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[4579.1— DUTIES OF GAS ENGINEER.—I should feel obliged if "Sigma" or somo of your other correspondents would give mo somo information concerning the duties of a Rus engineer. What books ought to be studied, Ac.? Is there nny drawing, and what kind ?— внАИАМ.

[4580.]—PLAN OF AVIARY.—I want to make an open aviary, so that I can divide it into two or three breeding compartments, or several smaller ones. My greatest difficulty is to feed and clean them when the divisions are in without having it uuslghtly when they aro out. I do not mind a little trouble, as Ï am pretty handy at wood or wire work.—J. II. P.

[4581.]—LINK MOTION—Will somo reader be good enough to send a sketch showing the action of the link motion ?—R. W. B.

[4583.]—GOLD LEAF.—Will some of your readers kindly inform mo how gold-leaf books are prepared in gilding so as to prevent the tendency of the leaf to fly about? I have seen gilders use them for out-of-dour work. The leaf sufficiently adheres to the paper to make it firm until it touches the gold size, to which it immediately becomes attached, leaving the paper quite clean.—Chemicus.

[4583.]— HALSE'S BATTEBY, Ac—Perhaps " M. D." or some other reader of "our" Mechanic, will give a description of how this machine is made. I have also some carbon dust that I waut to make into blocks for a , Bunsen battery. Will some reader tell me how to proceed to make them?—Northumberland Subscriber.

[4581.]—MANGANESE BATTERY,—Will Mr. Jarman be so kind as to stato how many quart size cells of bis manganese 1 lattery are equal to a one-quart Bunsen battery?— NORTHUMBERLAND SUBSCRIBER.

( 1585.] —AMBER MOUTHPIECE.—Can any reader tell me how the amber for mouthpieces is softened, eo that it can be bent or made pliable?—Ose Of The Oldest Subs.

[4588.]— WORKS ON COTTON.—Can any of yonr readers (particularly those interested in cotton spinning) give mo the паше and price of a good work on the cotton plant? 1 want something of this sort : a work that has plates of the plant, showing the leaves and flowers, also this pods in their varions stagos; also of different sorts of plants, such as American, Egyptian, Sea Islands, Surinam, Surat, China, Ac. If it had tho plates coloured, it would be better. I have seen, sometime since, somewhere a drawing of the various lengths of staples of cotton, from the longest to the very shortest, printed on paper, the paper being all black, and the cotton white, and numbered.—A Cotton Spinner.

[4587.]— HABMONIUM.—Will Mr. Hormann Smith tell me if I can remedy the following defect in my liarmoninin ?—All the notes in the bottom octave, with the exception of G and В flat, are very slow in speaking, while all the rest, four octaves, are very good. It makes it very annoying when playing. The tone is remarkably sweet and good.—J. T. Hill.

[4588.]—TELESCOPE.—Will black varnishing the inside of a terrestrial telescope improve its illuminating powers, or will it do harm ?—J, T. Hill.

[4589.]—TENDER FEET.—Are there any means of making the feet less sensitive во as not to cause blisters in the соигзе of a pedestrian tour ?—J. T. Hill.

[4590.]—TOWN GARDENING.—I have, in a Urge factory town, unsuccessfully endeavoured to grow geraniums and fuchsias; I attribute it to the absence of the sun's rays, and to having gas in the иоине, I should Дке to know what plants will grow and flower under these conditions—whethor they are annual or not—or whether they aro grown from seed or not. I also wish to grow a few hardy plants in boxes on the window-sills outside. I wish to know how to rear them from seed, and the best sorts for growing in the shade,—A Factory Lad.

[4591.]—EGG-BOILER.—Win any brotherrcader send me a sketch of an egg-boiler fitted with steam jacket, and tell mo the cost of fitting one about six horsepower ?—Improver.

[4598.] — TEETH OF CHANGE WHEELS. —Will "J. K. P." please to tell me how the teeth of chango wboels are struck out? I know how to strike out the epicycloidal form of tooth for wheels that always remain tire driver or tho driven, but do not know how they are formed when the wheels have to be chango d, as on the screw-cutting lathe.—С. C.

[4598.]-PIANO PINS.-TO "W. T.--I beg to tender my thanks to "W. T." for his answer to my former query respesting piano pins, and also to ask him another. I find said piano will not " draw up " within a semitone of the pitch without breaking. Can " W. T." tell me what to do under the circumstances? Can he tell me what sizes of wire to use, and if anything else is tho matter ?—Has Op Necessity.

[4594.]—GOMA OIL.—A German review says:—"The Japanese colony, near Plieraville, in California, has lately cultivated with success an oleaginous plant, belongiug to the nettle ordor, and called вота. The -small seeds, unclosed in the capsule, are so rich in oil that tho yield of one aero is estimated at 136 pounds of oil. The plant requires much watering, and it is hoped that by artificial irri gai on, three crops annually may be obtained. The young sprout3 are excellent as salad, the flowers give a rich food for bees, and the fibrous stem will probably be useful in textile fabrics. Goma oil, well refined, is equal to the best olive oil; has a very slight tendency to become rancid, and probably might form a substitute for olive oil In all technical employments. This oil can bo got in Germany from MM. Seegcr and Miiur, in Dresden." Docs any brother reader know somo more particulars about this plant, its botanical name, Ac? I find Uoi-nwah for a Chinese namo of Cannabis «of ira. Might not Go-ma proceed from that word ?—Bernardin.

[4595.1-HOUSES FROM STRAW AND WATERGLASS.—Is it true that houses have been constructed in England the principal material of which was bundles of straw impregnated with water-glass or silicate of soda? Some particulars might interest several readers. — Un Abonne.

[4596.] —JAPAN ISINGLASS. — Is this substance employed for any purpose in industry?—J. I. G.

[4597,] -INDIAN COIN. — Will some kind brother reader inform me from what country is tho following copper coin?—Obv.: an elephant, and above, the letter В in Indian character. Rev.: an Indian or Arab inscription. The coin is rather thick and somewhat larger than a farthing.—J. N. D. C.

[4598.] - CRYSTALS IN GREENHEART WOOD.— What are the acicular, gold yellow, brilliant crystals found sometimes in Turkish oak or greenheart wood? Might it not be Bebeerine >Greenheart.

[4599.]-EFFECTS OF CARBONIC ACID.—I shall be glad to learn through your columns what proportion approximately of carbonic acid gas (the deadly product of our coal-mine explosions) in atmospheric air is fatal to human life? Also what smaller proportion would have the effect of producing only insensibility in the victim?—A. St. Vincent.

[4600.]—PRINTING IN GOLD OR BRONZE.—Will any reader tell mo how I can print somo cards with gold or bronze ink V—Amateur Typo.

[4001.]—GILDING BOOK EDGES.-How can I gild the edges of somo books I have just bound ?—Д. H. I).

[4602.]—MELTING GLUE.—Will any of our cabinetmaker readers tell ine how.to melt glne properly? I mean so that I can keep it in the glue-pot and re-melt just as I want it.—S. N. К.

[461B.]—FISHING—Where can I catch small fish that will do to put in an aquarium, such as bleak, stoneloach and gudgeon.—E. Jamieson.

[4004.1—PICRIC ACID.—Can any of onr chemical readers tell me what is picric acid, and how I can detect its presence? It is said that it is nsf;d to Rive a bitter taste to beer.—S. H. B.

[46(15.] -ritOPF.LLING A VESSEL BY A WINDMILL.—May I beg some subscriber to inform ше whether it is possible to propel a vessel, lietid to wind, by means of a windmill working a fan or screw? A statement to this effect appeared in the Illustrated London Jvkjck, some weeks since, accompanied by a drawhie;.— Thos. С Burton.

[4606.]-BRONZING IRON IN PAINT.'^CaVany "of yonr readers inform mo how to bronze ironwork in paint ?—С. H.

[46071.—ORGAN BUILDING.—Will some kind correspondent inform me how I can make wood pipes (stop diapason) speak a little louder! Also, how can I harden brass wire, so that it will be adapted to make springs for organ pallets ?—W. PonTEUs.

[4608.]—FRICTION: HORSE POWER.—Will some reader state the amount of friction (in pounds i to be overcome by a horse in drawingaload of one ton on a level road, made as follows ?—1st. On granite pavement. 2nd. On a broken granito surface. 3rd. On a gravel surface. The two last supposed to be level surfaces. Also what amount of traction (in pounds) is required to draw a ton up a gradient of 1 in 20? Also, how many pounds of f orco is a noree calculated to exert ?—W. B.

[4609.]—AIR-GUN.—TO "T. A."—On p. 499, Reply 4044, " T. A." gives a very clear explanation of the lock of air-gun. Would he kindly give sketches necessary for the construction of au air-сапе, witli directions showing positionof air chamber, valves, charge, Ac.?—A. Hunter.

(4610.]-SHUTTERS.-Will any of my fcUow millers toll me if the shutters in a patent sweep (on the lead side), should be at the point or heel of tho sweep, the rest of the lead sido being board? I have an idea the shutters ehould come down, say two-thirds of tho way, and tho rest made up as a lead board at the Point.—Ost: Eye.

[4611.] — POLISHING VULCANIZED INDIARUBBER.—Can any roader inform me how to get a perfect surface on vulcanite for polishing, and what powder, Ac., will produce the finest polish on Ыаок vulcanite? I have a lathe and circular brushes for it: would cotton brushes bo any better than hair ones?—

[4612.]— PORTABLE MILL.—I am much obliged to H. W. Rovclev for his reply to my letter. I thank him much for telling me of Smoatou's work, of which I had not known. Thero is only one thing I noed remark on in his letter. He seems to think that the slow motion of the horizontal mill is a great drawback. It may be for some things, but this slow and powerful motion is just what is wanted for other things, е.ц., for agricultural purposes, such as Mr. Vallauce applied his to; and this, as he says in his letter in the English Mechanic, was capable of drawing seven ploughs, and had arms only 12ft. long. Surely this ivas " uffal work," and yet to porform it there was needed no "formidable train of wheels and pinions." If I wanted a mill to turn millstones I should give Mr. Revcley's plm a trial; butas I want л portable mil] it would uot suit. While' on the subject, would Mr. Revclev or any oilier correspondent give a plan for draining a'marshy field by wind power? In " Mechanical Movements," No. 259. thero is sometbing like wbatl want,but the worn wheel» would be diflîcult to got made here; and, besides, the form of buckets given would not suit, as sand and mud would have to be lifted out as well as water. The laud I waut to drain is near the river, from which it has been embanked; it is too flat to allow of sufficient fall for the drain. I would sink a well near the embankment, and over this niountlhewimiuiill; but whether a horizontal or vortical one would suit host I do not know. For an endless band, with buckets attached, the vertical would be best, I should Шик. If any practical man will kindly give mo an auswer I should bo much obliged — Derf Eriiac.

[4613.]-TREE STUBBER.-WÜ1 some one please describo a machme for pulling out tho stumps of trees? There is au American machine worked by horse-power Tho principle is, I believe, a poworful ecrew. Particulars would oblige.—Derf Errac.

[4614.1-ELECTROLYSIS—Will,"Sigma," or "Ignorant Irishman," or any other subscriber, kindly say whether electrolysis, such as electrotyping and decomposition of other substances, can be effected l>v tho aid of a magneto-electric machine? An anewer through the Mechanic will oblige.—Transpahient.

[4615.]—SEWING MACHINE ATTACHMENTS.-Can any or our readers tell me the best form of hem-folder for a shuttle sewing niachise; likewise instructions to make a marker, or creaser, as used in tucking a »kirt, Ac. ; and how to form and fasten the small guide, which I believe is attached to presser foot of machine during cording? Diagrams would oblige.—.1. F. R.

[4616.]— PROBLEM — Will " C. H. W. В. " or '- Вегпягdin" be good enough to solve the following? A force of 1001b. is resolved into two equal forces, acting at Au angle of 135Л find magnitude of either component.— Amicus.

[4617.]—QUERIES ABOUT OILS.—Con anv of ют fellow readers of the English Mechanic give' me thé following information ?—1st. What is the best method oí rendering linseed-oil siccative, without the use of litharge or other salts of lead? The usual method is to boil the oil with litharge, but this imparts to it too dark a colour for my purpose. 2nd. Is poppy-oil capable- oi being transformed into as qnicklv drying an oil a* Unseed, and whether it is subjected to' tho same procs*sv» »5 liusced-oil to render it siccative? 3rd. Is the " ben 10line spirit," now sold at the oil-shops for lichtinc purposes, the same eubstsDec as that sold by the chemists in small bottles, nnder the name of " benzine collas," and used for cleaning, Ac ?—J. T.

[4618.]—MANAGEMENT OF BEES.—I should fed obliged if you or a brother subscriber would inform tnc on »hat principle, and how the feeding-bottles for We s are constructed. Thoy are made so that the syrup only escapes from the bottle as fast as tho bees store it away I cannot find out how it is made. I should be glad. too. if some one would tell me how or where I could disjtos*of the honey, and what is the price per lb. generally madV I must say I was glad to see the subject of bees startol »1 the Mechanic, for I think it is a subject that a great many take an interest in, and if a brother subscriber, or some other, would give sonic information on theiriaimge ment of bees in a series of letters, 1 think they would be interesting and useful to n great many subscribers

Tlios. Pot»LTON.

[4619.1-HARD WHITE METAL.-Can any correspondent tell me how to make- the hard white metal tha' is sometimes used for models? I have seen cylinders brackets, Ac, of working models cast with this metal' and want to cast some with it, not haying the means to' do it with brass. I thinkit isrun d >wn in the la.lloover the open fire. Please state if it is any use forcosr-wbeeli. —Hammerman.

[4620.)-EMERY STICKS.-I see an answer about emery wheels by "Matrix." « ill he please tell rnc how emery sticks are made? I am told thoy arc ma.iu witi shellac and mineral naphtha, but du not know the proportions nor tho ma,lui operandi. An answer wffl oblige.—Hammerman.

[1621.1-CHLORIDE OF OOLD.-Wffl any of our numerous subscribers please inform me how the- above is manufactured, as I have some old gold I wish to make into the chloride ?—Yotrxa Photo.

[4622.]— NITRATE OF SILVER.—I have a silver solution which 1 use for electro-plating. How can it bo again converted into nitrate? Must it be crystallized, fused, and redissolved in nitric acid?—Young* Photo.

[4623.]—HORNS.—I have a few specimens of polished cows'horns: would am-one give mea recipe for keeping them a good gloss ?— Working Man.

[4624.]— PENDULUM SPRING.—I shall feel extremely obliged to " Seconds Practical Watchmaker " if ho would kindly answer the following questions, viz.— How to tell the proper length and strength of a pendulum spring. How to tell the pallets and lever depths in the depth tool, and likewise to tell when they uro correct when uprighted and in the frame. How to do the adjustment and tell when it is correct, and how to tell when the fusee chain is the proper length.—Ycvnu Jobber.

[4625.]—FLUORINE.—Can "-Beta" or any correspondent, inform me on what grounds the table at South Kensington, quoted by him, p. 449, reckons Fluorine among the normal constituents of our bodies? It differs from the other thirteen in the table by not being known to be ubiquitous in the mineral world. Thus, as nono is known in the home counties, the question would arise, if fluorine be necessary to us, whence do Londoners get it? It is remarkable that only fourteen elements appear ubiquitous on earth, and thirteen ol these, according to tho table, are necessary to man. ( nly one of them. Aluminium, has not been found in his body, though about the fourth most abundant in terrestrial nature, and though alum is taken as medicice, and in bread.— E. L. G.

[4626.]—TUNING BELLOWS FOR HARMONIUM REEDS.—Will any fellow reader be kind enough to give me a description of the bellows used in tuning reeds . as requested on p. 287, ante! A diagram would be useful. —Rkkd Tunkr.

[4627.]— DISCOLORATION OF LEATHEU.-Canany reader give me any information on the following:—I have been pressing some leathers into a ehape, hut after remaining in the presses all night, that they may retain their shape, 1 find them noarly black. I soak them in water before pressing, and the presses are made of iron. What I want is to get them as near to the colour after presslug as they were before, also a quicker way of hnrdening them, if possible, than by allowing them to remain in the presses all night.—G. À. G.

[4628.) — COILS.—If any reader of your jonrnal bas made a coil from the instructions given in "Dyer," will ho please state his experience and what difficulties were found to arise?—W. J. P.

[4639.]—MANGANESE BATTERIES.—I have tho specification of the patent of the "Leclanchc" battery, aud wish to ask if any of your readers can enlighten ше on the subject. The battery consists of two parts—tho generator and accumulator—the former being reaUy the> battery, but the aecumlator I c:mnot understand. It h is two plates of carbon, one of which is in a porous-pot The patent is No. 2.623, 10th October, 1800. patented in the name of Brandon. The price of the specification is 8d. I also wish to ask in what number Dr. Stono'* maganese battery is do -cribed.—Viator.

[4630.] —COACH PAINTINO.—Will any of our;brothev readers be kind cuough to inform me if there is a book published on conch pamthif'. and where it is to be bought and probable cost У And Ü there in пи such book, w ill ноше one be kind enough to give me instruction as to the mode oí procedure in coach painting V—Ají Old SubScribe в.

[4631.]— LATHE QUERY.—TO "J. K. P."—I return thanks to " J. K. P." for his prompt reply to my query 4461. Will he please refer to page ív. ol the laat number (283J of tho Enüubh Mechanic? He will thcro see ao Шп.-irated advertisement of a lathe by Greenwood Brothers; my head stock is like that one, and backgeared ; the mandril running in two collars ; the bod has я gap, with saddle and brackets, to carry screw, same as illustration, with swing p>itc. 1 wish to fit it to carry the saddle bnckwards and forwards, while the lathe is running. 1 Und there iß 8in. from centre of mandril to centre of loading screw ; will wheels of the 12 pitch do, when fitted, with backward and forward motion? Now, how many thread-) to tho inch, and what diamotor for leading screw? The one yon mention—8 threads and lefthanded—would not do in this case, I should say. P.S.— I should like to see his Bin. head stock, but my place of residence is 160 miles from London, which placo I should say is his abode.—H. Williams.

[4632.]—WEIGHT OF BAX.L.—Would "Ferrum," in reply to my question on tho weight of ball, obligo ше by the working of the sum, as I think ho has omitted a

Íoint in reference to obtaining the weight of a yard of in. round wire? I don't think ho will obtain it simply from multiplying the square of diameter by '7864, and I cannot seo that to divide 50 by 6 gives 100.—Ralph Willi Aus.

[4633.]—WEIGHT OF METALS.—Would J. Nash also oblige me with the name and publisher of a good practical work on the weight and strength of metala generally, and with the rules fer obtaining tho same? How docs he Und the cubic coûtent of tho ball to be 179 5048, and where does he get his decimal '5236 from in the

, 7* x '6236 x 7645 _4 и. * «.

formula —íT^id Ta ?Am 11° assumo that tho

ñamo (Hutton) in brackets is the ñamo of the publisher from which ho gets his information; if so, would he oblige me with the price and particulars? By " Ferrum's" rule there is a difference of 31b. in tho weight of cast-iron ball to that of J. Nash's, ao I am not oxaotly in a position to decide which to accept, and would bo £rateIulto J. Nash for information respecting the book. —ralph Williams.

[4634-1—ELECTRIC CLOCK.—May I ask Dr. Stone, who so amiably, some time ago, described the manganese batterj' with which his electric clock is worked, add to the ob ligation a wo are under to him, a short description of his time-piece, which, I am glad to learn, is giving him ao much satisfaction? I think, a considerable time ago, a aimilar request was directed to your readers generally, but met with no response, except in the "Editorial Correspondence Column," in which was described un arrangement of electric clocks, under what is known as the remontoire system, and one of which was, I believe, exhibited in the Great Exhibition of 1851, but there must have been many improvements made since. I under stand there is description of such clocks in the earlier volumes of your journal; but as I only go back to Vol. V., they are as hidden secrets to mo. Many Шапки to your learned correspondent "Sigma." — Elkctbo-maönet, Ko. 1.

[4635.3—WATER COLOURS.—Can any one give me tho process of making up pigments into cakos for watercolour painting ?—D. G.

[4636.1—INCUBATOR.—I want to make an incubator. By referring back to Vol. X., No. 238, pago 108,1 hud a sketch of one by Mr. J. Pinchen, but not having всеп one of any kind, and being entirely ignorant of their principle and construction, I am unable to understand it from Mr. Pinchen's very brief description. If he, or ноше other correspondent, would make mo understand it, I should feel greatly obliged. What is tho use of the glass case E, and how is the mother D made? How many eggs does each drawer A hold, and what are they placed upon? Are they wooden or zinc drawers? Is there an opening at tho end for tho chicks to escape through to the mut lu r, and do the black dots in tho outer end represent air-hole*! Is the lamp-chamber open all through to the jjlass саве? Of what, and how, are the vwutening-draverM constructed and connected with the egg-drawers '/ Is the zinc boiler entirely hid from view with the woodwork, and is there no danger of Btoam bursting it when corked up? What is tho best kind of lamp to use, and what degree of heat is necessary? What are the dimensions of tho different parts of the incubator V—Robin Hood.

[4637.]— FLEXIBLE CEMENT.—Could any of your correspondents suggest a flexi ble cornent, iñ place of the india-rubber solution, for uulting cloth and indiarubber; something that could be kept ready for use, dry quickly, and resist moisture ?—Pauvcs Pueb.

[4638.]—SILK WINDING.—How ought the silk of the silkworm to be wound so that it can be sold? Ought each cocoon to be wound separately, and tied up as one skein; or should the second cocoon be started where the first left off, and so on, until the skein is a large one? Or ahould about a dozen or во be wound together, so that the ends shall bo together, and then tied up as one skein?—С. H. Bolton.

[4630.}—DYEING WOOL AND YARNS.—Will any of your correspondents kindly inform mo if there is any book on dyeing wool, Ac, and scouring yarns, ftc. ?— N. E. W. в J .

[4640.]—SOUTH KENSINGTON EXAMINATION PAPERS.—Would any of your kind readers be so kind as to tell me where I could get 4 South Kensington Examination Papers? Subjects :—

Organic Chemistry—1st, or Elementary Paper, 1 n M 2nd, or Advanced „ 1

Inorganic „ 1st, or Elementary „ 9

»• »t 2nd, or Advanced „ 1

I have found it an uttor impossibility to get them about this neighbourhood—Hockmondwiko, Yorkshire. Bv inserting tliia you will oblige a triplo subscriber.—JB. H.

[4C41.ΗMILTjniLLS.—Can any one inform me howto harden mill bills, for I cannot get them to stand ?— R.D.

[4641.]—GAS-HOLDERS.—I havo a very leaky gasholder; it leaks at the rivets and all round tho angle.

Can uuy one tell mo the best cement to uso that would stop the leakage, and would ho lasting? I have put red and white load round, but it is not effectual; or would it ho safo to caulk it the same as boiler-makers would, while it is full ?—R. I>.

[4643.]—METERS.—Can any ono explain this ?— When we aro cleaning our purifiers our meter travels backwards. It has indicated 1,000ft. less, although we have shut tho centre valve.—R. D.

[4644.]—CORN FLOUR.—Will some fellow-reader kindly inform me the process by which "corn flour " is manufactured from Indian corn (or maize), also from rice?—Josiah R. Neane.

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Paris, p. 382.

Naval Architecture, 383.

Black Diamonds for Drilling, 382.

Adulteration, 3tt2.

Water-wheel, 8H2.

Sign Writing Sti2.

Harmonium Reeds, 382.

Photography, 382.

Treatment of a Chrysalis, 382.

Unnoticed Queries on Maguetism, 382.

Medical Ceil, 882.

Watchmaking, 382.

Incrustation in Boilers, 382.

Wire Netting Machine, 883.

Glycerine as a Substitute for Cod Liver Oil, Í

Anatomical Models, 383.

Paint for Aquarium, 383.

Gold Lacquer, 883.

Cotton Spinning, p. 406.

Fixing and Colouring Prints on Glass, 406.

Water Gilding, 406.

Re-working Vulcanized Rubber, 406.

Associate of Art Degree, 406.

Chemical, 406.

Cupelling, 406.

Testing Gold, 406.

Alabaster Glass. To Mr. J. Leicester, 406.

Alloys for Tin Foil, 400.

Cotton Spinning, 400.

Force Pump for Irrigation, 406.

Friction in Steam Cylinders, 406.

Millers, 406.

Brewing, 406.

Silvering Clock Dials, p. 407.

Sausages, Ac, 407.

Madagascar Matting, 407.

Cast-iron, 407.

USEFUL AND SOLENTLTIG NOTES.

REPAIRING LEAKY ROOFS, Etc.—The following is said to answer well in mending roofs that leak, and for similar uses :—Take two parts by weighted common pitch with one part of gutta-percha, melt together in an iron pot; it forms a homogeneous fluid much more manageable than gutta-percha alone. To repair gutters, roofs, or other burfaces, carefully cloau out of the cracks all earthy matters, slightly warm the edge л with a plumber's soldering iron, then pour the cornent iu a iluid etato upon the cracks while hot, finishing up by going over the cement with a moderately hot iron, eo as to make a good connection and a smooth joint. The above will repair zinc, lead, or iron, and is a good cement for aquariums.

SO CALLED » COLD GALVANIZATION" OF IRON AND CAST IRON.—The metal is firat cleaned by being

placed in a bath made up of water 1,000 lit res; chlorhydric acid, C50 litres; sulphuric acid, 60 litres; glycerine, 20 litres. On being removed from this bath, tho metal i s placed in a bath containing 10 per cent, of carbonato of potassa, and is next transferred t J a metallizing bath consisting of water 1,000 litres; chloride of tin, 5 kilos.; chloride of zinc, 4 kilos.; bitartrate of potassa, 8 kilos.; acid sulphate of alumina, 4 kilos.; chloride of aluminum, 10 kilos. Tho metal has to be loft in this mixture for from three to twelve hours, according to the thickness of the layer of zinc to bo desired.

PROPOSED MUSEUM AT BURXHAM, SOMERSET. —A feeling has been qxpressed that it would bean advantage to provide thetowu of Burn ham with a museum for the collection of the curiosities of the district. The idea (says a local journal) has been prompted by the fact that Mr. E. Rosser, of College-street, who has devoted Mh attention to geology, is willing to disposo of his collection. Ono large fossil possessed by Mr. Rosser is an Icthyosaurus, which is much admired. This splendid specimen of extinct animal existence was obtained from Street, near Glastonbury. He has also a very valuable ammonite. Besides the не, Mr. Rosser possesee* a good collection of minor fossils, stonos, crystals, shells, ¿te. ТЫ« would form a good nucleus for a nmsoiun, and we hopo means will be taken to make them tho property of the town. Some Roman pottery a-id other curiosities dug up in the neighbourhood would doubtless bo added by their owners.

A SPONTANEOUS COMBUSTIBLE GAS.—The Ыbromide oí ethylene, when mixed with' oxygen gas, take 4 fire spontaneously in the sunlight. The bromine appears to combine with the hydrogen in a inauucr analogous to tho union of chlorine with hydrogen in the euulight.

REAL AND APPARENT DEATH.—Dr. Laborde, iu a paper recently read by him before the Academy of Medicine in Paris, has endeavoured to show that the effect produced on a bright steel needle inserted into the body indicates whother death hasor has not occurred. When, life is present, he says, the needle, generally very soon, becomes more or less tarnished by oxidation; when, on the other hand, death has taken place, tho needle, even at the ond of half an hour or an hour will retain its brightness. According to tho British Mtdical Journal, M. Laburdu believes that, iu the first instance, the occurence of oxidation, with Us attendant electric phenomena, indicates that death is only apparent ; while, in tho second, the complete absence of oxidation is a sign of real death. The communication has boon referred to a committee, consisting of MM. Gavarret, Buclard, and Vulpiau.

PRESERVED BREAD.—This bread is proposed as a substitute for the biscuK and " hard tack " used at sea. It is easily prepared, though the process is somewhat tedious. The bread is baked in the usual way, it is then subjected to desiccation for eight to fourteen days, until it is thoroughly dry; it is then exposed for a short timo to the action of steam, and afterwards squeezed luto tablets under an hydraulic press for tweuty-four hours. The tablets can be preserved for years iu hermetically-sealed packages. Bread thus preparod retains a vitreous fracture, can be easily masticated by the teeth,is admirable for bouillon and soup, and experience has shown that 200 pounds of good fiour will afford 188 pounds of compressed tablets. An army provided with this broad and Lie big's extract of meal would bo prepared for any emergency that might arise. A soldier could easily carry several days' rations in his knapsack.

MUSSEL EATING.—It is surprising the quantity of mussels imported into our manufacturing towns. The working-men appear to feast upon this shell-fish with a marked preference, if we may judge by the large consumption of it. A visit to the markets of Manchester, and liko towns, will reveal the fact, that mussels were largely sought after and eaten by tho manufacturing class at tho time of tho year when some restriction should be placed upon their sale, for during the months of May, June, and July, they aro a dangerous commodity, not having recovered from the effects of spawning, and in many Instances produce serious mischief. We (Medical Prrtts and Circular) have lately observed the grave results which arise from a careless indulgence in mussels, from the general rash over the surface of tho body—so characteristic of unwholesome fish—to the protracted and, in some cases, fatal diarrhasa. In France, where mussel farming is cultivated with the same care as that of the oysters, and where they are placed under the operation of fishery laws, wo find, during four summer months, no mussels are sold for consumption in tho markets or shops. Even if they were, they would not be so dangerous as the large, fat mussels to bo found in our markets, and con sum od with so much reckleasnese as to future snfforiua by tho working-men. Disease is engendered and propagated through tho carelessness with which the dietary of our people is managed, and serious epidemics arise through incautiou. Accordingly, wo believe it should fall to the duty of inspectors of markets to prohibit the sale of unseasonable articles of food. How often do we see lobsters and crabs vended at a time when they are most baneful, and how frequently are our professional services required to minister to sufferings arising from tho injurious effects of stale or unseasonable shell-fish.

CAUSE OF THE FATIGUE TO THE EYES CAUSED BY ARTIFICIAL LIGHT.-M. V. Meunier states that the great difference between sun and artificial light is due to the fact that, of tho light emitted from the former, about half the quantity of rays are luminous and calorific at the samo time ; but, as regards our artificial light, for ordinary oil (colza oil), tho amount of non-luminous, yet calorific, rays is 90 per cent.; for for white-hot platinum, 98 per cent.: alcohol flame, 99 per cent.; electric light, 80, and gas-light, 90 per cent.; while for petroleum and paraffine oils, the amount is 94 por cent. It is this largo quantity of caloric rays in artificial light which causes the fatigue to the eyes; but this inconvenience may, according to the author, be almost entirely obvinted by intercepting the thermic rays by glass, or, better yet, mica plates. The use of these renders the light soft and agreeable to the eyes.

FLUORSPAR IN GLASS MANUFACTURE.—Herr E. Richters, of Waldcnberg, Germany, states that the substitution of fluorspar for lime in tho manufacture of glass allows of a groat reduction in tho amount of glauber salt, and greatly promotes the melting of the frit. As the result of numerous experiments conducted on a largo scale, ho found that, with the same consumption of fuel and similar length of time, tho amount of glauber salt required could bo diminished ono half bv substituting fluorspar which had previously been pulverised and calcined for the lime usually employed. Iu countries whore flnorspar can be had in abundance its introduction into glass manufacture would appear to offer many important advantages. The following are the proportions taken:—With fluorspar: Sund, 111441b.; fluorspar, 27*691 b.; glauber salts, 4*901 b.; manganese, 4*091b; charcoal, 2tH)lb.; glass frit, 299-OOlb. With lime: Sand, 116-401b.; lime, 15o51b.; glaubor salts, 8 0L'lb.; manga nose, 3001b.; charcoal, 2'OOlb.; glass frit, 248'00lb.

ANTIQUITY OF THE MITRAILLEUSE.—We give the following curious evidence that tho mitrailleuse is only a revival of an old invention, from "Grose's Military Antiquities" (1801), vol. iL, p. 165:—"A patent was granted by King Charles I. to William Drmumond, of Hawthornden, in 1636. for the sole making and vending, for the space of 21 years, of tho following machines and warlike engines invented by him. The patent is printed inhis works. The third is a sort of mnchine of conjugated muskots, by the assistance of which one soldier or two are enabled to oppose 100 guns, which machine from its effect, is called the thundering chariot, and vulgarly, the fiery waggon."—Spectator.

ТПЕ RIGHT AND THE LEFT HAND.—Dr. D wight, a writer in the Journal of Psychological Medicine, maintains thlit Ibe prevalent use of the right hand in preference to the left is not merely duo to habit or «Incitation, ont i« the result of a natural impulse, which he attributes to a difference in the endowments of the two lobes of the brain. He lays down, as probably true, the following propositions :—1. There is an inborn impulse to use, to excito motion, one-half of the brain in preference to the other. 2. Ono half tho brain, the left, has a more acute perception of tactile impressions, while tho other, the right, distinguishes more readily ■ different degrees of temperature and weight. 3. This arrangement is occasionally inverted." That we shall ever know the nature and origin of this impulse to use one side in preference to the other, Dr. Dwigbt thinks impossible; but a step is made, he remarks, when it is admitted that it is an impulse born with us, a part of our organization and is neither due to the arrangement of the arterial system, nor is the effect of habit.

A PUZZLING POSSIBILITY—When the RussianAmerican Telegraph is completed, the following feat will be possible : A telegram from Alaska for New York, leaving Sitka, say at 610 Monday morning, would bo received at Nikolaef, Siberia, at 6 minutes past 1 on Tuesday morning ; at St. Petersburg, Russia, at 3 mins.

Ïast в Monday evening; at London at 22 minutes past Monday afternoon ; and at New York at 46 minutes past 11 Monday forenoon. Thus, allowing 20 minutes for each re-transmission, a message may start on tho morning of one day, to be received and transmitted the next day, again received and sent on the afternoon of the day it starts, and finally reach its destination on the forenoon of the first day. Tho whole taking place in ono hour's time.

PRESERVED MILK.-If a full milk diet could be obtained for the children in every cottage, how often would the sickly infant live, tho poor, ricketty child grow into an active boy, and tho ovorgrown, consumptive-looking youth reach manhood. In fact, how much would the bone and sinew of the rising generation be strengthened, if children could have a liberal supply of milk food, instead of being brought up on washy substitutes, and kept quiet by sugar, stimulants, or opiates. The importation into this country of the pure condensed milk from Switzerland is another step in the right direction—the amelioration and condition of the poor-which modern science has taught us to take ; and we also hail with hearty satisfaction the announcement that establishments for the preparation and supply of immense quantities of the condensed milk are now at work in the county Cork, Irelnnd. In this manner the ■ green pastures" of the sister isle may indeed bo made to confer a substantial blessing upon "the crowded and heated towns of England, whose population in infancy is stimulated into unhealthy and unnatural precocity, instead of being soothed and fed bv Nature's own food during the ills to which juvenile existence is subject.— Food Journal.

WOOTZ.—In 1819, while Faraday was an assistant in tho Royal Institution, he made an analysis of wootz which attracted considerable attention, as, besides carbon, it was found to contain only silica and alumina, from which the conclusion was drawn that the peculiar property of the metal was due to the presence of silicium and aluminum. The uncertain state of analytical chemistry at the time of Faraday, says the Journal of Applied Chemutry, has induced Rammelsberg to repeat the analysis of wootz, and he has communicated the results of his work to the Berlin Chemical 8ociety. The following is Rammelsbcrg's analvsis :—Carbon, 0-867 • silicium, 0-136; phosphorus, 0099; sulphur, 0002. It will be seen that the metal contains no trace of aluminum and Rammelsberg doubts the existence of such a thing as aluminum steel. It is certain that the usual alloys of allummum and iron arc crystalline and brittle and not at all possessed of tho properties of steel.

REVERSION SPECTROSCOPE.-An important addition to the resources of spectrum analvsis has been made by /.i.llner's invention of a reversion*spectroscope, by winch extremely small changes of rcfrangibility, and consequently comparatively Blow motions of a star or sun-flame, can be detected. It consists of a spectroscope, in which, by reflection, the spectrum of a source of light can be superposed above a reversed spectrum of the same source; so that if a white flame eontainlng sodium be viewed, there will be seen in the upper part of the field a sodium Une with the blue end of the spectrum on the ono side, and underneath it a sodium lme with the red end of the spectrum on the same side The two bright lince may be made to coincide exactly by an adjustment; and if any change in rcfrangibility takes place, the motion of the line is doubled, and is also more exactly measured, because it is referred to itself as a standard.

I.m?„. PYKAMIDS-Co>- Sir Henry James, in a recent 1¿»"I M,.ji в ?yra?ud,s of EOTt, stated that in the i еЛы5 m er' *%И,йв the ГУгашН. some of the stones were 80ft. long These stones, weighing some 90 tons, were not found m Egypt at all, bnt were brought down the Nile a distance of 500 miles, and then placed in their prescnt position, 100ft. above the level of the ground With regard to their finish, these Syenite stones are of «he very hardest known, and yet thev are so exquisitely polished, and built in (to form я casing for tho king's chamber) with such superior skill, that the finest sheet or tissue paper could not be inserted between two of the stones and this after a lapse of 4,000 years. Such workmanship would excito the wonder ami admiration of the world, even in this ago of science and improvement. r

A PETRIFIED SEA-MONSTER.-A very beautiful and interesting petrified sea-monster has, according to u ïï.'l' P,lne Xevada -N«TM. been lately discovered about 100 miles to tho south-east of Hamilton, on a high plateau of land containing an extensive deposit of marine shells and the fossil remains of a large variety of extinct species of flsh. Tho petrifaction of this' particular monster is perfect, and is estimated to weigh about ten tons. "present i a dual appearance—tho head and bodv are that of a hunp-back whale, while the extremities extend into feelers and antennas, like the polypus or devil-fish with the exception that thev were evidontly during life lined with a hard and bony substance. The eyes are set in each side of the head,' which is flat and oblong, and are twenty-four inches apart. The mouth is nrmed with triple rows of teeth, which are sharp in front, but underneath and well into the jaw they turn nto grinders, capped by a solid osseous formation, a uning back from the widest portion oí the head

A NEW INDIAN MKDICINE.-We have received from Mr. Naniyau D*jl, of Bombay, a paper read before the Grant Collego Medical Society, containing an accountof a new Indian drug—the bark of Ailantui rxceUa Roxb. This tree is common in many parts of India and its bark can bo obtained in sufficient quantity for general use. Tho activo principle of the bark is called ailautic acid, and its taste is purely and strongly bitter. In doses of from one to three grains ailantic acid, given intemally.acts as a tonic and stomachic, exciting the appetite and promoting digestion. Whon given in large doses (from three to five grains), two or thrco times a dav its action is distinctly marked, especially in cases of torpid stages of the digestive function, attended with muscular and nervous relaxation and constipation. It is useful in lealrr) diarrho-a, and has been found of considerable benefit ш the first stag« of cholera. It is administered elthor as decoction, infusion, extract, or tincture of the ailantus bark, and pills can be made containing tho concentrated extract. The bark alone contains the active agent, in combination, as far as has yet been discovered, with lime, carbonate of lime, salts of magnesia, alumina nncrj-stallizablc sugar, gum, and a trace of volatile oil and lignin; its medicinal virtues depend entirely upon an azotized bitter principle possessing an acid nature and it is this which has been called ailantic acid. The' tree is figured in Dr. Wight'B "Illustrated Indian Botany."

ANSWEBS TO COBEESPOKDENTS.

*»* All communications should be addressed to the Editor of the English Mechanic, 81, Tavistockstreet, Covent Garden, W.C.

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L. Dickson (Anlnm).-To find the diraensinne of tV clHiumy for a statbnary boiler, multiply the nam),., of pounds of coal consumed under the boiler per horn by 12 and divide the product by the square root of tL. height of tho chimney in feet, tho quotient is the at.-, of the chimney in square inches at the smallest pari.

В. В.—Yes; apply to the office for Registration of I>.. signs, 1, Whitehall. You had better employ a rcsntcable patent agent. See advertisements.

J. Harper.—Send the drawing and description. If worms ertion they shall njipear.

E,'',0!;Es.J!i'!',Iia>duB)--The NoJyou mimtlea U aw likely the herring gull, which is common on the r*c> parts of the southern and western coasts. It resembUthe kittiwakc and the common gull in general atpearance; but the bill is yellow; legs, flesh coW ins light yellow, with an orange eyelid. Lu sunmi.-. the head, neck, tail, and undcrparts, arc pure white will a grey mantle, and black and white primaries It ■quite a mistako to suppose that the herring cull ttrJ only on the fry of fisfi which swim near the surfJ It cats both shrimps and «nail crabs, and mice anï small birds are not safe in its presence It lis, eTre been seen following the plough, and picking otttwor."^ and larvas from the furrows.

SABBAS.-Epidote is a silicate of alumina and lime There are several varieties of it; and it occur, ,' granite and other igneous rocks and various crvitil hue slates. »«.»j«TM

'•T.—No. Several wires are used in submarine câbler because copper wire is liable to break when roik-V There aro seven conducting wires in tho 1ЫИ AUanL cable.

12-5 sulphur, ami 12-5 charcoal: The Prussian contain 1 part less sulphur, asd 1 more of charcoal. ТЫ English contains 10 of sulphur, and 15 of charcoal

C. R. T.—No. It is quite a mistako. Asphalte ia a fon= of hydrocarbon, produced in tho interior of the eariB by the transformation of carbonaceous matter I is soluble in about five times its weight of aapbthi The mixture of gas tar with sand or lime i* what known as artificial asphalte;

F. W. GaiEHSOK.—Tuesday morning will be too laic.

J. TV asks why his "congratulation" ia not included in the list published. Simply because he said " t bt*r to congratulate you," &c. We cotüd flu columns and columns of such. Our plan hitherto ba-i been to selcrt racy and characteristic sentences appertaining to ihc English Mechanic from correspondents* letters, and give them in clusters.

The Sixpenny Sale Column is the only placo in which can appear queries sent bv Progre«, т. E bock T\. pcrimenter, English Mechanic "i Sunderland}, Uenxy Loiisdale. J

W. Smith (Northampton).—Xo stamps with your achange.

Kansas.—Cain is supposed to have married his sifter. On reference to the Book of Genesis vou will find the births of daughter* not recorded until* a considerably later period.

J. Melóme.—Consult article* on Electricity now appear

H. D. (Birmingham).—Described in back numbers.

NORTHDXBKRLAND SCBSCBIBEH.—2lS out of print; the other can be had.

R. Y. G.—Steam wns known as a motive power long before the time of Wart—even to the ancients.

John Fletcheb.—Apparently there is little difficulty in discovering your "method of secret writing." We did so in two minutes. Tbe following is the translation:—"This sort ot thing soen uses them up, but there aro plenty more in the labour market. What ко cheap as flesh ami blood? But we have forged tho fine wire; now lor the artist's touch."

John A. Maclean.—You will receive the paper till the end oí your present subscription irte of further charge.

R. G. В.—Too frivolous.

С. H.—No book ever published contained a tithe of the information to be found in our back volumes on the practical construction of the harmonium.

W. H. Thorpe (Reading).—A cubic foot uf wroneht iron weighs 4851b.; of cast iron, 4501b.; of cast brabs. 52.ilb.; of rolled brass, 5341b.; of cafrt copper, 5501b.; of gunmctnl, 5491b. ; of lead, 7101b.; of steel, 4i*)lb.

J. A.—Better apply to a surgeon accustomed to the treatment of the ear.

E. Russell.—We are glad you find our Mechanic •=*» useful. We shall, us hitherto, issue title page and index to each half-yearly volume.

Working Man,—Consult any optician or pianoforte maker. Third query inserted.

Hamilton.—Any dictionary will give you tbe required, information. Letters fur tho Queen are probably sorted by ноше trustworthy secretary, and from your letter to us we don't think any couuiiunicatiou ot yours would ever reach her.

One Of The Firm.—Assuming all you say to be correct you would certainly have the right to manufacture the iiriicles during whatever period the patent was kept up. Of course it will mainly depend on A.'s receipt, on which advice should be taken.

T. A.—Your letter appears unnoce^sary. You were not attacked in the letter to which you refer.

A. W. Adams.—See advertisement page?.

С ílorado.—Try T. R. Willis, 29, Minorleg.

F. G. С—We have illustrated and described several road steam-engines in back Nos.

M. SgriRE.—Exchanges must be prepaid.

S. Barker.—We cannot afford space.

J. В. Сосквгвя.—No apology is needed. We fully recognised the purity and zeal of your intentinu*, auil only regretted that the circumstances to which we alluded prevented our taking advantage oí theru. You know probably better than we do how difficult it is to prevent fraud i* such matters.

W. G. H.— We should be glad to receive a drawing лтЛ description of the saw, and, if worth anything, woulu insert it.

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CYCLOSIS IN ANACHARIS.

THE "American" or "new" waterweed is all too common to need much description. The cut (Fig. 1) will enable any of our readers to recognise it at sight. The leaves, of pale green, grow in a whorl of three, the stem being at this point exceedingly brittle. The plant is very easily propagated. Almost the smallest piece thrown into spring water, or into a stream or pond, will rapidly grow and increase, so that the inicroscopist who once succeeded in obtaining a piece may ensure a constant supply, live wheresoever he may. My own acquaintance with the plant extends only over about twelve months, but during that time I have devoted to it a considerable amount of attention. The results of my observations shiii now be given.

The leaves are narrow, and, when full grown, are usually about jin. in length, though in a specimen in my aquarium this length is very considerably exceeded. At the margin there is but one layer of cells, the remainder of the leaf being composed of two layers of cells, somewhat shallow, and of irregular shape and size. A leaf mounted in fluid or glycerine jelly, when examined by polarized light appears as a narrow frame of light when the prisms are crossed. This may or may not be from the presence of silex in these cells. I incline to the latter notion. With a purple sclenite and the proper setting of the prisms, these cells assume the peculiarly rich crimson colour which I have usually found to be characteristic of simple cellulose—such as, for example, the cells of Arabia and the parenchymatous cells of rush, of rhubarb, or rumex; and it may be mentioned that the vertical cell walls (separating cells in the same plane) are seen, under a high power, to exhibit precisely similar phenomena of polarization.

Por anything like a careful observation of the phenomenon of cyclosis in this plant a power of not greater focus than J" is absolutely necessary. A higher power would be useful, but with care and dexterous illumination much may be done with J" and a deep eyepiece. It is useful to begin our observations at the broad end of the leaf, and to gradually work our way up. The cut (Fig. 2) gives a fair representation* of the last leaf I worked at. It will be seen that the cells at the broader end are oblong; that in the middle they are irregularly rhomboidal ; and that at the upper end they become nearly circular. In the lower cells the current, so far as I have seen, invariably travels along the full length of the cell in a perfectly regular manner. Sometimes towards the middle I have found the axis of rotation to be diagonal, and at the upper end the rotation is not infrequently in a circle. When tho leaf is first severed from the stalk rotation is almost invariably suspended for a short time, during which the chlorophyll granules congregate at each end (rarely in the middle, though they are often said always to do so) in the oblong cells, and aggregate in a confused mass in the more circular cells. It is most interesting to watch the gradual commencement of the move

* A faithful full-size drawing would be about 30ft, long and 7 or 8ft. broad. I have therefore given portions of the leaf.

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ceased becovio deeply stained, and in time all the cell walls are also stained. Neither the current nor rotating granules are ever stained. The inert matter in the centre of the larger cells becomes stained, and is apparently granular. After the reagent has been applied for three or four hours, a very moderate power will enable one to see the movement of the current of protoplasm very clearly, and most rigidly to mark its bounds.

The younger cells appear to resist the test altogether. A writer in one of our scientific periodicals, some two or three years since, was of opinion that this reagent enabled him to demonstrate an intercellular substance, which, he said, became deeply stained. Careful observation, will, I think, show this to be a fallacy. A rigid optical analysis with polariscope and most delicate focussing does not reveal more than the simplest of cell walls (consolidated sometimes, with silex), but no intercellular substance. I have further to notice that the phenomenon of cyclosis is almost entirely dependent upon the influence of light. It is most interesting to вее how speedily general activity is resumed in cells that were dormant when an intense light is thrown upon the leaf by the mirror. Heat is also the necessary condition. From these considerations I think we can come to but one conclusion— that this is one of those phenomena we call vital, and that it may be regarded as analogous to the circulation of the blood through certain vessels in animals, and as being essentially related to that "simultaneous removal and replacement of matter" which distinguishes "living" from "dead" matter. H. P.

1, 2. Portion of leaf of ArwtcharU al$ina*trum—" a " the hollow spine. The circulating granules do not pass to the point, but make a short cut across.

3. A portion from near point of leaf, showing the more circular form of cell.

4. A cell showing a helical motion. All are magnified about 900 linear.

almost necessitates one to ascribe powers of volition to the granule. The protoplasmic current which carries the granules along is somewhat narrow—perhaps on an average the united current of two sides of an oblong cell would equal one-third of the whole width, and is in these longer cells apparently restricted to its path between the cell walls and the primordial utricle of Mohl. In the more circular (and younger) cells it is common to see the whole cell contents rotate about a central axis.

Very often currents in contiguous cells may be seen to flow in opposite directions, rendering it the more easy to demonstrate that this rotation is wholly distinct from circulation. But what is it? By what is it caused—Osmotic force, or, as has been suggested to me, electrical agency? In the attempt to gain a little light upon this matter, I have immersed leaves of the plant in various fluids of different densities. Perhaps I cannot do better than recount my experiments.

Glycerine Jelly.—This I made of medium solidity. A leaf immersed in it in a warm and moderately "fluid state was set aside for some time in an ordinary sitting-room in the month of November. I observed it every fifteen or thirty minutes for upwards of three hours; the whole of this time cyclosis went on rapidly. The next morning, however, all was still.

Glycerine.—I used Price's, of commercial quality. In every case where I have used this fluid at the temperature of the room rotation has ceased almost immediately. The same result has followed immersion in syrup of like density.

Iodine solution immediately stops the current.

Carmine fluid, slightly alkaline with potash, and but faintly coloured, also g-mcrally stops rotation. In some cases, however, the phenomenon goes on unimpeded and the current becomes slightly stained.

Acetate of Bosaniline.—The results with this are most interesting. It appears to stimulate the current. The cells in which the rotation has

THE WORLD: ITS FORMATION AND ANTIQUITY.

By Arthur Underhill.

( Continued from ¡rnge 484.)

Chapter VII.

ABOVE the strata of the Cambrian group lies a great class of deposits known by the name of the Silurian system. This formation was first examined and classified by Mr. (now Sir Roderick) Murchison, who, with that zeal in the interests of science by which he has been so uniformly characterised throughout his distinguished career, investigated the whole of this interesting group, and firmly established it as an independent system, both in lithological and palœontologieal features. In our own country it is found to be mostly developed in that portion of England and Wales formerly occupied by the Silures, whence the name. These people inhabited B large portio.. of South Wales, and some of the counties which border on that principality; but the system which has been named after them is not co-extensive with the region which they inhabited, and although it is sound for the most part there, still small masses, or outliers as they are termed, are found distributed over the whole country, and appear in places far removed from that at which it most copiously occurs.

The Silurian system is divided primarily into two groups, called respectively the Upper and Lower Silurian ; and these groups are subdivided secondarily into three subgroups, namely, the Ludlow, Wenlock, and Llundcilo series, as in the subjoined list.

UPPER SILURIAN.

Ludlow Series.—Red and green sandstones, with finely marked lamination and ripple-mark.

Micaceous greyish sandstone, clayey limestone (known as Aymestry limestone).

Shale.

Wenlock Series.—Limestone (known as Wenlock limestone).

Clayey shale.

Shuley lime and sandstones.

Grit, sandstones, and shales.

LOWER SILURIAN.

Llandeilo Series.—Grits and shales, white sandstone.

Dark limestone, flags, and slates.

It will be seen from the above statements that the.whole of the Crocks composing this system are exclusively clayey, sandy, and calcareous (limey).

The fossils of the Silurian epoch are very numerous, and there are a considerable number of species, upwards of 400 having been recorded, comprising fishes, crustaceans, annelids, several orders of molluscs and conchifene, crinoids and polyparia. Marine plants are also frequently found, and the whole of the organic remains testify to the sole creation of aquatic beings, as no fossil of any terrestrial animal has ever been found in the system.

The Llandeilo group is seen principally in tho county of Carmarthen, where it occurs on the banks of the Towy for a considerable distance. its gentle but picturesque scenery rendara it a pleasant change to the more wild and rugged rocks of the older formations. The little wooded hillocks, formed by the convulsions of a former age, give to the scene that quiet and peaceful beauty which excites within us an admiration of a passive, rather than of an active kind. Here we find none of those bare, hard, slaty rocks, whose jagged and rugged sides bear witness to the elemental vicissitudes to which they have been exposed; neither do we see those pointed peaks, whose appearance, at once picturesque and sublime, raise in us a sensation of admiration akin to fear; but we have before us the gently undulating ground, rounded and beautiful, with a quiet feminine beauty, so to speak, which soothes the searcher after the sublime and picturesque, as much as the more masculine contour of the Metamorphic and Cambrian groups excite and awe him. I cannot better show the difference between the scenery of these two groups than by comparing them to a sea, which in the Metamorphic and Cambrian distriots is as it were upheaved and lashed by the fury of some tropical gale, but which in the localities of the Silurian group is only stirred into the gentle swell, whose billows, wavy yet unbroken, give just enough of variety to prevent monotony, yet not sufficient to cause confusion.

This group, as found in the Caradoc range, exhibits certain peculiarities; the lime and sandstones, upheaved and dislocated by an emission of trap rock, are thrown up into elevated hills and rounded hummocks of considerable height ; and the sandstone is in places turned into quartz, by -reason of the contact of the molten trap, showing how greatly heat has changed the metamorphic rocks.

Immediately above the Llandeilo series lie the strata of the Wenlock group, the components of which are principally shale and limestone. This series extends from Wonlock as far as the Caradoc range, and embraces a large area of country. The strata are rich in organic remains, and the limestone affords a great proportion of that used for ornamental purposes, the richness of its fossils giving it when polished a variegated aspect most pleasing to the eye. Next in the system comes the Ludlow series, which consists of clayey limestones, grey, red, and green sandstones, and shales. This group is peculiarly interesting, owing to the variety of its strata and the great abundance of its fossils. The Aymestry limestone (so called from the town near which it mostly abounds] is useful in the industrial arts, yielding when burnt a very celebrated lime used as a subaqueous cement. It is in composition clayey or argillaceous, and non-crystalline, but is literally thronged with shells. In the sandstone of this group have been discovered tho remains of the first created vertebrate, or backboned, animals, in the shape of fish. These fishes belonged to' the family of sharks (Placoids), and were termed by Sir Roderick Murchison Splmgodi (murderous teeth), on account of the sharpness and length of those organs: they appear to have lived upon their weaker brethren of the ocean, and were, in fact, to use the words of the authorabove quoted, "without doubt tho pirates of the sea of that period." Fucoide, or sea-weeds, are very plentiful in this group ; and Encrinites (krinun, a lilv)—

so called from their resemblance to that flower

peopled the ocean's bed with their tiny forms. Although from their name it may perhaps be thought that these were vegetables, such was not the case; they were animal organisms of the order Radia ta, and were somewhat similar to a star-fish of the present time, anchored to the bottom of the sea by a long stalk-like appendage. Sea-urchin-like creatures were also rife at this epoch, in the form of Cyetideam (kystos, a bladder); curious in appearance were these little specimens of life on a lowly scale, somewhat resembling a small spherical honeycomb perched on the extremity of the waterlily's stalk. Bivalves, allied to the oyster and mussel of our day, also flourished in the seas of the Silurian epoch, together with a great л variety of Trilobites and other Crustaceans of a higher order.

This system has, in common with the two succeeding ones (the Devonian and Carboniferous), been the chief repository of that all-powerful metal, which has in all ages and in all states of society

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Aluminium ..

Barium

Cadmium

Calcium

Carbon

Cerium

Chromium ..

Cobalt..

Copper

Didymium ..

Erbium

Gluainunl

Indium

Iridium

Iron

Jargoniura ■ ■

Lanthanum ..

Lead

Magnesium ..

Manganese ..

Mercury

Molybdenum

Nickel

Osmium

Oxygen

Palladium

Platinum

Rhodium

Ruthenium ..

Selenium

Silicon

Strontium

Sulphur

Tellurium

Thorium

Tin ..

Titanium

Tungsten

Uranium

Yttrium

Zinc

Zirconium ..

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The Artiads exhibit an even equivalency of two, four, or six hexads combining as tetrads or dyads, as in the case of sulphur :—

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Dyad. Tetrad. Hexad.

Bases are metallic oxides which are decomposed when they come into contact with acids proper, or hydrogen salts when they yield a salt of the metal. Bases contain a metallic radicle called a ba*yl; thus potassium and calcium oxides contain the basyls potassium and calcium. Bases are not to be confounded with the baeylons radicles which form salts by combining with chlorous radicles. These radicles, if they are formed from a monad basyl, contain one oxygen atom; if the basyl is the dyad two atoms of oxygen exist, and a triad bash contains three oxygen atoms united by half their force :—

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Salts are formed by the replacement of the hydrogen atoms in the acids proper by basyls: the haloid salts are no exceptions, for sodium chloride (common salt) is formed, by tho replacement of hydrogen in hydrogen chloride, by the basyl sodium. It is therefore to be looked upon as a salt formed from an acid, rather than as a direct combination of the metallic radicle with a chlorous element.

As an instance of the formation of salts from acids by the successive replacement of hydrogen, we may take the tribasic acid, hydrogen orthophosphate :—

POi

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Na)

Na ( РО4

H )
Di-sodiuui

hydrogen
phosphate.

The metallic radicles which enter into combination with the acid radicle, need not of necessity, in a polybasic acid, be of the same kind. The hydrogen in the above orthophosphate may be replaced by different radicles, as in the case of hydrogen sodium potassium phosphate (1), or in microcosinic salt (2).

H 1

Nb \ PO, niii 11

К j H )

Acids, bases, and salts may all be classified

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