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ANSWERS TO COKRESPONDENTS.
'.* All communications should be *<ldrcssed to the Editor of the Esolish Mechanic, 31, Tavlstockstraet, Covent Garden, W.C
lx obedience to the suggestion* of a number of readers, we have decided on appropriating a portion of our space to a con* den-ted list of patents as nearly As possible up to the date of our issue.
The following are initials, fee., of letters to hand up to rYiday morning, June 3, and unacknowledged elsewhere :— S. Ropers, Thos. Selhv, Rev. E. Kernan, T. S. W., G. R. S., Berero, Gimel, C. Wyndham, D. Wright. Constant Reader. J. Sbarpe. J. Harmon.C. Burgess, W. E. D., R. H. Harrison. H. P., Anxious Nephew, G. A. S., G. Prew, J. Gillingham. J. K. P., G. R. S., W.Drew, Sceptic. F.R.S.. W Butler, James Kemp. Hopeful. J. W. D K- W., h\. Lloyd, J. Thomas, J. E A.. L- &J., E. Bubb. B. W. R.,H. Garland. J. B. Tenby, F.R.A..S, Ab Initio, J. F. Sunt. Alfred Hancocks, C. de T., W. Binns. Contralto, E R. T., W. H , Beginner. J. C. ,S., W. J.C., Hyoerion. Jas. Grimby, Alwavs Welcome. J. T. Capt. 8. L., Pavne & Sons. Geo. Luff, W. H. E., W. JJ. R , Robert Touge, Messrs. Mscquard, George Smith. II. T. Vivian, Brother Reader, 11. Bolton, J. H. T., W. B.
A. W. X. C —As a rnle, we select queries that are likely to evoke replies which may not only be useful to the querists themselves, but others similar!} situated. Ifence we prefer the information should pass through our columns.
Silent Rchukr will oblige by communicating the information to Mr S. V. Pocklington through our columns.
John C. Shiwan.—We can't afford space or money for Buch illustrated corrections.
Grasfikgs After Knowledge.—Mr. Hermann Smith, who received a letter of inquiry which he has forwarded to us, says:—"The writer has not given his name or address, as very likely he is ashamed of his poor writing, and Bo keeps dark. But I must confess those grasping after knowledge arc to me as interesting as the most elegant language of well educated correspondents." We reproduce this sentence from Mr. Smith's letter because we thoroughly agree with him.
G. R. L.—Your letter on "Health Helps" contains many good points, and some weak ones. It is, however, so jauntily put together that we have been obliged, reluctantly we admit, to discard it Mr. Rogers—11 you have any reliable information on the Western States of America in connection with emigration, we will put space at your disposal.
F. H. Linton — Isa Russian coin of the Empress Anna, and similar to Query 3860, reolied to by " Bernardin," p. 261.
E. H. C.—Too indistinct for illustration; probably un old jetton or counter of the 14th or 15th century.
D. D. Batti (Manchester).—Many thanks.
Bernardin.—A classified list of all the vegetable oils,
fee., would be a good subject for an article; also, on the
modes of refining tliem.
F. W. G,—The congratulation should by right have & name and address
T. Ward.—No stamps enclosed for advertisement.
J. H. I>.—Should be glad of the articles on silver coins, with as many illustrations as are necessary.
W. Scott.—We never send private addresses without the consent of the writer.
Our ever obliging "F.R.A.S.," in a private note, says r—" I asBure you I personally recommend the English MeChanic right and left to every acieniific friend 1 have, and to others who, without claiming any title to that appellation, yet wish to know what is going on in the way of physical and mechanical discovery; and I am bound to add that I never made any recommendotion more conscientiously. It certainly seems to me that such a twopenny worth as the Mechanic must ultimately act as " Edexrerum,' and swallow up not only its so-called competitors, but the mass of our popular scientific serials to boot." The Sixpenny Sale Column is the only place in which can appear queries sent by " Saepe," H. E. Turner.
J. Thomas-—You cannot obtain a specification until six months after the date of application for the patent.
J. Hatwood (Barnsley).—They are quacks of the worst description. On no account send them more money, or you will lose it. If you really wish to try galvanism, apply to some respectable medical man, and lie will recommend you a proper apparatus.
T. P.—Your views are correct. The sol-fa system is not superior to the old notation.
A New Subscriber.—See back numbers.
A Six Months' Subscriber.—To the Kegirftrar-General, •Somerset House. Cost trifling.
Thomas Smith.—See our advertisement pagee.
H. Ratner.—The 6s. edition has a key and also a, valuable appendix. We cannot recommend any book on the other subject named.
Traveller.—Apply to any optician.
J. W. Bedford.—The contributions you offer would be acceptable if up to the mark.
Veloce.—You will find some information on the subject of rubber tires in the description of the " Phantom" bicycle, n this numher.
Liverpool Reader.—See Mr. Perry's adve'tisenicut ou Vol. Viii., page 270.
Working Eor The Lifeboat— I enclose you 2s. 6d, in stamps for the Lifeboat Fund, being 3d. per 100 on the orders I have got for label printing. As an amateur printer, I hit on this plan to raise funds ror our boat, and to send more from this week's advertisement. I enclose you two or three specimens.— C. Forrest, Loflliouse, near Wakefield.
W, on Pitman's Phonography next week.
W. C. Collins—Thanka for the k nd offer.
W. B — You will see from a notice elsewhere that the day of publication will be altered without any alteration in the date. The English Mechanic will at the same time appear in new type. So we shall not only be stronger by the absoiption of "Scientific Opinion," but. we bupe, look better.
Amanuensis —Send name and address.
Capt. Peterson.—Another letter on the " Steam Lifehoat," which was in type before yours came to hand, is inserted.
Electrical Discoveries.—Isham Baggsnext week.
Paul Gill.—Nothing in the letter.
T. Gillinoham— Letter on the City of Boston much too dreamy for practical mortals.
Errata.—"J. K. P." writes:—In my note on hriss intttrumentfl. page 261, far " care " read " ease," and " gaio " for "jam" in my note on throttle vulve, in same page.
APPLICATION'S FOR LRTrBK-* PATENT DURING TUB" WEEK ENDING MAY 30, 1870.
1404 II. 0. M. Xtmena*. Wargrave, Berks, and B. Betlncotirt Boulogne-aur-Mer. Improvements in hardening, preserving, nnd rocintt building materials
1405 J. Fletcher, a, Bridgewater-atreet. Salford. Improvement* in coking and desulphurizing theooke after vbtaining the sn'ea, oil*, and other product* from cot)
1408 B. A. Leigh, Manchester. Improvements in shaft in-* and in transmitting power
1407 B. W'albink, Leeds, apparatus to expedite the fitting of "uppers " In all kinds of hoot* *nd shoes
1498 E. Leigh, Manchester, improvements In piles for engineering purposes.— A communication
1400 H. B. Brook. Westminster, an improved medicinal com* pound or stomachic cordial
iron W. E. Newton, 08. Chancery-lane. Improvements In earth closets.—A communication
lVtl B. Hunt. 1, Serie-street. Llncoln's-lnn. Improvement* in mechanism for fastening French or folding- windows at any desired point when partlallv opened.—A communication
1503 A. Cochran. Klrktnnfleld, Renfrew, Improved apparatus for discharging water from steam pipes
1*03 J. H.Johnson. 47. l.incolr.'s-imi-Ilwld*. Improvements In machinery or apparatus fur making metal cop tubes.--A cumin on teat ion
1501 J. Yule, Glasgow, improvements in motive-power engines
IMS T.J. May all, LitTord Mills, Kfnir'a Norton, Worcester. improvements in parlour foot-balls and other india-rubber articles
1500 W. E. Lake. Southampton-buildings, London, Improvements in supporting apparatus for the rollers of spuininu frames.—A communication
ISO? K. H. Pounds, 1, Kmmett-street, Poplar, improvements in ropes and cables
150H L. Perkins, 3, Seaford-atreet. Regent-square, improvements In connections for fire-engine hones and other pipes
1509 C. Tophaio Coleman-stre*»r, Bunhill-rnw. improvements In certain parts of machines for mincing or minutely dividing meat
1510 J. S, Stames. IS Broad-«treet, Hatcllffe, a new or improved ventilator for the cabins, holds, and compart m»nt* of ships
1511 J. McNaught and W. McNaught. st. George's Foundry. Hochdale. improvements in ninchloery or apparatus for washing and drying wool, yarn, or other fibrous materials
1512 W. K~ T,ake, Southampton-hulldtngs, improvements In washing machines.—A communication
1513 C. VV. Siemens, 3. Gre.it George-«treot, Westminster, Improvements in regenerative gas furnaces and apparatus connected therewith
1514 G. Thomaa, Colchester. Improvements In the construe* tion of gas stoves.
1515 J. W HorsfaU, Camden Town, Improvements in ventilating mines
l.MlfJ. Falconer, New York. U.S A., improvements in machinery for forming bats of wool fur felting purpose*. —A communication
151" J. Shanks. Arbroath, wheels for traction steam engines and other heavy vehicles
1518 8. E. T. Steane, Barking, Improvements In domestic Oreescapes
1510 A. M. Clark, 53, Chancery-lane, self-acting machine for cutting wood screws and eye-bolts.—A communication
L'.iWO. E. Barton, 173. King Kdward-street, Great Grimsby, breaking of ice for the preservation of fish and other purposes
1531 R.C. Robinson, Preston, improvements in fire-grates
1522 J. Appleton and K.O.Ross, Miuchester. an improved process and apparatus for preparing and finishing printed paper
1523 G. Schuck. 18, Idol-lane, London, an improved machine for watering and sweeping streets.—A communication
1524 I). Jones, Clerk on well, improvements in the manufacture and treatment of coal gas for illuminating purposes
1525 G. Lunee, South Shields, improvement in the treatment of esparto grass and other fibrous materials
1520 J. Bnllougb, Accrington, Improvements In looms, warping or beaming machines
1527 J-Bernard. **alisbury-street. Strand. Improvements In blast and other furnaces, and In extracting metals from their ores and from metallurgical products
152*! J. Webster, Birmingham, improvements in converters for the manufacture of steel and other metals
1520 W. Horton, Sheffield, improvements in centre bits
15(0 B. Cooper, Frotne, Improvements in looms for weaving
1531 J. Eastwood. Hradford. and H. W. Whitehead. Holbeck, improvements In machinery for combing wool, cotton, flax, and other fibrous substances
1592 W. E. Newton, 00. Chancery-lane, Improvements In looms fur weaving.—A communicUlou
1533 W. Arnold, Barnsley. and W. Carnclley, Manchester, improvements In steam boilers
1534 L. Walker, and F. A. Walker, Liverpool, an improved setting fid
1535 W. Malam, New-road, Rotherhfthe. an Improved furnaco or apparatus for consuming creosote and other hydrocarbons for the production of heat
1538 J- Bernard. Salisbury-street.Strand,improvements In the treatment of certain ores and metallurgical products, and in the extraction and recovery or their metals
1637 W. Astrop, Homerton, improvements in motive power
1538 A. Prerichs, Hamer Hall, ltochdale. improvements in machinery for spinning and doubling cotton and other Ithroua materials
1539 J. I, Taylor. Manchester. Improvements in washing, churning, and mixing machinery
1540 G. Keller. 12, Great Prescot-stroet, Goodmans-Holds, Middlesex, improvements in fire-arum
1541 W. Morgan, Uotherhithe, improvements in carriage axleARnd bearings
1542 it. Gammon. Warminster-road, Westbury, an improved railway sleeper for permanent ways
1543 J. Sellers, Treston, improvements in mileage indicators for vehicles
1544 -I. Henderson, New York, improvements in the process of refining and purifying cast irou for foundry and lor other purposes
1515 P. G. B. Westmacott, Elswlck. Newcastle-on-Tyne, Improvements in apparatusfor grindlugur polishing piato glass or slabs of slate stone, marble or other suhxtancej
1540 H. Blandy. Kottinghatn, improvements in the construction and arraugement of veasels employed m the manufacture or nitrous oxide gas
1547 H. Ko*e. Alhany-street. Reguit's-park, improvements In the mode of attaching mineral teeth
1548 J. Darguoand W. Dargue. Hradford, Improvements in machinery or apparatus employed in the process of bleaching, scouring', dyeiiiK. and (sizing warps or yarns and fabrics
1549 B.J. It. Mills, 55. Southjimpion-huildlngs. improvements In safety attachments for steam generators.—A communication
1550 J. Cope, New North-street, Pinsbury, an improvement in fct'-am engines
1551 H. A. Bonneville. 10, Sackville-stroet, Piccadilly, Improvements In hreech-loaaing fire-arm*.—A communlcat.on
1552 H. A. Bonneville, anewaud improved label holder and fastener.—A communication
1553 W. E. oedge, li. Wellington-street. Strand, A new or improved system or grooves Tor rolling and shaping iron or other inelals.—A communication
1554 W. B. Gedge, a new or Improved plough.—A communication
1558 G. Rtevens and J. Hendy, San Francisco, an electro-magnetic motor Tor sewing and other machine*
15M w. S, Moore, Porcival-stree.t, Uoswejl-road, an improvement in hand mirrors and other Ifkn articles
1557 W. J. Sciiiesinger. Union-court, Did Broad-street, improvements in producing rotary motion, applicable to egg heaters, churns, lioltlo was hers, washing machines, drills, it oln and other instrument*.— \ commiihlcutinn
1555 K. Tommasl, Paris, Uoulevnrt de Stras* ourg, 23, an improved theriuopreBi
15*9 H. Bmbctbt. Queen -street-place. London, taigr«»«'fsn«>»» In the oonstrunMon of atctm *lpp« *nd other *-—M* «rmp-lov•»)' tor the conveyance of paas*n*cv«, and In lb* oasia^La tat apparatus employed to prevent or le^cn »e«-sieiioa»» a« bAarf such veasels
1500 W. Cleland, Llnacre. near Liverpool, impmrod meat-1 and apparatus for exhau«tlng. rorelng. and panfyita- gaa I .heating and illuminating purpo«*>t
1501 9. H. Swphsni.Gra^s Talley, PiJironita, mavohinie* tgrtnding, ooncentraHng. and refining tin and otker or**
1503 A. Manbre. Baker-street, improvements in nj>raLrmt-x applicable to the conversion ofcerearand teg*table «iia«u&> inm saccharine matter
1501 E. a.Struhin.Nottlnc Hill. Improvement* in camersjiv reflecting and ipaimifrtng opaque ohj^cta—\ Momunm^
1544 G. T. l^eitch. Knthergian. a new asricultnral iropleasee
1S83 W. T. Hmall, 18a. Wi|lfam-str*»et. Holloway. irrjp«-;.^ ments in the method or methods or supply and eiit «f »air and other fluids, respectively to and from ayiia.rlu.ms, taali ciMterriH, and o-her like vessels
158i A M.Clark. 53, Ch*nc>r,v-]ane, maehinery for r*rnr, tins-and moulding sheet metal, which imp'owemeats aj> a*a applicable for other purpose*.—A commnnicsvtlnn
1507 K.. J, Collins, 15. 10. and 17. Bartholomew-doe*, impf^ menisinthe manufacture of embossed rabric* lu imitaai-si t quilting
1508 K. P. Williams. Great Qeorge-street, Weatmbxat^r. m provemeuts in railway switches or junction points
1500 C. D. Abel. 20. Southampton-buildings. ChanoM-r la-improvements in the manufacture of sockets and. tTcrrula -■ wrought iron and other metals.—A communication
1570 C. D. Abel, improvements in the manufacture of vroat^ metal tubes —A communication
15H O. D. Abel imorovementa in apparatus for drawing ti. sk«lps.-A communication
1372 W Partm, "ar-'-llles. improved apparatus l* . employed in gvmiifistlcperrormancas
1373 H. Hryant. Mart ford, Connecticut, an impr*apparatus for illustrating the motions or lomn of h. heavenly bodies and expUUiinsi various celostial pheuo.m#r»
15,4 w. Keamish.5, Klgin--ro*d, ^aint. Peter's-povra;. Pavd4»n. ton, constructing a cylindrical trm kerb for the r« ceni;repairing, and maintaining telegraph wires
1575 O. Mather. corUin improvements in machinery i ai-paratus us-d in sizing and dresking yarn
1279 J. F. Wiles, sun-court. Cornhill, improvements a electro-magnetic engines «•««*■
1577 W. E. Gedge, Improvements In knitting machine*communication
1578 A. V Newton, improvemenU In looms ror weavingooinmunicatlon ■■*»*
1579 L Mignot. Boulevard de Strasbourg, 33, improved o ■ chlnery for making ice
ltwoH. Bessemer. Queen-street-place, London, improvement In the construction of area aMn« employed for the. rs,,. % eyanee nrp isssengers' luggag- nd cattle, and in the mpn^rat ■ * employed Tor such purpose on board ships, and for lessening ojpreventing sea sickuesn
„fll r . „ PATKNTS SEALRTX
IHl J. L. Booth/Improvements In the manufacture »rnu> ror railroads
8598 J -,. Tongue, improvements In machinery or appseafti* ror sewing or etttehlnv together theimmbert orwpctfe ?,*rtJ ui.i volume in thu operation of bookbindlng.-A eom«fuiic»tK>n
8823 K. Johnson, lmprovmenta in thu arrangemeflt saa con•tTMotlon or granarlea.—A communication
3»r/5 G. T. BVmsfleld, improvements in the treatment of aromatic secondary monamines forobtftiiiincwlourluje matter . — A communication
M78 G. Ermen, u. A. Ermen, and W. Fostsr, \myroveraenta In the construction or brushes
t,S*7 9^U-A!**1-'mProv*mentBinpIoughinuid cultivators ft* tilling the soil—A communication
3724 H. E. Newton, improvements in traction englnes--A communication
48 W. Wield, improvements In machinery fur winding yarn or thrend on to bobbins
91 F. IL Knovitt, improvements in shutters and blinds for windows
lr» G. Kent ImprovemenU In rotary knife-dean lug and polishing machines
"23 J. Moysey and C. Thome, iroprovemente tn hackling machinery
770 W. Kalnfnrth and W. Halnforth. Jnn.. Improvements in rotary corn screens Tor dressing and separating grain
831 J. Bradbury. J. Bradbury, and J. Koberts, improvements in machinery Tor felting hat bodies
954 W. MacLean. Improvements in printing, lithographing, and itnootraphmg
948 A. Harlnw and J. Taylor, improvemeata In machinery or apparatus to be employed iu preparing cotton or other fibrous Substances for spinning
3451 T. Itelssig, improvements In making a new derivative or phenol, and in producing certain colours therewith upon texfMe fabric* and yarns
34(11 C. H. Hudson, improvements in cots or bedsteads, and guaids to be attached thereto
3403 E. T. Hughes, manufacture of elliptic springs, and in apparatus employed therein.—A communication
3403 A. W. I'ocock, improvements in meters or apparatus for measuring water and other liqu'dM
34*4 W. H. Willis, a new or improved apparatus for registering or Indicating the points of games
3445 R. Aoton and J. Mustard, Improvements in machinery for reeding card'ng engines
3172 W. Spence, improvements In the manufacture of soda crystals
347-i T. O. Green, appliance* *or use in the manufacture of an ides or earthenware ami chlnawara
3480 J. Peirce, improved compound machine for cutting tenons and mortises and sawing wood
3485 G. Hammer, improvements in cork-cutting machine*
3488 A. Mitchell, improvements in caissons or apparatus t» facilitate the hulldlng of bridge piers
3194 P. A. S. Langiois, and L. S. Thomassln. ImprovemenU In the manufacture or sulphuric acid
3495 K. Field, valves for at-'am fire-engine and other pumps
,141*4 W.TjTatham. improvements in machinery for opening tin ft breaking hard waste, rags of cotton, woollen flax, or bilk, aud for scutching aud osrdtng fibrous substances
3658 A. M. Clark, improvements in Jaouunrd apparatus.—A communication
8888 K. Shakespear and G. Illaton. improvements in sewing machines
3805 H. Green, improvements in lubricators
1018 A. H. Brandon, improvements In looms.—A eommunicition
3477 J-T. GrifTin, improvements in preparing, treating, and curing sponge to render it elastic aud suitable for use ass stuffing for hedn.—A communication
3488 r. O. Webb, improvements In t^e manufacture of submarine telegraphic cables
3490.1.0. Wilson, an improved revolving engine and rump
3507 J. Boyd, improvements in machinery fur winding yarn or thread upon conical surfaces
3523 w. >hanks, improvements In machinery for forging shoes Tor iiorBee
3541 J. H. Johnson, improvements in crucibles, melting pf'*9retorts, and furnaces,—A communication
854-J b. Krtwr«rd* improvement* In photo-mechanicftl prinilnn
3548 G. Preston and J. Prestige, improvements in apparatus for regulating the supply of wnter to waterclosets
3508 J, Kallantyne, improvements in the manufacture, of yarns or threads
3585 W. I. Hethertngton, improvements in motlve-po«er eiigtoes specially adapted for propelling «hip«
3015 Yf. E. Newton, improvements in harness for looms.—A communication
5031 B. Mo*s. improvements in kilns or apparatus for the manufacture of malt.—A communication
3035 J. Askew, refrigerator for cooling brewers' and dintillers' wort
8001 J. O. Martin, an Improvement in the manufacture; of finii'gs as a substitute for isinglass
3070S. Hiitler, improvement in the manufacture of lace in twist lace machines
!W A. M.i'iark, improvements In wroden pavements and Iu culi it : the i.locks therefor.-.4 eommnulmMnn
71> . ('hatwood aud J. Sturgeon, imj roemmia In clirect-nclin,-: _ . wer liammers
MIRROR OP SCIENCE AND ART. FRIDAY, JUNE 17, 1870.
IN oar recent articles on "Colour and Colour Blindness, it will be noticed that we have treated merely of objective colours; that is to say, of colours that may be said to have a real existence, arising from the decomposition of white light, and in regard to which the eye is to be considered simply as a passive instrument forming the organ of vision, and is in no way employed in the formation of the eftect it witnesses. But under particular circumstances the eye itself is capable of producing a certain degree of colour which has no real existence, and is risible to the eyo only as long as the circumstances that produce the unreal colour are capable of exerting their effect upon the organ of vision. To these colours has been applied the term subjectiveor accidental, and their production is owing to a reactionary property that the eye possasses under the influence of fight, more or less vivid, and which converts the organ of vision into an active from a passive state. This reactionary power is well described in a letter from Newton addressed to Locke, in which he decribes an experiment performed at the peril of his sight. Newton subjected his eye to the action of a great amount of concentrated light, by looking at the image of the Sun reflected from a mirror, andthen turning his eye,when sufficiently fatigued, to an obscure corner of the apartment, he closed the eyelid and prepared to watch the resnlt, when he saw a luminous image of the Sun, surrounded ■with coloured rings, which, growing weaker, by xegrees, finally disappeared. "I repeated this act a second and third time. At the third repetition, when the luminous image, and the colours which surrounded it were rapidly disappearing, and while my attention was concentrated in the expectation that I should completely lose sight of them, I saw them, with no little surprise, again make their appearance, and gradually become as vivid and strong as they had been at the moment when I ceased contemplating the Sun." This experiment satisfactorily establishes the fact that the retina, after having been excited by the action of a luminous object, is gifted with the power of calling up a succession of coloured images that have no real existence, but as the experiment performed by Newton is highly dangerous, and likely to be attended with disagreeable results, we shall content ourselves with describing experiments which equally well attest the active power of the retina to produce unreal images, and which can be performed without danger or difficulty.
If a red wafer be placed upon a white ground, as a piece of paper, for example, and be attentively examined for some time, there will be perceived around the wafer a ring of green, and if, after this, the eye be directed to a second piece of white paper, at the same distance from the eye as the first on which the red wafer was laid, an imaginary green wafer will be perceived of the same dimensions as the original red wafer, which will gradually grow fainter and finally disappear as the irritation occasioned by the red rays from the wafer gradually dissipates itself. This is the manner in which the experiment was effected by ISoffon, but Scherffer has noticed that the accidental colour was both more brilliant, and the outline better defined if the natural colour was viewed on a black ground, and the eye afterwards transferred to a white.
If the wafer be of a yellow or blue colour, the ey£ on being transferred from the natural colour, will see a phantom wafer of violet or orange; if it be black, the consequent object will be white, and vice eersa Therefore this experiment makes us acquainted with the fact that the accidental colour arising from the prolonged contemplation of a natural co our is 0f a complementary hue, the •erm complementary being understood to imply two colours, which when blended together produce white. An attentive consideration of the flmple experiment we have just described conduces us that two distinct phenomena are going
on at the same time, namely, that which produces the border of the complementary colour around the wafer while it is being examined, while at the Bame time the eye is so affected as to be capable of producing a phantom colour, after the removal of the wafer. To the first of these two classes of subjective colours has been applied the term simultaneous, to the latter, succedaneous. We will treat of the latter class first, taking M. Platcan as our guide.
The researches of M. Plateau on this subject have led him to decide that the disappearances of images do not vanish with a gradual and regular decrease of brilliancy, but are accompanied with a succession of disappearances and reappearances. The method of observation employed by M. Plateau was as follows :—While one of his eyes was closed and bandaged, he directed the other with fixed attention for a minute at least at a red paper, catting off all extraneous light by adapting a blackened tube of about fifty centimetres in length, and three in width, to his uncovered eye. When the eye was sufficiently fatigued, he turned his eye to the ceiling, without removing the tube, and without uncovering the closed eye. On the ceiling, he saw projected a green circle, soon followed by a red circular image of feeble intensity ; this red spectrum was followed by a green, which again gave place to the red, and so on, the red appearing as often as four times, though of course gradually decreasing in brilliancy. Notwithstanding Sir David Brewster's assertion that the manifestation of these phenomena are physically impossible in a perfectly darkened room, the complementary image, and precisely the same appearances, can be produced by closing the eyelids, and pressing the fingers upon them to exclude all light. This fact has required some modification of the hypothesis advanced by Brewster to aocount for the phenomena, of which we shall say more hereafter.
The experiments of Soherffer have decided that accidental colours are capable of combining and blending together precisely as objective colours; thus, the accidental blue and yellow form a green; the red and blue, a violet, and so on. The method of proceeding of Soherffer was exceedingly simple. He placed on a black ground small squares of violet and orange (the complementaries of these being yellow and blue respectively), and fixed his eye steadily first on one, and then on the other without moving his head, till each had been examined four or five times. He then turned to a white wall, on which he perceived three squares in juxtaposition, coloured yellow, green, and blue, the middle square being formed by the combination of the two accidentals, yellow and blue. If orange and green had been the objective colours examined, violet would have been the colour of thd centre square ; in every case, the colour of the mean would be a mixture of the colours of the two extremes. There is, however, one exception to this rule, which occurs when one of the objective colours is the complementary of the other; as, for instance, if red and green be the two colours subjected to scrutiny. The centre square in this case is not white, but of a dark neutral colour, if projected on a white ground, and completely black if the eyes be closed.
Since two accidental colours are capable of combining, it might be expected that an accidental could be blended with a real colour, and this is the cose, which shows that accidental colours have all the attributes of real colours, excepting stability. The experiment to show this combination is easily effected by changing the black or white screen which we have hitherto considered to be employed os the material on which the accidental colour is projected for a coloured screen. If, for instance, the accidental red arising from prolonged contemplation of the objective green be thrown on a blue screen, a brilliant violet will be the result. But it should be noticed, if the accidental red arising from the same circumstances as detailed in the last experiment, be projected upon a green screen the effect will be simply to produce a neutral grey, of a dark tone, that is to say, in general terms, that when the accidental image is projeoted on a soreeu of the same colour as the objective, the effect is simply one of obscurity. On the ether hand, when the screen is of the Bame hue as the accidental, or the complementary of the natural colour, the brilliancy of the phantom colour will be much enhanced, and stand out prominently from the neighbouring coloured surface. This will be the case, for example, if the exciting
ibject be yellow, and the coloured screen vioI.it. Such are a few of tin properties of suecedantov.i subjective colours. Before we proceed to mention '.he cause of the phenomena we will add a few of the familiarities pertaining to simultaneous subjective colours.
As we have already said, this is the name that physicists have applied to the accidental colour that is created during the contemplation of a coloured object. Many experiments prove beyond all doubt the capability of the eye to imagine colours while Bo occupied, and the simultaneous Ian of contrast is one of no little importance in the many trades and professions in which coloured decorations are employed, and the assortment of tints involved. As the coloured fringe, which we have described as appearing round the border of a luminous circular image, is not without its objections as a proof, and as an instance of the existence of this law, we will describe another experiment easily perrormed, and which dispels all doubt on the subject. Take two pieces o£ paper of abont twenty inches square, each of which is coloured by an even tint of two different (the one red, and the other yellow, for example) colours, of as near as possible the same intensity, and cut the two squares in halves. Fix the four pieces of paper upon a piece of brown holland opposite to a window in Buch a manner that two edges of two differently coloured pieces of paper may be in contact, and at a distance of about tea inches suspend the two other pieoesof paper each on the side of its own colour (these two exterior slips to serve for comparison). On examining carefully the entire arrangement, it will be seen that the two centre half sheets undergo reciprocally a modification of tint, and are no longer identical in colour with the separated sheets, but each has taken snch a tint as would result from the original colour being tinged by the complementary of the colour of the other strip. In the example we have supposed, the interior red strip will tend to a violet colour, and the adjacent yellow strip to a green. M. Chevreul. to whose ingenuity we owe this decisive experiment, had abundant proof furnished him of the existence of this phenomenon in his official capacity as Superintendent of the Dyeing Department of the Royal Manufactories of the Gobelins, by the complaints of drapers who had given cloths of a single colour, red, violet, or blue, to have black figures painted upon them; on the red cloths appeared to them green patterns, on the violet oloths, greenish-yellow ones, and upon the blue, orange-coloured, instead of the black that had been ordered. In each case it will be noticed that the colour with which the black appeared to be tin»cd was the complementary of the colour on which it was painted. M. Chevreul covered up the groundwork of the cloth in such a way as to allow only the black to be visible, when the designs appeared as black as could have been desired, and the fault was entirely in the ignorance of the drapers to this law of simultaneous contrast
The researches of M. Chevreul on this subject are extensive and exhaustive. We shall merely mention here the conclusions to which his experiments and experience have conducted him; they can all be deduced from the general enunciation of the law of simultaneous contrast. If two colours are in juxtaposition, of which one is the complementary of the other, since each has the tendency to overspread the surrounding space with its complementary tinge, the brilliancy of each must be enhanced, and the result mu%t be to produce colours of greater purity and brightness. The knowledge of this fact is of great us* in a variety of cases. For instance, the employment of red hangings and decorations in apartments is not desirable, since the effect of such a colour would be to give a greenish tinge to the countenances of the inmates, and destroy the reddish oolour which is highly prized in mahogany furniture, giving it the appearance of oak or walnut wood. Judging from optical principles, the head-dress that is best calculated to adorn a fair complexion would be a green hat lined with rose-colour, because the roae-tint is reflected on the countenance, and is further heightened by the complementary of the green overspreading the face. Undoubtedly, our example is a work of supererogation, but it equally well serves our purpose of illustration. ^
If white be brought into contact with any colour, it is of course slightly tinged with the complementary of that colour, but the colour employed becomes deeper and brighter. The same result follows from the involuntary eontreat of black, and any colour, and when black
portions, and bo swiftly whirled round from the centre point, each colour loses its individuality, »nd all appears of a uniform light gray (int. If the colours wore perfectly pure, the result would be a white light The diagram shows the proportional size of each sector in order to produce such a result. The arc of the circumference occupied by the Violet tint is SO dog., of Iudigo 40 dog., and of Blue GO deg., which occupies onehalf of the disc. On the other half are arranged the other four prismatic colours in the following proportions :—(ireen, CO deg. : Yellow, 48 deg.; Orange, 27 deg.; and Red, 43 deg.
But if ons of these sections be painted black, instead of the appropriate tint, the result is not a white light, but is of a colour the complementary of that which has not been allowed to appear. An easy method of determining the colour that arises from the mixture of any of the prismatic colours can be understood from the accompanying diagram, where each sector is supposed to be
and white are in juxtaposition, the former becomes deeper, and the latter more brilliant than
when viewed separately. The same modifications
of colour take place, though less distinctly, when
the two objects are not in contact, the alteration
of colonr becoming lees as the distance between
them becomes greater.
Simultaneous accidental colour manifests itself
in another entirely different manner, but not
less interesting, as is evidenced in Coloured
Shadows, which differ from other accidental
colours, which are difficult to perceive and
eminently transitory, hy their vividness and
strongly-marked characteristics ; " and the mind,
however convinced of their unreality, repels
with difficulty the notion that they are no simple illusions, no purely subjective appearance, but in truth real oolours." These coloured shadows are 1 produced with no great difficulty, and no very extensive apparatus. It is sufficient to interpose a body illuminated with white light between the coloured light and the screen on which the light falU, when it will be Been that the shadow is tinged with the colour that is complementary to the coloured light. For example, if we have a cone of red rays falling upon a sheet of paper, and an opaque body illuminated by white light be. introduced in front of the paper, the shadow will be intensely green. Of course, by varying the colour, by means of a succession of coloured glasses, the shadow of the interposed object may be made to pass through all the varying shades of the spectrum. Count Bumford has been one of the most enthusiastic observers of this class of subjective colours; he expresses his admiration in no measured terms. "The shadows," he says, "were tinged with an infinite variety of colours!
the most unexpected, and often the most beau- covered with the appropriate tint. Let us suppose tiful; they varied unceasingly, sometimes with 'aa' *Qe colour is concentrated in the centre of inconceivable rapidity ; the eyes were fascinated gravity of each sector, then, if any colour be left and the attention involuntary fixed on this magio oat> tne resulting light will be that colour which
tableau, equally enchanting and new. The. clouds carried by the,,winds seemed each in its turn to bring an endless succession of different colours with the mast harmonious tints." Yet this "magio tableau" was produced with the most simple apparatus; nothing more than two little apertures covered with coloured glass, sufficiently removed from each other that the light of the Sun which passed through these coloured glasses might throw two distinct shadows of the same opaque body. Although the opaque body must be necessary to produce a shadow, the experiment can be varied to show the light tinged with the complementary of the surrounding coloured light. Meusnier vouches for the success of the experiment performed in the following manner:—In a room where the illumination is effected by mean* of the solar light transmitted through a red curtain, the light of the sun passing through a small orifice out in the curtain, and falling on a white screen, will not be white but greeTJ.
However difficult it may be to believe that we are deceived in the colour of these shadows, it is by no means difficult to prove that we really are so. We are indebted to Count Bumford for removing all doubt, that attaches itself to this section of subjective colours, and for tearing away the veil of mystery that surrounded them. He arranged his apparatus as usual, and made quite sure that the phenomena of coloured shadows were duly manifesting their peculiarities, and attractions on the screen : be then proceeded to examine these shadows through a blackened tube, that cnt off all the surrounding light, and left visible the shadow alone, and, lo! all the brilliancy and attraction of the phenomenon had vanished, a colourless and obscure shadow was all that was visible, and the philosopher was convinced of the deception. The explanation of the phenomena of coloured shadows is to be found in a moral, rather than in a physical cause, and the theories that account for subjective colours will fail when applied to coloured shadows, and consequently considerable uncertainty attaches itself to this description of phenomena.
The explanatory theory suggested by Scherffer, and accepted by Sir David Brewster, will, with a slight alteration and addition, be sufficient to explain most of the phenomena that the subject of accidental colours produced. To make this sufficiently clear to our readers, it will be necessary to refer, even at the risk of repetition, to some of the well-known properties of colour. It is well known that if a disc of paper be painted with the seven prismatic colours in certain pro
is nearest to the centre of gravity of the remaining sector. For instauce, if Violet be painted black, or left out, the centre of gravity of the sector will fall in the line a. This line falls between the Green (g) and the Yellow (y), hence the prismatio celours without Violet would combine, and form a greenish yellow tint, in which the green preponderates. If green be left out the centre of gravity would fall between the red and violet, which is the true complementary colour of green. Hence, in all cases, the complementary of any colour can be determined by producing the line that bisects the arch it covers, to the opposite side of the circle, when the point at which it meets the circumference will indicate the complementary colour.
We are now in a position to explain how it is tl.at the contemplation of a coloured object devclopes in the eye a tendency to perceive a phantom object of a complementary colour, simply by supposing that the irritation occasioned by the red rays has to some extent destroyed the sensibility of the eye to red light, and thut in the contemplation of a white light the eye is in precisely the same position as in viewing the coloured disc when the red baa been omitted, when by the rule given above, the light emitted would be a green tending to blue. This simple theory is sufficient to explain most of the phenomena present in the succedaneous subjective colours, but there are certain peculiarities of which it affords no competent and satisfactory explanation, such as the production of subjective colours in complete darkness, and the combination of the accidental with the real objective colours. The first objection, as we have seen, was asserted by Sir David Brewster to have arisen from a decided physical impossibility; but M. Plateau, too long employed in these observations to be easily deceived, has stated that he has seen such an effect, and its existence is now so completely recognised by physicists, as to require some modification of Scherffer's theory, for it is manifestly absurd to suppose that the insensibility of tho eye to a certain coloured light should in the absence of all light, produce a complementary colour. Neither can this theory be held sufficienily to explain the irregularity with which the accidental image vanishes, and the occasional reappearance of the natural image. The ingenious theory of M. Plateau seeks to evade none of these difficulties, lie begins by remarking that accidental images are due to a physical modification of the organ, since the size of the accidental image is considerably modified by the distance of the surface on which it is projected, from which it is to be inferred that the visual angle is constant, and
that consequently the ima^e is increased, according as we refer it to a greater distance, wuieh U in accordance with the fact. "We see no reason, says he, " why it should be so on the hypotbesi< of a moral cause; the image should then always appear ti us of the same magnitude u fc object."
This prefatory remark being; admitted, it«? be necessary to consider the effect produced Bit the retina by the contemplation of a eoluared* ject, both during and after the action of a coloured rays. It seems most natural to sappo that after the organ of vision has been excited i* coloured light on the withdrawal of the c-au« <: excitement, the retinashould gradually regain itnormal state, which would occasion the persutence of the primitive impression, growing feebler as the impression vanishes, yet without cuangieg its nature, till, like the oscillatory motion of i pendulum, it passes through its normal state, j point of rest, when the reactionary property produces the subjective image, which, when it h»i again reached the maximum degree of brightness, gradually tends to reproduce the primitive impression. AH the phenomena that depend npos time, that is to say in which time enters essestially in order to produce the phenomena, axe explained by this ingenious reasoning, and by an analogous reasoning, with relerence"to spare, the phenomena of the simultaneous subjective colour? are explained. "If while the retina is subjected to the action of the coloured light, we examis? the parts of the organ whioh surround the plan directly excited, we see that the normal state s not found except at a distance more or less considerable from the contour of that space, and thai this normal state is reached in passing through the effects of irradiation, and of the accidental colours of the second (simultaneous) claBS." Here then, we have presented to us two kinds of osoiJ-' lation, one of time and the other of spare, which separately considered, are sufficient to explain all the phenomena with which we are occupied, mod M. Plateau has pointed out "that they are connected with one another in the most natural manner—that they are simple consequence* of the law of continuity." M. Plateau does not abscAutelj deny the existence of the law of involuntary contrast, but he rightly doubts its competency "to explain,all the circumstances that accidental colours present, and we think it will be admitted that where possible, it is better to trace the effect from physical causes th.-m from moral, and that the reasoning of M. Plateau is more satisfactory than that of M. Chevreul.
We cannot close this short article without expressing our sorrow and regret that the researches of M. Plateau, and o£ M. Fichner, scarcely inferior to him in his enthusiasm, but less happy in his deductions, have been crowned with a common misfortune. Too enthusiastic in their endeavours to produce these subjective colours, and analyse the sensations, they have been smitten with blindness. Under proper medical treatment, we believe M. Fichner recovered the use of his eye, but the illustrious Professor whose name has been mentioned so m my times is thoroughly incapacitated from pursuing those inquiries, which have shed around his name an immortal lustre.
A PRACTICAL TREATISE ON THE
By Hebmann Smith.
THIRD DIVISION.—CHAPTER IV
Of Tub Channels Of The Sound-boasd.
The masses of uir which nre enclosed in a pipe are not brought with the same ease into every possible kind of vibrating motion, bat by msans of external action each mass of air is enabled only tn give those particular vibrations which are not opnosed to the reaction iio.it within.—Ojehsted.
0 whatever extent you may be tempted to
investigate the nature of the harmonium, you will do well to take the sentence of the great Scandinavian philosopher as the fitting prelude to a thoughtful survey of the characteristic features of the instrument, and of the varieties of quality possible in its tones. The stops of the harmonium form a topic for critical discussion, aud each speaker on his own showing professes to he a judge and conuoisseur. Nothing is more common than the demand foragood oboe stop, a good clario
* The copyright of this treatise is reserved by the author.
net, trumpet, and violoncello, and other conceivable stops to fit the musician's fancy—nothing more common, unless it be the assertion that somebody possesses or knows somebody that possesses an instrument, harmonium or organ, with stops of so perfect a kind that the best judges could not distinguish their sounds from those of the genuine instruments with which they are supposed to compete. The extent of the delusion is the measure of the imperfect knowledge of the limitations of art, and of the lack of real acquaintance with the instruments brought into comparison. No professional artist would admit the claim for a moment, unless with a smile of condescension to the questioner. Imagine asking Barrett, or Puzzi, or Lazarus, or Piatti, how far they were deceived by the tones of organ or harmonium in the disguise of oboe, horn, clarinet, or violeocello. The old ambition is rife as ever. The dream of the alchemists for an universal solvent, the quest of the Eosicrucians for the transmuting stone, trouble us no more, yet men after another fashion endeavour
to pass through Nature's bounds, and all in vain. Our counterfeits pass with energetio warranty as quite equal to originals; but the true seer is never deceived ; the fine royal mint-mark is beyond dispute, and makes visible its supremacy. We imitate wonderfully well the flavours of fruits, and tho perfumes of flowers, yet our skill in chemistry is abashed in the moment in the presence of the simplest offering from orchard and garden; in all our attempts there is "a hidden want," and we are obliged to confess that Nature holds charms in her laboratory that we cannot match. In the same mood of thought we view musical instruments as Nature's work. The several classes of instruments formi ng the modern orchestra belong to distinct types, and however we may vary these in grade and power, and increase their mechanical excellence, yet we cannot originate a new type, nor afford to banish a single species. The for m of each instrument, the mode of its musical excitation, and the range it can compass, these determine the characteristic tone by which we identify the species, and hence it will be obvious that if we depart from the type, and make new moulds after our own fancy, the natural results cannot possibly be the same. Our imitation may be a marvellous good likeness, yet it would be dangerous to our self-complacency to place it side by side with the original—or paste diamond lying in the effulgence of the one fair jewel flashing and smouldering in her hair. Do not lightly allow this view to pass from your mind. Let it be firmly impressed upon you that the thorough comprehension of it is of essential value in the study of our instrument. ■Fixity of type ensures the reproduction of character. We copy the form and mode of the chief solo instruments of the orchestra, and the tones we listen to are the same in kind as those heard by our forefathers. The family likeness is recognised in every country where the art is practised. Take for instance the "Oboe" or « Hautbois." A tube of certain length, two reeds, the slender throat, slender as the throat of the nightingale, a pipe of conical bore, and apertures at definite distances, and the tone from such an instrument is of so nnmistakeable a character that we identify it as belonging to B species, and call it for all time "oboe-tone." The form and the mode determine the product; alter these in any degree, and the result will inevitably be a different result. Do you ever consider that the innuenceswhich go to produce that sensible existence m aenal waves which we call "tone " and quality of tone " is as truly a compound of forces acting in definite relation, and si imulating the ear to recognition just as much as the food we taste and discriminate is a combination of chemical constitnents in definite proportions? There is no change in the result of any of these combinations, though there may be in our attempts at its attainment. Here the words of Oersted come in to our aid, and indicate why there is no chanoe. Natnre in these, and we might as truly say, in all her movements follows the simple plan of taking the P"h of greatest ease. Water tending to its level ■7 Projectile pursuing its flight aod sinking to its rest, the planet tracing its orbit, all are seekinwe line of greatest ease, under the composite and many-sided influences impelling and surrounding them. With as absolute a certainty, sound is generated according to the associated influeuces
under which it comes into existence or activity,
In the making of Oboes, art faithfully abides
The form of the sound? Yes, the expression
We say of men, character displays itself; we have many proverbs that emphasise our belief in inherited virtues and vices, and the family likenesses that bespeak parentage and affect behaviour. In like manner, pipes, channels, and other musical agents, have predispositions which are always ready to display themselves. Each gives tho tone that comes most natural to it, most
easy under the forces that bear upon it—the greatest ease is its nature, because the inanimate has no will, no aspiration. A channel that is connected with a reed gives not its own tone, but the tone resultant from the combination of itself with the reed; the offspring takes after both parents. If the channel is deeper at the pallet than at the reed, the tone will bo very different to that given by a channel that is deeper at the reed end, or ^that arches in'the centre. Even a pipe 8ft. long, if only bowed the mere fraction of an inch more at the centre than at the ends, will give a perceptibly different quality of tone to that which will be produced from a pipe with perfectly parallel sides. A fact of significence if you only consider it.
We have now to study the shapes to be givon to the channels of our stand and you will readily gather that we place more value on the appreciation of the principles concerned in the structure of the harmonium than on mere arbitrary measurements, which, whilst they wholly misled the learner, cannot fall to cause disappointment when results are tested.
Remember and forget not the words of Oersted; thoughtfully considered they will help you over many'a difficulty, and give a new interest to the facts that arise under your observation.
Continuing the argument, we shall in our next chapter place before you several illustrations of the various forms of channel for characteristic registers.
(To be continued.)
(Continued from page 269.;
T A Q Another form of parallel ruler. The
Jltl«7« arms are jointed in the middle and
connected with an intermediate bar, by which
means the ends of the ruler, as well as the sides,
are kept parallel.
150. Traverse or to-and-fro motion. The pin in the upper slot being stationary, and the one in the lower slot made to move in the direction of the horizontal dotted line, the lever will by its connection with the bar give to the latter a traversing motion in its guides a a
151. Stamp. Vertical percussive falls derived from horizontal rotating shaft. The mutilated toothed pinion acts upon the rack to raise the rod until its teeth leave the rack and allow the rod to fall.
1:"2. Another arrangement of the Chinese windlass.
153. A modification of the tilt or trip hammer. The hammer helve is a lever of the first order.
154. A modification of the crank and slotted cross-head. The cross-head contains an endless groove, in which the crankwrist works, and which is formed to produce a uniform velocity of movement of the wrist or reciprocating-rod.
155. The gyroscope or rotaseope, an instrument illustrating the tendency of rotating bodies tn preserve their plane of rotation. The spindle of the metallic disc, C is fitted to turn easily in bearings in the ring A. If the disc is set in rapid rotary motion on its axis, and the pintle F at one side of the ring A, is placed on the bearing in the top of the pillar G the disc and ring seem indifferent to gravity, and instead of dropping begin to revolve about the vertical axis.
156. Bohnenberger's machine, illustrating the same tendency of rotating bodies. This consists of three rings A A1 A* placed one within the other and connected by pivots at right angles to each other. The smallest ring A* contains the bearings for the axis of a heavy ball B. The ball being set in rapid rotation, its axis will continue in the same direction, no matter how the position of the rings may be altered; and the ring Aa which supports it will resist B considerable pressure tending to displace it.
157. What is called the gyroscope governor, for steam engines, Sec, patented by Alban Anderson in 1858. A is a heavy wheel, the axle B Bi of which is made in two pieces connected together by a universal joint. The wheel A is on one piece, B and a pinion I on the other piece B1. The piece B is connected at its middle by a hinge joint with the revolving frame H, so that variations in the inclination of the wheel A will cause the outer end of the piece B to rise and fall. The frame H is driven by bevel gearing from the engine, and by that means th<
* Extracted from a compilation by W. H. T. Bnouw. Editor of [he " American Artisan."
pinion I is carried r>und tie stationary toothed circle G, ani the whoel A. is thus made to receive a rapid rotary motion on its axis. When the frame II and wheel A are in motion, the tendency of the wheel A is to assume a vertical position, bat this tendency is opposed by a spring L. The greater the velocity of the governor, the stronger is the tendency above mentioned, and the more it overcomes the force of the spring, and vice versa. The piece B is connected with the valve-rod by rods C 1), and the spring L is connected with the said rod by levers N and rod P.
158. Traverse of carriage, made variable by fusee according to the variation in diameter where the band acta.
159. Primitive drilling apparatus. Being once set in motion, it is kept going by hand, by alternately pressing down aud relieving the transverse bar to which the bands are attached, causing the bands to wind upon the spindle alternately in opposite directions, while the heavy disc or flywheel gives B steady momentum to the drillspindle in its rotary motion.
160. Continuous rotary motion from oscillating. The beam being made to vibrate, the drum to which the cord is attached, working loose on flywheel shaft, gives motion to said shaft through the pawl and ratchet-wheel, the pawl being attached to drum, and the ratchet-wheel fast on shalln
161. Another simple form of clutch for pulleys, consisting of a pin on the lower shaft and a pin on side of pulley. The pulley is moved lengthwise of the shaft by means of a lever or other means to bring its pin into or out of contact with the pin on shaft.
162. Alternating traverse of upper shaft and its drum, produced by pin on the end of the shaft working in oblique groove in the lower cylinder.
163. See-saw, one of the simplest illustrations of a limited oscillating or alternate circular motion.
(To be continued.)
PARSONS' WHITE BRASS.
A T the conversazione of the Civil Engineers 2\. held B feJf nights since, Mr. P. M. Parsons, well known for his labours in the improvement of ordnance, sent samples of his white brass. Exactly of what this very peculiar alloy consists i says the Engineer) we shall not pretend to gay. It is unlike Babbit's or any other white metal with which we are acquainted, will not clog the file, and has in practice proved very effective. It
differs materially from the generality of alloys known as white metal, being harder, stronger, and soncrons ; it is, in fact, as its name implies, a species of brass, and behaves like it under the tool when bored or turned, and it is susceptible of a very high polish ; at the same time it fuses at a lower temperature than ordinary brass, and can be melted in an iron pot or ladle over an ordinary fire. This renders it useful for fitting-up engines and machines where first cost is an object, as it can be run into the plummer-blocks or framing to form the bearings, bushes, sockets, &c, without tho expense of fitting or boring them, or it can be cast in metal moulds, or like ordinary brass or gun-metal, in sand or loam. The white brass has been found by carefullyconducted experiments to surpass in durability all other anti-friction metals against which it has been tested, and to prevent heating of the journals. The durability of the white brass was ascertained several years since by some very carefully conducted experiments on the Great Northern Railway, with carriages running in the express train between London and Edinburgh, the axles being fitted with bearings of white brass at one end and ordinary brass at the other. These experiments were made under the direction of Mr. Sturrock, late locomotive engineer of the Great Northern Railway, who states that two bearings under No. 45 brake van, East Coast Joint Stock, diminished in weight 2oz. in running 19,400 miles, whilst the two brass bearings in the other end lost 21b. 4oz.; that under No. 36, thirdclass, E. C. J. S., the two white metal lost only 2 against lib. 6oz. whilst running 20,000 miles j and two under No. 35, E. C. J. S., thirdclass, lost only 2Joz. against lib. 12oz. of the brass bearing whilst running 20,000 miles. The bearings during these periods ran perfectly cool, and were lubricated with oil.
MANAGEMENT OF GAS.
AT the seventh annual general meeting of the British Association of Gas Managers, on the 7th inst ate the rooms of the Society of Arts, Mr. Magnus Ohren, vice-president, in the chair, the Chairman, in the course of his address, referring to purification, said that nothing was more unsatisfactory than the present state of the ordinary coke scrubber, and it was a question whether iron could not be substituted advantageously for coke. One fact, however, had recently been ascertained—Wis., that purification by scrubbing was not, after all, such a friend to gas managers as they had supposed it to be. The amount of sulphur in the yfts varied from day to
day. The gas referees appointed by the Board of Trade had to determine what should be the maximum of snlphur compounds allowable in the gas of those companies under their jurisdiction, and, therefore, their proceedings were of the greatest interest, not only to the public, but also to the gas managers. The referees had not yet issued any public report on the subject; but experiments were in process, under the instructions of the referees; which, unquestionably, would throw much light on the point. Among others, a systematic series of experiments was being made to ascertain the efficiency of each separate part of the various purifying processes adopted in gasworks. The Chairman then alluded to a new apparatus devised by the gas referees for the more efficient testing of the gas of the companies for sulphur compounds other than sulphuretted hydrogen, and thought that its adoption should, in j ustice to the gas companies, be properly taken into account by the referees before they fixed the maximum of snlphur to be allowed in the gas of the companies placed in their supervision. One of the questions referred to the referee had been to determine the burner to be employed in testing the gas for illuminating power. As appeared from their report, the referees carefully examined the various kinds of burners in use, and also some new ones. Their inquiries also revealed in an extraordinary manner the badness of the burners in common use. The investigation of the referees, as detailed in their report, showed that some of the burners gave barely 20 per cent of the real illuminating powers. These facts prove in B remarkable manner that the fault had really lain with the consumers themselves, who have been in the habit of wasting the gas supplied to them, and throwing away large sums annually by the use of shamefully bad burners. This was a point of great importance to the public, and it was to be hoped that the result of the publicity given to this report by the Board of Trade would be to lead consumers to adopt better burners.
COCOA UNDER THE MICROSCOPE.*
(Continued from page 175.)
\\ J E now proceed to the consideration of the V Y facilities afforded by the microscope for the detection of adulteration of cocoa, those offered by chemistry having been already shown in our last number. On examining a seed of cacao theobroma, we notice that it consists, We all seeds, of an outer membrane, or husk, enclo'
* From the f>od Journal.