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.si- so M keens an equal or uniform rotation or, its oealy. *o "JJgKT the Very uneqtisl speeds round Its •^'Tmn,1 liTto 4 from Perigee to Apogee; and «? Jutm«tmw I" the two motion, is the cause of Sfi ^ foTwliQ the moon Is farthest it passes us libratwu; for « neo t own rotation continues troitery «^'v--££.*„ more on one side. Then when £rmTMoon is nrtreSt U passes quickly, and show, us tDeJT.?n the ort^rsidc. Thus, the moon's very uniform rotation mu own axis, and very unequal .peed taToil l* beautifully d'-ows the two separate motionV Bnt this same action that so slightly » • "ate. the moon is shown with the greatest Intensity in ?*.»,».. rrfsaturn • for they are so near their priK?S £ to n« only stretched out "at but have Ecu obl.ged to separate Into several rings by he dlfteriw .peed, doe to their respective d.stance..' TYPOGRAPHICAL ERROR.-"Ab Initio" writes: Th.re I. a ead error at page 13, onder the heading
JenSri tWk it sho.ld be 69 yards 1ft. 81in"
THE TRANSIT INSTR0MENT.-" R. E. T." lavs--" Apropos to the very able and interesting ■riieis on the Transit instrument and its uao, in this ES "Sumoer of the Enclish MEcna-itc. will lo^ aUow me» inform your readers that the gontle«?an who was the originator of eheap telescopes is oow eo^uged in an endeavour to construct a cheap tMMU instrument for working men, which while 4t will not aspire to the accuracy of the most expensive instrument., will enable a person to get correct mean time to within 5 or 10 .ecoods? When complete, it will he brought under public notice through your Journal."
SPLtCmG LEATHER BELTS.-" RT.8." says:♦'The following-cement requires only to bo tried, and it will come intogeneral use. If properly dene. It is quite Jl.. »- , I... ^,.i,,i i»«th*r- —Dissolve Nelson sopaque
REPLIES TO QUERIES.
[1611.]-APPARF.NT PAR ADOX.-"IT.B." Is dissatisfied with - Qullosa." "Fneunia has MMM division with multiplication, and " U. B. reJWWWr explanation because " J B." savs nothing is not ,qual to nothing. I must remind "J. B and U 11. that the base of the operation Is the assumption that a docs equal b. Thl. should satisfy " U. B/-excelsior.
[lR8fl.]-MEASURING PATTERNS-The method given by " C. J. B.," for finding the cubic contents of patltnu, is evidently correct, but the same method would not always do for finding the cubic contents of the rosfinsTfrom the pattern (which, I presume, is what "Green" wants). Very often the interior, or any part, has to be taken out by means of a core-a common pipe, f .r instance ; the pattern is generally made solid, inS tl, • interior 1b formed by a core If the pattern is solid, the way to Bud the content, of the castiags 1. thls:-Flud the quantity of water displaced by the pattern and the core separately, and subtract the latter from the former, and the remainder will be the eubio cmtenis of ths casting. When the eastlngls large, the pattern is rot made solid for obvious reasons; sometimes the mould is built up with bricks and loam, and swept up to the required shape by a lew boards, and no pUtern i. required at aII. In all eases, when the eastings are large, the contents must hi, foun.l by calculation, the rules for whioh are to be found in any work on men.uratlon—Scire \ Olo.
r*0I41-TR1CYCLE. -I apply tho motive power on a rtonbre 5-in. crank axle direct from the shoulder, without the aid of lever, of any kind.-W. P. J. P.
r20271-INDICATORS FOR ELECTRIC BELLS. —"R ^"understands the electrical action but not the mechanical. The adjusting weight Is m balanced that a crtrretit through either magnet att.eks the armature and leaves the same rn the nllrnctrrt posmrm after fhe Contact is broken. The kitchen piish, therefore. ls-h«ed to throw back tho card by making contact. — r \'tm-stor.
raoM] —CLEANING SLIPPERS -"Inquirer" wanu to know how to clean his slippers Let him di.solve Ipa. of oxalic acid In half a pint of warm water, and when cold, sponge his -Uppers over with it This will fetch the dirt and grease off. and when nearly drv rub a little olive oil in; this will soften them and improve them, no doubt, to hi. liking.-unlearned
[2W5.1 - SOLVENT FOR MARINE GLUEMintral naphtha ia the proper solvent for this substance.— W. W.
P0851-SOLVKNT FOR MARINE GLUE.-Has our friend "J. 8." tried ftcsfT Marine glue is made liquid enough when held In a flame —iota.
 and [SMSI-HARDEVING MILL BILLSThe VIII. and IX. vols, ol tho Enolisii Mech Ahic I contain practical recipe, which have been amply tested, and acknowledged to be of f/reat terrtct. It strikes mo very forcibly that there is "the same difference amour millers in handling the mill bill, as between one writer In holding the steel pen I hsve seen a stone-dresser cast aside one bill sfter another, as not St fornse, when the same tools, in the hands of his comrade, dressed the stone properly. Before diamond dressing maohines came in, millers were proud of their good work, and in a visit to a mill lately, where, in
. r 1... ¥ !...>■.. ,1.,,, I ii,.,i,i' ,> inir .if UIil
r2091.1 -PENDULUM-The swing ol a pendulum llin. In extreme length, for 3 degices, Is found thSB3° x circumference of circle Inches.
S6tp 821n. diameter j Z2\ t„ii.
or 713 of an inch Mr each degree of swing.—tj Q. B.
fWWJl-STAINlKG WOOD.-If F Drop will put .oine iron or steel filings in aJa. boitle and fill up with vinegar, the mixture, after standing some hoar* wlih occasional shaking, will stain wo.id a jet black 11 the wood has been previously washed, once or twice, with a strong decoction of logwood chips, which should be boiled and applied warm — Scri'tatou.
t20»7.]-STAINING WOOD.-I may say that a Jet black stain for wood is sulphuric acid (oil of vitriol), Willi which the wood is to to brushed over, and held elose to a fire. The acid really cartxmitei the wood to a slight extent. Experiment will best show whether the acid requires to be diluted or not. It Is better not to use it stronger than necessary, and t'ie woodwork should be well washed aiterwards, to remove all traces of add.-Q Q- R.
r2098]-DISC()NNECTlNG STEAM PIPES.-I think leather waBhers would probably suit " Scotch Mechanic"—Iota.
ri093V-DISCONTNECTING STEAM PIPES.-If "Scoteh Mechanic" would whiten one side of his india-rubber washer with whiting when making bis Joints he might disconnect them muny times witnoutbrenklng them. I have used Irdla-rabtor washers for manhole joints on steam boilers for years and by whitening them they have lasted for years, being taken off every few weeks lor cleaning.- B. W.
[21011—DARK TENT.-An amateur photographic friend of mine has used successfully for several years a dark tent, composed of three or four thicknesses of black and yellow calico, which I understand oulto shuts out all hurtful light. Will not this suit "«. R. F"? It is light and durable, mid when worn out costs but little for renewal.—1} Q. R.
[2108 ]—STEAM WHISTLE.-I send a sketch of a section of a steam whistle, which is formed of either brass or bell-metaL A is cast hollow with a flange,
So more, as will dissolve the ?«•••«---, i——-» -: ■ ,
warm place on an ov.,n or boTler. The splices should
be made nice and thin, pasted with tho cement, put
together and cramped between two pieces of wood, or, if
xTarne number of joints are to be roadcatrmo time. lay
Ito belt at full length on the floor, paste each splice
separately, and rub it on the top with a piece of thin
wood squeeslug as mttch of the cement from between
the ioints as possible, and left overnight until properly
BREAD M\KING.-"A. B." writeB :-" T. Estce
asks for a »ond method of making yeast for homo use.
He ii welcome to the following, which I had from a
■eook lu a nrst rate family in London, who never used
bakers bread :-Take 2oi. of hops as fresh as possible
with 3qts. »f water, and boil two hours; let it stand
■boot five mrantes after taking off the fires then poor
through a sieve over lqt. of malt; let stand until only
warm-not cold; then put in lpt. of patent yeast, or
some of the same sort previously made, which is far
better; let it stand all night to work, then bottle on,
and it will keep good for two months. It Is best not
to let yourself run (entirely «nt of the last brew as
some of it Ib required to mix with the new yeast to
work it properly; If you have none, a pint of patent
yeast from the baker's will do. If T. Estee tries this,
I should be glad to hear with what succesB.
TO MR HENRY D. BARNES—" The Secretary of the Museum of Fire Arms, Peckhanwye, P^n" his compliments, through the Editor, to Mr. Barnes
. r . [* w. .......T.l l.,,v.. nnv nhlfHtCtOn tO
and bolted on the engine at C r, F is a cock plaeed into it working with the handle K, and a screw M, to keep it iight. The cup G Is screwed on to tho tern A, and lenviug a narrow passugo, E K, all round. The piece GIB hollow, having holos LL in its sides, and a pillar H standing on its centre, on which is ocrewed the bell O O, the tniu edge of which is brought just over the opening E, aud hair an Inch above it. Oa opening the cock F, the steam enters the cup N, through the holes L, which causes the shrill screamlug sound. Holes M M are made at the top of the bell O, to allow the steam to pass out, aud improves the sound. The sounds of tho whistle are regulated from shrill to hoarse by the size of the concentric, pait where the steam escapes, depth of bell, aud their distance. —F. B. Knox.
[21110-TESTING MILK.—The lactometer sold in the shops at Is., with dirsctions for use, is the most ready way of ascertaining the quantity of cream present; the hydrometer for determining the deusity, or relative richness in caseine mattor, and dilution with water—Patek.
[2112.]- CONFECTIONERY'.—" Practical Confectioner," by Csx, Longmnu, and Co., 8s.; Confeetionery lu "Industrial Library," Houlston' Is. 6d. Every description of lozenge, drop, candy, &c., is to befound in Cooley's "Cyclop, of Practical Recipes," published by Longman and Co., price 28s.—A LoVM or Books. „
[21U.J-GUTTA PERCH.V STRAPS—I have used, mauy straps and -bands, for which, when runulug at high speeds, the bestlubriean! is cold water. Whenever they became stiff, as they will in cold weather, or when out ol use for a timo, I soaked them iu warm water, and brushed them with a stiff brush.—H. B. M.
[211ft]-WATER POWlvR-200 gnllons per min. falling-iOft. produces 11 h. p.,but as about ouc-thlrd of this would be absorbed in overcoming the iuertiaof the wheel andgearing, the wh.cl being of good construction, with properly ventilated buckets, there would remain 1or useful work 7 horse power. But a turbine would be preferable to a wheo! under the circumstances stated.—C. S.
[21I7.]-CEMENT FOR IRON ROOM.—"T. S. H." should put strips of well tarred felt between the Iron sheets, where they overlap, or he may caulk thejoints with oakum, and then tar it all well, and throw on sand.—Iota,
[2121.]—BOILER TAP.—If the plug of the tap is во mode«9 tobe removable by taking out the «crew underneath, tuke it out. and having put some oil aud flour emery on the part that works In the tap, re-insert It, and turn It about, frequently withdrawing it, until the surface Is ground bright, and the plug perfectly Ate tbo tap. Then wipe off carefully all the emery, and smear the plug with tallow. On re-Inserting it, It will be found that owing to its dinmeler being reduced by the grinding, it will go through the tap too far for the washer lo get a bearing on the under part of the tap; the square on whieh tills lite must therefore be filed as far up as is found to be necessary, na-l the hole in which the screw works drilled and tapped deeper. If a new tap is wished to be put in, there is no cemonting lequircd, but some white lead well worked into a washer of felt, which is put on the screwed end of the tap after it is inserted into the hole, and the screw nut Is then tightly screwed down on It. To prevent a tank from leaking, let nothing but rain waler be put luto the boiler.— W. W. ë
[2I24.]-EARTH CLOSETS. —If "R. M." can manage to get a drain from the bottom of the vault to carry off the liquid matter, he will And his alteration a successful one. Л second pan connected to the drain, wbou the place Is used only os a urinal, will make the ob better still.—Scribbler.
[2124.J-EARTH CLOSETS.-I believe the same difficulty was experienced at the gaol at Reading, Berks, and that a remedy was found. If the Governor there were applied to, he might furnish the required information: and if "R. M." by this means, finds what he wants, it would be useful to other's, if he would send It for Insertion in the English Mechanic. —C. S.
[21260-JOINING WIEE.-If "E. H. B." wishes to splice copper wire, he has only to twist the ends together; If strong iron wire, each end should be turned up and laid over one another for a length of about 2In., and then wrapped tightly with copper or good iron wire,—Iota.
[2128 ]—ASSAYING.—The process, as performed at the Royal Mint and Goldsmith's Hall, occupies Ave closely printed pages In Ure's." Dictionary of Arts, Manufactures, and Mines." There are numerous illustrations of the apparatus, and table», to which it would be better to refer than attempt a clumsy abridgment of so lucid an account.—A Lover Of Books.
[2131.]—PUMPS.—" Plumber" seems to have got somebody else's work. Ho wever, if he has it and has to make the best of it, perhaps this reply may be of service to him. From 40 to 50 (call It 45) gallons of water per minute falling 8ft. will produce a tenth of a horse power, but as the friction of the turbine and gear will absorb about one-third of the power ex
Eended, there will remain but the fifteenth part of a oree power for useful work. A turbine might be made to utilise this, but it would be a mere toy machine. Supposing it made, however, it would deliver through the pipe described, and to the height named, 3 gallons of water per minute. This quantity is so small as to be practically useless, and therefore some other means of supply should be advIeed.—C. S.
[2I31.]-PUMrs.—The quantity of water available, say 50 gallons per minute, being so small, and the fall only 8ft, would it not be well to inquire whether. Instead of a small turbine, a water ram would not prove more efficient, thus dispensing with the machinery of pumps, &e.? I have seen them employed for the purpose of supplying water to houses in the country, where a smal 1 fall of water was at hand, one great advantage being that the action is continuous-, requiring little or no attention. There are one or more hrms in London who pay great attention to this class of water engine.—H. B.'M.
[2135.]-WASHING BLUE.-Mix flnely-powdered Indigo with starch paste, and make it into cakes of the required size and form.—Guillaume.
[2135.]-POWDER BLUE.-" Roasted cobalt ore and carbonate of pótasela, of each one part; siliceous sand three parts; fuse together, cool and powder Lsed for bluing the starch in getting up linen."— Cooley.—H. В. M.
[2140.]-POOR LAD'S QUERY.-If he will write to me, I will glvo him the best advice 1 can.—T W Webb, Hardwick Vicarage, Hay, S. Wales. [It Is very kind of the rev. gentleman to answer " A Poor Lads" query by post. But would not the same or similar information be useful to other Inquirers if sent to our columns 1 We are sure that Mr. Webb would so word his reply as to be Interesting to all.—Ed. E. M]
[2147.]-DIVIDING PLATE.-AS to holding the pulley still with a division peg, as usually made that amounts to an impossibility. You have a long, thin spring, with a peg sticking out eome ¡in. at the top, instead of the peg being as short as possible say Jin., with a knob that you can lay hold of without impeding your sight, as well as saving your finger nails, and avoiding hurting the Angers In pulling bock the strong springs that are sometimes put to make up for the abominable length of the peg. The peg ought to be Axed t* a bar that will not bend at all, working on a joint at the lower end, and forced up to its work by a spring of some sort, or a wedge Jammed in behind it, against something solid; and this plan would help to preserve the holes. I think a good plan of holding a pulley steady would be to let the edge run cloec against a firm block of wot.d, and set it fast after every time of ehirtlng by a loose clip like a carpenter's bench vice on a small scale.—J. K. P.
^l?î??^~THE WORKMAN'S INTERNATIONAL EXHIBITION will open at tho Agricultural Hall on July 5th. The last day on which apiil¡cations for space will be received is April 25th. I shall be happy to forward every information, aud space papers, Ac, to anyone sending a stamped directed envelope, or they can be had on personal application at 150, Strand, or between 7 and 10 p.m. at the St. Mark's Club, 11, Brownstreet, Duke-street, Oxford-street, W,—Robert BurGess, Local Secretary, 22, George-street, Oxfordstreet, W,
[2100.]—MAGNET. — One or two pairs of Smee's elements,quarts, in moderate action, will make your magnet permanent if you wind plenty of insulated wire round It.—Bruin.
[2167.]-I,ATIN.—" A New Subscriber" will find
[2169.]—PROBLEM.—Draw a line D E parallel to
0 В Ü - С E. Solution: Uon-
—UNANSWERED QUERY.-Old coins are generally black enough, but if you cover them with line plumbago powder, heat moderately, and rub briskly, you may mako them as black as you like.— Bruin.
[2172.]-BINDER'S CUTTING PRESS.-I should be most happy to give "Maschil " a description of а cuttisg press, but it would only be wastiug our Editor's space, for the tools and wood would be more expensive than buying the articles properly made. A new cuttiug press, plough, and pin caa be obtained for 32s.; a secondhand apparatus for le.-s.—Ab Initio.
[2175.]—LIFTING POWER.-The screw and the wedge are on the same mechanical principle—that of the inclined plane; and therefore, it the angles are equal and the external force applied equal, they should raise the same weight. Which it may be best te use must depend on each particular case.—Bruin.
[2181.]-DERBY CEMENT Is a proprietary article,
.—CONSTRUCTING COIL.—If'" Nemo" has
[2188.].—BICYCLE WHEELS—As I make blcvcles
[2196.J-NAMES OF PUBLISHERS.-" Annals of England," 3 vols, 8vo, 15s„ Parker, 1853. On Bell Ringing, "Clavis Campanalarla" I am unable to give the price or date of; " Campanologln Improved ; or, the Art of Kinging Made Easy," 3rd edit., London, 1733, Is a little book that contains all the terms made use of, and may be met with occasionally on a book stall. It Is now many yeare since I ceased to be—A College Youth.
[2217.]—THE WAMPOOM—or better, the Wampum —was the money of the In.'.inns of N. America (wampum Is an Iroquois word meaning mussel). It consisted In little tubes made of shells, fastened upon belts or strung on deer sluews and worn as necklaces. The purple beads were made of the clean parts of the
common clam shell [Verm» mercenaria), the
[2223.]-ENGRAVING ON 8LATE.-I do not know whether there are any special toole for this purpose, but if I wanted to do anything of the kind, I should get some of the larger kinds of wood engravers' tools. They are to be obtained at any of Buck's shops in London. If tho figures on the dial are required of a large size, they should be cut out with a chisel.—Saul Rymea.
[2223.1—ENGRAVING ON SLATE.-To F.R.A.S. —Use the ordinary gravers, of a large size. The work is very pleasaut. Sold at Buck's.—G. E. Crick.
[2225.]—VACUUM IN CYLINDEH.-In a high pre« sure non-condensing engine the piston has frequently to be forced back at a pressure of three or four pounds above the atmosphere. This Is partly owing to friction in the steam ports, pipes, Ac. If the exhaust pipe U too small, there will of course be a great amount of back pressure. I once heard of a partial vacuum being obtained by leading the mouth of the exhaust down to the surface of a stream, but 1 cannot say if this was actually the case.—Machinator.
 — TINCTURE OF IRON.— To -Vacant Head."- You had better buy what you want, at6d. per oz. It will never pay a man to make his own medicines. A little knowledge Is a dangeroos thing where the stomach has to be acted upon.—G. A'. Crick.
[2220.] —TINCTURE OF IRON is made from the sesquloxlde of iron, hydrochloric seid, and rectified spirit. No one can make It as cheaply as he may buy It In small quantities. An ounce may be procured for od., and will make 30 or 40 doses. As to its medical properties, no human being con condense an account of them into thrco or four lines. It is a tonic, and le used In 20 different diseases at least—Luke The Labourer.
[22270-LIFE BELT,—The most reliable life-belts are those which are sold by the Royal Humane Society. -G E. Chick.
'[2231.] — ENCKE'S COMET. —For an elaborate answer to this query see "Omicron's" letter on another page.—Ed. E. M.
[2232.]-PROBLEM.—The hypothenuse А В of s right-angled triangle Is divided at 8, so that A D : В D
Solution: Let А С:
flOTES AND QuEiSIES.
... o - ay Now substituting this value of x in (3) we get y
r-^B-i-TO "FEU FOLLET."—Will "Feu Follet " be pleased to give his proccs» for bleaching wax by chlorine withnnt destroying itB burning qualities?
— A Yol)>'G Meciiahic.
[«.'«0]-PORTABLE CARPENTER'S BENCHWill any render furnish me with a plan or a few suggestions for making a portable carpenter s bench ?—
r2261 1-PITCn OF PROPELLER. — Will some brother reader give me the most correct method ior calculating the pitch of a screw prot-eller? A diagram, showing how the Wade should be divided, will greatly oblige—Thomas J O'connor.
roooa] —RHUMKORF'S COIL.-Will "Sigma" have the kindness to explain the manner in which the nrimaryand secondary wires are wound on the bobbiu of the Rhumkorf coll? 1 believe this is the most powerful machine at present known.—Thomas J. O'connor.
[■••■■ei 1—DISSOLVING AMBER—Will any brother reader tell me how to dissolve ambor?—Oatseve Diamond.
WW i_pKNnULUM— Havinghungtwopendulums on a" rod and setting one in motion towards the other, the one that was remaining perfectly still, after a few moments, began to move with the other. Will someone describe what caused the other to move?-OatsEye Diamond.
r2-.>651-SCREW CUTTING.—I want to form a screw 4in. pitch, 4in. diameter, and 12in. long, on a niece of Jin. wrought tubing, with sheet line. What Bhape will it require to be cut in the sheet, so as to form the screw round the tube? A rule for doing this from some of our correspondents will much oblige.— J. G. W.
r<>266i_iv\A.SrIING MACHINE.—Will some reader kindly inform me how to make a washing machine for domestic use? Being only an artisan I cannot afford to purchase one of those expensive machines advertised—artisan.
T2,!0r 1—WORK ON ELECTRICITY.—Will some reader (perhaps "Sigma") kindly recommend me a o-ood modern work (stating price) on electric science, describing in detail tho theory of the iuduction coll? A work—whether in English, French, or German, would suit.—S. T. P.
r2-.(j81—POLES OF MAGNETS—If my question
wilfnot be anticipating " bigma's " intention, 1 should
like to have explained to me why the magnetic poles
or Doints of maximum attraction lie, not at the actual
extremities of the magnet, but a distance within. &c.?
The reason of this fact in magnetism has always
puzzled mo, especially as I And the same fact
mentioned but not explained, by several other emi
aent electricians. Electro-magnets, I understand,
have their poles much nearer their extremities than
permaneut magnets, thus explaining, according to the
law of inverse Squares, why the magnetic field in one
case ia so much greater than in the other; bnt what I
want chiefly to know is, whether there 1b any theory
explaining the point in question.—H.
 -FOSSILS.—Will any correspondent inform me in what way slabs of stone containing small fossils are prepared? If appears that acid of some kind is u*ecl which eats away the stone around the fossils, leaving them standing out like basso-relievos from tho surface of the Btone. If washing with acid be the only preparation, I cannot understand why the fossils, as well as the stone between them, should not be destroyed.—H.
[2270.]-MOTION OF WATER.—What quantity of water will pass through a lin. hole (round) at SSlb. per square inch ?—J.crompton.
— PURIFYING NITKIC ACID—Will anyone give a method for purifying nitric acid after having used it for dipping brass castings?—J. Cromptox.
[0272.1-G A LVANOMETEB.—Will" Sigma " or any other electrician kindly give me a description of an Indicator or galvanometer for indicating the strength or the induced current from an Induction coil /—A. J. Hayward.
[2273.3—DR. KITCHENER'S TELESCOPES.—Is it known to any of your readers taking an interest in the telescope what became of Dr. Kitchener's instruments (about 50 in number, I believe) upon his death? Wero they sold by auction, and is it known who possesses the Beauclerc object glass ?-G.
r274.]_VAKNISH.—Many thanks to "Worcestershire Sauce "and "Gilder" for their prompt replies to my query. In regard to woodcuts and prints, I suppose the same process will apply to thein as to maps, but will it answer with pencil drawings ?—InQuirer.
[2275.1—SUN GLASS FOE TELESCOPE. — Will any of my brother readers kiudly inform me what kind of glass is placed before the eye-piece of telescopes for viewing 'he sun .'—J. II. Ward.
-GRANITE POLISHING.—Will any brother mason kindly inform me tho process adopted in polishing granite?—whether putty powder or emery ia employed, and how to apply it? Full particulars will greatly oblige.—Marble Masor.
r2277 1—GRINDING. — How much wheat should mill»toue« 3ft. 41n. and 4ft. respectively, grind in 12 hours on an averngc, with power in plenty? Would any practical brother reader kindly give the result of his experience 7—Seroids. r2278.1—DRAINAGE.—Can any of your corrcspon
^ . ■'_#.._« ma *l,o nomou of !}("'
the ••tulk, with tho various nr<jccsscs it goes through until nt for the market?—Ross.
[2281.]—AURIFEROUS ORES—Can any of your numerous readers give me information ss to [he treatment of auriferous ores, and of ores contain lug sulphur, arsenic, aud other base metals, with the view of utilising each, together with drawings of furnaces, flues, condensing chambers, Ac. used to carry out the work, also tho best way to separate the gold from the pyrites—commonly called black sand—that is sent from Australia, and whether the sulphur and arsenic Is saved ; If so, by what process? Would the IntroduC' tion of electricity Into the mass while under trcatmer t of chlorluo be or any advantage, or whether it w"" Id prove dangerous? Would a hot or cold blast be of any service ?—Ross.
[2282.]-POWER OF STEAM.—Will any reader Inform the writer If steam passing through a tube 32ft. long to a small high-pressure engine would act with as much power as if nearer* to the boiler? Of course he s aware of the greater loss by condensation; but, apart from this, will steam act with as much force after passing through 32ft of a tube as if It only passed through five or six feet ?—B.
[22S3.]-PAINTING THEATRICAL SCENES.— Can any of your readers give me information on the following points:—1. How to paint theatrical scenes on coarse calico with (if possible) water colours? In order to prevent the smell of oil. A full description, including how to prepare the calico for the colour, and how to mix the colour, ia requested. 2. Where to obtain the necessary colours? 3. Could any varnish be applied that would not crack on being rolled up, to protect the colour?— H. N. H.
[2284.)—MEDICAL COIL —TO "SI3MA."-W111 "Sigma" oblige by telling me how I am to know the primary er secondary handle of his medical coil as described in Vol. X, p. 513 ?—J. S.
 -MIXING BR ASS.—Will some reader tell me the way .to mix common soft brass?—Caster.
[2286.]—GENET A CYLINDER.—Win BOme horological reader kiudly give directions for selecting and turning in a Geneva cylinder, describing how to arrivo at the different heights, and slitting whether the cylinders when bought from the shops are with or with
dents inform me the names of books or pamphlets,
r2270]—WATER.—Can you inform me how to test
T2280 1—CHINA GRASS.—I should feel obliged If "Vrnest" (query 1894) would inform me where to procure seed of the China grass plant or Uriica Xivea, and also the best means of separating the fibre from
out plugs, or are the plugs to be bought separately? also if the cylinders are ready escaped, or is that left for the workman?—Cylinder.
-DAMAGED LENSES.—Is there any means of making a telescope of service again, the glasses of whioh have become opaque—haviugbeen in a fire? If so, how can I do it?—W. H. P.
 — CHARCOAL FOR RUBBING DOWN SILVERED CIRCLES.—Can any of your many wellinformed correspondents give me a few hints for making the above 7 What kind of wood to use? what heut to apply ? whether to be burnt alone or mixed with any other substance? Any Information would be welcomed.—Iota.
[2289.]-GLYCERINE.—I find that It does not pay to distil my glycerine. Will any scientific friend inform me how 1 can make glycerine of a brownish tint fierfectly clear, with a small outlay of money, and ittle loss of material 7—Glycerine. -BROAD LEAD PENCILS.—A very useful pencil for drawing foliage, &c. was in use some time ngo, invented by an artist, Mr. Galpln. sjan anyoue tell mo where they are to be purchased now ?—InQuirer.
[2291.]-ENGRAVING ON METAL.—Will "Engraver" kindly tell me the use of the scrapers and points which ho mentions in his query 2010, and to what temperature the gravers are lowered?—YoUNd Country Watchmaker.
[2292.]—GEOMETRICAL METAPHYSICS.—What could be the origin of the notions geometers get of regular figures—such as point, line, surface, circle, sphere, cube, &c ?—F. Bosmans, Louvain.
[221MJ.-STRANGE MECHANICAL MOVEMENT. —Let atop—such as is used for astronomical demonstrations—be put Into motion, present to the upper part of its axis the edge ol a metallic spiral, tho axis of tho top will adhere to the metal as if it were a loadBtone, enter the spiral and follow its curvation; at the end of tho spiral It returns backwards, and repeats again the same motion. The sight of this struck me because it appears ngalnst the rules of common mechanics. Could any of your readers favour me with a Batlsfaetorylexplauation of that curious phenomenon? —E. V. V., Louvain.
[2294.]-THEOREM.-Would some of your mechanical correspondents favour me with a demonstration of the followlLg ?—With the same perimeter the area of the circle is greater than the area of an ellipsis.—E. V. V., Louvain.
[22050-rROBLEM.—Where ought to be the centre of a circle C for bisecting another C1 in two equivalent parts ?—E. V. V., Louvain.
[2290 ]-MONOG RAM DIE.-Can anyone tell me bow to set to work to cut a copper counterpart to a steel monogram die? What toolB are required?— Cantab.
[2297.]-VIOLET INK.-Will anyone give me a recipe to make good dark violet ink ?—Cantab.
r2299.]-KEMOVlNC. OIL PAINT FROM SILK. —1 have a large bit of white silk which has been sized and painted on with ordinary oil colours. Can I get the paint off without injuring the Bilk 7—Cantab.
[2299.3-GENERATION OF ELECTRICITY—TO "SIGMA."—I venture to ask "Sigma" to tell me what is the cause of the spindles in our spinning mules generating electricity when running to such a degree that if I touch one with my linger it will make sparks fly off and electrifies the piecers every time they piece a thread, if ho could give me any advice how to cure this ho would bo conferring a great favour — Lancashire Lad.
[230O.]-MOULDS.-Whatmaterialisbest for moulds for fancy ornaments? Would gutta percha answer a s well as beeswax ?—B. C.
tMOJO-WEIGHT OF WROUGHT IRON GATES. — Will Borne reader Inform me of the best method to obtain the weight of wrought iron gates and leaclng. y measurement, or where r can get good books on *ho subject?—W R. Southwell.
[2302.]—POLISHING SCOTCH PEBBLES.—Would ■ome one inform mo how to bring the surface of a pebble In an i-ven face, and afterwards bow. to polish I —Amateur Lapidary.
[2303.]—TEA URN.—I have a tin tea nrn which makes the ten a very dark colour, and quite tasteless. Seme time aao the tap came out. I had it put in by a common tiumau. and since then it has never been right, although before it was an exceedingly good •ne. What is the saisa ?—Caution.
—PALO DE VEL&S—What is It ?—Robt. J. Johnson.
[2305 J-FORMANISING.—This is a process of preserving wood. I wish a few partlculsrs about it from some of our kind brother readers.—Contractor.
[2306.]-MORE STEAM WANTED.—The enclosed la a section of a small boiler I hnve 3ft. 6ln. high and 1ft. bin. diameter, and which I wish to make drive an enpinc with a 3jin. cylinder at a abont 601b. or 701b. pressure, but I liml I cannot make ■team fast enough. I therefore wish to ask some of my fellow readers to kindly inform me If putting in—say, four or five liin. tubes round the smoke flue (which Is only SAin. diameter) would malto it answer my purpose, or is the only remedy a larger boiler, and if the latter, what sized boiler should I require ?—D. C. W.
[2307.]—RIVET MAKING.—How and in what way are rivets made by machines—about Jin. diameter ?—
[2308.]-MELTING CAST STEEL.—I have been trying to melt some old scrap steoi in a crucible, and have sneceeded, but I find it too hard to work. I •honld feel obliged if " Practical Moulder " would give any information regarding flux.—Scrap Steel.
[2309.]-ETCHING ON GLASS.—Would any brother reader kindly give me a few hints oa ctohing on glass with fluor spar ?-belle Iblk.
[2310J-SPIRIT TAPS.—Wanted a good method of (rinding spirit taps.—Belle Isle.
[2311.]—NEW WORM FOR VICE BOX.—How caa I put a new worm to a vice box that has slipped thread? 1 have seen one or two that have been done, and which are as good as new.—A. E. B.
[2812.]—HISTORY OF IRELAND.—Will any of your numerous Irish readers kindly inform me of a complete, reliable, and moderately-priced history of Ireland?—A Young Irishman.
[2313.]-ENAMELLING CAST IRON.—How can I procure a white enamel on cast iron, with full particulars ?—Arthur Jones.
[2S14.]-POLISHING FRETWORK.—I should be glad if "Gutllauino" or some other correspondent wonld inform me of the whole modus operandi at polishing—whether he uses any size to stop up the little holes and crevices in woods like oak preparatory to applying the polish. The objects I wish to polish are fretwork ; also where to buy the proper polish? The stuff 1 have by me is very thin.—C.
 TELESCOPE CONSTRUCTION.—Why are astronomical telescopes constructed Bo long, as I have two of 2ft. and 4ft. focus respectively, and I find that by using an eye-niece (with the small telescope) half the focus of that 1 use with the large telescope, It equals the large one in every respect, and I cannot see what advantage the largs one haa over the small one >—
[2316.]-THE SLIDE VALVE.—Can any of your correspondents recommend a good book on the slide valve and the valve motion, and tlft name of the publisher, and the price?—A Constant Reader.
[2S17.]-CURVATURE OF THE EARTH.-Perhaps some professional correspondent will glvo his "field notes 'of practical curvature allowance, so that others may plot and test it. Along a still water line preferred.—Theodolite.
[2318.]-ETHEREAL SOLDTION.-W111 "Sigma" kindly inform me where to procure the ethereal solution of gold spoken of in reply ;to ;Mr. Sharp (2040), also the means of applying it, and whether the steel requires any preparation? If he will ho will greatly obllge.-B. 8. Burden.
-BOILER.—I am about putting down a small steam boiler—the Bteam to be used for boiling two troughs for boue button making, &c. I should be glad If some of yonr renders could inform me the best way, and if I can put water in the boiler when steam is up without a pump? steam will not be required very high.—John Jones.
-CHIMING.—I want to make or alter a clock so as to make it chime the half hours as a ship's bell is struck—thus, at half-past 12 to strike 1, at I to •trikc 2, at half-past 1 to strike 3, with the same pause between the second and third strokes as in an ordinary clock exists between the strokes for the quarter and half hour; this would go on till 4 o'clock, when it should chime 8 in four pairs of beats, and then commence again at half-past 4. The pauses to be between the second and third, the fourth and fifth, and the sixth and seventh beats. Can any brother reader say how this can be done ?—An Old 8ai,t.
[23210-SW-AN'S PROCKS8.-What Is the modm operandi of the autotype or carbon photographic process invented by Mr. Swan? and is it successful upon parchment ?—Scribo.
[2.122.]--PRIE DIEU.—Can any rcadertell me where I couln obtain designs for a prie dleu to be executed in oak wood-uot too elaborate—but that necessitates a little carving in the panels, Ac. ?—Good Catholic.
cnbic feet per minute (often more) by causing a dam to bo put across the brook, and giviug a pressure as shown on sketch to turbine or other form of wheel? Will the accumulated wutorin brook be an aid as furoe to the quantity regularly running as named above, a length, say, of 80 yards, being back water to dam?— G. P.
[2324.]—GYMNASTICS.—As I am going to construct a pair of parallel bars, I wish to know the best plan of having them fixed up. What I have seen were fixed in the ground, but I fear they would soon get rotten, being exposed to the weather. In " Modern Gymnast " a sketch is given of a portable pair fixed to a frame. Would "Bierlala" or aoy of your gymnast rorrespondents who have had experience in the matter be so kind Hs to advise me which is the best plau? Is there not a process which would render the wood not so liable to decay ?-gyhnastikos.
[2325.]-IRON ORE■(.— Will G. E. Davis Inform me how to estimate thequantltyof protoxideandperoxido in iron ores?—J. N., North Country.
[2326.]—VIOLIN.—Can any of yonr readers tell me the exact'pressure on the belly of a violin strung to concert pitch ?—Cremona.
[2827 ]- READY RECKONER.—Can any brother reader inform me where I could "procure a ready reckoner for calculating tons and cwts., giving,the fractions from Id. to 5a. per ton ?—J. W. M.
[2328.]-DEFECTIVE GUTTER.-1 have a doubleroofed building; the gutter is of Glssgow east iron, and in wet weather the water oozes through the pores in small drops and makes tho building very wet. Can any of your readers iufortn me what is the best thing to do to make it perfectly waterproof ?—Salop.
[2129 ]-MATTING—Can any reader tell me how to clean matting?—Minmhaiia.
[2330.]-THE BOOMERANG -I possess three specimens of the boomerang, but they totally fail to achieve what I have read of them. Will someone suggest the true method of using them?—Salmo Salar.
[2331 ] —PATENT DRYERS. —Can any of our readers inform me of what patent dryers (far paint) is composed?—H. Beech.
[2332.]—UNNOTICED QUERY. —How are the perforated and traced patterns for embroidery and braiding effected on paper, and on the materials, directly ?—STiTcn.
-BRILLANTIfJE.—Will some kind reader of the English Mechanic inform me how in illumine is made ?- Pkrfumk.
[2384.]-POLIsniNG HORN AND SHELLS.-Will some brother reader kind'y tell me the way to polish buffallo horns and tortoise shells ?—W. Crockbb.
[2335.]-CONTACT BREAKER.—Can any of your readers advise me the best form of contact breaker for an induction coil to give a 7ln. spark? The ordinary forms are a source of continued expense by the platinum points melting away.—A. E. Tucker.
[2S86.]—BRONCHITIS.—Can any brother reader inform me of a cure for the above complaint, or rather what it has left behind it? About three years ago I had a very severe attack of it, aud ever since I nave been more or less affected in the chest and windpipe, with a husky voice; very apt to take cold, with a cough not very violent, but very distressing. All that I have taken seems to have no effect on my voice. I sometimes fear it will end In consumption if no remedy can be had. My age is 28. Any information will be a great favour.—A Three Years* Sufferer.
[2337.]—STEAM INDICATOR.—Will some reader kindly tell me of any work on the Bteam indicator ?— Marine.
[2338.]—SAW TEETH.—Would "Mill Sawyer "be so good as to give a sketch of what he considers to be the best form of circular and deal frame saw teeth? —R. T. 8.
[2139.]-SIZE OF PULLEY.—I have an Sin. centre screw cutting lathe with overhead motion, and 1 want to drive it from a shaft that Is running at 24 revolutions per minute. Will any brother reader kindly tell me the diameter of pulley I require on this shaft to drive the lathe to speedP— Marine.
[2.140.—WIRE COVERING.—No one seems to have noticed my query asking what sort oi cotton Is most Bultable for covering wire. I have a covering machine, but cannot get a suitable cotton for my purpose. Perhaps some one will give me the requisite Information*—Over Sands.
[2341.J-CANOE.—I thank " Maty " for his notice of my question respecting a canoe, and beg to inform him 1 want it of suitable size to carry one person, and to bo similar in shape of those used by the canoe clubs. Would be glad of any instructions he could give me as to best material, or anything else.—Over Sands.
[2342.]—FACINGS FOR HARMONIUM KEYS.— My hai m nium keys are of worn-out ivory. Can anyone suggest a method of facing them either by enamel or otherwise ?—Progress.
[2343.]—LUBRICATORS.—I shall deem it a great favour It-c me of your numerous correspondents who are qualified by experience of Roscoe's self-acting lubricators will nd\ i»e as to the following:—1 am the ownerof a 10-horse traction engine, and have had one of Roscoe's No. 2 lubricators fixed by a practical mechanic on the top of the dome—the engine was built by Fowler, of Leeds; my driver received the instruc
tions from the mechanic how to work It When tallowis put in (when there is steam) it la all blown out ov«r the top of the engine. The fire is kept on in t l»e engine all niulit, so that we cannot get any tallow os% the lower end of the lubricator before the end < -f ttao. week; also, will yon inform me the best way to Appl.ft the needle lubricator to ths motion bars—the present oil-cup is fixed in the centre of the bars? I lin-l the needle lubricators act first-class on all the bearfa/ra at the engine, and are most Invaluable. I would advise all owners of engines to have them applied, aa they are moderate in price and most simple to fix. and when filled a quarter of a pint will last a week.— ProGressive Age.
[2344.]-CYLINDER.—Perhaps some of myfeTlew readers will give their opinion upon the following form of cyl'.nder—It occurred to me a day or two bark. Possibly it may be nsn'ul to some who cannot bore &
true cylinder:—A A is a long cylinder sliding steam titrht in the outer cylinder—it is made steam-tight by glauds, tho same as in the piston-rod. Steam bttugadmitted at one end of the outer cylinder, it nnturally acts upon the inner one as on the piston of other engines.—W. H. Thorpe.
[2346.]-REPTILE8.—Will some reader give me a diagram. Ac, showing the geological distribution of reptiles throughout the globe? -lynx.
[2346.]— GEOLOGY. —,Can some ono mention the name of a good manual on geology—price about 10s.? — Permian.
[2.147.]-THE TELESCOPE.-lst. How can I ret my telescope set exactly north and south, also east and west? It is fixed with cement into the top of n large drainpipe tilled up solid, to which is attached a trianglo ol iron with legs—one ateach angle, one of which, much longer than the olhcrtwo, is let into a large square of freestone, and fixed with lead. The whole telescope, stand and all, can move round this leg to any distance* and can be raised or lowered by. means ot two nuts as* much as needful. The two other legs rest on pieces of tin, and can be shifted east or west, as required. 2nd. Wishing to look at the sun, I took out my "flat " and" removed all the silver and then replaced It, aud then found that by using a piece of coloured glass between my eye and the power, I could do Bo with little or no danger to my eyesight—at least, so I think—am 1 right or not? 3rd. How can I convert north polar distance Into north or south declination ?—H. A. C.
[2348.]-ELECTROTYPES.—r thank "Sigma" for the ready way in which he answered my question. Ifc is the outer surface that I meant, and not the one in contact with the monld. so I shall have to make my nmulds on a different principle, as he says tho onter surface is generally rough, and the articles I am coating are small wax hemes in the shape of a man. so that the inner or smooth surface is Inside, and is not seen, while that part that is visible Is the outer and rough surface. Will he kludly tell me bow 1 should make moulds for this purpose, aa it seems to me to be different to making medallions, which I can manage very well ?—E. R. H.
[2119.]—BILLIARD BOARD.—Can any of yonr readers give me some practical advice on this matter? How to set about making one, and the modua operandi? Where to obraiu a slate bed of 8ft. by 4ft., and probable price? Is not also the cloth very expensive if wanted for a larger-sized table? Can you buy the cushions ready made f Guess (excuse the Ynnkeeistn) there be a proper place for each of these things, but wliero is it, and how do you work tho oracle F Any information will be very acceptable. If a billiard table oi an average character could be economically made by an amateur, doubtless many of your leaders will feel Inclined to try it.—Cantab, London.
[23S0J-RA1SING WATER.—What is the best and cheapest way of raising water from a well 30 \ards deep ?—W. S. O.
[2351.1—ALCOHOL.—What is the best chemical te»t to find the presence of alcohol in any kind of liquid? —alcohol.
[2352.]—OVAL.—now can I get a correct oval, and whether the width Is governed by the length? lean strike them several ways, but they are not correct, as 1 think an oval should not contain any part of a circle, —G. Hunt.
[2353.]-WORIC ON THE VALVE.—Does any reader know of a work in which I could find a cumulation on the dead weight valve. Sav, suppose I have a Sfn. dead weight valve to fix jo a boiler, and to be wegbted to 801b. By what rule am I to make my calculation?—John Kershaw.
[2354.]—SPRING STEEL.—I wish to temper a large quantity of springs, similar to tho bicycle spring upon which the saddle Is fixed. As I cannot make these sufficiently elas'io by tempering in the smithy fire. I should be very much obliged If some experienced hand will give me the best shape of oven, Ac, for this purpose, with description how to go about my work to accompUsh this object.—Brittle.
[2.155.]—CANOE BUILDING.—Will "Steersman" or otie of my fellow readers be kind enough to inform me what wood is best for the keel and ribs, also the dimensions for the same for a wooden canoe nhout 20ft. in length? I have examined several, aud find the keel is curved at the end* to form the bow and sternpost. How Is this managed, and how are the ribs bent to their proper size? A section would assist me very much.—c. D. R.
[2356.]—GOL D.—I have some gold In a finely-divided state mixed with sand. Will some chemical contributor inform me the easiest way of separating the same—
XETTTOD OF COPYING STATUARY IN VARIED POSITIONS ON ONE PLATE.—I e«n beat explain my method by giving my first experience. I had occasion to make some card copies of a small marble atafoe of the "Greek Slave," and thinking It would make a much more attractive picture if it could be copied in a variety of positions on one card I resolved to attempt It. I took for the background a atrip of dark bTown cotton velvet, arranging it so that the lower portion covered the top ana hung a few Inches over the edge of » small srand. Placing the image on the centre of the stand, I got the proper slip and focus with the ordinary camera, and made a (hint maTk around the base on tue velvet, then moved the image to the right and left of the firat poaitlon, Mnfr careful that onf- position should not interfere with the other, «m4 marking around the base each time, that I might kholr lost where to place it In the subsequent operations. I then prepared and exposed my plate, covered the camera, moved the image to the nextposition, and exposed again as before. On developing my plate, I found I had a remarkably flne negative of one object in three positions. AlmoBt aay number of positions may be obtained in this way, but the time of exposure mast be lessened as the number of positions Increase, and each poaitlon ahonld receive an equal exposure. Whether the idea fs n)w to every one I Cannot say, frtrt that ft may he a useful one to many is evident. To such I give It. Those who photograph statuary for the stereoscope would do well to try It.—S. W. White, in Phil. PluA.
IWriiTJKNOE OF SEWING MACHINES ON HEALTH.—Some prejudice has been excited against the uae of me.wtng machines on the score of their alleged Injurious etTecta on health. As the result of some investigation on the subject, we [British Medical Journal) may avow our conviction that these statements have been greatly cxagnerated. They apply, we believe, chiefly Co those worked by one foot only; and we are qntce unable to discover that there la any kind of objection on the score of health to those In which both feet are employed. Tn America, where tbe nae of machines is yet more common than with us, the attention of medical men hns hcen a good deal directed to the subject, and with, we believe, tolerable unanimity of reault. Aeainst the double pedal machine in common use in .'England, ft" far as we can learn from Inquiry amongst those who have had tbem !for many years in constant employment, there Ib not the slightest evidence. Of their sauitary advantages in saving time from a sedentary and very tiresome occupation, and thus favouring relaxation and exercise, it la not •ecessary that we ahonld speak.
THE AMVTEUR MECHANICAL SOCIETY.— The Brat an mini druner of this society took place on Thursday, th 117th inst., at the Freemason's Tavern. Great Queen-street. Among the members present! weinHenrv I'erigal, Esq.. F.R. A.8.; Colonel Clarke, CSlpt Sandemau. and many others.
NEWDISINFECTING APPARATUS.—■*!>. George Fraaer, of tbe linn of John Eraser and Sons,exhibited and explained at a recent meeting of the Medical Officers of Health Association a new apparatus for which he has recently obtained a patent. The object, Irlo supply a ready means of disinfecting all clothing, bedding, 4c, that may have been used by persons suffering from fever or other infeotious disease, it aach apparatus were erected in all populous districts, it is highly probable that the spread of many diseases, would be considerably cbeckad. The apparatus and' iu working may be thus briefly described:— A brick oven or chamber occupying a space 8ft. square, is erected, in the lower portion of which is a covered fur-l taaice and flue capable of raising tbe Internal atmosphere to the required temperature, tlve front beingenclosed with a sliding door. A closed truck or car-' rlage is provided with shelves, racks, and doors, and1 it is intended to collect the clothing in these carriages' from tho infected houses, and convey it to the chamber. The front door is then opened and the truck placed inside, the fire lighted, and the process of disinfection takes place, sulphur or other fumes being used. When the process is completed, the truck i» su»sUi taken to the house and the articles removed. The chief points In this patent are: I. The whole of the vapours given off during the disinfection are, by a peculiar arrangement of flues, made to pass through (lie furnace, and are thus consumed. 2. The clothing la not removed from tho truck until returned to the owner. 3. The carriage which convoys the clothing and retnrns the same to the house from which It was taken, ia itself disinfected on each occasion, with the clothing, &c. 4. The apparatus is not expensive.
VERMILION -The blackening of vermilion which has given many much trouble, Is caused by the decomposing action of light, being analogous to the darkening of the silver salt fn photography, and it aay be entirely prevented by mixing one-eighth part of flne flowers of sulphur with the dry 'vermilion beforeaUdlngth.-oil.
DES1LVERING.—In many cases it may be useful to know a liquid which will dissolve silver without attacking copper, brass, or German silver, so aa to remove tne elfver from silvered objects, plated ware, etc. It Is simply a mixture of one part of nitric acid with six parts sulphuric, heated In a water-bath to 160° Fahr., at which temperature it operatea beet. By thia means the old silver attached to plated ware, old d aguerrcotypo plates, etc.. may be removed and saved without any necessity lor wasting acidB in dissolving a large amount of Ussicsb metal.
CURIOUS FACTS IN REGARD TO SOUND.-The following curious observations In regard to tbe transmission of Bound have been car»fully verified by an extended series of experiments: The whistle of a locomotive is heard 3.100 yards through the air j the noise of a railway train, 260 yards ; tho report of a musket and the bark of a dog, 1800 yards; an orchestra or the roll of a drum, 1601) ynrds ; the human voice reaches to a distance of 1000 yards j the croaking of frogs, 900 yards; the chirping of crickets, 800 yards. Distinct speaking Is heard in the air from below up to a distance of 800 yarda ; from above, it is only understood to a range of 10i yards downwards. It has been ascertained that an echo ia well refloctod from the surface of Bmonth water only when the voice comes from an elevation. Other similar phenomena In connection with tho transmission of sound have been observed, but the results disagree either from Inaccuracy in tho observations, or from the varying nature of the circumstances affecting the numbers obtained. Suoh variations occur to an extent of ten to twenty per cent, and even more. The weather's being cold and dry, er warm and wet, are the chief Influencing causes. In the first case, the sound goes to a greater, and, in tho second, to a lesser distance.
DR. USSHER'S ADVICE—To be pasted on the flyleaf of the EfJOLtSH Mectiamc and all other books— "If tHou art borrowed by atrMnd,
Right welcome shall he be
To read, to study, not to lend.
But to return to me.
For oft tmonf ted knowledge doth
Diminish learning's store.
But books, I find, I often lent
Return to me no more."
Read slowly, pause frequently, think aerlously, keep cleanly, return duly, with the corners of tho leaves not turned down.
THE MANCHESTER STEAM USERS' ASSOCIATION.—We have Just received tbcannnal report of this useful association. The report says that during the past year 58 boiler explosions came to the knowledge ot the officers of the association, which boilers Were not under their inspection. By these explosions 80 lives were lost, and 126 persons were injured. There can be no doubt that the association does good work, and not only the steam users, but the country is indebted to It—in the first place, on account of the accidents it Is instrumental In preventing; and secondly, for the practical information It distributes through the press monthly for the benefit of ail.
THE SUN.—Never, surely, says the Aihmnttm, has the sun been so mnch looked at as now! In Europe aud America, in India and at tho Cape, In any place where there are telescopes and spectroscopes, and astronomers to use them, there tbe sun Ib closely watched. At Kew Observatory photohelingraphy Is a part of the regular dailv work nf the establishment, and from tfme to time the results, and the conclusions they warrant, are laid before the Koyal Society. Out of all this, It is thought that onr knowledge of the Sun's constitution must be Increased. All possible advantage will be taken of the eclipse of the sun In December next; and under Instruction from scientific committees, parties will be sent to Algiers to make observations, aided by flic best of modern appliances. Meanwhile, Father Seeehl. of the Observatory at Rome, is publishing evory day a picture of the Bun, in which all the visible spots and all the prominences, with their chances, arc represented. A daily solar bulletin, though a rough one, may perhaps be useful.
HYDRAULIC PRESSES. -The hydmullc-or, as some persons erroneously term it, the hydrostatic— press was patented by Bramab In 1706. It has, therefore, been known to tho world, the Engineer says, for seventy-four years, anil Is bow applied iu a multitude of operations, which absolutely eonid not be performed at all withont it. Presses everting a force of 500 tons, and having ranges Of 10ft., 12ft., or even 15ft, and being capable of exerting n force we have named at any part of the stroke, are by no means uncommon. Wedon.it stretch a single point When we say that no arrangement of screws or levers would supply ns with a press of equal I'aTgo, power, and speed. It Is no', that an aTat>g«MiH'nt of levers could not be planned quite able to exert the strata of which we speak; but sueli an arrangement would lack all the characteristics whfflb are ossoutinl to a mechanical device Intended to serve tho purposes of manufacturers. For example, had eh-; work done In raising the tubes of the Britannia Bridge been performed by a simple lever, one arm mtlst have been '41s,'<(i:ft. longer than the Other: and to enable a Th to raise the load through 100ft., the lb must have passed through space for a distance or Rl,ft*22 miles In simplicity, in cheapness, and in eftieiencv. the hydraulic press stands totally without a rival. Whether assuming the form of the gigantic apparatus employed in bending-armour plates, or that of a little JOcwt. jack, it is equally coinpact, inexpensive, andolegant.
JLNSWERS TO COKRESPOOENTS.
HOWARD RYLAKD, OF BIRMINGHAM.
A Mb. Howabtjrtlam* offered last year, through our pages, to supply for 13 stamps a key label, embossed with name and address or tbe sender. Advertising nt first from Union Chambers, Union Passage, Birmingham, Mr. Howard Kyland afterwards—probably for very good reasons—changed bis address to 79, High-street, Birmingham. Fi*e correspondents hare written tons, stating that the? sent stamps to Mr. Ryland, but cannot get their labels. Two of them have addressed tbe police authorities on the subject, and have received the following letters! —
*' Borough of Birmingham Police Office. 1st February, 1870.
"Sir,—Sergeant Jeans reports that U. Ryland hasan office at High-street. Birmingham, but has not been there for sit weeks. The last time we heard from him was from Hereford. His letters are called for by his rather. There u na doubt but tfut they are strindtert.—Yours truly,
"G. Glossop, Chf. Sapt., J.i., CC.
« Mr. ."
"Borongh or Birmingham Police Office. 20th Jan., 1370.
"sib,—In answer to your letter of the 19th iostant, I beg to say that our Sergeant Jenns has bejn to Union Chambers, and finds tlutt a Mr. Ryland did live there ahout tlmt time, but has since removed to Hereford, bat cannot ascertain where, Several persons hare been making inquiries fur him since he left, upon the some subject, and no doubt he w a swindler.—Yours obediently,
« Mr, .*'
It will be seen thtit for several weeks past we haTe given ettracts from advertisers' letters, which have been sent to ns unsolicited; in faet, wc know nothing of the writers of these letters personally; they all agree that the Kkgltsh MeChanic is an excellent medium, for advertisers. The follow* ing is an extract just received :—
• ANOTHER TESTIMONY.
VELOCIPEDE BRAKE-CHAIN.— When we be^nn to advertiae, we had no iden of tho larrem'lifi.g power of your journil. By its use w« have received applications for onr brake-chain from all parts of the Throe Kingdoms, and from all aorta and conditionsof men; while numerous testimonials to Its utility ntt-'st the favour in which it is held. Wo are ooafldant that if we bad gone to work In the Blow and old-fashioned method of introducing It to the dealers and leaving ft. iu their hands, years would have elapsed before we had done as much as we have done In the last few months. Among others, we may mention that the chain has been adopted by His Royal HighneSB the Prince Imperial of France, who has honoured us by expressing himself most unqualifiedly in its favour, We congratulate you <>n your enlargementand Improved appearance.—David Harcoitht and Co,, Crank, sash, and Shutter Chain Manufacturers, The Loz 'lis, near Birmingham.
TtfK SixPRNNY Sai.k Column is the only part of the paper in which can appear Queries sent by John Steward, "Briyhlouiaii." "Oluybnoku," "Scrihn" '3rd and "4ta queries), W. R. Harvey, J. Wroe, " Mosac,"'* Kola Nut," '■ Albertu* Magnus," ;< Fred," " A Youth," E. Williams.
A, R. T.—We know nothing of tho savings bank you allude to. Custom, which is sometimes morcpowerful than grammatical rules, has decided the pronunciation of the words you refer to.
A Xouho Our..— Read recent papers on the "Earth, its Figure and Motion."
ScaiBO.—First query inserted, second has been replied to recently; third and fourth we cannot reply to. We do not answer hy post.
pRinTtn.—Fail bairn and Co. (see advertisement).
It.NonA.MU8.—Sec recent bark numbers.
Coaaosiorr.—See 'Useful Notes."
AMATKua cannot surely hive read Mr. Proctor's papers on the earth, concludrd in our last.
Swimmkr.—Sell your gold chips and buy a chain. To use your own words, "it would be cheaper."
Gko. Davis.—You are to lie applauded for your fidelity to Dr. Bedford, hut your latter, which contains insinuatioas, would lead to no good if inserted.
A Fbikwd Ok Tiik Gvveotob writes us a letter in which he says that a poor man whom he knows has invented a wonderful machine, which will save millions of money; and he wants us to give an opiuion on the worth of the intftnx If the machine is so valuable, it should he protected hy patent, and then its value will mainly depend on tho demand for it. But all that glitters is not gold, and particularly that which fascinates the imagination of inventors.
W. M.—Elementary information on taking photographs was given some mouths since.
Old Dip writes so indistinctly that we hare been reluctantly Obliged to drop his letter into our vsry capacious waste basket.