pended the moulds, G. The edges of the pieces should peculiarities at least of my own adding, which are I con

cigar boxes, with a flat rim glued round, fin. broad and
in. thick, the leaves to be done the same both sides, the
to be lined with black velvet, and the back and edges
backs only on one side, so that it will form a book; then
covered with marble paper, forming the hinges with
cotton glued on the back. It being so far prepared, next
get a yard of in. wove elastic, cut 9in. off, sew the ends
together; next cut a piece out of the rim fiu. in breadth
top and bottom, to allow the elastic band to be inserted
round both sides, lin. from the left-hand side of the
margin; your slides are to be placed under the elastic,
which can be made tighter by giving it a stitch through
the centre. The small bit taken out of the rim can be
glued in the same place by making it a little thinner, so
that it will be level, and made neat with a little paper
over. You place your slides under the elastic to the
left, then turn your book round and fill the other side
the same way; one book for vegetables, and another for
animalcula, and so on.-S. SCHOLEFIELD.

[5643.]-IMPRESSION OF SEAL.-"Sub Sigillo "
will be able to get a better cast of his seal by the electro-
type process than by any other, without fear of damaging

as possible; this has also four holes to allow the air to pass out. The action will be easily understood: the tin funnel, which forms a part of the top is filled with oil, the piston rod is forced down to the bottom of the cylinder; communication is thus made through the hole Fwith the receiver. On lifting the piston, communication with the receiver is cut off, the air above the piston is compressed until it forces up the upper valve, or until the small piece of copper tube comes into contact with the india-rubber (which it should do each time) and so allow it to escape. The piston at each stroke should be allowed to remain at the top for a moment to allow the air to escape, and the oil from the top to descend on the piston, which thus becomes, like the top valve, hermetically sealed. Now, whatever inequalities exist in the pipe, instead of allowing air to pass back into the receiver, these will rather allow the oil to pass, which accumulating each time at the bottom of the pump, will each time the piston descends, be forced above it again, so that with ever so rough a tube in reason, and ever so badly constructed an apparatus, results may be attained which the more expensive apparatus cannot exceed. With this contrivance, which I have made out of one of the tubes of Palmer's candle lamps, at the expense above mentioned,. I can exhaust a large paraffine chimney in about ten strokes of the piston, and have performed all the ordinary vacuum experiments with electricity, &c. P.S.-The handle should be ma de to screw on and off, and in putting the machine tog ether, pass the rod up from the bottom, the edges of the leather, of course, turned upwards, as in sketch; afterwards screw the bottom on. In the absence of anything better, the bottom may be even stopped with a cork and sealed.

-HECTOR.

B

[5654.]-CHEAP AIR PUMP.-Perhaps the enclosed sketch of air- pump will meet the want of "C. H. H." R is a tube connecting the pump with the receiver, K. There is a valve, V, at the bottom of he cylinder, and, another valve VI, in the piston P, both opening downwards. The piston works air-tight through a collar of leather at the top of the cylinder. When the piston P is pressed down to the bottom of the cylinder, all the air which it contained will be forced out at V. When the piston is drawn up, the valve V closes, preventing the entrance

of

R

air from the atmosphere; and whenever the piston passes the tube, R, the air from the receiver immediately rushes into the cylinder, another descent of the piston expels this volume of air, and thus the action goes on. The valve V in the piston prevents any accumulation of the air in the cylinder, after the piston rises above R, and enables it to act smoothly and equally. By this simple contrivance the process of exhaustion may go on indefinitely, there being no valve of any kind between the cylinder and the receiver. (Extracted from Cómstock's "Natural Philosophy.") This is certainly a simple and cheap instrument. If "C. H. H." is any way handy he might make one for a few shillings.

JUNIUS.

[5655.]-OPEN PEDAL PIPES.-Richard Walker will find this a good scale for his organ:-CCC, 8in. wide, 9in. deep within; CC, 44in. wide, 5in. deep within; C, 2gin. wide, 5lin. deep within; height of mouths from the block, a shade over the width, for 2in. wind, for 3in. wind cut a little wider.-SHEFFIELD SUB.

[5656.]-PARAFFINE LAMP.-The cause of the formation of soot at the corner of the wick is that the aperture in the cap over the burner is not large enough. If" J. F. R." will take a small round file and cut down the cap a little on the side the defect occurs he complains of, that will remedy it. I should also advise him to soak his wick in strong vinegar and well dry it before putting it into the lamp, which will prevent all smoke.

-G. H. S.

[5658.]-HARD ALLOY.-See reply to query 5575.J. N. D. C. [5660.]-QUICKSILVER.-This is probably impure, and may easily be cleansed by distilling in an iron retort, the nozzle of which should dip in cold water contained in a bowl or other suitable vessel. The operation is more safely performed out of doors in case of any accidental escape of the highly poisonous fumes. If a retort is not obtainable, "Hammersman " may make one by welding up one end of a bit of two-inch gas tube (say eight inches long) the other end of which has the usual thread. Then close one end of a corresponding screwed coupling, by either welding or screwing in a disc of iron, in the centre of which the end of a bent gin. or in. gas tube is screwed. This forms the cover which, when screwed on, should be tested with fire or other clay. Perhaps & simpler retort may be made with a small glue-pot pan, or other similar iron cup, covered by a piece of thin boiler-plate, cut in shape of Fig. 1, and with the three

lugs bent over so as just to pass over the edges of the pan. One or more wedges between the lugs and the flange will then secure the cover, which, after charging the retort with the mercury, should be luted as above. Fig. 2 and 3 are sketches of both retorts. A wood fire will be sufficient.-J. T.

[5663.]-DEFECTIVE COIL.-The fault is evidently in the battery. Although "Inquirer "gives the solution of his battery, he does not state what the elements are. Very possible the fault is polarization of the negative elements. Whether another battery would give a stronger shock depends on the construction of the coil, but most probably it would.-MECHANICUS.

[5667.]-TELESCOPIC.-In answer to "Scorpio," p. 239, I send diagram of a simple and efficient method o

mounting a diagonal plane for a reflector, which will
not, I think, need much explanation. The vertical and
horizontal adjustments are made by two flat plates of
metal, which revolve on two binding screws, adjusting
All that is required in
screws being unnecessary.
adjusting is to loosen one of the binding screws, and
move the plane until the reflection of the large mirror
is central in that direction; when right, clamp the
screw, then move the plane in the other direction, and
clamp the other screw. The three strips of steel may be.
riveted to the back plate as shown.-W. PURKISS.

[5668.]-FACING STONE STEPS.-Use Portland
cement, the best, and this in no place less than fin.
thick; wet the stone well also before applying it, and
there will be no fear of scaling.-J. B. PRIMUS.

long, 1in. wide by in. I always use a zinc cylinder, about Sin. diameter a id 8lin. high, but two slips of zinc, 14in. wide and 9in. high, placed in the containing-jar opposite the broadest sides of the carbon will answer as well. You have no need to use very thick zinc, ordinary sheet-zinc will do. Use as large a porous cell as you can get; 3in. by 9in. is a capital size. The dioxide is the black oxide, represented chemically by MnO2.A. J. JARMAN.

[5692.]-FISHING-ROD FERRULES.-Has "Salmo" tried" Brunswick black" for his fishing-rod ferrules? I use this and have found it answer very well. I do not know what it is that tackle-makers use for the purpose. -MUZZLE-LOADER.

(5692.]-FISHING-ROD FERRULES.-Warm the ferrules and paint with sealing wax varnish, i.e., black sealing wax dissolved in methylated spirit; the solution may be made either hot or cold: the same is used for blacking and varnishing bindings of rings or of splices, and for many occasions in fisbing-tackle making and mending where a non-elastic varnish is required.WORKING WOMAN.

[5698.]-TURBINE WATER WHEELS.-Mr. Gleed will find many examples of the modern turbine, both at work as well as in print; but notwithstanding their supposed theoretical perfection, I should advise him to adopt the original simple form of which I enclose a sketch in outline. I presume from his giving the presure at 201b. that he has an available fall of about 30ft.. which will produce a very great power in a very small compass. Turbines have been at all times universally in use in mountainous countries, where high falls with moderate streams continually occur, and the proper name of this water wheel is "Ritrecina." The design is an accurate drawing of hundreds of existing water-mills

RIGHT HAND

SHOOT

9IN

[5670.]-NEURALGIA.-I can fully sympathize with "J. C. G." as regards that painful complaint, neuralgia. Having had several severe attacks of it myself years ago, and in the same spot-the back of the eye-I am in hopes that the remedies I have found effective may prove so with him likewise. The great point of course is, to prevent the attack on the slightest symptoms being felt; and neuralgia always gives a good warning. Take about 3 grains of sulphate of quinine twice in the day; or, if "J. C. G." does not find quinine disagree with him, as much as 4 or 5 grains. This knocks down the enemy at once; at least I have always found it so. Do not neglect the slightest warning, but take the quinine at once. Should the enemy, however, have working with a 30 ft. ¡pressure of water, more or less, obtained a lodgment, the only effectual remedy I can with less than a 2in. nozzle, and driving one pair of mention with any confidence is extreme cold. A stream 4ft. 4in. heavy stones, grinding at the rate of six bushels of very cold water long continued, ice, or ether-spray an hour, clean bran and fine flour. It is supposed to bo have been with me most effectual; it is a slightly pain- constructed of wood, but iron, of course, will do as well, first; but let "J. C. G." persevere and he will not repent ful remedy, as it a little increases the reuralgic pain at it.-H. C. K.

[5670]-NEURALGIA IN THE FACE.-There are no specifics for disease. It is the patient, not the disorder, that requires treatment. The causes of neuralgia are numerous, and therefore the treatment must largely differ to be successful in many cases. The vaunted remedies for neuralgia are based upon the fact that (excepting in disease of the nerve structure or surrounding tissues) neuralgia invariably ceases of itself within six months, even if it recurs every year, as in "J. C. G.'s" case. If "J. C. G." would send his address to the Editor for insertion in the Sale Column, I would gladly write a note to him on the subject, having formerly suffered much from the complaint myself, and having therefore much sympathy with other sufferers.

-S.

[5678.]-TRICYCLE.-From the result of my experience I should advise "Griffin" not to use ratchets on the driving wheels; but to fix one wheel only to the crank axle on the off side, and let the other wheel run free, which I find answers very well.-HAMLET.

[5677.]-PNEUMATIC SHUTTLE.-The pneumatic loom, as exhibited in the Islington Exhibition, and previously in the Belfast Exhibition, is patented by Messrs. Moreland & Coulong, of Belfast, from whom a detailed account of it may be obtained. The shuttle is impelled by atmospheric pressure. The box at each end of sley is lined with cork, and covered over the top, so that when the shuttle enters it is comparatively air-tight; the back of each box is fitted with cylinder and piston, the rod of the latter being connected with, and actuated by, a crank placed on each end of crank-shaft; the cranks actuating the pistons are so placed that when the sley is moving away from the face of cloth, the pistons are moving forward; a connection between bottom of cylinder and enclosed part of box allows the air thus compressed pop-gun. Although the patentees claim a good many advantages for it, as a practical individual in the working of power looms, I do not think it is destined to become a successful rival of the many methods now in use for throwing the shuttle. Apropos of looms and weavings, I should be glad to see far more queries and letters on this useful industry, as few people are aware of the extent to which power-loom weaving, in some of its most intricate branches, has developed itself out here in Ulster. In the production of flax-woven fabrics, from the finest damask to the coarsest grey Holland, I may say it has no rival.-LEH TEB.

to act on the shuttle in the same manner as the child's

[5677.]-PNEUMATIC SHUTTLE. A pneumatic shuttle is precisely the same as an ordinary shuttle, except that it has the parts between the "cap-hole" and the shoulder about 1fin. long, and the same shape as the inside of the shuttle-box, to act as a piston. That referred to at the Working Men's Exhibition was not so made, hence the great escape of air, and the chief reason for the excessive power required to drive that pneumatic loom. The writer's experience says: don't waste time and money on pneumatic looms.-GARDE LE ROY.

[5689.]-MANGANESE BATTERY, ETC.-In reply to "Mechanicus," the size of carbon block I use is 9in,

FEED TRUNK

90 FEET

if more suitable to the views of the constructor, and it may be reduced in its dimensions to suit any kind of work required. It should be noted that the "Ritrecina" or turbine is only, however, used for speedy work, never for slow or heavy motion.-H. W. R.

[5696.]-VIOLIN.-Mr. T.W. Boord seems to forget that the soundpost is placed on the right side of this instrument, therefore a bar which runs through the centre of the violin cannot disturb it in its place, neither will it interfere with the position of the brace, which strengthens the inside of the belly, as that is glued along on the left, and the bar lies between both.-EDWARD B. FENNESSY.

[5702.]-FROM A. J. JARMAN.-"A Beginner" cannot make his own gas-carbon. It is a residuary product of gasworks. Go to any gasworks and ask one of the stokers for a piece of scale that gathers in the retorts; he will understand you. This obtained, you can cut out pieces as you like, and save the dust to mix with the manganese. The containing-jar is an ordinary large preservejar. The porous cell must be obtained from an electrician, which can be obtained anywhere at 1d. per inch - that is, 6in. round porous cell, 6d., &c., meaning 6in. high. The cap is not riveted; it merely clamps the carbon-block. Mr. Wm. Tonkes,-You are quite correct respecting the letter on p. 81.-A. J. JARMAN.

[5704.] GAS. It would scarcely be worth while to put up a retort, &c., for two lights only (I preto attend to it oneself would grow wearisome. Where sume "J. M." means single jets), the bother of having establishments are situated away from public gasworks and use, say, 20 lights and upwards, it pays well to have a properly arranged gas apparatus, which the gardener can attend to as well as his daily work. The gas will not then cost more, but something less than town gas. But if" J. M." still wishes his queries answered he shall receive satisfactory replies in a future number fromGARDE LE ROY.

[5704.]-GAS.-Will not " J. M." find an 8in. retort too small to be economical?-BEN. G.

[5705.]-BIRD STUFFING.-If it be a dried skin it must be steamed on the flesh side till flexible, taking care not to wet the plumage. If the bird has to be

be skinned do not wet it, but make an incision from the point of breast-bone to vent. Strip the skin down on each side till joints of wings and legs can be reached; cut off these and the rump, and strip skin off the back and neck to the skull turning skin of neck inside out; cut off neck from back of skull and remove eyes and brains. Strip legs and first joint of wings in like manner, and remove flesh from bones, and remove flesh from second joint of wing by cutting on underside Then form body of tow tied into shape by packthread, Double a piece of fine wire and twist the doubled part of it to a length sufficient for the neck and passing the two ends on each side of the body twist them firmly together just under where the tail will come and leave putty and lap tow round the twisted wire to form the their ends projecting to support it. Fill the skull with neck, also round bones of legs and wings to replace the flesh removed. Put the tow body into the skin, sticking the end of the twisted wire into the putty to support the head, and if all seems right sew up the skin. Then run pointed wires up the hollow part of the bones of legs and through the body, clenching them in the tow on the other side. Then set up the bird, putting it in the desired attitude and supporting the wings by pins or wires till the skin dries, when they may be removed; stick the eyes into the putty. For preserving the skins, dress with 2 parts powdered arsenic, 1 burnt alum, 1 cayenne pepper, and for success. practice, quantum sufficit.-J. B. PRIMUS.

[5707.]-FRENCH POLISH.-Take twopennyworth of alkanet root, one pint cold-drawn linseed oil, and one pennyworth rose-pink, or more alkanet and pink if the pinky shade is desired deep. Leave all together in a pan over night, then rub on your table in morning. Leave it on one or two hours, then rub off with linen cloth. A beautiful gloss will be the result.-M. DUFFY. [5707.]-FRENCH POLISH.-Deep scratches cannot be removed except by glass-paper and repolishing. Dulness of polish may be remedied by a thin fresh coat on the old one.-J. B. PRIMUS.

round the copper; cut a strip of sheet zinc, an inch wide into pieces, which turn round a rod into cylinders large enough to surround and grip the jacketed copper, and solder the wires from these to the next zinc in series. A chain is thus formed, which though not quite so convenient, will cost a halfpenny for each shilling a purchased chain would cost, and be just as effective.SIGMA.

The

fattening fowls in coops. Buckwheat meal is considered
the best food for fattening, but it is not easily procured
in this neighbourhood. If you cannot obtain it, an equal
mixture of barley and Indian meal will be the best sub-
stitute. The feeding-trough, which should be placed
before the fowls at regular intervals, must be kept very
clean, or it will impart a sour taste to the food. You
must not omit to give them either gravel or sand to assist
digestion. Soms breeders advise only a very limited
[5744.]-TO PICTURE-FRAME MAKERS.
supply of water; I think that is a mistake. I should
certainly allow them to have access to it at all times. got at most dealers in gilt moulding, they certainly
corners used are very thin stamped brass, and can be
Fattening ought to be completed in about a fortnight. ornament a frame, and are very accommodating in cover-
after that period they lose weight. If you have a warming up a bad mitre (for an amateur is almost sure to
ventilated outhouse, place the coops in it, and if it can
With regard to the breed, the best fowls for the table otherwise, and use small brass pins, common pins
be kept dark between the times of feeding all the better. snip a little gold off). In putting on press gently with
the fingers to the shape of the moulding, half round or
are Dorkings, game, and Creve Coeurs, or a cross be- clipped with a pair of scissors will do very well to about
tween the Brahmapootra, and Houdan. Weight, as a gin. long; use a small awl to bore with, price 3d. a set of
rule, influences the price.-J. WALKER, Keele, Stafford-four upwards, according to size.-W. Z. W.
shire.

[5719.]-EBONITE.-Ebonite is a compound of sul

[5720.]-STOVE.-Musgrave's slow combustion stove will fully answer the requirements of "M."-VIVIS

[5744.]-TO PICTURE FRAME MAKERS.-"Amateur" phur and india-rubber combined under heat and pres-ornament. It is composition ornament, and is made as will require a sulphur or plaster mould to cast the sure (i. e., high pressure steam), it is but another name follows:-Mix 71b. of glue, 341b. of rosin, lb. of pitch, for vulcanite.-R. N. 14 pint of linseed oil, and 2 pints of water (more or less as you want). Boil together, stirring till dissolved stir into it whiting as much as will render it of the cos sistence of putty. Press it into the mould, which o first. Mix only what you can use before it gets hardened, as you must steam it if required to be worked again. You may stove it a little to dry quickly, then remove it from the mould, and glue on your frame; make secure with needle points or brads.-M. DUFFY.

SPERANDUM.

[5720.]-STOVE.-Dr. Arnot's is the best. If Welsh coal be used, and the stove fitted with the self-adjusting draught apparatus, it may be left for hours untended. I also prefer the open fireplace invented by the same ingenious physician, which is lighted at the top and fed from beneath, both for cleanliness and economy. Having tried many methods I speak from experience.-consciousness at about seven miles of height. The speed [5746.] BALLOONING.-Mr. Glaisher began to lowe of a balloon depends entirely on that of the wind as it travels with the atmosphere, not through it.-J. B.

H. B. M.

[5721.]-EXECUTOR'S ACCOUNTS.-Merely make a
debtor and creditor statement, entering all receipts on
one side and all payments on the other. Balance the se,
and if the items are correct and legal, and the "cash in
hand" agrees with the account, nothing more is needed.

[5724.]-GLUTEN. - Gluten is insoluble in water,
alcohol, and ether, but it is taken up byacids and alkalies.
The acid solution is precipitated by an alkali, and reci-
procally the alkaline solution by an acid.-BEN. G.
[5724.]-GLUTEN.-This substance is dissolved by
caustic alkalies and acetic acid.-BETA.

[5708.]-HYDRO-ELECTRIC MACHINE. It is im-J. B. PRIMUS. possible to make this machine cheap. In the first place, it requires a high-pressure boiler insulated on glass legs, provided with a row of jets of iron tube (about 40 or 50) with brass mounts, containing partridge. wood mounts, with about fin. hole through them. The boiler should be capable of standing 80lb. pressure of steam; the prime conductor is a zinc-lined box, containing rows of points to collect the electricity from the jets. The electricity is generated by the friction of steam against the wood jets.-R. N.

[5712]-SILVER COIN.-In reply to "O. E. S.," I beg to state that I cannot find his coin mentioned in any numismatic works that I have. If it is genuine, it must be very rare, but I am strongly inclined to think it must be a forgery. If "O. E. S." lives in London he should show it to some large coin dealer, and ask his opinion, or to same competent numismatic friend.-HENRY W. HENFREY, M.N.S., &c.

[5712.]-SILVER COIN.-The coin mentioned by "O. E. S." is one struck after the death of Faustina Sen., and the inscription refers to the asylum for orphans established in her honour. It is mentioned in a catalogue before me, and, if genuine, "O. E. S.'s " specimen is worth about £2.-S. J. H.

[5727.] POLISHING EDGES OF GLASS. - York

stone and water will smooth the edges if not splintered,
pumice powder mixed with rotten stone first, then putty
powder, both applied with willow wood are the polishers.
-AN ENGRAVER.

[5728.]-MAGIC LANTERNS.-" K. M. E." can do as I
did. Get woodcut of lantern to guide you; make of block-
tin 10in. high, bottom is one inch up, and perforated in
a few places with holes, to keep cool; the body is nothing
to make, simply a box; cut a round hole in front, and
solder slips a a, above and below, make the nozzle with

PRIMUS.

[5746.]-BALLOONING.-1. Mr. Glaisher was within the barometer fell to 12in.; but what altitude this really an inch of his life, as he believed, by ascending to where indicated is quite uncertain, as no direct measurements of balloon heights appear to have been yet made. They would be easy with two passengers possessing sextants, and able to use them simultaneously, while a third read the barometer; or might even be managed with one sextant. 2. The rate at which balloons travel is precisely that of the wind; indeed, they have no

motion through the atmosphere," the flame of a taper being said to be absolutely unaffected, except at the moment the balloon is in one wind and the car in

another.-E. L. G.

[5746.]-BALLOONING.-Messrs. Glaisher and Coswhich point faintness and difficulty of breathing in well on one occasion reached a height of seven miles, at creased to such an extent as to endanger life. The speed attained by a balloon varies, of course, according to the wind. With what sailors call "half a capful," miles an hour have been accomplished.-VERTUMNUS.

[5752.]-PIANOFORTE PINS.-Apply a red hot piece of iron two or three times to the broken wrest pin. If any hold at all can be got of it, it will be easily re moved; otherwise it will be necessary to drill it out.R. A. M.

[5756.]-WHEEL-CUTTING ENGINES.-W. G. Wil. liams will find all about the adjustable interpolator is Rees's "Cyclopædia," at least, that is the work I was referred to by the gentleman who furnished the photos. from which the engraving on p. 12 was done. I have not seen it myself, but there is only one way that I can see open for using the instrument. Say you want 101 teeth from a row of 100 divisions: measure the diameter of the circle of 100 holes, and calculate its circumfer ence, and divide that by 100 for the distance from hole to hole; then as you are to get 101 divisions into the space of 100, it is clear that the distance between the 100 new holes will be of that of the old ones, and the 101

[5713.]-WELSH GROIN (2).-It has occurred to me since giving the reply on p. 261, that the word "Welsh " is here, very probably, a corruption of gauche. The French, on the first introduction of groins of double curvature, must have called them "ogives gauche," and the English for ogives being groins, a most natural anglicizing of the above would be "Welsh groins." The ogives or groin-ribs of medieval vaulting, which were indeed the fundamental and formative organ of the entire architecture that we call "Pointed" and "Gothic" (but which the French know by the perfectly true and philosophic name ogival), were never twisted, "gauche," or allowed to deviate from a vertical plane; and the way they nevertheless were adapted to bear two in-flanges to slip under these. It is handy in packing and alidade will have to be shortened or lengthened by the tersecting vaults of unequal height may be seen in the example I cited, the nave of Winchester Cathedral (A.D. about 1400) or the later one of St. George's Chapel, Windsor, the only two cases I remember of this problem, for which moderns would have resorted to "Welsh groins."-E. L. G.

[5718.]-WELSH GROIN.-Germans call their neighbours over the border "Walsh," whence the appellation of the Celts in Wales given to them by the Saxons, and of our walnuts, which are of Lombard origin. The name Tedeschi, applied by Italians to men and things German, is not a German word, as stated in a note in the ENGLISH MECHANIC some time ago, but the nearest approach they can make to the pronunciation of "Deutsch,"which is what the Germanscall their language. And, if I recollect rightly, it is Professor Max Müller who gives us the above information, and says, too, that Deutsch is derived from " deuten," and means signifi. cant."-J. K. P.

[5717.1-CACTUS.-With regard to the culture of the cacti in this country, it is found that, generally speaking, they ought to have a season of complete rest, followed by one of violent excitement; that is, they ought to be kept almost without water from October to March, and then watered profusely while they are coming into flower. They ought all to be grown in pots well drained with cinders, instead of potsherds, as the latter retain too much moisture for the delicate and succulent roots, and they all enjoy bottom heat, which makes them throw out abundance of fibrils. When received late in the year-that is to say, in October or later they should not be potted till the following spring; and when raised from seed (which is frequently sent over even in dead specimens) the seed should be sown in silver sand, and the yonng plants when transplanted should not be watered for several days.-H. C. d.

[5717.]-CACTUS.-Cactus should be grown in pieces of broken brick, old mortar, and sweepings of floors; should be kept in a dry house, and get very little water; once a month in winter, once a week in summer, will be often enough to moisten the soil, taking care to allow no water to go on the plant.-VIVIS SPERANDUM.

[5717.]-CACTUS.-You may grow cactus in old mortar; no water during winter, plenty in summer, and syringe the leaves.-W. HOLMES.

[5718.]-POULTRY KEEPING.-I am of opinion that there is no operation connected with the poultry yard which requires greater attention and experience than

also for showing with opaque lantern, which does instead
of nozzle. This sketch will show the shape. The chimney,
b, is made in two parts; b fits over the rim on top, and c
over b, as shown. The condensers (buy at Cox's, Lud-
gate-hill) fit in round opening, d. Object glass in tube
(buy also) fit in end of nozzle e. The sliders place close
to condenser in space between front and nozzle. I got
a tinman to make as good as any optician for 58., and
japanned black. It must be done neatly.-M. DUFFY.

[5729.]-STEAM BOILERS.-I am afraid if "W. A."
uses such small tubes as " external diameter he is
likely to make a very serious mistake, as they will be
only about " bore, which, I think, would soon be made
up with sourf. Could he not put in six tubes, say 1"
diameter, as he would then be able to get rather more
heating surface and less liable to choke ?-BOILERMAKER
No. 1.

[5780.]-STRENGTH OF BOILERS.-Strength of good boiler plate, average quality, = 44,8001b. per square inch, sectional area of the plate's thickness, multiplied by the thickness of the plate, divided by the internal diameter in inches, gives the bursting pressure in pounds per square inch. Allowance for riveted joints being as follows:-Strength of plate = 100, double riveted joint

07, single riveted joint 56. Testing bar iron is usually done by breaking a piece off the end of bar, and carefully examining the grain. So also is boiler plate, but I usually examine the burr, which is punched out of the hole, and if found to be mushed or badly cracked upon the die side, I condemn it at once. Indeed this is a very good test for any kind of flat bar iron, as well as boiler plates.-BOILERMAKER No. 1.

[5731.] EARTH CIRCUIT. Yes. The current returns to the sending station by the earth.-BEACON LOUGH,

[5732.]-HORN SPOONS.-Horn spoons are made in
several places in Germany; in England I believe the
querist may find them at Messrs. Fisher & Sons, Orchard
house, Sheffield.-BERNARDIN.

and should not touch the skin; it may be prevented by
[5748.J-GALVANIC BELTS.-The zincs need not,
it is moistened. Pulvermacher's chains are convenient,
making a loose oilskin case to slip over the belt after
but it is pure clap-trap to say they are any better than
the simple forms any one may devise. Here is one;
get some copper wire, No. 10, cut it in lengths of an inch
or inch and a half, solder to the ends of each an inch of
thin wire or wire.cord, and wrap a piece of fine flannel!

100
100

100 difference between and for every successive Tul division, according as in working you turn the plate of the machine round "with the sun," or the contrary. I gave my substitute for the wheel gauge, with description W. G. W." The gauge, as sold by the rule makers, is of its use, on p. 328, Vol. XI., to which I must refer divided on a boxwood rule, about 20in. long, beginning with about No. 5 gauge, and the very small ones are done on a sheet of brass about 8in. by 3in. The numbers correspond to that number of parts to an inch-thus, No. 10 gauge is tenths of inches, and the corresponding wheels have ten teeth for every inch diameter, always recollecting to add two divisions to the pitch diameter for the height of the teeth above that line. I think the wooden rules are 12s., and the brass ones about 7s. or 83. but any scale of divisions of an inch will do as well. As, for example, most rules are divided to 8, 10, 12, 16 parts to an inch on one edge or another, and would serve for those gauges if you only bear in mind the two extra divisions wanted to every wheel, of whatever size, for the points of the teeth.-J. K. P.

passed through an aqueous solution of sulphate of cop-
[5768.]-CHEMICAL CHANGES.When SH is
per (cupric sulphate) a black precipitate of capric sal-
phate (Cu S.) is formed, and sulphuric acid is found in
the fluid

The solution of proto-sulphate of iron remains un-
SO2 Cuo" + SH2 = CuS + SO2 Ho2.
changed. The solution of alum is also unchanged. The
solution of corrosive sublimate (mercuric chloride) is
decomposed.

Hg Cla+SH Hg S + 2HCl
Mercuric
Mercuric
chloride
sulphide

A

At first, when only a small quantity of SH is present,
colour of the precipitate deepens. The whole precipi-
we get a white precipitate; as more gas is passed the
tate is a mixture of mercuric chloride and sulphide,
solution of sugar of lead (plambic acetate) gives a black
and as more sulphide is formed the colour deepens.
in solution.
precipitate of plumbic sulphide, acetic acid remaining
CH3

Co

спл

Co Pbo" + SH2 PbS + 21 Co Ho
CH

ONE WHO DID IT.

[5767.]-WATER PIPES.-A pipe 24in. in diameter will pass more water than two pipes 12in. in diameter.H. E. M.

[5769.]-DIVIDING PLATE.-My old dividing plate, by Holtzapffel, on a wooden pulley of 5in. lathe, is of brass, 11-64 thick. If your pulley is of metal, whether gunmetal or iron, the divisions may be drilled into the solid, which is much better than a removable plate. Of course you should have your pulley made with a broad rim on the face for this purpose. I consider iron by far the best for a real workman's, or, indeed, any lathe.J. K. P.

to

QUERIES.

[5845.]-TELEGRAPHIC.-Will some of the readers
of this journal, who are acquainted with the following
is the ordinary length and size of the coil in telegraphic
subjects, kindly answer the questions below? 1. What
needle instruments, also the size of the wire used? 2.
The best and simplest method of balancing or fixing the
needles? 3. The best varnish for the wooden tops of
battery cells, &c., and such like general purposes ?-
H. PAGE.

It was stated some time ago, at an inquest held in
[5846.]-CARBONIC ACID v. CARBONIC OXIDE.
London on the bodies of a man and his family, who
were suffocated by inhaling the fumes of burning char-
coal, that death was caused by carbonic acid. Is it not
true, however, that death was caused by carbonic oxide,
which is lighter than either air or CO2, one of the pro-
ducts of the combustion of charcoal, and highly
poisonous ?-INQUIRER.

(5777.] LATHE HEAD-STOCK. In answer
"Bierlala," he will find full particulars about grinding
mandrels and collars in Holtzapffel's third volume,
p. 1,245, onwards. A sketch of 54 headstock would
delay the printing of this a week, so I send it to the
editor to be forwarded. You will find it a bad plan to
put the collars on as you propose, as it will increase the
thickness of the mandrel unnecessarily, making it harder
to drive and will entail a great deal more fitting than
the usual way.
To prevent jamming, there is a collar
fitted tight on the mandrel and adjusted by the nut
[5847.]-MACHINE FOR WEAVING COPPER WIRE.
which keeps the pulley in its place, which collar works-Can any one tell me of a machine which will knit or
against the broad flat face of the back fixed collar.- weave thin copper wire in long narrow strips ?-THOS.

J. K. P.

[5793.]-LATHE.-I have left a query or two of Tom Brown's unanswered, thinking that the contents of p. 256 would enlighten him. He must recollect if his two fifty wheels just reach the distance, that the slide-screw

will have its motion reversed for want of what he calls his carrier. In explanation of the numbers given: if your screw has ten threads per inch, and you always drive with a fifty wheel, then you must put on the slide screw a wheel of five times as many teeth as the number of threads you want; and the numbers I furnished, taken in succession thus, suit for 11, 12, 14, 16, 18, 20 threads per inch, which are Whitworth's pitches from down to tap.-J. K. P.

[5794.]-ARITHMETIC AND ALGEBRA.-Barnard Smith's book, which I have little more than seen, is as good for self-instruction, I should think, as any other. For the step from merely elementary algebra to the ininitesimal calculi, its chief applications, I would recommend the late Professor Whewell's "Doctrine of Limits,' especially if there be any new editions, as the first was, unhappily, very badly printed. Any of the works of Professor De Morgan are to be valued, he being, as I think, by far the best living popularizer of mathematics, high or low.-E. L. G.

[5806.]-TIN CAN.-"H. W. R." must again have "omitted a coefficient" or something, to make the area of a circle whose radius is √2 8·1416011. It is 6-2831858 = 2, which I called 2, merely meaning that it was 2 of the units I was using for comparison. Insert after this, and each of my other figures, and all will be right. The sides of the same can are = 4, while the sides and bottom of the 78 can (of Mr. Revely's form) are each 3, making the whole surface of each of these cans equal, namely, 6. What I undertook to prove (if he will look again, p. 163) was not that my can had the maximum capacity, but merely that he was wrong-that his had not the maximum. How this could be proved, without calculating surface and contents of two cans, one of his proportion and another of a better proportion, I cannot see. These two have their surfaces, in square units, each = 6; while their contents are, in cubic units, his == V8 = π

132

.-E. L. G.

= π

and mine

(5809.]-HEADSTOCK.—TO “S. D."-The section of your bed is very much what mine is with a 5" head, but is very short; not but what a short lathe is useful for many, indeed, the majority of purposes.-J. K. P. [5814.] WILDE'S MAGNETO-ELECTRIC MACHINE.-I do not see my way to helping "Infelix" nuch, unless by the suggestion that possibly he is revolving both armatures at the same speed, and makes the breaks synchronous. In this case, of course, the current from the first would not be developed in the second; otherwise, his failure must be due to some errors of construction, which can be discovered only by Inspection.-SIGMA.

[5818.]-DEXTRINE.-A form of dextrine, known as British gum, is used in calico printing as a thickener. -CHEMICAL.

(5823.]-AIR-GUN.-I always pump in the air until I can do so no longer; and, as I have never met with any accident, I presume there is no fear of bursting the breech. Mine was made by a good London maker. It is adapted for shot or bullet. If using shot, I first send down a wad, then the shot, and, last, another wad. With a well-fitting bullet, the wads may be dispensed with. For a description of the mechanical arrangements, I Taust refer "Gamekeeper" to the indices of back volumes. I remember seeing an illustration some time back.-W. L.

20.

MAINWARING.

[5848.)-ETHENE.-Would any kind reader oblige me
with a diagram of the decomposition which takes place
in the manufacture of ethene, 3 H, from spirits of wine
with sulphuric acid ?-J. T. S.

BODY."-Will "Nobody" kindly inform me the price
[5849.]-WATCH CONSTRUCTION. — TO "NO-
and the publisher of the French book on watchmaking

mentioned by him?-COMPENSATED BALANCE.

[5850.]-THE QUEKETT CLUB.-Will some one
kindly inform me if the meetings of the Quekett Club
are still held at the London University College or not,
as I have some idea of some alteration having taken
place?-J. C.
[5851.]-QUARTER BELLS FOR CLOCK.-I am going
to make a model turret clock, similar to the one I de
cribed in your journal some time ago, only on a small
scale for the house, and I wish to have the quarters
struck on four bells, as at Westminster. I should be
thankful if any of your readers could inform me where I
could obtain, in London, the bells. The notes required for
the quarters are C flat, B flat, A flat, E flat. The hour note
is struck on A flat, an octave lower than the A flat of the
quarters, and the bell might be about the size of a saucer.
On a large scale, I have done the thing with excellent
the hour on E flat, the largest bell of the quarters, but
effect, only using the four bells as above, and striking
properly the hour' note should be an octave below the

A flat.-S. MADDISON.

[58521-SKATES.-Will any subscriber kindly tell me the best way to make a pair of skates to fasten without any straps, and show parts of them with size, &c., and oblige-ONE WHO LIKES SKATING?

[5853.]-SCHOLARSHIP.-Could any of my fellow readers imform me if there are any scholarships open to competition in connection with the Royal School of Mines, or any other technical educational body, the examinations for which are conducted by the Science and Art Department? I once heard that there were a few preparatory scholarships given to intending competitors for the Whitworth Scholarship; if so, could any one tell me the conditions and subjects of examination in these?

-W. C. ROYALT.

(5854)-DRAUGHTSMEN'S DUTIES.-What are the duties of draughtsmen in a large engineering establishment? I wish to make myself competent for that job, if I can. I am a fair mechanical draughtsman, but have little mathematics beyond the elements.-W. C.

ROYALT.

[5855.]-STOPPING AND FRENCH POLISHING.— Would any reader inform me what "stopping" is generally used by French polishers to fill up the pores in new wood before polishing, and how to make it; and, also, how to make the kind of glaze that is used to finish a cheap job-what is termed fiddle by a good many polishers ?-ONE WHO HAS GOT THREE MORE SUB

SCRIBERS.

[5856.]--QUILTING.-I want to quilt some large articles, such as bed quilts, &c., and find great difficulty in getting the material under the arm of my machine, a "C" of Howe's, which is too heavy, and yet the arm not long enough. Is there a machine for the purpose; or what machine do quilt manufacturers use ?-A SUBSCRIBER'S WIFE.

much indebted. It is there stated the ebonite tube for secondary coil should be 18in. long, with disc of ebonite at 8in. from each end, leaving Sin. clear. Having drawn it off to scale, preparatory to constructing a coil to that dimension, I find, allowing in. each for the discs, I have just 11in. for secondary. I find the rings of fin., 1-26in., will take just about 6 to the inch, making 11 x 6 together with the thin discs of No. 28 B.W.G., say about to be some error in the length or the number of discs. =66 discs, instead of 99, as recommended. There appears Would "Inductorium" also favour me with his opinion on the following ?-I have a coil with about three miles of silk-covered wire No. 85, and the primary, abont 716. of No. 9 B.W.G., which I purpose to take abroad, and use in the construction of one such as recommended by him, adding thereto, as per quantities given. The prí mary is wound by hand-that is, the wire is thus insulated instead of being wound with cotton in a lathe-with narrow silk ribbon; on the horizontal plan, the condenser, about 60 in series 7 x 9, insulated by cartridge paper soaked in paraffine, and also a sheet of thin gutta-percha between every layer.-VEGA.

[5860.]-YELK OF EGGS.-Will any of your numerous correspondents inform me of the constituent parts of the yelk of eggs, and how best to make a composition possessing the same properties, and the cost of it either by weight or measure ?-JOHN BAILES. [5861.] COMPENSATION BALANCE.-I beg to tender my best thanks to "Seconds Practical Watchmaker" for the very lucid manzer in which he has affected by atmospheric changes of temperature, and not auswered my inquiry. I was thinking how comparatively so thick a substance as the balance should be so easily the thin spring supporting it. I have a plate lever watch with a gold balance, made by an eminent London maker, it varies with the temperature, and I am fearful (even if it were not so expensive) to change the balance for a compensated one, supposing there may be some difference in construction, or preparation, of the other parts of the watch required. Perhaps I may again trespass on "Seconds Practical Watchinaker's" kindness to inform me if my fears are groundless? also if a compensation balance, all of which are made I should suppose according to rule, to approach correct adjustment as nearly as possible, might be put on with advantage without undergoing the more elaborate and expensive process of adjusting? A mere balance of itself could not be very costly, and it would not le required for extreme temperatures.-EcONOMY.

[5862.]-GROVE'S BATTERY.-I wish to add strength to the platinum, and think of mounting it in an ebonite slate is secured in a frame, but before doing so wish to frame cemented with shellac, in the same way that a ask whether there is any better method, as platinum is too expensive a metal to play with.-M.

[5863.]-LOOKING-GLASS.-Can any correspondent inform me of a cheap method of filling up scratches on the quicksilver side of a large looking-glass ?-G. H. S.

[5864]-WATER POWER.-Can one of your correpondents oblige me by stating if I can obtain sufficient power from a turbine attached to a fin. water pipe at a pressure of 15lb. to the inch, to work a small grinding lathe or a 6in. fan ?—J. H. G.

[5865.]-SULPHURIC ACID.-Would some correspondent let me know if the sulphuric acid sold at the druggists, for two or three pence a pound, is good enough for those purposes that require a tolerably pure acid? Also if methylated spirit called finish will do for making ether, chloroforin,J&c. ?-J. W.

[5866.]-MODEL PADDLE STEAMERS.-Will any fellow-reader oblige by giving directions how to make clock-work motion for model paddle steamers of from 2ft. to 4ft. in length? An illustrated description would be a great favour.-POOR WELSHMAN.

[5867.]-MOUNTING SPECULA. I have a bin. speculum, 5ft. focus, which I wish to mount on the Herschelian principle. Will one of my brother readers (perhaps Mr. Newten) kindly help me by informing me at diameter of tube required? A slight sketch would be what angle I am to place the mirror, also the length and very acceptable (showing the position of the eyetube, &c.) if it is not asking too much.-SILENT.

[58CS.]-THE SUN'S RAYS.-May I solicit the kindness of our valued friend "F.R.A.S," or Mr. Proctor, to answer the following query? What causes the great divergence of the sun's rays after passing through an opening in the clouds, or even through an opening (devoid of glass) into a large building? It seems strange that the divergence should be so great in the rays of a luminary 90,000,000 of miles distant,-not that I call in question the facts of astronomers as to the distance, &c., of the heavenly bodies, but the above I cannot satisfactorily account for.-BETA.

[5857.]-WATER WHEEL-Wishing to attach water-
power to a portion of my works, I shall be glad if some one
of your readers experienced in water-wheels would give
his opinion respecting the merits of a breast-wheel and
a turbine. I have a large body of water, with a fall of
about 12ft.; the shaft requiring to be driven must go
120 revolutions; it is at present driven by a 20-horse
engine. The river from which the water is taken is sub-ploughing by power.-GALWAY.
ject to heavy floods, consequently the tail water rises
too, and puts the wheel into backwater. I have a breast
well, but I have no experience of the turbine principle.
wheel at present driving 90-horse, and it does its work
Any information will oblige-VIVIS SPERANDUM.

[5869.]-WIRE ROPE.-Will any of your practical correspondents kindly inform an old subscriber whether in. galvanized iron rope will withstand breaking with a ton dead weight at 1,200 yards distance? I want it for

[5828.]-MICROSCOPIC.—If “Chase" will re-read my reply (No. 5566), he will see that I proceeded on the assumption that his microscope was, as he himself described it, a £5 instrument, and that its highest power was in. I stated then that I was afraid to guess its magnifying power. Now I am still more unable to do "Chase" says his lens is about 1-16in. Does he mean 1-12in. or 1-20in.? What is the length of his micro-brick oven to an iron one, but I confess that my stupi scope tabe; what eye-piece does he use; who is the maker of his objective; is it an achromatic combination; if so, what is its angle of aperture? These are a few of the queries "Chase" must answer before I can attempt to give another guess at the power of his lens, which, if an achromatic 1-16in. objective of even decent performance, is miraculously cheap. I must apologize for the space this reply to so vague a question vccupies.-H. Ŝ. H.

[58411-SPEAKING TUBES.-"Nab's" plan will answer all he anticipates.-H. E. M. [5841.]-SPEAKING TUBES.-In answer to "Nab," I recently had fitted up a tube of which the total length was about 90ft. It was of the hard brown rubber, lin. diameter inside, and had half a dozen sharp elbow bends in it. It was perfectly satisfactory. I do not suppose that an extra 10ft. or 20ft. would make any appreciable difference in the distinctness of sound or articulations.

-W: L.

[5858.]-GLASS BURNING.-If "Kemp" has succeeded in constructing a kiln from the directions given at p. 476, 4823, Vol. XI., will he kindly give a rough working diagram of it? I much prefer the operation of a dity is too great to conquer this description. I am already much indebted to Mr. D. F. Ashton, but I ventured to make a final appeal to him in my letter, p. 64. let. 513, Vol. XII., but without success. All the difficulties therein mentioned no longer present themselves, save the brick furnace. Will Kemp" or some brother reader help me in this, and also tell me what fuel is best, and where the earthen-pan is to be obtained? I have [5874.]-CHARCOAL.-Would some of your readers burnt some enamelled glass in a crucible in quicklime kindly inform me the best method of extinguishing to try the colours, and have succeeded perfectly in pre-wood charcoal from the retorts to prevent it igniting paring them. All I now want is to construct an earthen without renewed fire? Also the way it is ground for kiln to vitrify the pigments on the window glass. I urge foundry purposes; end if any danger connected with the the motto at the head of my instructions on "Dissolving grinding, what means taken to prevent it? InformaView Painting," and as I am at all times ready to lend ation on this subject would much oblige.-JUVENILE helping hand to the best of my ability, I do hope some CHEMIST. one will do the like by-SABLE.

(5859.)-COIL-TO "INDUCTORIUM."-May I be allowed to ask "Inductorium" a question with respect to his coil, given August 5th, p. 472, for which we are

body" inform me how to spring a lever watch in the easiest manner?-LEARNER.

[5876.]-INTENSITY COIL.-Can any one inform me of back numbers containing information of an easy method of making a small coil, say for 4 half-pint Smee's batteries; also cost of materials for the same, and oblige-BEN. G.

[5877.]-COLOURED LETTERS.-Can any reader tell me how the colours are mixed for painting large block letters in colours, so that when rubbed with size they will not run as when painted with water colour? I want red and blue for large texts.-M. DUFFY. [5878.]-BOOK-BINDING.-How is the sewing part of binding done; how are the numbers of a book threaded together; are there two threads worked at the one time ?-M. DUFFY.

[5893.]-FASTENING MARBLE SLAB.-Will some
one tell me the best and the most permanent way of
fastening a marble slab nside the pedestal of a monu-
ment, and if in. slabs are thinner than those usually
employee ?-A COUNTRY MASON.

[5894.]-FREEZING APPARATUS.-A machine, of
French invention, makes ice by the re-condensation of
ether, first evaporated by a small fire. The ether flies
alternately from one to the other of two sealed vessels,
and suffers no loss while the vessels remain tight. Is
there an English maker of this apparatus ?—G. F. O.
tell me of a blue dyeing material, aniline or other
[5895.]-BLUE DYE.-Can any fellow reader kindly
wise, that may be used in a slightly alkaline solution? Is
there not an alkaline blue known by the name cyanine?

[5879.]-WATER POWER.-I have a supply of water through a fin. pipe, with a head of 800ft. supplied to my-BLUE DYE. door with a 3in main; what power could I obtain from this, andwhat is the best means of applying it, a turbine or awater wheel. ?—Aqua. [5880.]-MAGIC-LANTERN AS A PHOTOGRAPHIC ENLARGING APPARATUS. - Is this practicable? With my lantern lenses, by fixing them in a dark box, and placing the negatives two or three inches in front, I can get a much enlarged image on the ground glass at a distance of about 2ft., but it is not clear and sharp; and if a strong light shines through the negative, the picture is all the colours of the rainbow. Will some one be good enough to say whether the magic-lantern lenses can be used for this purpose; and, if so, how can I remedy my defects ?-CAMERA.

[5881.]-CHLORATE OF POTASH.-Will any of your correspondents who have had practical experience in the manufacture of KO CIOs, kindly give an account of the process, describing the plant required for making, say two tons weekly, and relative quantities of raw material required, viz., CaO MnOg, and KC1?-R. H. D. [5882.]-BLACK BRONZE.-Will any reader of the MECHANIC be so good as give me a recipe for bronzing brass articles black, and how to apply it ?-GALA.

one ac

[5883.]-COTTON SPINNING.-Will some quainted with cotton spinning give a good recipe for varnishing top leather rollers, one that would last moderately and work smooth, so that the fibres of cotton in passing through the rollers will not take up so much ?-CARLTON.

[5884.]-EXAMINATIONS FOR SURGEONS.-Will any obliging reader answer the following: What are the subjects for the preliminary examination for a surgeon? -YOUNG MAN.

B

[5885.]-CISTERN.-If the cistern A, B, C, D. 12ft. deep, be kept constantly filled with water, and two pipes, E e, and Ff, of the same diameter, be fixed in the bottom of the cistern, so that the top of the pipe, E, e, will stand 2ft. above the bottom of the cistern, and the top of the pipe, Ff, will stand 8ft. above the bottom of the cistern, which of the pipes, E e or FJ, will discharge the greatest quantity of water in a given time at the common level, e, ƒ?—Q.

D

[5886.]-VICE BENCH.-Would you allow me to ask "J. K. P.," through the medium of the ENGLISH MECHANIC, if he would be kind enough to send a drawing of a vice bench (one that can be made by an amateur) of wood if possible ?-H. E.

[5887.]-ELECTRICAL QUERIES. THE SULPHATE OF MERCURY CELL.-1. If I heat 1lb. of mercury and 31b. of sulphuric acid in an evaporating dish how much of the sulphate will it make, and what temperature is required? 2. If I connect the wires of a sulphate of mercury cell, and let it work to exhaustion, would the whole of the mercury that was contained in the sulphate be deposited at the bottom, and what becomes of the sulphate of zinc (I suppose it is) from the zinc plate? 3. Can I re-form the mercury into the sulphate again without much trouble by the process in my first query, and if so I suppose I should have my battery kept working as cheaply as any form of battery, notwithstanding the expensive nature of the materials at the onset?-COLONEL B.

[5888.]-HARMONIUM STOP ACTION.- Will our kind and valuable friend "Adept " do me the favour of informing me of the simplest and most effective stop action for an ordinary harmonium of two and a half rows of reeds; also the mechanism required for a grand jeu at knee or for stop.-EVERETT.

[5889.]-BOLOGNA SAUSAGES.-How can I make the colouring for staining the skins of Bologna sausages a good red ?-MIMIMUS.

[5890.]-MANDREL FOR WATCHWORK.-I shall be obliged if any of your correspondents would kindly give a description, and, if possible, a sketch of the best description of Swiss or English mandrel for watch work, with slide rest.-T. E. FREEMAN.

[5891.]-VENUS AND THE SUN.-Will "F.R.A.S." kindly inform me how near he or any other observer has seen Venus to the sun's disc, especially if within the corona-of course I do not mean during her transit; also if the illuminated disc of the planet was darker or brighter than the background against which she was projected; and if the planet was darker, if he can suggest the probable cause of the superior brightness of the background? I would also ask if that portion of the planet's disc which is not illuminated by the direct rays of the sun becomes visible when she is very near this dise? My reason for troubling "F.R.A.S." for these questions is, that I think his replies may enable me to conceive a probable cause for the zodiacal light.

IGNORAMUS.

[5892.]-SOLAR LAMP.-Perhaps you or some of the readers of your journal will be able to give me a clear pefinition of a solar lamp, and also of a solar argand lamp. I have a large powerful magic lantern for which I want to procure a good bright light. I have heard of the above-mentioned lamps, but do not know what they are like, and cannot obtain any information concerning them in the place where I am now living. I should therefore be very much obliged to you or any of the readers of your paper for any information on the subject. I am, and have been for some time, a constant reader of the ENGLISH MECHANIC.-G. B.

fellow reader, practically acquainted with the subject,
[5896.] ELECTROTYPING.— Will some obliging
give me the details of commercial electrotyping; the
batteries mostly used; the best solution; and the method
of taking the cast of the wood block? I know all about
the subject experimentally, but it is a marvel to me how
it is done at the price, and in so short a time.-R. N.
four cells of the above at a half mile resistance. I have
[5897.]-MANGANESE BATTERY.-I want to work
only 40 yards of No. 16 wire in use. Would Mr. Tonkes
wire placed in the circuit will give the effect ?-SAMUEL
be kind enough to say what size and quantity of small
LEXICON.

RINGING.-Will some one be kind enough to say what
[5898.]-COTTON COVERED WIRE FOR BELL
is the right size leading wire to use with four manganese
cells; also where it can be obtained in London ?-S. L.
[5899.]-CARBON PLATES.-Who are the makers of
them? I know many dealers, but that is not what I want.
S. L.
I shall be glad if some one will give the information.-

[5900.]-ATMOSPHERE.-Will any of your scientific
contributors be kind enough to state what reason there
lines in the spectrum do not exist as dust or vapour in
is to suppose that the substances which cause the dark
our atmosphere. Humboldt thought that there were
pected.-M. P.
more substances flotsam in the sea of air than we sus-

[5901.]-MEDALLET.-I have a medallet, or token,
with the inscription "The Haughty Queen humbled by
give me any information respecting it?-S. J. H.
the King of Prussia," 1757. Can any of your readers
[5902.]
initiated in the matter of turbine water-wheels, tell me
- TURBINE. - Can any of the courteous,
what amount of fall a 24in. column of water must have
to drive a 6in. centre lathe? Also, how much a 2in.
column to do the same ?-C. F. BAILEY.

[5903.]-SULPHATE OF MERCURY CELL. - In
working a telegraph by this battery, should the cells be
arranged for quantity or intensity; and what difference
does it make in the deflexion of a magnetic needle; and
is pure zinc necessary for the positive, or will that sold
at the metal shops at 4d. per lb. do, and answer as well?

-W. C. C.

[5904.]-MECHANICAL MOVEMENTS.-Would any kind subscriber say whether C. Parson's patent, described in the "Mechanical Movements," No. 194, p. 365, Vol. XI. ENGLISH MECHANIC, is expired or not?-EKLOM.

STEPANFETCHIT.

[5913.]-MICROSCOPIC.-Will some corresponder Inform me of the proper diameter of lin. in., and fin should be set to form a compound objective for the mi focus achromatic lens; also, the right distance ther croscope?-GOLDSMITH.

chemical correspondents inform me of a delicate text
[5914.] TESTING WATER. - Could one of your
CLARETTE.
for vegetable matter in well or river water ?-Sr.

[5915.]-ARTIFICIAL IVORY.-Could any one tell me how to make some kind of artificial ivory for harmonium keys ?-IVORY.

USEFUL AND SCIENTIFIC NOTES.

SEWING MACHINE CONTESTS.-At the Workmen' International Exhibition, lately brought to a close at th Agricultural Hall, nearly fifty sewing machines wer exhibited, noticeable for invention, improvement, some for strict imitation of Howe's, Wheeler & Wilson's of George-street, Blackfriar's-road, London. 5. Second awarded as follows:-1. First Class: H. Cyrus Symons Singer's, and Thomas's machines. The prizes wez: class: Messrs. Judkins and Edward Ward, London: Arthur J. Maxfield, Birmingham; Wm. Taylor, Great Driffield; Westmoreland Brothers, Nottingham. chine, advertised as the "A. B. C.," Machine, " nings, for imitations of the new "Singer" Family Ma Third Class: Messrs. John A. Blacklock; George Jer latest American Wonder;" A. Clegg, of Finsbury, fe the Elliptic Hook Machine; John Asten, Colchester; J. W. Connor, Maidstone.

A NEW GUN.-There is in the course of erection, is the east side of New York Bay, a gun that will throw 800 five ounce balls in one minute, to a distance of abor two miles. The shot may be either red-hot or cold. The gun is circular, and appears like two discs of heavy ire plate, about 4ft. in diameter. Upon one side is a fanzel to convey the balls through to the proper chambe without cessation of firing or diminution of speed. Thi muzzle projects upon the periphery of the circular ma chine, and may be elevated or depressed at the will e guns may be worked by steam power or manual labour the gunner, by the trunnion upon which it rotates. The if by the former, it will throw from five ounce balls eight-pound shot and shell, thus making it a destructive implement of warfare.

UNNOTICED QUERIES.

IN future, if any query remains unanswered for four weeks, we shall insert the number and subject of the query in this list, where it will remain for two weeks, if not previously replied to. We trust our readers wi look over the list, and send what information they can for the benefit of their fellow-contributors.

Since our last "Eklom" has answered 5003; "Wire." 5087;," Muzzle-loader," 5086; "An Engraver," 36 "Sergius" 5233.

5240 Refrigeration, p. 119.
5244

if for distance of hammer-stroke two-fifteenths and a
[5905.]-MUSICAL STRINGS.-I should like to know
minute fraction is the true maximum, and whether one-
fifteenth is the true minimum, the mean being one-tenth
of the distance from the end, or equal to 36 degrees, and
an imperceptible fraction of the circle, of which the
length of string is equal to the circumference?-5251
THE PRECIPITATING PROCESS.-Can any reader
[5906.]-COPPER EXTRACTION FROM ORES BY
give details, cost, results, and general modus operandi of
this process? I have heard that ores containing only
one-eighth per cent. of metallic copper can be treated
information with a view to practically carrying out. I
with profit upon this system, and should be glad of
believe the process is largely developed at Alderley
Edge, in Cheshire; and think, if thoroughly explained,
it would meet the wants of many having to deal with
copper ores of low quality.-H. W. E.

estate-plans, &c., &c., to colour, and am desirous of
[5907.]-LIQUID BLUE.-I have a great number of
obtaining a good liquid blue that will mix freely with
gamboge, and form a good green if required. When
serving my time with an architect and surveyor, I used
a liquid blue that answered well. It was as thin as
water-quite transparent-but if left exposed to the
air, became sticky. It mixed freely with any other
water-colours. I believe this colour was, at the time I
used it, something like twenty years old. I cannot now
cellent journal in hopes that some of your numerous
obtain the recipe for making it, so apply to your ex-
make liquid blue or any other colour.-WAter-Colour.
scientific readers can give me some information how to

[5908.]-THERMOMETER.-Will any of your corre-
spondents kindly inform me the cause of the following
entirely lost its colour; to such an extent, indeed, that
fact? The spirit in one of my thermometers has almost
it is as nearly as possible invisible in the bore of the in-
strument. The instrument is fully exposed out of doors
for this.-F. G. S.
winter and summer. Of course there is no visible cause

[5909.]-STEREOTYPING.-Would "Leeds" or any
other subscriber (Nos. 4742, 4784) kindly say how the
casting is accomplished; and, if a casting-boxj is ne-
cessary, describe it? I can succeed with the flong, but
when the metal is poured on it does not penetrate to
the bottom of the mould, and an imperfect casting is

the result.-PATER.

kindly inform me what the lithographic varnish is used
[5910.]-LITHOGRAPHY.-Will some brother reader
for? I can succeed in transferring to the stone, but
after six or eight impressions the work runs smutty.
A few simple directions will much oblige.-PATER.
[5911.]-TORCHES.-Will some one kindly oblige me
(and doubtless many others) by writing how torches are
made, such as are used when skating by night? I want
to get ready for the season.-METER.

[5912.]-TO MILLERS.-Can any reader throw any
light on the new process of manufacturing four without
millstones?-SERGIUS.

5246

5247

Mounting Buterflies' Tongues, 119.
Copying Paper, 119.
Dissolving Ivory, 119.

5248

The Ripening of Pears, 119.

5249

Pattern on Linen, 119.
Varnish for Clay Pipes, 119.

Brewer's Truck, 119.
Heating by Hot Air, 119.

5258

Wire Drawing, 119.

5262

Size and Power of Boiler, 119.

5269

The Manganese Battery, 120,

5270

Enlarging Photographs, 120.

5278

5282

Paper Foliage, 120.
Abyssinian Blue, 120.

5283

Verge Escapement, 120.

5285

Splitting Selenite, 120.

5290

Damaged Barometer, 120,

5292

Percussion Action for Barometer, 120.

5293

Cement for Leather, 120.

5298

Glue, 142.

5299

Large Induction Coil, 142.

5306 5304

Photo-Reliefs, 142.

Flexible Writing Slates, 142.

5307

Black Japan, 142.

5309

Carriage Painting, 143.

5811

Shrinkage of Type from overheating in Stere

typing, 142.

5313

Power of Engine, 143.

5319

Chemical and Brewing, 143.

5321

Dressing Millstones with Diamond or "Bort," 1

5324

Removing Paiut and Tar, 148.

5335

Soldering Brass Tubes, 143.

5937

Filtration, 143.

Silvering Specula, 143.
Ulverston Pig Iron, 143.

Dry Colours, 143.

5342
5340
5343

5344

Silvering Process, 143.
5848 The Phantom Wheel, 143.
5354 Club Wheat, 143.
5354 Mineral India-rubber, 143.
5359

5460

Teeth of Wheels, 143.
Engineering Establishments, 143.
Self-acting Inclined Planes, 143.

5362

5361
Inclined Planes. To the Bev. E. Kernan, 144
5369 Instantaneous Photography, 141.

5370

Hot-air v. Steam-engines, 144.

5374

Counterpoint, 144.

5379

Wine in a Glass, 144.