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into the hopper of common sense, comes out in the following simple shape:—How lone will £S7 at 5 per cent, compound interest take t< income £'>l)()0? Surely, uot even " Algebra" personified w tlJcirt* that algebra is wanted for such a common-place bi . arithmetic as this, an ordinarr interest sum. Five per cer jn £87 will he S7 shillings; add this to £S7 and we have £P /s. This is one vear. Then 5 per cent, on £91 7». will .ie£'10s. 4d. Add thisto £91, Sic. This makes two years. We have only to go on with such augmentation, till we get £2000; and then '■ Algebra" will know what time it would take. It would be a shorter "time," both amassing »nd doing, than he seems to think; and I purposely avoid all " fancy" modea of calculation; 1 ^n on the moat humdrum footing. But we need not pursue the problem, since it is abundantly clear that our friend did not first ask himself whether his own case possessed even possibility Thanks to his own beclouding algebra, his miud failed to discern that his compound interest not only need not grow where he wants to put it, hnt also really it would never exist at all jn relation to the £'^000; of which the superabundant yearly influx of £167 is the proof. In this manner, in the problem of every professed algebraist, there is always some stnltifying element, some groundwork fatal to his owii platform, so that the hypothesis dors not even exhibit verisimilitude. The "problem" is always as if I propounded, Suppose a man had no mouth, and could only drink through his note? then how many peeks of fried potatoes would he cat ?" Eat? you say; how could he cat?" So also our " Algebra's" compound ntercst is the eating without a mouth. The science (excuse plainness) is all rnbbith. The French Institute decreed that phrenology is too vague to be called a science. Algebra is like phrenology; and, if it would not be civil to say they are both humbugl, we may certainly say they are both mistakes. —Gihel.

[412SJ.-DISTILLED WATER.-"Moses" may make a cheap and handy apparatus for tliis purpose bv soldering down the lid of a tin saucepan with a hole cut iiito the top, nto which a pipe is firmly fastened. Then he should get a small tub—a butter cask for instance—and bore a hole in the side an inch from the bottom. A few yards of ordinary gas-pipe, with one end passed thoough the hole in the tub. the other luted on to the pipe in the lid. and the remuind r coiled up in the tub, will complete a still which I think wil 1 answer his purpose. The tube should be filled with cold water (which may require changing now and then), the saucepan three parts full of water put on the fire, something placed at the end of the pipe projecting from the tub to catch the distilled water, and his apparatus will go on with its work without requiring much attention. Of course an old kettle will do as well as a saucepan, and anything that is watertight will answer the purposes of tho butter tub—Saul Rtmea.

stamps by steam such as are used in the Black Country for stampiug tea trays, waiters. Sic. ?—C. D.

[4139.]-STAINS IN VEXEF.R,-Will any brother reader kindly inform me the best way to remove stains from veuecriBg without injuring the wood'-—J. B.

[4140.]—FOREIGN CARMINE.—Where is it made, and how?—A. P. S.

[4141]-KLLIPT0GRAPII.—I have been looking out for some time for an instrument that will describe ellipse, such aa is used in isometrical perspective drawing, but have not yet seen a really practical instrument Could any of your readers inform mo if such an instrument has been made that answers the purpose better than drawing lines through points by the hand, or by the compasses from four centres? — Thomas Smith.

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[4123].—SOLDERING.—Tho proper dux for brass is borax mixed up with Bath metal solder. If the brass is of inferior quality he must use nearly half black solder, which is generally called spelter soda.—J. M.


[4127]—MOUNTING CHART—Would anv reader inform me how charts, Sic., are mounted on cloth, and the kind of cloth which answers best fur the purpose; I have tried several times but owing to the paper expanding anil the cloth contracting when wetted, they do not lay quite smooth one on the other? I should also like to know'how to varnish charts and drawings. What sue and varnish should be used? —constant Reader.

[4128.]-WATCHMAKING.-Will " Nobody," or any kind subscriber kindly inform me how the jewels are fitted to the plates of watches? I know it is the custom of country watchmakers to aend their jobs that require new jewels to London and have them fitted; but I should like, i f possible, to be able to fit them myself. Another question I should like answered if any brother reader aan do so. What aiu I to do with a watch that has bad a magnet applied to its balance; since «hen it has lost about an hour every day. I have been iuformed by a friend that if all the steel in the movement is dipped in a liquid prepared for the purpose, and theu cleaned in the usual way, it will go as well as ever; but, unfortunately for me, ha cannot recollect of what the liquid is composed. Can any reader inform me?—Compensated Balance.

UlafAj-FISHERMKN'S NETS.-Would some obliging reader inform me how fishermen make their nets, as I wiah to make some for the garden. A small sketch showing how the twine is passed would be of service; also what stuff to make them of to prevent them rotting?—Scolopendrium.

[4130.]—FERN CASE.—I asked lately for a design for a Wardian case for ferns and moss, and received a replv, bnt the design though substantial enough is clumsy and anything but a parlour ornament. Perhaps you would be kind enough to reinsert the query?—Scolopendrium.

[4131.]—SUNDIAL.—At what angle should thegnomon of a dial he placed so as to cast no shadow on the longest day at mean noon supposing it to be placed exactly opposite the point in the horizon where the sun first appears on June 21.— W. H. C.

[4132.]—TELESCOPE.—Is it good work for an 8jin. rellector to pickup Jupiter when only 9° of the sun, and at what distance from the sun ought the same instrument to pick nji Mars and Mercury —W. C

[4133.]-SIDEREAL THIE.-IIow to set a sidereal clock at exactly sidereal time, and how to test its performance ?

[41340-STAINS ON CLOTH—Will a brother re»der kindly inform me if there is anything for removing the red stains from black cloth caused bv diluted sulphuric acid or sulphate of copper being spilt on it? -II, A.

[4135.J-STEAMINQ BOTTLES,-I want a small boiler to steam dirty bottles in a tub. Can any of onr readers give me a hint how to plan one that will not eost mnch, and also state what pressure of steam it will require to boil the water in atnb containing—say 40 gallons?—Simplex.

[4136.]-EGG HATCHING MACHINE.-Would some one of your readers give rae the Information in detail of how to make an egg hatching machine, with the particulars of the process of working, and oblige?—P. G. M.

[4137]-BRAZ1NG BAND SAWS.-Will some kind correspondent give me instructions on brazing hand saws?— Subscriber To New Volume.

[418«.]-DESIGNS FOR STAMPING TEA TRAVS. &c. —How could I obtain some good designs for the working of

[4143]—DYEING WOOLLEN CARPETS.—Can any kind reader inform me if there is a work published that gives in detail the processes of the printing and the dyeu.^ of woollen carpets, &c.?—Amicus.

[4143.]-POTTERY.—Will someone be to good as to tell me how many degrees of heat are required to bake an ordinary china plate, and to give mo the calculation whereby this number is arrived at ?—Minnehaha.

[4141.]-FIRE CLAY—Will any fellow reader kindly inform me how to make fire clay and earthenware on a smafl scale as I wish to make some pipes for water?—Amicus.

[4H5.]-01L VARNISH.—Will some "brother" kindly inform me of the best known oU varnish for oil paintings of value?-J. 8.

[4146 ]-BOOKS ON PRINTING—Would anv brother reader tell me where I could procure a good work on printing for young beginners? I know of one, hut the price it 7i. Gd. I want something at about 2s.—Young Printkr.

[4147.]—COIN OR MEDAL.—Will one of vour nunii.matic readers tell me what the fallowing is? It "is not quite so large as j farthing. Obv.: sinister bust prolile of George IV. nndraped, laureate! legeud—Georgius IV. Dei gratia; 1827 under head. Rev.: Brilariia sea'vl ou shield with, trident in left hand, right hand on shield, rose, thistle, mid shamrock conjointly liuder. Legend: Britannia Vox. Fid. Dcf.— Energue.

[4148 ]-RAMSBOTTOM'S PISTONS -I want to know if it is possible to change the rings of Raiuabottoni pistons without taking them off the cylinder, and also if it is possible to make the Cornish high pressure valves to work with one face, as the two faces are always getting out of order ?—One In Need.

[414!)]-ELECTRICITY AS A RKMEDY FOR EPILEPSY'.—1 should feel grateful to " W. A." or any of your scientific correspondents informing me if electricity is a remedy for epilepsy, as I have been su'Jering from it S years, anil am tired of doctors, besides having lost a good deal of my hard earnings, and received no benefit ?—T. M.

r4150.]-I10ILER rEEDlNG.-Ca.i any correspondent tell me of any method of getting water into a boiler containing compressed air without the use of a pump? A speedy and intelligible answer will greatly oblige?—Amicus.

[4151J-BOTANICAL QUERY.—Will some botanist kindly tell me which of the Urchidar it the following. It answers in most particulars to the description of the "Orchis ustulata," only great stress is laid in botany books on its dwarf growth, whereas my orchis! i3 decidedly tall. Sepals dark purple forming n helmet, inrluding the two sin il 1 petals, lip white, spotted with purjile, deeply o-eleft; spur, short; bracts, about half as long as the germ, upper ones/purple; spike, oblong, rather crowded; root knots, two; leaves, green, lower ones, broad and egg-shaped; height, from 8 to 10 or 12in.; Habitat, meadows in North Yorkshire.—E. M P [4152.]-MANUFACT11U\G GAS FROM VEGETABLE SUBSTANCES.—Can any of your very numerous correspondents tell me where I can find an account of the method of making gas for illuoiinating purposes from waste vegetable and oily matters. I am informed that Paris is partially lighted with such gas; but I cannot learn how to make it. I wish to learn the method thoroughly in order to practise it abroad in the wilds of South America where I am going. If • it be an Eogliso patent, I would, of course, willingly pay for permission to use it.—Diego Uson.

[4153.]—COLOURING WIRE.—Will any kind reader inform me if there is any fluid by which I can coat, or stain Iron wire a dark straw or brass colour; also, what is used for colouring pins?—A. E. O.

[4154J-ENGRAVBD STEEL PLATE.-I have a valuable ateel plate which, after having had some copies printed, I wish to preserve for future use. Will some correspondent tell me how to prevent its rusting. Sec.? It has been returned from the printer's slightly covered with wax.—II. W. H.

[416.5.]-PHOrOGRAP'niC AND DISSOLVING VIEWS. —Could any of our friends who understand optics assist me? I want a half-plate lens for taking photos., and a magic lantern. Is it possible to have the two combined in one lense with a 42in. condenser? Could any of our kind friends inform me where I could get the lenses, and their cost, and if it is really possible to have the two perfect lenses combined In one?—A Subscribes.

[41S6.]-BOOK ON WATERWnEELS.-I shall be obliged il any of our fellow readers can refer me to a good practical modern work ou the construction of waterwheels, in either the English, French, or German languages'—


[4157.]—REED ORFAN.—Having read the various articles by our talented contributors upon the pipe and reed organs and harmoniums. 1 have come to trie conclusion to bnild one of these, and as I have not tho room at ray disposal for a pipe organ, 1 have thought of a reed organ, the (free) reeds of which I would enclose in short pipes. I want 2 manuals and 8 rows of reeds, the stops, I should like being double diapason 16ft., flute 8, fifre 4, bassoon 8, hautbois 8, flute 8, clarion 4. Should the pipes be circular, or would a uy difference be made in sound by making them the shape of the reed frame, a ad what would be the sizes and modifications required for the various stops, also, should the reeds be fixed at an angle with the axis of the pipe, or laid horizontally within it. Would tho " H. B." oblige by giving small diagram of tuning-screw action in Myers Eolophons, and could 1 apply it to the pipes. Also, about what size would the Bound board require to be, as I intend to follow " An Adept's " instructions in the woodwork." If " II. B.," "Eleve," or any of our talented writers would favour me with their advice, they would greatly oblige.

[415S.]-WATER PUMP.-Will any brother subscriber give a rule for finding the number of gallons a pump will lift per min., having a loin, steam cylinder, a 8in. ram, lOin. stro£e, making 20 strokes per niiu.—One In Nerd.

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l belongiug to a telescope.

I hareimohjfc class belongiug to a telescope, which is rendered useless br having a numberof scratches on it. Will some of your hoi readers inform me how they can be removed? If it ii necessary to grind and polish it again, how is this done,sal what tools would be required ?—E. G.

[4167.1-EMIGRATION.—Will Mr. R. Smith, or anrolirbrother reader, kindly inform me where I can obtain, the be*' work on the cultivation of Indian corn and other Amcrieui frrni produce, and also the best work giving the lores! anJ most reliable description of the United States genrrillt, and the newer States in particular, naming the puoliihir and price in each case?—Kansas Emigrant.

[4168.]—THE VALUE OK A TESTRIL—Will Mr. Ifafrey inform rne the exact value of a Tejcril? The coia il mentioned by Thakcspeare in "Twelfth Night," Act iLscea: in—B.

[H69.]-RUSTED JOINTS.-Can any brother mbscriber favour me with how to makes mated joint?—Amo Votu.

[4170.]—SMOKE BURNING.—I should be mart obliged to any subscriber who could give me a few hints about the construction of smoke burners in a'ateam boat theanoaii: of air-heating surface, See. ?— Enoi NEER IN A Foo

[4171.]-CHEMICAL.—Will one or our ever o%»r chemical servants kindly inform me how I anf mt&l MnSlU into MnlKM. My object being to make auapair sulphate by thit meant ?—Manganic Oxide.

[4172]—BORING BAR.—How is a boring bar ispjortd in order to bore out the brasses (while in their pl«»! » w" standards, so as to have them true with each ouia.Unpractical.

[4173.]—CLEANING GALVANISED VESSELS.-On behalf of one of the geutlcrsex, I ask is there any weans of cleaning a galvanised vessel used for washing.' When the clothes are being boiled, a kind of scum attaches itself to the clothes and is almost immovable.

[4174]—GEOLOGY— An ere witness to the sinking of a coalpit in west Cumberland. Materials were broagtit to the surface from below, slate and shale in abundance, wits datinct traces of vegetable matter, such a* leaves, anil rrra stone fruit, but changed or petrified. Al adept!of i'tfl/cet from the surface the mines come upon two trees, as "■•? «• expressed thern "Like two gsce posts," which were brought to die surface in fragments, but sot a trace of the woody fibres could I discover, except the internal Hating »ad the bark eppureutly changed into coal. Perhaps some of your noracroos Borretpondcnta couKl solve this problem, How lo»S '■" ince those two trees rlrst grew that were foutuUtO feet below the surface?—Veritas.

[417.->.]—OLIVER CROMWELL SHILLING -What it it worth? A sivpence fetched about £20 a few years back at t, Christies— ConraKV.

[4176,] — CALLAXD? GRAVITY BATTERY-Will "Sigma " or some oilier correspondent give me a descnptic-u of Calland's gravity battery mentioned in No. 37*. folio M», and also statu the length of wire to be wound on the ptn'H(; lum of Bright's electric clock, described in Vol. IV., folio 39b 1 John Davies.

[4177.]-BEES AND BEEKEEPING.—Would "Anon" ("Replies to Qucrira " No. 3913) kindly inform m» of w.5°,ra Pavnc's " Bee Book " raav be had, and the price j and could he tell me whether an entrance hole should be made ill a duple1,' or whether the bees should enter through a lower hive Could lie tell me also the proper size for glasses to set over duplets, and how long they may be taken ?—Apiator.

[4178.]—MALLEABLE CAST IRON.—Will any of my brother readers inform me if there is a wort published on malleable cast iron? Any information wiU be thankfully received?—Castor.

[4179J-CRAYON DRAWINGS.—Will any subscriber kindly inform me how to use coloured crayons, how to lav on the colour, when to 'ise the stump, and if when finished to wash it over with anything?—Wishart.

[4180.]-A NEW COMET.-I read the following '-" Brussels paper :—" Dr. Winnecke, of Carlsruhe, has just i«r covered a new comet, which it only telescopic. This comet i* situated on the eatt of the tun, above the constellation ot the Pisces. It can be obterved only after midnight, and a lo*v power will show it. It has the appearance of a nebula whose diameter was 113th of the moon's on the 29th of »'* last. The movement of this comet seems to he in a l'l*:ie nearly perpendicular to the celestial equator, aa its movement in declination is teu times greater than its movement in right ascension. Ou the 20th of May itl movement in declination was a semi-diameter of the moon. This comet has no tail for the present." I anxiously waited for the last number of the English Mechanic to see more details about ton comet -, but no allusion is made to it. Has any of our astronomical friends seen it?—Foreigner.

[4181.]-CALCULAriON OF BOILER PRESSUREWould some one name to me an engineer's book that would give me the method of calculating correctly the pressure on boilers by size of valve, and length of lever and weight ot ball, as there must be above one way of calculating; 'or instance "One in Need" proposes a question and get* * weight of 681b. from one, and 671b. loot, from another, ano 581b. 184 deg from another as the weight to be placed at the eud of lever,—Throttle Valve.

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r*t82.}-MARKING BOILER PLATES.—Any reader who raiy he acquainted with the practical methods of mnrking the templates for boiler plate* wil! greatly favour rue by cxnliimin* bow it ii done, (riving any simple rules and constructions fir driving the various lines which may occur to him. As an cinraple, he could take the case of a Cornish boiler having the shell plate* cylindrical, and the flue plates conical, and also carrying a dome on the top. There will, in this case, I suppose, be four templates, nz., two for the shell, one for the dome, and one for the flue.— Template.

[41RS/J-CHARCOAL BISCUITS.—Can any of your - ■ vtt.Ts oblige me with a good recipe for muting charcoal biscuits?—¥. C. R.

fiUHj-LATRE WORK,—If some knowing one at work would answer these questions I should feel obliged: — flow are those two beautiful ivory cups turned in case B. No. 26 in the Kensington Museum -. is it by the swash plate? I bought in Switzerland at a little shop in the mountains from a wood carver, & match box. From the finish and the moulding!, it had been done in a lathe. But how? He would not tell me, but said it was very difficult. This I do hot believe, or he would have charged more for it. neither was he a man who could invest in an expensive machine; so I know it was simple. The cross section is a flat oval, with a moulding turned at each end. and the lid fits to perfection. The inside is simple enough in the eccentric chuck; hut the orktside beats me. I see in last number, June 10, a lathe for *-vie with eccentric chuck, with cmndrants. What are quadrants to a chuck; and what is the principle of Lowe's rucdullion cutter?—J. P. G.

[4186.]—SILVER COIN.—Will some numismatic reader Lindly inform me whose the coin is of which 1 enclose full


sized copy? It is, I believe, a Rnmnn denarius, rather thick, and of pure silver. Is it rare?—H. R. G.

[4186-]—SHEATIT1NG IRON SHIPS WITH COPPER. —With reference to No. 3466, page 140 of present volume, may I ask "Patience and Perseverance," or any other willing to oblige me with the information, who is the patentee or inventor of the plan for covering ships' bottoms with a thick coating of some adhesive material painted on hot, and copper in minute particles, dredged on and rolled to make a smooth aurfneo; aW, bow long is it since this composition Whs first tested or made public. Any information on the subject will much oblige?—J. M. -o.

r4t87/)_STEAM CARRIAGES.—TO G. PREW.—Would G. Prew, whose steam carriage is illustrated in last week's paper be kind enough to favour his fellow readers with a more minute description of it, especially the boiler?—Liiti.e John.

r4188.]-50FTENING ASH TIMBER—I want to bend some ash timber Sin. square; boiling or steaming does lot make it soft enough. Would any of our chemical writers inform roe if anything could be put in the boiling water that would make the timber softer?—J. L. B.

[1180.]—CONDENSER.—I should feel greatly indebted to "Sigma " if he would hare the goodness to inform me what sire of condenser I ought to make for a coil of the following dimensions:—Iron core 6in. x Jio.,3 layers ol" primary wire and 21 layers of secondary, half No. 30 and half No. 32; No. •St) wire being wound on first, aud then No. 32, If he would also tell me what sire of Bnnsen battery would he suitable, 1 should be still more indebted to him?—Elictbon.

[4V.K>.]-EMIGRATION TO THE CAPE AND WEST INDIES.—I shall be glad tnknmv what advantages the Cape, or any of the islands in the West Indies—Jamaica or Trinidad —oETer to an intending colonist? 1 see Mr. Rogers proposfs K'tnsns as a suitable place for emigrants. Will he kindly inform us if the Government ol that State is thoroughly united and settled, and vbetbi r there is anythfng to be feared from the Indians who occupy its western portion?— R. R.

C4lDl]-DOG MUZZLE—Will some brother reader tell me through our Mechamc how to make a wire dog muzzle? I hear of them being made so that the animal can drink and not bite. As hydrophobia is just now very prevalent, aud as the doctors tell us the ordinary leather muzzle tends to increase it. I think the subject is worthy of the attention of my fellow readers.—Bunting.

[4198.]—CUTriNG GRANITE—I have a piece of granite ont of which I wish to take a piece an inch square, and polish i' by hand. Could any brother reader inform me how I can U<> it?—Che incus.

[4183.]—COINS.—Can yon or any of my brother readers inform me in your valuable paper what the two following

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clothes with the intensifying solution above-named. May I also ask our kind Editor to encourage ns much us he can nrticles on photography, as I am sure there are mtiny :imatenr photographers who read the Mf.chanic, and thoroughly enjoy the articles on photography.—W. G. C.

[4193].-SENSITIVE FLAMES—Will you or any of my fellow readers be kind enough to give me some information with regard to the properties of the sensitive flame, and the apparatus requisite for producing it.—F. W.

[4190].—CEMENT FOR FASTENING BRASS CAPSTO BOTTLES.—Will any of my brother readers answer the following V What is the best cement for fastening brass caps on glass bottles so as to stand washing?—Nkw Subscriber.

[4197].—WARVHNG BY MEANS OK HOT WATER — What is the enuse of the rushing and jumpiug noise in the hot pipe from boiler to the (cistern hot) circulating principle? Why docs it not rise as the water heats in the boiler instead of going in pushes? Also, which is the best principle, the circulating or the pressure? A little information will oblige.—A New Subscrirer.

[4198].—GAS STOVES.—In the English Mechanic for June 3 I saw the particulars of a gas stove for cooking purposes. Would " A Dentist" kindly inform, through the Mechanic, if the gas stove would bake bread; if it would I should'ike to purchase ouejwithlfonr cooking burners, as by the description gi\en it seems to be the very stove for economy, cleanliness, and adaptability for housewifes generally. —geo Rue.

[4199] —IRRIGATION.—Can any of your numerous correspondents recommend a pbtnfor irrigating a meadow? The top part, five acres, is quite a yard or more from the top of river. Which is the best way to get the wuter up this yard, as I am disposed to irrieate it if the expense would not be too much. Is there a practical person amongst your readers who would give an estimate of what it would cost, and if not too much I should he glad to have it done.—Geobgk.

[4200].—PRECIPITATING COCHINEAL.— Will some reader tell me what chemical hesiles bichloride of tin will precipitate cochineal. Bichrolide of tin is too expensive and unmanageable. I should al*i be much obliged by information respecting the modt of obtaining a dark for darkish) green precipitate. Arseniate of potash and nitrate only gives a very light, almost white, green, under my hand.—B. A.

[4201].—RED LEAD—Can any one impart to me the means of preserving (ready raited) red lead for ranking steam tight joints in a soft state. Hitherto I have kept it in water, but it alwaya got hard in a few days.—Staem.

[42021.—BALANCING LOCOMOTIVE*.— Would one of your practical readers inform me of a good rule for balancing a four or six-coupled locomotive, fho rule I have been working to is not to be depended upon.—Staem.

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at once by tipping the handle. It is very serviceable for beading out plauts, carrying away cut grass or turf, gathering up leaves, or when manuring the ground. The roller barrow is equally adapted for grass lands where horses and carts cannot be employed, and for croquet lawns, being always sufficiently light to be managed in case of need by a lady. It is in use at the Crystal Palace, Kensington, and other gardens, where its handy qualities have rendered it a permanent favourite.

LIGHT IN RELATION TO OPTICAL INSTRUMENTS—At the usual weekly meeting of the Biringham Natural History and Microscopical Society onthe3lst ult, Mr. C.J. Woodward, 11. Sc, read a

faper on '* Light in Relation to Optical Instruments." le commenced by observing that in order to understand the manner in which light is propagated, the transmission of force by wuves must bo understood, and especially the transmission of vibration by the atmosphere. According to the accepted hypothesis, light is propogsted in a manner analogous to that of sound. The med.ura, ether, receiving the pulsations of a luminous body, transfers them to the retina of the eye, and thus produces in us the sensation of light. '1 he ether waves are themselves invisible; aso-called beam of light being luvi-ible except there bo haze or dust to intercept it. The constitution of aluminous body, us an assemblage of luminous points, was explained and illustrated. The law of inverse squares, und its application in determining the relative brightness el two lights, was illustrated by several experiments. A statement of the laws governing the reflection, ot light concluded the paper.

GLASS NEEDLE-CASES.—The following Is a description of a needle-case that would appear to possess more neatness and compactuess than most devices of the kind. A tube is used of glass, opaque, white, opal, lavender, turquoi.-ie, black, or other colour. The Inventor draws with the blow-pipe a long point at every throe Inches of the tube, lie separates the lengths, and with the tfvrtc of the blow-pipe melts down the point, formiug u nib as a finish at bottom of case, lie then grinds the other end flat, und

smooths In flame; a pnd of cork is poshed to the bottom Of the case to receive the points of needles or other articles. He then places the articles iuslde, and finishes with a peculiar metal spring, slide, scoop, and cap In one.

PRESENCE OF MANGANESE IN MILK AND IN BLOOD.—The presence of manganese, as an essential constituent of milk aud blood (human, as well as animal), has been known for about 20 years past, but M. PollaccI gives in a French scientific journal some particulars about the method of detection of this metal In the two animal fluids referred to, of which milk contains this metal in the largest proportion ; the milk is first evaporated (300 grins, are taken) t» the constituency of a paste; this la carbonised by heat in a platinum crucible; the charcoal thus obtained is pulverised, and next completely incinerated; the ash is triturated in an agate mortar and lixiviated with water. In order to eliminate the salts soluble therein, especially chlorides; the residue is treated with very pure nitric acid, aad the solution thus obtained is evaporated to dryness and calcmed in a test tube; after cooling, a tew drops of nitric acid are added, and the contents of the tube ngaln boiled; next, a few grains of puce-coloured oxide of lead are added, and the liquid again boiled ; a more or less deeply purplish* coloured liquid appears on leaving the tube at rest for a short time, which is due to the formation of permangauic acid. No quantitative researches have, as yet, been made by the author.

TINNING OF IRON WITHOUT THE AID OF Heat.—The chief point of interest In this matter is, that the tinning of iron in the cold cannot succeed at all, unless the bath used for that purpose contains, in solution or suspended, au organic substance like starch or glucose, although no precise scientifto explanation of this indispensable condition has been hitherto

f;iveu; the brrreU employs the following bath—To 100 itres of water are added 3 kilos, of rye meal; this mixture ts boiled for half an hour, and next filtered through cloth; to the clear but thlcktsh liquid are added 106 kilos, of pyrophosphate of soda, 17 kilos, of protochlorlde of tin in crystal* (so-called tin-salt), 67 kilos, of of neutral protochloride of tin, 100 to 120 gnus, of sulphuric acid; this liquid Is placed in well made wooden troughs, und serves more especially for the tinning of iron and steel wire (previously polished) for the use of carding machines. When instead of the two salts of tin just named, cyanide of silver and cyanide of potassium are takeu, the iron is perfectly silvered.—Cosmos.

DECREASE OF THE RAINFALL IN FRANCE. — S. Meuuier states that It appears more and more certalu that the annual quantity of rain in France is rapidly decreasing; the cause is attributed to the cutting down of forests,and to the fact that no sufficient oare is taken to keep the mountains well covered with suitable vegetation, so as to enable their soil to grow trees in abundance.

TELEGRAPHIC IMPROVEMENT.—The Amtrirnn TehqripheT describes a valuable improvement in relay magnets, by W. W. Smith, of Cincinnati. Ohio. The Improvement consists in arrauging the connections of a relay so that the main circuit Is divided, one half passing through each helix, and uniting again on the opposite side, instead of having the conducting wire of the two spools continuous, as in the usual manner. It will be seen upon a moment's reflection, that, by changing the connections of a magnet of the usual form, and arranging them upon Mr. Smith's plan, that the total resistance will be reduced J of the original amount, while the two helices will exert their magnetic influence in conjunction upon the soft iron cores, as usual.

TOBACCO AND ITS ADULTERATIONS.-Aecorrting to John O. Draper, who contributes an able article, against the use of tobacco, to the G-tlazy, for June, tba adulteration of tobacco varies greatly with the character of the preparation. In that intended for chewing, It consists chiefly of molasses or common salt, rarely of leaves of other plants. In cigars and cut tobacco for smoking It is by no mean* common, and consists usually of hay, paper, or leaves of the dock, rhubarb, cabbage, elm, and oak, all of which are, comparatively speaking, harmless. In snuff, on the contrary, adulteration is very common, and the substances used are, in many cases, exceedingly injurious, including such articles as chromate of lead, bichromato of potash, powdered glsss, and different kinds of oohers or oxide* of iron. The lnttor are nearly always found In the Scotch snuffs, and rarely occur In the Welsh and Irish.

REWARDS TO INVENTORS.—Amongst recent Parliamentary papers issued, Is one which gives copies ol reports, aud correspondence as to the rewards to inventors proposed in the army estimates for the current financial year. These rewards are as follow:—A grant of £10') to Mr. C. F. Guthrie for an ingenious and efficient rolling-bridge applicable to defensive worka It Is proposed to pay the sum of £900 to Mr. 8. A.. Goddard for his improvements in breech-loading cannon. In the case, of Mr. Parsons, who alleged that the Paliiser gun was really invented by him, the matter has been referred to Mr. Gregory, the presideut of the Institute of Civil Engineers. The Treasury has sanctioned a graut of £500 to Commander Colomb, as a final reward ou account of his signals for naval nad military me. The Treasury has also resolved to ask Parliament for £1700, to be granted to the representatives of the late Jacob Snider, for his invention of breechloading rifles,

EMIGRATION.—Private letters from Melbourne represent the labour market as much overstocked, although immigration is still eucouraged by a large party. The fact is that Victoria is at the present moment passing through a severe crisis. Mining property has become greatly depreciated in valu*, partly froai the natural exhaustion of the works which have been long in operation, aud partly from the numerous instances of fraud in the su-called *'auriform* discoveries," and the country ha* n»w been so thorong ily "prospected," tint it Is liar lly likely that any rich deposit will remain um-v.-aled.

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Iiithebto, during summer time, there has been a marked falling offin our correspondence. It is not so this season. In fact, the number ot our correspondents—and we can never have too many of them—is increasing. This is the best sign of the growing nterest felt in the English MeChanic. Mr Batty, of Fennell-street, Manchester, in a letter just received, says:—"The Enolish Mechanic is becoming quite an institution of the country." So the Loudon postmen think, who have to bring hourly to onr office large bundles of letters. We have had to" provide them an extra fee when the " Christmas Box" fund is collected. We have had to postpone this week F. R. A. S.'s communication on The Light of tbe Stars, Mr. Proctor on Meteors, Algebra by Gimel, Brazilian Railways hy J. G Comets by W. F. Dunning. To Millers by F. Davis,"Hydrostatic Weighing Machine by A. B. Duckham, three letters on Music and Musical Instruments by Harmonious Blacksmith, The Sun's Parallax by Hugo, lettera on Trade and Commerce, Lunar Actinity by W. R. Best, The Herne Knitting Machine hy a Practical Man, Practical Hints to Millers, Cotton Spinning, Bicycle Riding by S. James, &c., &c. Toi-xists' Teips.—Our invitation for information for tourists has been most liberally responded to—in fact, to such an extent that we cannot insert all the letters on the subject which have reached us. We did not want exactly glowing descriptions of beautiful scenery, over which some of our correspondents have gone into raptures, but districts pointed out and objects described which would be particularly interesting to scientific tourists. Devonicnsis is thanked for his description of Barnstaple, J. J McCartcv for his North fWales, A Mechanic for his description of same district, and A. Crofts for his particulars of Dover ALrRKD Millbogb.—No stamps enclosed. UuTEa.—One of the bsst remedies for tender feet this time

of theyear, is to wash them daily, or twice daily. E.W.—We cannot afford space for an illustrated notice of a bicycle, in order to elicit opinion thereon. E W. must be a very inattentive reader of the English Mechanic for many years past, or he would not have sent such a thing G. M. Rather too speculative for our columns. J. E. Key.—We cannot inform you,

J. W. R.—We read your letter and threw it aside, and the

following day we read it and threw it aside asecond time.

It contained some good information, and some equally

good criticism •. but it was vitiated by incivilities towards

another correspondent, and, therefore, rejected. Though

men may differ, there is no reason why tney should not

credit each other with good intentions, and treat each as

gentlemen, and particularly when they enter on scientific

matters, and hare no scllish interest to promote.

J. W.—You should always put the drawing on aseparate sheet

of paper from that on which the description appears, as we

like to send the description to the printer, and the drawing

to the engraversimultaneously.

J. Wareqau must consult indexes.

The Sixpenny Sale Column is the only plaee in which can

appear queries sent by James Levesque, A.O., and DPM

H. Locke.—No stamps. Exchange not inserted

James Light.—Yes.

Tatius.—The rubbings of the coin you send arc not plain

enough for our engrauer. It is best to send sketches F. N. B—See back numbers. T. Tade—Your suggestion is impracticable. E. Boncek.—We cannot, as we do aot know either your

capabilities or position. F.W.—First part of query inserted. For second, see recent

back numbers, n: Dolan (Leeds).—The stamps were duly received and the

numbers forwarded to the only address you gave viz

"Leeds." They were returned through the Post Office, the Leeds postmun not being able to find you. Your second letter only contains the same vague address. Please send yonr exact address and eight stamps for the re-postage of the numbers. You have given yourself, us, and the Postoffice a deal of unnecessary trouble. J. BiADBtjRT.—We cannot say. Try S. and B. Solomons,

Albemarle-street. Croydk.—We cannot.

Blacksmith (Ontario). With every wish to oblige vou, we dare not allow you to ask for the information through our l',">-?';, The *y '» far too sensitive to be treated by nnskilled persons. Let your boy see a medical man at once and don t tamper with his eyes yourself A Woeeuan-s Appeal—"The Hsrmonious Blacksmith has written us in reply to a ■• Blacksmith's" complaint in a letter, under the above heading in our last number, that he (the "Harmonious Blacksmith.") does not write enough on|3ubiects of interest bis to " brother blacks" the H. B. h»Buo desire to l.enefit any one class as such but wishes he were" privileged to suggest means for benefiting all classes If any fellow-correspondent" does him the honour to think that he can keep him to any lawful knowledge he may command his help." Our own pages bear witness that this is no were idle offer, and we think that a ■• Blacksmith was jus 'a trifle unreasonable and incorrect when he complained thai tbe " H. B." wrote on nothing but musical instruments. He Ant written on many other things and has never withheld any information aakedof him. which wasinhlspowertogive. itshould he mentioned, however thathe is only half a" Blacksmith "and very "Harmonioua liencc he doubtless possesses more information (the fruit of long experience) on musical subjects than some ethers The English Mechanic -Mr. R. A. Proctor tays—"The J'>r.i.i»ii Mechanic will'grow to lie, iritis not already he i.■list powerful scientific oreun in Emrlnnd There arc |

some ill-natured remarks about It in tile Astronomical Register for the current month. It would be utterly ulisurd to mulct the English Mechanic of the best parts of its power by a too rigid exclusion of all but strictly scientific matter." We noticed the remarks referred to, hut took no notice of them on account of the insignificance of tho journal named. It does not circulate as many dozens aa tbe English Mechanic circulates thousands. The information it contains is very stale anil very dear, as a shilling part contains about as much information aa four of our pages. G. F. S. thinks the idea of connecting two bicycles, and makfng a four-wheel veloce, as suggested by a new reader, last week, a happy one. C G. R.—You ask too much. It is not fair that our generous correspondents should also be asked to communicate iuformation through the Post Office. H. Childr.—When built send a drawing. W. E. Sedgley— Two other lettera on shorthand,'all

taking your side, are inserted this week.
J. Dodshon.—We don't know the address.
J. W Castly.—See answer to W. E. Sedgley.
Geo. Freeman.—See answer to G. V. S.
Inductoeium.—Next week.
J A. T.—See answer to C. G. R.

P. W. G.—No doubt tun have been tiken in. The advertise-
ment shall not be inserted again. No one, if we can help it,
shall use our advertisement columns for dishonest purposes.
Now the horse is gone, no doubt P. W. G. will close the
stable door. Be more careful in future.
John Jeffrey.— We do not send receipts privately for love or

money. The query column Is own to you. J. Hamson. Thanks for suggestion about indices. G. F. S. says he has discovered a new motive power which would, provided it could be applied, achieve wonders; but he has not the means to patent it. Has G. F. S. tested the discovery by experiments? If he is i-ertain. let him comr muuicate with some capitalist of knwn honesly, and iu all probability he will not be denied. Trust begets trust. John A. Ley—What blocks do you want? Trade And Commerce.—Received letters from Fact Col

lector, Percy Johnsnn, K. W. M„ and Foreign Clerk. Rowland A. Elliott, of St. Helen's, sends his congratnla

lions on the improvements in the English Mechanic. G- M , Little.—The tourist trip given is not sufficiently detailed. The same correspondent says that Adept again appears in prist; he hopes he will favour him with a reply to his query (3837) respecting organ pipes. J. D. Morgans—Please send description to accompany

engravings, which are prepared. C. H. W. B—The continuation of Mathematics came to hand. W. H. Hunt.—You should take no notice of Isaac W. Wolfe. He made so many btur.ders, and wrote about matters on which he knew nothing, that as a correspondent we simply had to alio* him the door. We refused to insert any more of Ins letters, and have several by us unused at the present time. So to revenge himself, he abuses us elsewhere. Let him do Bo if it affords him ary amusement; he cannot possibly hurt us. The journal in which he writes has become the receptacle of our rejected correspondence.

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Subscriptions to be forwarded to the Editor, at the office,

31, Tu via toe k -street, Coveut Garden, W.O.

Amount previously acknowledged .. ..£189 12 7

J. lfuxter .. 010

ft- s. , 0 10

H. Childs, Blandford .... 0 2 0

H.c.b. ;; % % \

P. B.McG \\

£189 19 7

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I powerful scientific orgun in England.

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."WSt R. T. Hrnches, garment for sanitary purpo«ei.-Awamunicatlon

.v.*. J. Wild. Rochdale, Improvements in the mtnufsctn"^ pile fabrics

;wi.'i Q. u. Praser, improved means of diiinfeet, tir ordrrim clotiiMK. bedding, so.

■tfiui H. M. Marsden, improvements ia ths rosnufafltureor sheep shears

■•«rai W. B. Oedge, a seir-ooting «pparsta« for preventing accidents from ntwm machinery.—A oumjiunication

aeftS J. Martin, fabrics and material* repellent of water, anJ in apparatus therefor

37U It. Tumor, improvements In maeMnerr for pntmrlng, twisting, or spinning cotton and ofherfJorous mmterwa

37S3 W. H. Baxter. improvemMils in saaeaiaerypr*pp»rsius for weighing or measuring corn «7-« P- P- ffenveuutl. aa linomrti feedfn? inftstand fi6 H. D. Dwyer, an Improved mode of roofing building* t» W. B. Newton, improvements in the Dunufaoture ot sugar.—Acomuiu.iicmUo.i vl

10-1 H. B. Newton, Improvements In bUllard-table cushions. —Acommunjcation »

I7i -*. H. (iossip. improvement* in the manufacture oi umbrellas and parasols ,. .,,M

Wi t3. W, Fuller, imiirovementslnthe construction of bottle* intended to contain iter's ted and other liquids

374 J.Tenwick. improvements inholdlnn hngnrs used in raping or mowing machines, or other machines of like charneiyr Nil W. ti. Newiou, improvements in

iHi A. V. Newton, improvements in fluid meters.-A communication

(WO W. B Gedne, an improved apparatus for subcutaneous extractions and injections.-A communication - , *.

755 J. Dunnachie, Improvements in stove* for drying bnc« and other articles In pottery

MOO. W. Pox, tmprovemwnu in the treatment or eod-liv"'. CASior, and other inediciuni oils W* A. (My. iinproveinonts in weighing muchine* .. .

lOWi W. lestv. imprtivetnvtnts in oompoaitlon* tor coaiiu* ships' bottoms nnd other like purposes

lwtrt W. Simpson and A (lardner. engines worked by »tc»!D or oilier motive power

nil W.Brown, improvements in the eonetrnction or thru*i blocks, phimmer blocks, and suah like mechanism uiea m steam ships

1452 W. ti. Lake, an improved valve or stop-cade—A comniiuiication

5711 W. McKenzie. T. MoKensie, and J. McKenzlo. tmpro"ments In apparatus for sharpening the cutters of mo*ins machines.— A communication

.H7W R Thomas, a now or Improved apparatus for propeillDC steam ships

3731 J. Hargr-aves and T. Robinson, improvements i" %w treatment of pyrites and in obtaining produots therefro"1 . S7M T. O. McUiarmld. improvements in the ris: of 9h»Pflno vessels

8741 S. Walker and E. Holt, improvements in steam putnp'n' engines

*71l N. Grew. Improvements In apnaratu« for mea»»nn* the weight or volume of water or other fluid suppliea to stc*111 boilemor other vessels.—A communication

^701 B. (3. Herrmann, improvements in the separation ot metals

3773 J. H.Johnson, improvements In the production of caitirou, iron.and steel.—A cominunicaiioii

nft A. V. Newton, an improved knitting machine.—A communication

iw w. G. K. Pcnley, improvements In pi pea for smoking tobacco

S3fl W. E. Newton, Improvements in preparing sur'Ace* for skating in all seasons,—A communication

«i,HJ B.AilioitaiidA. ri. >ellem, improvements in the construction or axle-boxes for railway, tramway, and Owk. similar engines, carriages and trucks , ,

407 W. K. i*ke. Improvements in spring seats and i>«a bottoms,—A ooininunioati-m £!2JM£ H.iils. improvements in the manufacture of g*» , 81(3 r. Keely, improvements in the manufacture of lcor<a iaonos

Ml A. A. Newton, Improvements in manufacturing barre's anil other round vessel1* of wood.-Acommunioatton , w

*N J. H. Davkos nnd W. B. Vates. ltuprovemeiKS in looms lor weaving I'M < . Joseph, improvfmentsin filters.—A communication IU>7 R. I)e U\ Rue, iwprn.ora.Mtn m cn^gnet maJlets 1154 w. ic. i,-*ktj. iin.i.'uveiotfut* Iu reversible butt binge* —-v cuiiiiiinnloatif n

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THE following is the publishers' announcement in the last number of Scientific Opinion:— "74, Great Queen Street, Loudon, W.C. 29f/( June, 1870.

"This week's issue of Scientific Opinion competes its third volume, and brings the existence >f this publication, in its present form and under te original Editor, to B close. The proprietorship and conduct of Scientific Opinion have now 'passed into other hands, and this journal will henceforth be incorporated with The English Mechanic And Mirror Of Science, an illustrated weekly periodical of great popularity, and one mjoying a very large circulation.

"Correspondents in all future coinmunications are therefore requested to observe the change of address, and to note that the day of publication is altered from Wednesday to Friday in each week.

"Subscribers will continue to receive Scientific Opinion in its altered form in completion of their prepayments; and it is hoped they will find increased inducements, in the more extended :cope of The English Mechanic And Mmnoa Of Science, to renew the patronage originally acorded to Scientific Opinion.

"Books for Review, Advertisements, &c, Sec, Aiould henceforth be addressed respectively to he Editor and Publisher, at the Office, No. 31, Tavistock Street, Covent Garden, London, W.C."

THE FLIGHT OF A STAR. 3y A Fellow Of The Royal Astronomical Society.

we have, on a former occasion, referred to the fact that our great English philosopher, Mr. William Huggins, F.R.S., has succeeded, by the aid of the spectroscope, in determining not July that the most brilliant star in our heavens [Sirius) is travelling away from the earth, but even, within very narrow limits of error, the rate in miles per second at which that glorious luminary is winging its stupendous flight through the depths of space. Since then several communications have been addressed to the English Mechanic, confining the expression of a wish for more definite nf ormation on this subject than the bare reference above alluded to affords. We now, therefore, propose to endeavour to give some notion of the principles on which Mr. Huggins's very extraordinary results have been arrived at. We cannot hope to do any more; and even to effect this in in intelligible way, debarred as we are from the lse of mathematics, will tax all our powers of ;>opularizing a very abstruse subject, and all those of attention on the part of the reader of this article.

In the acquisition of knowledge in any fresh branch of physics, or in the pursuit of any novel form of scientific investigation, more or less intimacy with other branches of science must be, of necessity, presupposed; and it would simplify our task exceedingly if we could legitimately assume the acquaintance of the student with the undulatory theory of light. Inasmuch, however, »s we are writing for those who may have been It-barred, by want of time or opportunity, from the chance of familiarizing themselves with this special subject, we must, in the outset, give such » short exposition of its leading features as to lender what is to follow intelligible. A careful re perusal of our series of articles on "What •Stripes the Sunbeam " will, further, be essential to its proper understanding.

In treating of the dispersion of light by means of a prism (on p. 146), we merely enunciated the fact of Kr.fh dispersion without making any attempt to theorize upon the subject. It now,'however,

behoves us to say something of the nature and constitution of light itself.

We derive, then, the notion of what we call light from the impression on the eye caused by the undulations in B medium which apparently pervades all space, and which has been called— not very appropriately—the luminiferous ether. Be this medium what it may, this much is certain, that each ray of light travels through space by absolutely equal and regular steps or vibrations. The number of these in any given ray is perfectly measurable and invariable, but is different for different rays; so that, in point of fact, we can identify any given ray by the length of its vibrations, steps, oscillations, or whatever we may call them. Now, although the number of vibration* performed in a second by the luminiferous ether varies, as we have intimated, for each colour, yet, in vacuo, the actual velocity of all rays is equal; so that white light has been happily compared to a crowd of men and children all running at precisely the same rate but with steps of various lengths, the shortness of the children's steps being compensated for by their frequency. Of the equality of this velocity of all the differentlycoloured rays, we have evidence from the everyday observation of astronomers that the aberration of all these rays is identical. We have spoken, on page 120 of our last volume, of the eclipses of Jupiter's satellites, and a little reflection will show that if, say, the violet rays travelled quicker than the red.when the satellite plunged into the shadow of the planet it would change colour, fading out from white to red through the various colours of the spectrum, the red rays being the last perceptible, as the last to reach the earth. For the same reason the satellite ought to appear violet or blue at the commencement of its reappearance. As a matter of fact we know that it retains its white colour up to the instant of becoming invisible, and emerges from the planet's shadow again without presenting a tinge or tint of any kind.

Unwilling as we are to encumber the student with more detail than is absolutely necessary for the comprehension of this somewhat difficult subject, we shall abstain from any description of the manner in which the length of the various undulations, their number in an inch, and the number of them which are performed in B second, have been ascertained. A tolerably accurate table of these data (at all events, as a differential one) will be found on page 35. It will be more to our present purpose to examine the bearing which they have upon the matter which we have undertaken to discuss.

Well, then, as we have said above, light of all colours or degrees of refrangibility travels at identically the same rate in vacuo. But suppose that a ray of white light falls upon a prism (p. 145) how will that affect its rate or mode of motion? In this way: it will be retarded, or the rate of propagation of the undulatory motion will be diminished. In other words, the progress of the ray will be slower in any refracting medium than in vacuo. And besides, our prism, in refracting the rays unequally, really retards them unequally, delaying the violet the most and the red the least; so that the latter travel the fastest and the former the slowest, intermediate colours progressing at intermediate rates.

It is almost unnecessary to add that all that we have said with reference to the visible rays of the spectrum, applies equally to the dark lines crossing it (Fig. 5, p. 172), and that the rate, length, and frequency of the vibrations necessary to produce light of their precise refrangibility, are susceptible of mathematical determination with all conceivable accuracy. This, as will be seen in the sequel, is a point of the utmost importance. Assuming this to be all clear to the mind of the reader, we now proceed to derive an illustration from a wholly different branch of science—acoustics; for, although sound is propagated through the air at the rate only of 1,090 feet in a second, and light travels at least 900,000 times as fast, yet the circumstance of their both having their origin in undulatory movement— albeit of very different media—enables *us to employ one of these effects to explain the other. The waves, then, of the deepest note of an organ pipe audible (as a musical sound and not a mere noise) are about 64 feet in length, and occur some seventeen times in a second; these we may conceive to be analogous to red light. The length of the waves of a cricket's chirp are certainly less than an inch long, and between 30,000 and 40,000 of them are formed in the same interval: we may imagine these to correspond with the violet rays. Now, in saying this, we have assumed both the

Bonrce of sound and the ear of the auditor to b.i stationary. A very little consideration will show that, if either of them be in motion, the resulting sound will be modified. For, suppose that a note is being sounded on a horn such as to induce 440 vibrations or waves in the air in a second of time, if we approach the trumpeter at a rate bearing anything like an appreciable proportion to that at which the sound is travelling, more of these waves will reach the ear in a second, and the pitch of the note will rise; if, on the contrary, we travel away from our imaginary musician with any considerable velocity, the waves of Bound will have to overtake us; fewer of them will reach us in a second, and the pitch of the note will fall. M. Buys Ballot, between twenty and thirty years ago, experimented on this subject on a. railway in Holland; and his experiments were subsequently repeated in this country by Mr. Scott Russell, who brought them under the notice of the British Association for the Advancement of Science in 1848. Both M. Ballot and Mr. Russell found that the whistle of a rapidly-approaching train sounds a higher note than when the train is stationary, and as it recedes from the listener it sounds a lower note. We believe that in the case of some experiments with a moving train and a stationary observer this difference amounted to a semitone; and that, when the auditor was himself travelling in a train which met and passed the one whose whistle was blowing, the resulting sound differed a whole note from that yielded by the same whistle when both the locomotive and the experimenter were standing still.

All this may assist ns in comprehending how motion, towards or from any luminiferous body— if such motion be sufficiently great to bear ll measurable proportion to the velocity of light— may either exalt or depress the refrangibility of the rays which reach the spectator, and so shift the rays —and, of course, the dark lines —either up towards the violet end or down towards the red end of the spectrum, according as we are approaching to or receding from the source of light.

One more consideration will help us in the apprehension of a point of detail in Mr. Huggins's very wonderful researches, and that consideration is this. Throughout our papers on "What Stripes the Sunbeam," we have tacitly assumed—without, however, anywhere actually asserting—that the bright spectral lines of various incandescent vapours are not only invariable in position under all circumstances, but also in thickness, we having purposely suppressed all reference to the fact that the breadth of the lines is affected by the density of the gas. To take an example, of which we shall now very soon make use, the line F (p. 172) is very sensibly expanded when hydrogen at the ordinary atmospheric pressure is employed instead of that in an ordinary vacuum tube, with which comparisons are usually made. The reason of our former reticence on this and other minor points had its origin in our indisposition to overload the subject already sufficiently complicated with a quantity of detail which could only tend to distract the attention of the reader who might be labouring to master its fundamental principles.

Assuming the student, then, to have grasped the idea that in travelling with any considerable velocity towards a source of light, we meet more waves of that light in a second, and be in effect increase their refrangibility—and that, on the other hand, in receding with sufficient rapidity from the luminiferous body, we diminish the number of vibrations or undulations which reach us, and so degrade their refrangibility—we are nowprepared to follow the details of Mr. Huggins's observations and to appreciate their results.

Sirius is a star which, from its great brilliancy and the marked distinctness and intensity of the four lines in its spectrum, early attracted his attention, and to which he has devoted a large amount of consideration. Owing, however, to its proximity to the horizon, anything like measure, ment of its spectrum is confined to a period of about an hour on each side of the meridian; and, in fact, the extraordinary difficulty of making any measurement, at all of lines which fluctuate with the undulations of the atmosphere, can only be appreciated by those who have themselves examined a star, having much south declination, with the spectroscope. From this point we had better let Mr. Huggins speak for himself.

"As it was obviously impossible," he says, " to determine with the required accuracy the coincidence of the line of Sirius when the much broader band of hydrogen at the ordinary pressure was compared with it, I employed a vacuum tnl e fixed before the object glass. In all these oboer

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rations tho slit used was as narrow as possible. . . . The line from the spark appeared, in comparison, very narrow; not more than about onerifth of the width of the line of Sirius. When the battery circuit was completed, the line of hydrogen could be distinctly seen upon the dark line of Sirius. The observation of the comparison of the lines was made many times; and I am certain that the narrow line of hydrogen, though it appeared projected on the dark line in Sirius, did not coincide with the middle of the line, but arossed it at a distance from the middle which may be represented by saying that the want of coincidence was apparently equal to about onethird or one-fourth of the interval separating the components of the double line I). I was unable to measure directly the distance between the centre of the line of hydrogen and that of the line in the spectrum of Sinus, but several very careful estimations, by means of the micrometer, give a value for that distance of 0040 of the micrometer head. This value is probably not in error by so much as its eighth part." After giving an account of many carefully conducted experiments, to prove that it was really the line F of hydrogen which he was observing in Sirius, Mr. Huggins proceeds :—

"From these observations it may, I think, be concluded that the substance in Sirins which produces the strong lines is really hydrogen, as was stated by Dr. Miller and myself in our former paper. Further, that the aggregate result of the motions of the star and earth in space, at the time when the observations were made, was to degrade the refrangibility of the line in Sirius by an amount corresponding to 0-040 of the micrometer screw. Now the value of the wave-lengths <>f 0-01 division of the micrometer at the position of F is002725 millionth of a millimetre. The total degradation of refrangibility observed amounts to 0109 millionth of a millimetre. If the velocity of light be taken at 185,000 miles per second, and the wave-length of F at 486-5 niillionths of a millimetre (Angstrom's is 486*63, Ditseheiner's 486-49), the observed alteration in period of the line in Sirins will indicate a motion of recession existing between the earth and the star of 41-4 miles per second.

Of this motion a part is due to the earth's motion in space. As the earth moves round the sun in the plane of the ecliptic, it is changing the direction of its motion at every instant. Tuere are two positions, separated by 180s, when the effect of the earth's motion is a maximum — namely, when it is moving in the direction of the visual ray, either towards or from the star. At two other positions in its orbit, ot 90' from the former positions, the earth's motion is at right angles to the direction of the light from the star, and therefore has no influence on its refrangibility. . . . That portion of the earth's resolved motion which is in the direction of the visual ray, and which alone has to be considered in this investigation, may be obtained from the following formula :—

"Earth's motion towards star = r, cos \, sin

"Where r is the earth's velocity, / the earth s longitude, t the star's longitude, and \ the star's latitude.

"At the time when the estimate of the amount of alteration of period of the line of Sirius was mode, the earth was moving from the star with the velocity of about twelve miles per second. There remains unaccounted-for a motion of recession from the earth amounting to 2'J-4 mile.* per ttcond, which ice appear to he entitled to attribute to Sirins."

Such, in the words of their great discoverer, is an account of tho astounding results arrived at by the employment of a few glass prisms and a narrow slit. It seems to ns to require no addition or. our part to render the principles on which those results depend apprehensible to every one who will take the trouble to read it carefullv

through. Two aids, however, to its comprehension, it may possibly 1* expedient to supply. The first is the information that the millimetre mentioned above is 0-08987 of an English inch; the second consists of a diagram showing the slight degradation of refrangibility of line F in Sirius. With these, and a careful perusal of what has preceded them, we would fain hope that the student may have no difficulty in perfectly realizing the mode in which have been ascertained both the direction and velocitv of the Flight of a Star.



By Aethcr Uxderhiu..

(Continued from page 337.)


SINCE the debris, waste, or dregs of each convulsion were deposited in regular strata over every part of the earth which might at that period be submerged or under water, and since each such deposition always partook of a nature different to any preceding or succeeding one, it follows that strata are always found in the order of time of their deposition; that is to say, that the older formations are always beneath the later ones. Thus the carboniferous system was deposited before the oolitic system, and if yon should search the wltole world you would never find the coal above the oolite. To make it phiiner, suppose several systems represented by the numbers 1, 2, 3, 4, to have been deposited in the Banie order—viz., first 1, then 2, then 3, and then 4, we should iu such a case never find them in a reversed or inverted order, as 2, 1, 8, 4, or 1, 3, 4, 2, <fcc; although from local disturbances of the crust we might frequently find some of the intermediate Btrata absent; as 1, 3, 4, or 2, 4, or 3, 4, or, perhaps, 4 alone, or 1 alone, resting on some igneous rock. The knowledge of this fact is very useful in the arts, for if we know what formations are upon or near the surface, we can tell accurately that certain rocks will be absent in that locality, and so save the expense of a useless search for them. For instance, if we should discover (referring to our former example) No. 3 at the surface, we should never think of looking for No. 4 there, although we might find numbers 1 and 2. In consequence of this fact, geologists have classified rocks in order of superposition, and the list appended to this chapter exhibits this order. They are placed primarily in fiveclasses, called respectively, primal-)-, transition, secondary, tertiary, and superficial formations. These classes are subdivided into systems, and tiiese again into strata. The division into classes has been made, because all the systems in each class bear a certain resemblance to each other, both in conformation, and fossils or organic remains. Thus tho superficial accumulations consist of surface soil, mud, gravel deposited at the mouths of rivers, and diluvium or drift erratic blocks, and contains remains of present animals, including man. The tertiary class (or that immediately below the superficial) consists of marls, clays, crag (or halfformed limestone), and thin strata of sand, and contains fossils of animals and plants of a bygone period. The secondary class is formed of large beds of clay, chalk, shale, coal, limestone, sandstone, and ironstone, containing fossils of plants and saurians (or big lizards). The transition class is composed of strata of limestone, sandstone, and shales, having very few fossils, and those of an exceedingly low organization. The primary class is formed of vast beds of slate, quartz, gneiss, crystalline limestone or marble, and is wholly destitute of fossils. As it may interest my readers to inspect for themselves some of the different systems and classes which are found iu our own country, I may mention that in and around London, and from thence as for as the Humber, ami including all the eastern counties, the tertiary deposits are found. In Buckingham, Hertford ami Bedford, the chalk system occurs. In Shropshire, the old red sandstone: in Noithampton, the oolitic; the Cinibiian, mica schist, and gneiss, in the mountainous counties ; and the new red sandstone, and carboniferous (coal-bearing) B; stems, in Staffordshire and Leicestershire.

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By Richard A. Phoctor, B.A., F.R.A.S.,
Author of "Other Worlds than Ours.' ctv.

(Continued from page S13.)

IT had been noticed that many meteors seemed to enter our atmosphere with a velocity fai exceeding that which would be fae to bodies travelling in nearly circular orbits arooni the sun. The observations on which this concWV.: had been founded were, indeed, not wholly satii factory, because it was a matter of extreme difi ■ -nit v to time the motions of the meteors athwai the heavens. It was comparatively easy for t« observers, at stations far opart, to take obaem tions of the same meteor so accurately that it actual path through onr atmosphere could b determined; but to ascertain exactly how man seconds it occupied in traversing that path in by no means 60 easy. The suddenness with whit ashooting star appears, the short duration of i visibility, and the necessity of noting very ace: rately its apparent path among the stars, all tcs to make the determination of the actual num>« of seconds occupied by the meteor in swoopathwart the heavens a matter of extreme ii culty. Yet observations had been made %i: indicated, as I have said, a velocity far gmv than that which would be found in the ca». • meteors travelling in a nearly circular t*around the sun. We know what that vefarif would be : a body at the same mean distance to the sun as our earth, would travel with the «=' mean velocity, or at the rate of some 18 nu>>* a second. Such a body coming full tilt vx? the earth, would traverse our atmosphere >: rate of 36 miles per second. Bnt, as a marfact, it was found that some meteors travela* a rate considerably exceeding this—cvef when they were not directly enconnteriu. earth.

Now, if this had been accepted as aete. proved, there would have been only one sanation of the phenomenon. We know so •" what velocities can be generated by the ^ attractive influence under such and such cir-3 stances, that whenever wo find a body W with a given velocity in any given part el s solar system, we know forthwith what is range of its path, from what distances it i oome, and to what distances it will pass V It may seem that in the present instance problem must be complicated by the eflccts o! earth's attraction ; but iu reality the earth ot: largely affect the motions of these bodios. the earth were allowed an all but infinite I* to attract a meteor from an all but iufiniti tauce, the meteor would finally reach the t with a velocity of barely six miles per second. will be conceived, therefore, how relatively s must be the part of any meteor's velocity di

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