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[1831.]—MOTION "F WA.TEU.-Thu amount of water passing through a 9* pipe 12ft long, 1ft. hcail, is 1(15,877 gallons per hour* — Maty.

[1831.]—MOTION OF WATER,—I think that " A Subscriber from the First." will iiutl the following table useful to him, which shows tho velocity per second, due to different heights or heads :—

Height—Feet Velocity—Feet.

1 8.

2 11-314

3 13 85,6

4 16

5 17-8S9

8 lU5uit

7 21 llili

8 22-017

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lo 25298

Tho height being 1ft., the velocity through his pipe will be 8ft. per second ; therefore when the pipe is9in. In diameter, nrea being 83-flin., the discharge per second will be 6107-25 cubio inches.—Striboh.

[1859.]—MATCH MAKING.—Mr. Ch. Mertons, at Lessines (Belgium), patented three months ago in that country, his lately invented dipping machine for matchmaking— Raihond Staeb.

[1805.] — WHITE METAL BEARINGS. — When the chair is cast, have it hollowed so that it will hold the metal, fasten the chair in its place, put In the spindle packed up, put somo clay round the spindle to keep the metal from running out, pour to the centre of Bpindlo, cut off any projecting metal, lay some strips of cardboard on each side of the spindle, put on the top part of chair clay round the spindle as before, and pour through oil hole. This mode requires neither fitting nor boring. I have seen lead used alone, and wear very well.—Milly.

[1887.]—PUTTY.— Let " Hurtus" got about 201b. of whiting, and pound it up line, then add enough raw linseed oil to make It iuto a stiff uniform dough. I found it took three pintH, and that was not quite enough. Then hammer it well out, as thin as it will HO, and work It well till it comes soft enough. I was told that one pint of oil wns sufficient for 151b. whiting, but found three pints hardly enough. This is the best and cheapest putty. He had better add the oil as he wants It—not all at once, and warm the putty before a Are—Augustus.

[1889.]-BELGIAN AND FRENCH PERIODICALS.—No journal similar to our ENOLisn MeChanic is published In Belgium or France. In no one, such variety of instructive matter is to be found, as they respectively and for the mist relate to Borne special branch of science. If my fellow correspondent "Argente " will communicate with me through our Mechanic what subject he more especially preters, or what branch of science, mechanics, or technology, he wishes to be Informed on, I shall be glad if 1 can to answer his demand—Raimond Staes.

[1894] -CHINA GRASS DIVISA.-I have also been puzzled by tba; name, and never could get any conclusive Information about the plant; the following article appeared in several French reviews :— "Dr. Grothe, director of the manufacture of Kammelsberg. near Berlin, employs with great success, for making figured stuffs, much in demand for England, yam of China grass, white or dyed in different colours. He produces the China yrnss dieisa {sic) in a plantation he planted, and which yields 60 per cent, dry fibre, and 30 per cent, long and very line filaments. In the mountainous regions where the soil and the severe temperature form a serious obstacle to cultivation of flax, the Urticacea; in genera], and the China glass in particular, resist perfectly. (?) The 1'russian Alining Office Ids taken into serious consideration a culture which feems tofui ulsh an accessory and very precious resource to the miners oi the Harz and of Hanover." I made several inquiries, but always failed. I even wrote to Dr. Grothe, but did not receive any answer. If later 1 learn anything, I will communicate it to our English Mechanic 1 supposed also thnt divisa might he a fault of impression for dioiea, or for diversa, different kind.—Behnabdin.

[1895.]-C0WR1E COINS.—The following letter from Lord Alfred Churchill, to tho Secretary of State for the Colonics, which I extract from the " Technologist, of July, 1805, deals with this subject:—" The Council of the African Aid Society have had nnder their consideration the necessity and advantage of finding somo metallic substitute for the cowries, hitherto in uso among the natives. A currency ought to be adapted to all the wants nnd habits of the people for whose use it is intended. Cowries, as a circulating medium, have been for a long time In use in the countries of the Bight of Benin and the Niger territories. Since the annexation of Lagos to the British crown, all the English coins have been introduced there. They arc coming Into ufo among the natives, but do not suffice for the general wants of that portion of the community. The loweBt English coin In circulation is the farthing. The value of this is 30 cowries, but a great manv articles of daily consumption are purchased much below that price. Unless, therefore, some smaller coin be Introduced, cowries cannot he abolished or replaced as a clrculatingmedium. In the interests of progress and civilization, of which Lagos is an outpost, It is desirable that tho currency should be solely metallic. The Council of the African Aid Society have had an opportunity of seeing the small coins—one mil each—now being struck at Her Majesty's mint In Loudon, for Hong Kong Those coins being each one-twenticlh of a penny, or one-fifth of a farthing, would be the vnluc of six cowries. As nothing worthy of mention can be bought for a lower sum than six cowrie", those coiuB would respond to all the minor wants of the native Africans, while their being perforated, so ns to enable them to be strung as cowries are now Btruug, would render them equally safe and convenient as cowries, while they would not be more than one-seventh of the average weight of the smallest cowries used in the interior trade. The Council of the African Aid Society beg leave, therefore, to suggest to Her Majesty's Government that it would be advisable, and of general advantage, to introduce perforated coius of a similar size and value, in the I

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currency of Lagos, Cape Coast, Ac. The Council also beg leave to suggest that the perforation, in a similar maun. r. of other cuius iuiendod for circulation iu native Western Africa, would tend greatly to facilitate their nsu aud favour among the people." I send a sketch of the "mil" above mentioned; this may, perhaps, Interest soma reader. White cowries (cypiasa moneta), are extensively Imported in Western Africa from India; Hamburg firms, established at Zanzibar, send away blue cowries, whichseem to yield a great profit. A hole is made in the shells, and they are strung on threads of rulm fibre ; 40 shells = 1 string. Many merchants in Lagos occupy eight or ten girls stringing cowries. 2000 blue African cowries weigh 80 or 901b., the white Indian ones 35 to 401b.; 200t> = about it dollar.—Bernardin.

[1898.]—EQUATION-In the last number of your paper, page 640, C. II. W. Biggs announces his Intention " In a short time to commence" his " Notes on Algebra." Permit me to express a hope that "C. H. W. Biggs will first master the question before undertaking to teach others, otherwise those readers of the English Mechanic who put their trust in his "Notes," will be in danger of falling into errors, as, for example, that the square of — s/5a; + 10 Is — 5x - 10; or that

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See reply by C. H. W. Biggs to ri896] Equation, page 615. The reply by "Hugo" to same Equation, same page Is quite correct. -senior Op.

;i89fl.]—EQUATION.—If Mr. Biggs will consult Wood's Algebra, he will find ln;the chapter upon Quadratic Equation, page 118, tbe equation fully discussed In Its unaltered form: x + Jbx + 10 = 8.—H. C. C.

[1910.]—TURKEY STONE.—I cut a lump of turkey stone Into twelve oil stones when I was an apprentice, partly with a sheet of copper, and partly with a sheet of load, of course (IttPd to wood frame for convenience, in both cases with sand and water, but I cannot remember which cut it quickest.—Jack Plane.

[19l3.]-GAS BURNERS to burn common coal gas are not of much use to Illuminate dissolving view apparatus. I have tried several, including a 60-hole argand, but always found camphorated colza oil more effective. My experience led me to adopt the improved oxyhydrogen burner when I want more light than oil will give ; the apparatus is very simple and quite safe. —C. Ward.

[1929.]—LACQUERING—In answer to "Inquirer,"

1 beg to send him tbe following method for lacquering brass-work. If he is going to proceed on old wotk he must first boil tbe articles in strong soda ami water, Bo as to get off the dirt and old lacquer; then scrub them with sand and rinse them. The next process Is the dipping, for which bo will require an earthenwaro pan capable of holding the articles, which he must fill with aquafortis, which he can obtain at any chemist's;

2 pails of clean water and a box of sawdust. If be has any means of keeping tbe sawdust hot all the better, and a nice clean brush. Now he will have to proceed as follows :—Tie the articles on copper wire, dip them in the acid, then rinse In the wster and well rub them la the sawdust till thoroughly dry, and then brush the sawdust off. If there are any parts that want relieving this must he done with a bright steel burnisher and a drop of stale beer, then the articles arc ready for lacquering ; but If the articles have tarnished, to restore their brightness he must dip them again, but he must dilute the acid with ten times its weight of water, rinse and dry as before. Now tor lacquering them he wHl want something to beat them on; a plate of iron with a gas-burner under it will db; but If he has an oven that will do as well. If he wants that red gold tint on his articles. It is best to get French gold lacquer and mix a drop of red lacquer with it; he must heat the articles so that he can just bear the hand on them, and then with n soft camel-hair brush lay the lacquer lightly on, care being taken not to lay it on too thick or to get the articles too hot. If there 1b anything else that" Inquirer" wants to know, 1 shall be happy to inform him.— W. Ssabrook.

[1931.]—LINCOLNSHIRE IRON.-I beg to inform "R. W. M," thnt the ironstone of this district contains In Its raw state from 30 to ."5 per cent, of iron of a very good quality. The average price for the ore in wnggons at the mines is from 4s. 9d. to 5s. 3d. per ton* and 5s. 3d. to 5s. 9d. per ton delivered at the nearest wharf. Should " R. W. M." require further Information, I 6hall be glad to help him.—Blast Furnace Engineer, Frodlnghnm.

[1934.]—LOGARITHMS. - To "Y. P. W."— Chambers' "Tables of Logarithms," contains seven figure Ubles.of logs., log. slues, cosines, Ac, and natural siiies and cosines, with a heap of other information; proper title "Mathematical Tables," gives a few' examples at commeiiomeut to explain the tables, has no treatise. Can be had anywhere for 3s.—Maty.

[1054.J-CEMENT FOR PARAFFIN LAMP-Let "Noodle" get twopennyworth of shellac and melt It by the firoin a tin cup, to which he may add a small drop of water.to keep the shellac from burning. Whea melted he then may fill the brass socket aud slick in his reservoir; he will fiud ho has a good job.—Ling Fl9H.

[l'J(il.]-CAT!PENTERS' PRICES.-I have put up fencing of four railings and one stake post: have morticed the post aud pointed ttio railing* for Gd. iter length, but thoy were lort. long, that however is immaterial. The posts and rails had to be put up. but if put up at per chain it would make a considerable difteronce ; they were laid out ou the work ready lor use gratis.- Usleakmd Platelayer.

[1904,]—CARPENTERS* PRICES.—Posts, 12s. per 100 for mortising; Id. per pane of 4 mils for chopping

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From (7) and (8) by transposing and dividing-,
o - c a' + &» - <■ (a + 6) - (6 — c) *

e - b a* + c* - b (a + c) - (o - b) z'

whence, by multiplying up and reducing,

z(o5 + 6' + C-ao-tc-cao = a3+o>- <?J — 2 n'

c + 2a<l>-2b>c + 2bc'>-Abc

whence dividing each side by the co-effir/ene of » ft will be found that z = a + b - e. I should be g.'.d' to see a neater solution from some abler pen than mine —Sesiob Op.

CIMO.]-MOULDING MACHINE—If "Jonath" would visit any of tho undermentioned plices ho would see moulding machines at work. To *s one for half an hour will give him more knowledge iiVn..a "R1,*..10 hi» query. Houldwortu'B, QtittvliirlSuM T01?hs'S; Howard's, Bedford; fVwry' Enfield Lock; Royal Arsenal, Woolwich. It dm places are inaccessible to him, I shall be happy to afford him full details in the English Mechanic.

T^i.9?0.1.- 7ARNISH FOR IRON PATTERNS. The following is WUat I have seen used with success In several foundries In Glasgow; It is better than Deeswax :—When tho pattern comes from the finishing shop smear It all over with oil rubbed on with a bit ^ iWa-MCi p"Ut in tbe drying stove all night, so as the oil will burn in; if not in a hurry for tbe pattern repeat the dose. I can recommend this, having seen It done and having dono it myself pretty often.—N. L. „ t19TM-]—MQUID GMJE.-I have mads a strongliquid glue by treating Russian glue with a littlestrong acetic acid; add a small quantity to tbe powdered glue, cork tight, aud let It stand for some hours; you will find It soften; by adding more acid you can make it of the consistency you require it. A common recipe for ordinary liquid glue, and which I nave used, consists of 8oz. best glue, dissolve iu Jpt. water, add 2,oz. nitric acid; cork up tight.-J. Chebry.

[1981 ]-ENAMEL.-If Mr. Walker will try tbe following, I think he will find one or both answer his purpose :-No. 1. Oxide of tin 8, flint 3, b. rax I. No. i. Oxide of zinc 2, Cornish stone 8, whltlajrl.-forA. [19850-SIDE LEVER ENGINE— I bee to Inform

SulTold Amateur" that the aide lew engine was that which used to be almost entirely »*d for marine purposes. I think it was Invented by J«mes Watt, but I do not know if he patented it. The principle otttds engine Is similar to a beam engine, only the beams are down at the sides (of the engine,) sua tne>' are connected with the piston by means of a cross head and connecting rods. The other end of the beams or side levers is connected with the crank. The advantage of this kind of engine is that all the moving parts ar» balanced by each other. Tbe connecting rod from the beam to tbe crank Is very long, therefore motion is transmitted to the crank very equally aud with very little strain. The heaviest parts of the engine are brought very low down in the boat Tiio disadvantages are that It occupies a very large space, it is very heavy, very costly, and not applicable to screw bouts. —H. Chapman.

[1087.]—WHAT 18 IT?-It if B pedometer for counting the number of steps In walking, not mush Id use now. Time tells the distance travelled over, tor the walking rate Is nearly uniform forencb Individual, and is soon ascertained by counting a few mile stones ouce or twice.—H. W. Reveley, Reading.

ri«87.}—WHAT IS IT?—1 believe the instrument "Querist" has rot hold of Is a pedometer, which is worn in tbe waistcoat or other pocket, and measures, the distance walked. Each step taken causing a vibration of the weight, which acts In one of the toothed wheels.—Iota.

[1989.]—NUMBERING BOOKS. — A bookbinder would stamp the books In gold for a very small charge, or the numbers might be painted on the backs in oil colours, black figures on a white ground.—Iota.

[19S9.]-NUMBERrNG BOOKS.—Gum tbe Lack oi your paper, write your title numbers, Ac, in good ttw, but blot immediately with blotting paper; afew hour* after size with common size or gluo water, let this thoroughly dry. nnd then varnish with pale copal, cut up, and stick on in the ordinary manner. Of course wo suppose a sheet or a few sheets to be rone at the same time to be worth this amount of trouble, but when dono this mny be termed everlasting—S. T.

[1990.]—METALLURGY. — Tho most recent and complete work ou this subject is that by Dr. Percy. It is published by J. Murray, price 21s.—Bf.ta.

[19«1 ]—CANVAS CANOE.— I would persuade our friend against milking his eanoe of canvas on ribs; it is impossible to obtain good lines, or in 1«» technical words, no curve cau be obtained; tho outline boat would consist of straight lines as nearly approaching tho curves necessary as is posilile in lessening the distance of the point of attachment to the frame, but the result is in the highest degree unsatisfactory.—S. T.

[1901.]—CANVAS CANOE.—After laying down tbo keel and fixing stem and stern-post, let " S. F." make

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[4005. l-RAZORPA3TE.-Crocusandtallow,mixed with pestle and mortar. Obtain ut a watchmaker s tool warehouse— S. T.

[10050-RAZOK PASTE.-In reply to •• Dundreary r can safely recommend the following :-Reduce emery t, an impalpable powder, and sift through Hue gauze io catch any large particle; mix the powder with a. much spermaceti ointment as will form a thick paste, audlay on the strap— Gitcue M Anito.

[2005.T-PASTE FOR RAZOR STROPS is thus made :-Oxide of tin, levigated loz.. saturated solution of oxalic acid sufficient to form a paste. 1 his composition is to be rubbed over the strop, and when dr> a little wnter may be added Oxalic acid having a great affluitv for Iron, a little friction with the above pow dcr will give a fine edge to any raior.— 1 Autau.

r200fil-TO CLEAN STEEL ORNAMENTS. "Young Wife" may clean them by rubbing them over with some fine emery and oil to go. off the rust mid then removing allthe traces of oil and emery. rub them with a clean brush with some crocus ami w»«w; lastly, polish off with a little dry crocus-thls irfflTitaj.thMB if they arc not very rusty •, but If they arc it will be impossible to do anything with them.—A. A. A. [4007.1 -TEMPERING DRILLS.-IIeat your drill oa.lull red, allow It to cool slowly then rub thy

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Let Rand S Jc

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"r on a\rSt'orweY grindstone; now lav the point i vour drill on a lump of Iron previously heated red h-. and the moment your drill has attainedth«! colour W,m require, dip and stir it in cold water (or oil, If a .mall tool). The gradations of temper iire -mild, blue, hard, dark straw, very hard, pale straw.-S. T

[2007 1- TEMPERING DRILLS-Heat the drill II li^ no from the point until it become, blood-red; nen dip it in water about an inch, hold It to the light, and you will see a blue tint, which gradually descends, and vXnit 1. about l-16th of the point slack it

VJIL L F R E W

ram.!- Con Tents Of Iron Pans.-to find

the o7b c content, of iron pans with circular or rather spherical bottoms, you must ealculuto the body ot the pan and the bX/dUtinctly. The body of the pan fs a evlinder ■ to measure It multiply the square of the dUmUerby-rsM.and the product will be ho area ol fee bsse; multiply the area of the ba» bythe.height nnd the product will be the solidity. If the bottom is nTf of aP»phere, multiply the cube of Ito *£%«[.£ <MM and divide by 2 ; the quotient w 1 ^tl.e.olidi > If the bottom is the segment of a sphere to I times no smmrc of the radius of the base of the segment RddX«uarc of It. height; multiply the sum by the Se gh ana the product by -SUM for lb<■ .olbdlty , add the solidity of the cylinder to that ol the bottom for

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tlie total contents. If the measurements .re takeu »nd calculated In iuches. divide by 277-474 (cubic inches in 1 gall.); the quotient will be the

contents in galls. If in feet.

multiply byOJJcubicg.Us. in

lft. nearly), the product will

be also galls. Example—

A circular pan 14ft. diameter, height of body 8ft..

height of the bottom, being a segment of a sphere, 4ft,

J2 X 12 X Wrt x 0 = 678-58Wft.

0x6x3(+4)x2x -5530 = 1174864

Cubic contents in feet .

in gals ..

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Do. da Mii.es Jennings

[2003.]—WHEEL CU ITING.—In answer to " Burslem," special machinery seems Indispensable for a speclsl job, and it is absurd to rig up au apparatus for a few wheel, whon you can get them cut for you for a trifle. What you must have for the purpose is a division plate, containing all the numbers you want, and a cutter framo to carry the cutter, on a vertical spindle. I have seen patterns cut, or rather plaued out of white metal In a lathe by means of a single point tool of proper form held horizontally—J. K. P.

[20121—MULTITUBULAR BOILER.—The way in which the tubes are fixed Into multitubular boilers. Is a. follows:— They arc put loosely in first, and whilst in their place a conical plug of steel is driven into the ends so as to open them a little, nnd so fasten them into the tube olaUs. If they arc not perfectly watertight they have to be caulked a llttlo to make them Bo, —H. Chapman.

[4041.]— MAGIC LANTERN— Inanswerto"George," I would say he will get as much practical information on the construction of magic lanterns In the back numbers of tho English Mechanic (Vol. VI., paues 3'J.">, 444,441, &c, &c.l as any work on the subject that I know of. A. to J-plato photograph lens being suitable for a magic lantern, I know by experience that thcro is no lens more so If a long range Is required with a4lln. condenser. The lantern requires to be 45ft. dl.tnnt to cover an 18ft. screen, and will give a clear nnd distinct picture with oxy-hydrogen light. A }-plate lens will give the same siic picture at about 28ft. distant. Condensers for magic lanterns are of various forms.No. 1 plano-convex, No. 4 plano-convex and double convex, No. 3 two planoconvex, which I think gives the best results. No. 1 being only used for the common construction of lanterns. Distnncc between condenser nnd front lens is &4ia Condensing lenses may be had mounted almost from nny optician. The price of'a4Siu. is £2 2s.; 3}in., 18s.-J. V.. V., Edinburgh.

[4021]-MAGIC LANTERN—The price of double condensers 3Jin. brass cells is from 14s. to l<s. Any optician will supply them, but Cox, of 56 .Ludentuhill, or Pumplirys, of Hiimlngham, may be rolled on for quality and pTlae. I have seen a J-plato portrait lens used with good effect, but " Uucrnsoy " writes from personal experience, thereforewkh authority on the subject. "The Magic Lantern, aud How to Use

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i. done in klers of wood or iron heated by steam, ffhe 1st require, about 4 to Bcwt. of lime made iuto thick cream, aud freely .prlukled amongst the waste as it is thrown in the kicr. The washing requires plenty of water and is done in ordinary dash wheels. After being w.Bhed the waste Is Bteeped iu a solution ot muriatic acid In water (4 to 3 per cent, of acid) then drained and sweetened by placing under a shower bath using plenty of clean water. The 4nd bowking is done with soda ash, and takes from 3 to 5cwt. ol ash per ton of waste. The drying Is generally commenced In an hydro-extractor, nu.1 then finished in a stove or the open air. which is preferable. If «3° desires further information I shall be happy to give it to him.—Feu Follet

[2042 1—VENEERING.— Soak yonr glue until It rrelatiuises in old water, carefully boll In proper gluenot warm your veneer; all the rest depends on three points of detail- cleanliness, close contact of the Surfaces, and the expression of all excess of the glue -i.e as small a quantity really between the Burlaces o be united as Is prsctlcable.—B.T.

ftfrn ]-AM ALGAM—Kill some mercury with pure fin foil; when It has lost Its quickness apply with small quantity only of clean tallow.—8. T.

[40211-AMALGAM.-Mix your amalgam with as much lard as will mnko a thick paste and spread it on the cushions with a knife.-gitche Maxito.

[20*31—AMALGAM.—"T. O'Connor" will find tho following useful :-Melt together 3m. of tin, Sox. of ziuc an<f Ooz. of mercury; when cold, powder ana mix with 4oz. of lard, and lox of bees-wax.—Beta.

r*0Ul- MENDING GUTTA PERCIIA.- Doe. J i.a'u'd mean an india-rubber ball ?-lf Bo, wo can tell him how to repair it. A gutta percha ball soems to present no difficulty. A patch could be hua ed and put on, unless, indeed, the ball be very ok: then tho material will b! found perished, and very difficult to deal witb.-S. T.

f2020.]-PHYSIOGNOMY.-Lavoter [» the best authority. There are cheap aud dear edition, of his work.—Briefless Barrister.

[40*J]-STAMPING IN COLOURS.-Presses for this work mav be bought by auy one. and with practice any mav do it. A prepared gummy Ink is spread on a steel die in which the dovic- is sunk ; the surface is then wiped clean with the ball of the thumb, leaving the ink in the device. The paper to bo stamped is placed on the die and a leather " matrix is brought down on to it by moans of the press, and is by it forced iuto the cuts, the ink ndheriug to the paper forms a coloured Impression In relief. This process is caUed •' relief " .tamping.—Iota.

[2038.1—8US DIAL—" T. S. H." to ".Tuplter. — The hour angles for a horizontal suu-dial In latitude 5«°, beginning at the 14 o'clock line, and reckoning eastWuru and wostward. are U° 20-, 25° 15', S9° 14', 51°

45' 71° 50' 90° 'T S IT

[4012 i-CLERK OF WORKS.-A clerk of works is a man placed on the bulldiug by tho architect to watch the Interests of the proprietor. He must be "•<•''<»<:nuainted with all kinds of building materials and thofoiK'lily understand where and how each article ought to be used, whether wood, Iron, brick or st.mc, and has power to allow or reject anything he consider.not according to contract.-jack Plane.

[S0421-DUTIESOF CLERK OF WORKS—I think •• Aspiring Mason " will find the following the duties of a clerk of works :-He will have to look after the workmen, see the work is properly finished, point out to the nr.hitect any Improvements he may thinx nt, make up hi« weekly report, and send to tho architect, draw most of tile working drawings, and measure up nil extra win к; in fact, ho Is iiotlilncr more tlmn the superintendent of tho work In the absence of the architect.—Delta.

r2043.]-l>ILLS—" Wry Face" finds it a difflrull matter to take pills In the ordinary way. Nothing is better iliau an oyster; It is acapiinl thing to carry a pill m the stomach Usé it In this way :—Slit the thick part of a nitlre oyster and pur in the rill, thon swallow lhi> whole. Children who are fund of oysters, and who cannot be made to swallow pll «.may be Ihus effectually deceived. Another mode of taking offensive pllK or nauseous medicines. Is to prepare the mouth befiirohand by seme aromatic substance; for instance, chew a clove or a piece of orange peel or lemon p"el, or In lieu of this first put into the mouth в bit of alum,—Tautau.

[2043.]— PILLS— In reply to " Wry Face," there are several plans for rendering pills tasteless. Home of these plan« are patented, some not. The principle aimed at In all Is to cover the pill with a film which shall resist the action of the saliva during the short time that the pill is in tho mouth, but that shall bo removed in the stomach. This dim may be either metal, as gold or silver leaf, or a varnish composed of balsam of ti.lu, or some similar substauce dissolved in spirit, or a costing composed of mucilage of tragacantti and sugar. I have repeatedly been told that coated pills have passed through the whole length of the lutestlnal tube, and bsve been passed unaltered through the system Undi'r these circumstances I leave your correspondent to judge what good (hoy had done. A plan which I myself have found very efficacious Is to »crew each pill tightlv up in fine tissue paper or cigarette pnper, cutting oft* the superfluous material. Л similar plnn is adopted with balls for dogs and horses The English Mechanic Improves. and I am glad to see thoquotatiou from " Montaigne" restored to the head of the Correspondence columns. —arthur W. Blacklock, Newbridge, Hardgate, Aberdeen.

[2043.] — PILLS. — Flr«t see that your pills are thoroughly dried, then stick each wllh a pin ihe head of which is bent down like a pot-hook f ; now dip the pills one at a time in a strong solution of gum arable and hang on a string to dry In a warm place. ТЫ« will not only render the pills tnsieless, but prevent the deliquescence some kinds are subject to.—S. T. [2043.]—PILLS.—If "Wry Face " will apply to any chemi«, he will lind that his grievance can be remedied without much trouble or expense,—Beta.

[204«]-GYMNASTICS.-The following works are recommended:—" Gymnastics," by Chlosso, price is. ed., Walton and Mabcrley; " Course of Gymnastic Exercises." by Rolland, price Ss. Od., Oliver and Boyd; "Roth's Movements or Exercises," price Is. ; " Ling's Gymnastics," by Koth, price Ss. Od., Groombrldgí).— Beta.

[2049,]-LANTERN LENS.-A single plano-convex lens would do, but the result would not satisfy you. Jinny cheap lanterns are nearly useless on this acoount; go to a little more expense to purchase a double condenser, or if you have a good flint planoconvex, get an optician to adjust another to it. Write to Cox, of Ludgate-hlll, or any practical optician,— C. Ward.

[2I>49.]-LANTERN LENS.-If " Lime Light wishes to have good results from his magic lantern, I would recommend him to use the doublo combination 3|in. condenser.—J. E. V., Edinburgh.

[2053.]—BEECH.—Expose the wood to the presence of steam in a oovered vessel for a few hours, then withdraw it and allow it to dry slowly. It should be under pressure of some degree, even if not more than 1 or 21b. to the inch.—S. Т.

[206t.]-HYPOCHLORIC ACID.-Snch an acid has not yet beea discovered. The only oxygen acids of chlorine are:—Hypochloroui acid, HCIO; chlorous acid, HCIO,; chloric acid, НСЮ.; and perchloric acid, HCIO.,.—Ernest.

[20550-COI.V.—The piece, as per engraving, is a weight of the double crown of James 1st, There are others of various weights according to the denomination of the gold coin, the unit 22s.. the crown 0». 6d the thistle crown 4s. 4Jd., the half-crown 2s. fld. f have standard weights of all the above, as also those issued in 1018. The weights were issued by Royal proclamation from tho Royal mint, nrd the chief officers in all cities, boroughs, and town corporate of Englnnd nnd Wales were commanded to provide such weights nnd scales as provided by the master of the mint, and all persons were forbidden to have or use any other weights for the gold coins. Vide Kuding's " Annals of the Coinage," page 374.—D. T. Battt, '«, Feuntllstreet, Manchester.

с PPSJ-SO-IIT OR COUNTER.-In answer to Mr. Smith, the engraving represents a card counter I have a similar one in my possession, with Vs Vid Instead of XU. English coins were made of tin and copper, and now are of branze, but brats ones were never struck.—Henry W. Henprey, M.N.S., Marknam-house. Brighton.

Г2057.}—ZINC PLANT.—Form a feeble solution of acetate of lead, suspend in it a piece of zinc and some brass wires, the latter represent the branches of the tree.—Ernest.

[2057,]-ZINC PLANT.-"A Late Subscriber, E. 8." Is mistaken In supposing that it is merely water in the bottles in which zinc trees are made. It is a solution of acetate (sugar) of lead, in water that is used for that purpose. A piece of copper wlro Is attached to the enrk of the bottle long enough to reacli to the bottnm. und if you want branches to your tree put pieces of wire across, you tiually fasten a small lump of zinc on to the top part of the wire, take care that if. is im merscd In the solution, enrk up your bottle, ami in a few days your tree* will be complete.—Henut ChapMan.

[2 '49.]—AQUARIUM.—The great bugbear In armarium manufacture consists in haviug a rabbet for the glass iimtead of a groove, the former entailiug trouble and vexation without end. Take, then, a groove, and make the putty of red lead and copal varnish ; in a few days all is hard, sound, nnd insoluble The putty must bo used as made, as it sets very quickly.—S. T.

[2059.]-CEMENT FOR AQUARIUM.—I have kept fish of uiauy kiuds in my nquarium for years: it Is put together with red lead putty, common putty is useless. lied lead putty is red lead (in powder) worked up well with white lead (in oil) as stiff as it can be conveniently used; leave it a few days to harden.—Jack Plane.

[20C3.]-MEASUR1NGTIMBER,—Numerous works have been published on "Measuring Timber," but geuerally speaking one work is as good as another. Of course everyone will recommend his ownorthe one which he has been most accustomed to use. I have been for sometime in the timber trade, and Und that Aitkin's tables nro as good as anybody's. Cost I think 4s. 6d.—Gitche Manito.

[20ii3]-MEASUKING TIMBHR.-R. Livingstone should obtain "Hoppus's Measurer, "price about 2». It may be obtained at a second-handbook shop for considerably less.— Jonatii.

[W>(H.]"QUESTION ON LIGHT—Tho numbers of vibrations per second, of the mean rnys of the several colours of the sppctram are. in millions of millions —Red 49?. ornmre 528, yellow 529, greeu 081, blue 048, indigo 080, violet 72s.—Ernest.

[20«!.]-ZINC PLATE FOR BATTERY.-To amalgamate zinc plates, clean thoroughly with diluted muriatic acid; pour the mercury on, and spread It over wllh a brush; allow them to drip, aiid they will be ready for use. The best sheet zinc of the requisite thickness answers the purpose as well as any other kind-J. E. V., Edinburgh.

r20firt.]-ZINC PLATE FOR BATTERY.-Had "G. Deku" put in practice the slight knowledge he seems to be in possession of in regard te his query, he would have found the practical part of It so easily acquired as hardly to need troubling the Mechanic for information upon so simple a matter. The ordinary commerciïl sheet zinc will do, procurable from any metal warehouse. After scouring the plate clean in the acid solution with a piece ol rag or a brueh, pour upon It a little mercury, nnd by still continuing tbe rubbing " G. Deku " will find the meicury spread itself evenly over either side of the plate, making the amalgamation of the plate, if a matter of question, one of very little difficulty indeed.—H.

[2000.]—TO AMALGAMATE ZINC PLATE FOR BATTERY.—G. Deku can make the mercury flow over his plate by adding a little ef the pure acid and then rubbing ltovorwith a piece of tow or waste cotton, then well washing it In plenty of water. I f he cannot get on, will he write to our English Mechanic ?— A. A. A.

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I shake it well, nnd Ihe« filter, sfterwnrrt» я little bit of nit. Mlv. to replenish waste frorjj ft and filter. I have sometimes, especlallv after' a lot of paper, mea the bath nearly black above entirely removes it.—Mus.

[2070.]-STENCIL PLATES—Does our frie; Vicar " adopt the plan of cutting his stencil p] of thick foil fun nllny of lead and tin): if freeiloni may be gained even In tbe repetit same design by depanfng from the strict Sftssajj lines. In cutting a fresh stencil pinte еуеипяД old pattern, an apparently accidental dovlathnfj be exaggerated to give greater esse. Meticxs type has bem used f ir the purpose nnmed In 1st but there is none of the richness of colour obta| by stencil colouring as to décalcomanie trantS obtainable at shops in Oxford-street on either the Regeit-circus; but the writer has never ... subject suitable for the purpose named.—S. T.

[2072.] — PITCH. — Shoemaker's wsx is _ melting together about equal quantities of cer'"" black pitch and rosin. When thoroughly me. small quantity of a common oil is added, to soft* compound. Tbe quantity of oil dependson the I ■ of the year, more In cold and less in hot weatbas: ■ make it lighter In colour It is drawn out by the 1 -^ An article called prepared piicli Is now sololi **•' trade; it merely requires to be melted, and % «•»" added.—Crispin. .»■■■■

Г2073.]—CEMENT FOR PARAFFIN LAM •"'■ have one in dally nee that was repaired some 2 •""* «go with white lead. The white lead must be m - ri. t., free from baryta, Its commonadulterant. am w.' lamp must be laid aside for at least a week л -* —S. T. T 9-M

[2075.]—WATER-PIPE SWEATING. - T] posed sweating is a condensation of vapour spheric moisture on tbe surface of the pipe lower temperature of the water contalneU —S. T.

[2079.]—VARLEY'S PATENT COIL.-Пе'. send you diagram of Varley's patent coils useii Office instrumente. It

[2008.]-CONTENTS OF IRON PANS —To And

355

this, multiply the square of half the diameter by

113 and by tho beight. For instance, the first pan contains: 11 x 11 x 3»5 x 11 58 0in. =

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[2057.]-ZINC PLANT.-Tho sine plant can be made by "A Late Subscriber, K. S." by twisting a piece of wire round a lump of zinc and inserting one end in the cork of the bottle; then attach other pieces of wire to the zinc nnd twist them In any form he may think proper; some put a little china doll iu between and beads of various colours, which has a curious effect ; then fill the bottlo up with water so as to cover the zinc, and put a llttlo eugar of lead in, and letit stand perfectly still; the tree will begin to grow. A pennyworth of sugar of lead may be obtained at any chemist's—enough for 3 or 4; it will cause a white cloud, which clears off.—A. A. A.

[2057.]-ZINC PLANT.-Thls is easily prepared by suspending a piece of granulated zinc in a strong solution of acetate of lead. In a short time beautiful plates of lead will form upon the zinc, and increase till the solution becomes exhausted,—Beta.

2 x 2 x 113 x 2 522 cub. ft. 118 cub. in. To measure the euble contents of a globe, multiply the cube of the diameter by 0 5230. —ebnest.

[20080-CONTENTS OF IRON PANS.—To find the solidity of a sphere or globe multiply the cube of the diameter of the sphere by'5230. and the product will be the solidity. To find the solidity of the segment of a sphere.—To three times the square of the radius of the base of the segment, add tbe square of the height, and this sum multiplied by the height and '5230 will give the solidity.—Jonaiit.

[2008.1-CONTENTS ОГ IRON PANS.-The contents of a pan in the shape of the annexed sketch, can bo found as follows :—To three times the square of the radius С F. add the square of the depth F G; and this sum multiplied by the depth F G, and the product again by -5230, will give the solidity of the bottom; aud the product of the diameters А В and С D, nddtd to the sum of their squares; and this sum being multiplied by the depth E F and again by -2018, will give jhe solidity of А В С D, which, added to the solidity of the bottom, will give the contents of the pan tequired. To find the cubic contents of a globe multiply the cube of tbe diameter by 5230, or the cube of the circumference by 010887.—J. Linton.

[2069]-PHOTOGRAPHY'.-In reply to "Lex," there is no stated amount of alcohol used for the purpose he speake of—merely a few drops or so: but I should advise him not to use It at all. With some samples of paper I have fouud that it tends to blister ihe paper, whilst with others I believe it almost prevent« it. In no case, however, should I advise methylated spirit. 7"Aoi is best out of the operating room altogether, either the spirit of wine or the ether, both being impure. My method of w rklng is to pour back the solution (after sensitising) Into the bottle wherein | is some kaolin, and the uext time that 1 want to use It

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is same size as the coil itself. Ihe only difference In this coll Is the needle and the two permanent bnr magnets, which stop the injurious effects of lightning upon tho coil. It works exceeding well, muchqulcker than the old system. If H.H. H." wishes, I will send him a diagram of contact keys used in these instruments. A'A' permanent bar magnets, В needle which has north and south poles as marked, С С colls, D pinion of needle.—W. Ooldino.

[20810-PHOSPHORUS—If •■ M. P. S." will look at my recipe for phosphorus peste In No. 257, page 588 [17fi01.1ie will see that the phosphorus does not require powdering. The proof spiilt will do that quito sufficiently.—Gitche Manito.

[2081.]—PHOSPHORUS.— If »М. P. S." tats». '• duces into a florence flask lpt. phosphorus and SpU. of rectified spirit, and heats in hot water until tilt

Shoaphorus has melted, nnd then (Inserting a vre]] tting cork) agitates briskly till cold, be will find * Shosphorus, on pouring off the S. V. It., sufficient ne for " paste." See Beasley, p. 393, for an рчш11а| uitfermcnting paste.—A. P. S.

[2084.] —GRANITIC PAINT.— The employed for the granitic paint is silicate of r which is supposed to harden the pigment with t It is admixed, and combine tlum In a durable neither of which points arc, so far as my expe goes, successfully attained,— S. T.

[2097.]—STAINING WOOD.—F. Drop probably I not given his work coats enough of i-tain to overno the blue colour he speake of. If the etaln is n» properly, this is the reason of Its not belnr» Ы enough ; he must do It several times, until the 1 colour is overcome. If this does not succeed, X* give him, through our Mechanic, a recipe that » answer on his requiring it.—Gilder.

[2097.]—STAINING WOOD,-Drop a little i phurlc acid into a small quantity of water, ЬгпэЬ. i •the wood and hold to tbe firo; thie will prodsÀ fine black, whloh will receive a good polish. Ort Jpt. of vinegar, loz. of dry lamp-black, doz. of | rust sifted; mix and let it stand fora и-.тк. ; иг 4 coats of this on hot, and then rub with Una oil, and you will have a very deep black,—M Ink Ei; A

[2097.]—STAINING WOOD-1 think if P. Jj were to give the wood a strong solution of salo tartar before applying the copperas, It wouldi y

ßrobably die black. This process is effective
:ather, and might be so with wood. I think
worth the trial.—An Initio.
[2102.]—VALVE.—I have used the annexed

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r2l36.1-I>IVlDlNG PLATE.-In answer to

tale." « 7°ur Pl»t«l»« 1»tne Pd11bt- and y,?u J"iT?
room for only, say «lx rows of hole., you will whet I
f*° f,n mine, rix.. S*\ V'8,100, 96, 84, 24 (the last for
Sard usage to save the others), as good numbers as you
"!„ Y,»t?. If yon want to do ornamental work by the
- double counting" of Captain Ash, then you must
nave 1M instead of 96. If you want large strong holes
andrsnnotfetln 360, then 240, 192. 140. 135, 100, 72,
are useful number.. That was the last I made. Be-
fore tbat. I made one for my own use of 300 outside,
then 11 13, 14,17,19. all in one row. with 216,140, 96,
*4 inside of that. If your plate is flat from ou tslde to
centre von can get in many more in the diameter you
mention, and I consider one of 13 rows, that I once
mads, complete enough for mo»t practical purposes.
Thenoe of the cutting engine, figured this week, has
37 row. containing every number up to 100 ana
ranging a. high aa 360. Good gunmetal is much bet-
ter Aan bras?. I get mine at Boweu's, Dorrlngton-
.treet. Coldbath-square Ask for best gunmet.ll
have .prions thought, of taking the gunmetal pulley
off my lathe, and putting on a cast-iron one, as the |
holea will last better. Division pegs, or "Index
vices " are, in my opinion, always made wrong. l»o to
Wilkinson, by all means, if you want something tirst-
■class, without being ruined. It la a chance if it did
not come to him at last, If you took it anywhere else
<o get it done. Say your outside row li Jin. from

5
•edge, and distance between rows — and state number

B 32,

•of rows you want, and direct to me at Pitcairn's, Library, Xing'!) College-road, N.W., and I will write out a list for you.—J. K. P.

r2l37.J—PITCH PINE WOOD.—" Pinastor" had better get tome of Stephens' wood stains. The cause of the wood looking opaque when stained is, the staining material has more body than it ought Very good stains can be made of burnt sienna and Vandyke "brown, in certain proportions, but Stephens' are more transparent. I ace the "Welsh Shepherd" recommends one coat of oak varnish. Is he aware that it will not stand long out of doors, and some of it is the veriest rubbish possible. Stick te the boiled oil for the outside, two or three coat, of it -, never mind beating it-. If heated look to your brushes, or you may get them burned up by the hot oil. "Pinaster" may depend upon this information, as I have bad experience for these last 24 years as a house decorator. All wood stains do not get darker in course of time; ■of that 1 am quite positive, and do not wish to mislead.— GlLDEB.

[2138.J—HARDENING MILL CHISELS—I advise •G. Doubled*.- locoathls mill chisels with finelypowdered p u siate ot potash, make them red hot, and plozuj them into urine; then brighten and Cemper.—A.: Iwirio.

BOTES AID QUERIES.

continually in water, and I am told the water has no
effect upon them.—Non-adhesive.

[2144.1-FKLT AND AMADOU PLASTER-WI11
some one describe the modus operandi for.covering
the surface of felt and amadou with isinglass, Ac.?—
APS

[2145.1-RKPOLISH1NG A VULCANITE WATCH CHAIN.—Will some kind reader Inform me how to repolish a vulcanite chain which has become deadlooking with wear, so as to make it like jet again 7— A Country Vicar.

[2146.—VENEERING.—Will one of your subscriber, kindly inform me how to veneer a table, Ac, and the tools required ?—H. E. D.

r2147]—BENNETT'S CHUCK.—I would be much obliged if " J. K. P." would explain Bennett's chuck for the benefit of myself anl fellow reader, of the Mechanic. Also if he would meutlon a way ol keeping the mandrel of the lathe still when using the division plate and index.-KENMNGTON Amateur.

[J148.1— TALLOW. — Will some brother resder describe the best system of refining ships' grease into tallow?—Young Beginner.

[2149.]—SURVEYING.—Can aHy reader tell me what book will give the best help to make surveys and valuation, of dwelling houses and land to be mortgaged toe building society?—Reader.

[•2150]-LIGHTING GAS LAMPS BY ELECTRICITY.—I have heard that a means has been discovered of lighting street gas-lamps in a town simultaneously with electricity. Can anyone tell me if suoh a system is in operation, now, whero and .how it is done ?—Canadian.

[2151.1—HARDENING MILL BILLS.-Will any reader Inform me how mill bills for dressing French stone, are hardened, end what I. used for hardening ?T. Marsh.

[2152.1—PAINT ON BICYCLES.—I wish one of your many subscribers would answer me these question. :— How Is paint put on bicycles?—iB it common oil paint? and what give, it the glazy llook? Is it some kind of varnish?—A Subscriber.

[2153.]-VERTICAL SAW FRAME.—Would .ome
fellow reader give me some information on saw
frames? I have some large oak trees 2ft Sin. through,
and I intend to put a frame to cut them. Explain
the different parts and what strength to make them
—it will have to cut 3ft. logs down :o lft.4in.—to take
in any number of saw. up to foutceen. Also the best
way of fixing the log. while being sawn—the logs are
mostly round, and will want good fixings. Give the
length of stroke. The weight of foundation required.
—J. T. W.

[2154.]-HARMONIUM-TO "ADEPT."-I am
1 trying to build a small harmonium with two rows of
reeds to represent four stops, and I should esteem it a
great favour If our good friend "An Adept" will
advise me which are the best reed,
to purchase for a small instrument,
also where I can purchase them, also
if the feeders will act aa well on the
bottom board of case; If so, that will
save me much room? I also should
be much obliged if he will favour me
with a sketch of his silent feeder
valve for bellows that was named In
January 14. as my valve, make more noise tbat I like
to hear.—W. D.

[2155.]—LACTARME OR MILK ALBUMEN—
How can I make this in a dry state,so that it will
keep similar to the albumen of commerce, that i. in
flake, very like sbellao 7—Lac.

[2156.J—ZINC ASHES.—What are zinc ashes, where can I purch.se them, and what is the price per ton? —elder Kin.

[2157.] — AN INSTRUCTOR FOR PLATELAYERS.—Will some of our brother correspondents Inform me where I can „'it a book that will instruct me how to set out a raa.us of any dimension—say from one chain to one mile, and the proper distance from a pair of points to a crossing of say one in two upwards? Whut I mean ia the correct radius from the point, to any spread crossing for a permanent way, I think there is a book as an instructor for platelayers ?—Unlearned Platelayeb.

[2158]— ARTIFICIAL LEG. — Will some kind brother give me the drawings, and inform me how to make an artificial leg below the knee, and what is the best material to make it of ?—W. R. E.

[2159.]— CLAMS.—Will any reader show me how to construct a pair of clams for 'splicing or jointing leather—such as those used by roller covcrer.? A diagram will greatly oblige.—T. Simmb.

[2139.]—HARMONIUM.—Would some kind reader tiate how many rows of reeds I could have for an harrooulum, the case of which is the size of a fiveoctave Alexandre's make? If some one would state bow I could fit it up with two rows T should be much

obViztd, and, likewiso. what kind of reeds, Ac. would

I* rkraired, aa I am entirely ignorant bow to proceed;

but haling made the case, bellows, <tc, I want to finish

it.-j.wr

[21*'.]-POOR LAD'S QUERT.—Will sone kind astronomical reader advise me? Having but very limited means, I thought of purchasing one of Wtay's JJin object glaanes, price £2, but seeing in our last Dumber that a 5m, specula would cost the same. I am rather Jn a fix which to have, and abould esteem it a favour for a gooi opinion.—A Poor Lad.

[2141. j—SPLITTING QUILLS.-How can I split quill* in half—I bare tried several means without success? Should tie quill, be soaked or aof tened ?— Cbowqcixl.

:<2H2.}-SOFTENING CAST IRON.-Can I soften cast iron before turning? I have a face-plate to turn; •Beg so bard, the tool will not cut it.- G. B. K. jat3-}—GLUE TO RESIST WATER—Could yon ■B me of a glue tbat will resist water, or of any compstttion for fastening wood together, so aa to resist *at»r! There i. a Arm iu London, I think, who make ■ejeks lor carpet printers; these blocks have to be put

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to make a good paste or cement fur clothing iron rollers?—!. Sihms.

[31620-8E AMS OF MACINTOSH.-Can any fellow reader tell me what Is used for joluing the seams of a macintosh or waterproof cost?—G. W. D.

[2163.1-LEATHER BAG MAKING.-Would soire one tell mo how to make small leather cases—such case, being made of paper and covered with leather by gluing the leather on the paper cases—suoh as are now used by ladles and geutlemen ?—T. H. P.

[2164.] —PHOTOZINCOGRAPHY.— Will somo of your intelligent correspondents be kind enough to favour me with the titles of some of the bent books on the subject of photozincography and anastatic printing?—I desire to know ths "ins and outs" ol the printing.—W. H.

[2165.]-W0RK1NG MEN'S KXHIBITION.-Can any correspondent say if any employer Is eligible to exhibit an article of bis own invention in tho forthcoming WorUng Men's Exhibition, and say to whom to apply forparticulars?-MORELiOHT.

[2166.]—MAGNET.-Can I make a magnet by battery power? Will Smee's battery do; bow many cells? My magnet Is 71n. x ljiu. x {in., hoiseshoe-shapc, tempered steel.—J. Gabell.

[2167.]—LATIN.—Can any brother reader Inform me if there is a system for self-teaching Latin ; where I could obtain it, and what would be the cost ?—A New Subscriber.

r2188.] — DIMENSIONS OF MODEL STEAM ENGINE.—Will some brother reader give me tho dimensions of fittings for a model steam enginecylinder 3in. stroke, ljin. bore? What size steam pipe should I require, and leegth of lever for safely valve 7-R.R.

[2189.]-PROBLEM.—Draw a line D E parallel to the base B C of a tiiaogle A B C. so that D E is equal to the difference of B D and C E.—P. B. McG.

[2170.]-AN UNANSWERED QUERY.—Will some correspondent tell me how to blacken old copper oolns? This query was asked some time since, but has not yet received any answer.—Gitcue Sianito.

[2171.]—BORING MODEL CANNON.-l beg to return my sincere thanks for the instruction furnished on the above subject. Being unable to make the halfround boring bit referred to, will either of my kind instructors be geod enongh to inform me where 1 can obtain the same?—J. S.

[2172.] - BINDERS [CUTTING PRESS - UNANSWERED QUERY. — WiU anyone oblige by giving a description of cutting press referred to by "J. J. A," query 1467? I can bind first-rate, but cannot out with an ordinary knife. It would uo doubt confer a boon on many of our reader..—Mabchil.

[2173.]—GAS'WORKS.—Will " Rotherwood" be so kind a. give a few more particulars about his economical gas works in Reply 17.11, p. 613, as to construction and operatiou in gas manufacture; also where the E. G. works are to be had?—Johannes.

[2174.]-MAGIC LANTERN AND MICROSCOPE. —I have a magic lantern with 3|in. condensing lenses and Bhould bo glad to know what would oe the cost of a good microscope to attach to it-suitable for showing animalcules In water, Ac, Would a powerful lens. u> burn camphorated paraffin give a disc of light sufficiently large and clear to show microscopic objects to an audience? Could the same instrument be so adjusted as to be used iu the daytime as a solar microscope ?—Frayer.

[2175]-LIFTING POWER—Has the wedge or the .crew jack the most power in lifting?—T. H. H.

[2176 ]—BLAST FAN.—I would esteem it a favour If one or more of your reader* would give me some information as to the construction and arrangement of a blast fan suitable for a smith's forge fire.—C. T.

[2177.]—PROBLEM.—With a point in the perimeter of a given circle for a centre to describe another circle, an arc of which shall divide the giveu circle into two equal parts.—Indagatob.

[2178 ]—CIRCULAR DISC—What must be tho size of a circular disc to be fixed on its centre in the boundary of a circular orifice lft. iu diameter, so that exaetly one-half the area of the orifice Is covered by the disc ?—Indagator.

[2179.]—GRINDING SPECULA.-Will steel, iron, and metal make a tool to grind and polish glass specula? For the purpose are the grooves cast or cut in the grinding tool? Can a glass speculum be ground, If firm, level and stationary? Is it possible to grind a .peculum parabolio without first grinding it spherically r—Andrew Johnson.

[2180.1-ENGINEERING IN GERMANY, Ac—Is there a mechanical or engineering sohool or college in

[2100.]-PRESSURE ON COLUMNS. — Will any .,„,„.,„„,,.„

brother subscriber tell me how many tons'pressure Germany whero pupils are instructed In practical as four iron columns will bear standing upright as shown, well as theoretical engineering, and where? Thanks

to Mr. Biggs for his answer to query 1934, and may 1 1 a»k him if he will kindly furnish mo with a solution of the following, whioh appeared in the Science and Art Department examination papers a few year, back?—" If an arc of a circle measure 50ft., while the radius is 18ft., what is the area of a sector whose base is tho given aro»—Y. P. W.

[2181.]—DERBY CEMENT.—Will some one oblige me with a recipe lor Derby cement for mending jet, vulcanite, china, or glass ?—G. S. H.

[2184.]—CONSTRUCTING COILS.—I am about to make a cofl, and intend to use about six mile, of No. 36 copper wire covered with silk for the secondary. I want to know what length of No. 16 cotton-covered copper wire I should use for the primary, alse about what number of sheets of tinfoil lft. square would go to the pound? I also want to know what length of spark I could get from the coll, also how many of the bichromate ..f potash bottle-batlerles ought 1 to use? Is wire, covered with composition, better than sUk or cotton-covered wire, or would wire, covered wiUJ ootton first and thee with the composition, be sun better? Is there any substitute for gutta P"0" tissue, and what kind of cotton or silk is used tor In plain figure. 1—W. R. E. covering the wire In shops whero it is sold covered .

[2161.] - PASTE FOR CLOTHING IRON 1'he.e last three queries I havo ofteuseeu asked, DUt ROLLERS.—Will any reader please to tell me how have never seen them answered. -»""■

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[218n.b TAXIDERMY. -On application for th.' work meu'ioned by your correspondent, I find that it baa been out of print for 20 years. Can anyone infi>rm me if thcrj is any other published, and who by ?— Sold.

[2184,]-.SULPHATE OF LEAD BATTERY.-I will feel obliged to any of your readers who will be sn good as drscrlbe lmw these batteries are inado. I understan'l .VIoseley's patent battery constat» of copper caps tinned, and flx'-d ou a central wire. In It actually necessary to havo tho cups so tinned? and is a porous cell requisite? Would я solution of sulpha» ot lead not do to charge Sraee's cells with ?" Sigma" has promised a description of all batteries now known or used, but it may be soin» time before his papers bring him on to that part of the subject, and in the meantime many of your leaders as weli as myself may be at a standstill for want of the Information.—fronti Nulla Fides.

[2185]-MILDEW ON ENGRAVINGS. — I shall feel much obliged if one of your correspondents will inform me how to remove mildew from picture printd, and how to prevent it.—Constant Header.

Wise.]-BAROMETER TUBES. — Thanks to "Amath" for his Information on the ealety valve. I have яошо barometer tubes (new ones), and iu laying by they have got covered with a aim inside that makes the mercury look muddy when it is put In. Can anyone tell mo tho best way to clean them ?—CompensaTion.

[2187.]-NAPHTHA AND GAS TAR.-Would any brother subscriber give instructions for making naphtha and anything else that can be made from gas tar, with a description ot vessels, &c, required for the same f About 80 gallons of tar isas much as I intend to use for that purpose weekly, which will, perhnpe, give an idea of the sizes of what will be required — J. H. M.

[21KS.]—ORNAMENTAL WOOD AND METAL CUTTING »ACHINE AND VELOCIPEDE. — Having for some time seen advertised in our paper Cunningham's fret-saw, drilling apparatus, and kinograph, I should like to havo the opinions of a few of our subscribers who may have tried them ав to whether they are useful machines, well made, of good metal, worth their price, and, in short, all they profess to he. I should also like the oplnlou of some of our velocipedista if in every case a drlving-wheol above 3oïn. ceases to be an advantage. I have an ordinary 36in. and 33in. bicycle, but I want to get nearer the ground, and I think of reversing it, so bringing the small wheel to the front and making it the guiding wheel, and putting tho wheels farther apart and driving It by a crank working In a bearing between the wheels, and communloating with the driving wheel (the hind wheel) by a connecting rod I as outside a locomotive; or with a pedal working like the elsowjointof abell-pull and connected as before:' shall I use my old wheels, or bavo tho driving-wheel larger—say eft., and, perhaps, the front wheel smaller —say 2ft, and which driving-gear shall 1 use ?—Gim

CRACK.

[2189.]—CIRCULAR RAIL.—Can any reader inform me how to make a ciroular rail for a model locomotive? It must be constructed on a framing of some sort, so that I can lay It on the floor ot a room without Injuring the carpet, Ac — F. G. C. *[219i>.]-THE ORGAN. —Can any brother reader tell me the way in which an octave coupler is made? also how a composition pedal is connected to the stops f A drawing of each will oblige.—Organine.

[2191.]-TURRET CLOCK.—Would Mr Maddlson kindly Inform mo what advantage he gute In the nse of cast Iron wheels in his clock instead of brass—moat generally used? I never sawone erected successfully with iron wheels. I should think that an iron wheel working it a pinion of iron or steel would work harshly together, and also be liable to stop through rust collecting between wheel and pinion.—Tintac.

[2I92J-SULPHATE OF AMMONIA.-Would Mr. G. Davis, or some other among your talentod correspondents, inform me of the most improved and simplest way for finding the degree of strength of sulphate of ammonia ?—Basin.

[219S]-FINE CHARCOAL.-Can any subscriber Inform me whero I may obtain fine prepared charcoal for rubbing down silvered circles, &o. Ηit is generally in short square sticks,—Termus.

[2194.J-INTENSITY COIL.-Can any fellow reader inform me how to make a small intensity coil powerful enough to fire gunpowder?—Coil.

[2195.]-SMOKELESS LAMPS.-Woald Henry W Reveley, Reading, who sends a sectional drawing of smokeless lamps without a chimney, in your journal of Jan. 21, 1870, kindly furnish particulars as to construction, length of eon« and hollow globe, and how the wick is raised or lowered?—Practical.

[2196.]-NAME8 OF rUBLISHERS.-Is there a book published entitled "Annals of the Wars of England ?" and if so, please name the publisher and price? if not, I should like to know the name of the publisher and the price of the " Annals of the Wars of Europe." What would be the most simple work on bell-rin^in"the publisher, and price ?—H. G. Redditch. P[21»7.]-TO GEORGE E. DAVIS.-l wish, through the medium of the English Mechanic, to thank G. E. Davie for the information he has so freely given and to request him to give me further information on the following points :—1. How to estimate sulphuric acid in salt cake? 2. How to separate barium from strontium? 3. How to estimate chlorine by volumetric analysis? 4. How to analyse roughly a sample of patent manure—such ав Standen's? 6. How to estimate the ammonia in a sample of manure ?—

DlBCir-ULUS.

[2198]-BORATE OF BARTTAS.—Could any correspondent give me a simple plan how to make borate of barytas ?— Hanlet.

[2199)-TF.I,ESC0PES.-WI1I «A. R. T.," p. 61*, or any other of your correspondents answer me any or all the following questions :-l. What is the probate reason that I cannot get a good view of the sun's spots with one of Solomon's £5 telescopes? 2. \t hat

will he the probable cost of putting a rack on the focussing s'lde of the above telescope? S. What will be the best and cheapest way ot mounting one of (»olonion's £5 telescopes on a stand, the legs to be made shorter when not in use? Perhaps " Pollux," on p. «04, will be able to give some information about a suitable staud for a working man's telescope, as he seems to know what they have to put up with when they cannot afford the more elaborate and costly workmanship of an Equatorcal stand, viz., the primitive and uncomplicated mechanlem of a brick wall, and tho elevation, depression, and sideral motion of the instrument as to be performed by muscular power!—H. F.

[2200]-ENGINE AND BOILER FOR LAUNCH. Will any of our friends, having experience In such mattere, kindly Inform me what style and size of engine and boiler is best calculated for driving a launch 3«ft. long hy 9ft. broad, with number of blades, pitch ot screw, and probable cost ?—Solicitor.

[2201]-STHAM ROARER -Will some kind reader inform me how to make a cheap and simple steam roarer to act in place of a bell for a mill 7 I should also like to know if it is obliged to be made of brass? There was a plan of a steam whistle in the English Mechanic a short time back, but the drawing wns very small. I failed in making one off it that would act. so I wish te have the plan and dimensions of one of those sort called a roarer, which are so much used now for works.—Youno Engineer.

[2202.J-WHEEL SKATES.-Will some brother reader kindly inform me the best plan for making wheel skates ?-C. Francis.

[2203]-FLOUR DRESSING MACHINE.-I am trying to fit up a small machine so that I can run down a few sack« of secouds flour whenever my other machine is broken down, and occasionally »few grists. I hnve made a 12in. cylinder which will take three Bheets of flour wire nud one of sharp wire? What number of wire ought I to use, and how many brushes, and what fall ought tho cylinder to have ?—A Country Miller.

[2204.1-PROBLEM.—The diameter of the plate of a hydrostatic bellows is 12lu., a weigbt of 2501b is placed upon It ; what will be the height of water in the pipe?— W. B. S.

[•.'205.]-PROBLEM.-Whatlsthe atmospheric pressure when the barometer staud? at 30id. ?—W. B. S.

[220r..]-CERA«'O MANUFACTURE.-Tha»ks to "Beta "and H. B. Miller for their information. On iuquirlng, however, at Berth's and Quaritch's I find that instead of 20»., 28s., Ac, Brongniart's book is Sos Are there different editions at different prices? It is not needful that the works sought should be in French —a good practical English or French book at a moderate oharge, especially if treating on the preparation of colours for painting, and printing, is what I require.—Iota.

[220-J-CR1CKET BAT3.-HOW are crioket bats made? I have tried my hand at one several times and failed ?—A StinscRiBER In Canada.

[2208J-REFINING BEESWAX.-Some time ago "Feu Follet," in reply to "Pulp Maker." offered to detail the process of reflulng with chlorine: would he please do so, as I wish to try my hand at it?—A Colourman.

[2209.J-OVERLAND ROUTE. - Will "Selwyn" explain why, if the Overland route ria Marseilles la also ein Southampton, the "Postal Guide" makes the distinction of the routes for letters, thus—India via Marseilles 18., via Southampton 9d.? Hew do the 9d enes go ?—Iota.

[2210.]—BAR MICROMETE R.-Mlght I ask Mr. Proctor or some obliging correspondent to be kind enough to favour myself and your innumerable astronomical readers with a drawing or description of a bar micrometer and its Held of view, and explain its uses? What Is the difference In use between it and a ring micrometer ?—Iota.

[22Il.]-OBJECT GLASSES.-Referring to Mr. Furkiss's letter on t' subject in the English Mechanic for March 4th. might I ask him to be kind enough to say iu what year he knows y Andromeda to have been divided by Mr. Buckingham's instrument with a power"! !' ?and alse if he can inform me how many seconds apart they then were, and how mnny at the present time ?—Iota.

[2212.J-SPIRAL SPRING.-Is the spiral spring reliable as used for steam pressure gauges? I presume that eteel springs are only useful within narrow limits—say a range of 101b. or ..01b. What I want is an extremely accurate means of registering pressure, increasing by a pound at a time, between the two extremes I have stated. I suppose this might be done by communicating the pressure to a hand travelling round a well-divided dial, but my difficulty is in what way to communicate it? The principle of the steelyard would seem the best way of applying the weight for the division of the dial. Can anyone suggest a better?—F. Q. Q.

[2213.]-STANWAY'S VF.LOCIPEDE.-I hope Mr. Stanway will answer a few questions respecting his velocipede—a description of which is given in the Mechanic for March 4th. Does he propel his velocipede by means of hie feet as well as his hands? and how does he manage to steer it, as the handle appears to be fixed between the levers, In consequence, there would not be room to get It round a sharp curve? Is it steered with the feet or hands? What is the distance between the front wheels? Please to describe the method of steering, Ac; also what is the price of such a velocipede, and the name and resldeuce of the maker? If he will describe how it is constructed in front as well he will much oblige.—An Admirer or The Velocipede.

[2214]—CANOE,—I am about to build a canoe. Would some reader kindly let me know where I can obtain a book containing practical Information on the subject?—c. D. Richardson.

[2215.]—STAMPING SHEET BRASS.—Can any reader tell me how to sivc brass the appearance of bronze, and where I can get dies made for »tamping, sheet brass ?—Tyno.

[221в.Ь CARRIAGE PAINTING.-Would someone kindly lnfotm nie how thepaiutfor carriage work

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is mixed Î and also how to mix the paint for —Young Painter.

[2217.]-WHAMPOOM MONEY. - Om- English Mech Anic has spoken several times of Cowrie money or »hell money. I ehould feel obliged for some information on tho Whampooms of North America,— Pioneer.

[2219]-GE0METRY,—Is there any geonwtrical means for proving the following theorem7—Having three circles on a plane, and drawing tangen« common to two, those common tangents have their interscctlone on the same straight line,—X. X. »

[2219.]—SIL1CIOUS GALENA.—Could some reader give me a few details on the modern methods i,t reducing sillolous galena, also on the substitutes lor nltro-glyeerine (blastingpurposes)?—Feu Follet.

[2220.]-SOLDERING.-I want to solder a 2in. cast iron pipe to a 2in. lead pipe. I find a difficulty in tinning the cast iron pipe. Can any friend Inform me how I can do it?—G. D.

[2221.]-SHORT SIGHT.-Are there telescopes sold for short sighted people ?—Ethardo.

[2222.]-REDUCING LEATHER TO PULP.-Do you or any of your chemical readers know of я solvent that will reduce sole leather to a state ot paste »— W. W.

[2223.]—ENGRAVING ON SLATE.—What kind ol knife or graver la employed, to engrave the lines and figures on a elate sun dial ?—F.R. A.S.

[2224.]—BOILER—Thanks to "Vivas Spenordum" for his kind answer ro my query, but will ho bo kind enough to give me a few more particulars? 1. Could I not put in tho feed cistern at once without pipe ami funnel as shown? 2. What would be tho quannrr for 50-horse power boiler per week (7ii hour«); pressure, 451h,? The water is very much impregnated with lime; scale very hard-like porcelain almost. 3. Has my brother reader ever tried carraqun in a boifer much incrusted, for my boiler is very intricate ?—Ost m A Fix.

[2225.]-VACTJUM IN CYLINDER. —Will' some brother reader kindly Inform me if the exhaust steam on leaving the cylinder of a high-pressure engine cansos a partial vacuum, or has the piston to be forced against the full atmospheric pressure, or 151b. on the square inch ?—Vacant Head.

[222e.]-TINCTURE OF IRON.-How is the tlnetm-e of iron used in medicine made, and what complaints!» it supposed to cure ?—Vacant Head.

[2227.]— LIFE BELT.—Where can I get or how could 1 make a life belt for boating purposes ?—A Va

L0NEM8IS.

[2228]—ADDRESSES WANTED-Will any kind Kuglisli brother reader give the full addressee ol some of the most important coal mines in Orest Britain ?—A Forbiqn Correspondent.

[2229.}—WORKS ON CHINA GRASS.—I want some good works on China grass—either English, F rem*. or German, Ac. If a brother correspondent will answer my query, stating purchaser and price, be will much oblige.—A Mellist.

[2230.]—REMOVING FLY SPOTS.—I have « rerr fine old engraving, but, unhappily, quite covered with fly spots. How can I remove them? I have trftd several ways, but failed,—Pera Y яо Ferra.

[2231.]—ENCKE'S COMET.—Will you please be good enough to ask " Omicron" to explain what is meant by solving an equation by the method ol least squares—au expression that occurs in his aceoantoi Kncke'e comet ?—T. Waghork.

[2fci2.]-PROBLEM.—Can any reader favour me with a solution of the following problem from Tndhunter's " Smaller Trigonometry, chapter X. :— The hypothenuse А В of a right-angled triangle Is divided at D, so that A D is to BD as С В is toX A- Show that

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¿* a + b

—J.M. Small.

[2233.] — STAINED GLASS. — Will Mr. Joseph Leicester or some other able correspondent inform me how ornamental church windows are palute4 anil stained, aa I have a little knowledge of some part, except ingredients that are used? I know there is » reddish brown colour painted on the glass for opiqtw and shading purposes called flux—It is mixed will turpentine. I want to know what it is composed ol; when it is burnt In a kiln it is very hard, and cannot be scraped off. I want also to know what ingredients are used to slain plain glass in parts where wanted, such as yellow, blue, Ac. For windows, as above, 1 have seen glass when taken out of tho kiln with a red colour or deposit on them, and when cleaned uff leave a bcantlfsl clear yellow stain on the class—nccordiuir to the design painted on.—Gustavo Knox.

[2234.]-TO "JUPITER."—Will •■ Jupiter" kindly tell me where he procured his 3in. refracting telescope of which ho writes in evident praise in the last Issue of tho Knglibii Mechanic, and what he gave for it? Will he give me his Idea of the apparent diameter of Jupiter as seen by him with a power of 75? I have this moment completed some observations with a Gregorian of 41n. aperture, and a power of about ¡Vi. Jupiter certainly did not appear to mo to be more than tin. in diameter, nor could I detect more than л mere suspicion of the " belts," but then it was not > good night. Will "Jupiter" kindly tell me the highest power his objeot glass will ndvantageoosir bear, and the apparent diameter of the planet "Jupiter" has seen with highest power? This vrfll supply me with anoint of departure from which I art deduce for myself other measurements— Гшмгв.

[22S5.]—HOSIERY YARN.—How can I double and twist two threade of hosiery yam from one to four per Inch?—Tinker.

[223(t.]-DIRTY CETLING.-Can anyone tell mo why the joists show through dirty ceilings, te., whenever a joist Is the ceiling is muoh cleaner thnn the space between them, which gives It a ribbed appearance?— Minnehaha (gitche Manits).)

[«37.]— SALERATUS.—What is it?—A. P R

[2238.1-FORMULA FORCALOULATING POWER OF ¡sriRAL SPRINGS,—Would any reader kin . ij

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