See also:

• COLOUR (Lat. color, connected with celare, to hide, the root meaning, therefore, being that of a covering)

COLOUR (See also:

• LAT

Lat. color, connected with celare, to hide, the See also:

• ROOT (late O.E. rot, adopted from Scand., cf. Norw. and Swed. rot, Dan. rod; the true O.E. word was wyrt, plant, represented in Ger. Wurz or Wurzel; the ultimate root is the same in both words, and is seen in Lat. radix)
• ROOT, ELIHU (1845– )

root meaning, therefore, being that of a covering)  . The visual apparatus of the See also:

• EYE
• EYE (O. Eng. edge, Ger. Auge; derived from an Indo-European root also seen in Lat. oc-ulus, the organ of vision (q.v.)

eye enables us to distinguish not only See also:

• DIFFERENCES, CALCULUS OF (Theory of Finite Differences)

differences of See also:

• FORM (Lat. forma)

form, See also:

• SIZE

size and brilliancy in the See also:

• OBJECTS

objects looked upon, but also differences in the See also:

• CHARACTER (Gr. xapareri7p, from xap&crew, to scratch)

character of the See also:

• LIGHT

light received from them . These latter differences, See also:

• FAMILIAR (through the Fr. familier, from Lat. familiaris, of or belonging to the familia, family)

familiar to us as differences in See also:

• COLOUR (Lat. color, connected with celare, to hide, the root meaning, therefore, being that of a covering)

colour, have their See also:

• PHYSICAL

physical origin in the See also:

• VARIATIONS
• VARIATIONS, CALCULUS
• VARIATIONS, CALCULUS OF

variations in See also:

• WAVE

wave-length (or frequency) which may exist in light which is capable of exciting the sensation of See also:

• VISION (from Lat. videre, to see), or SIGHT

vision . From the physical point of view, light of a pure colour, or homogeneous light, means light whose undulations are mathematically of a See also:

• SIMPLE

simple character and which cannot be resolved by a See also:

• PRISM (Gr. rrpivµa, properly a thing sawn, Irpii"ety, to saw)

prism into component parts . All the visible pure See also:

• COLOURS, MILITARY

colours, as thus defined, are to be found in the spectrum, and there is an See also:

• INFINITE (from Lat. in, not, finis, end or limit; cf. findere, to deave)

infinite number of them, corresponding to all the possible variations of wave-length within the limits of the visible spectrum (see See also:

• SPECTROSCOPY (from Lat. spectrum, an appearance, and Gr. a-sore y, to see)

SPECTROSCOPY) . On this view, there is a strict See also:

• ANALOGY (Gr. avaXo-yLa, proportion)

analogy between variations of colour in light and variations of See also:

• PITCH
• PITCH, MUSICAL

pitch in See also:

• SOUND
• SOUND, THE (Danish Oresund)

sound, but the visible spectrum contains a range of frequency extending over about one See also:

• OCTAVE (from Lat. octavus, eighth, octo, eight)

octave only, whereas the range of audibility embraces about eleven octaves . Of all the known colours it might naturally be thought that See also:

• WHITE
• WHITE, ANDREW DICKSON (1832– )
• WHITE, GILBERT (1720–1793)
• WHITE, HENRY KIRKE (1785-1806)
• WHITE, HUGH LAWSON (1773-1840)
• WHITE, JOSEPH BLANCO (1775-1841)
• WHITE, RICHARD GRANT (1822-1885)
• WHITE, ROBERT (1645-1704)
• WHITE, SIR GEORGE STUART (1835– )
• WHITE, SIR THOMAS (1492-1567)
• WHITE, SIR WILLIAM ARTHUR (1824--1891)
• WHITE, SIR WILLIAM HENRY (1845– )
• WHITE, THOMAS (1628-1698)
• WHITE, THOMAS (c. 1550-1624)

white is the simplest and purest, and, till See also:

• SIR

Sir See also:

• ISAAC (Hebrew for " he laughs," on explanatory references to the name, see ABRAHAM)

Isaac See also:

• NEWTON
• NEWTON, ALFRED (1829–1907)
• NEWTON, JOHN (1725-1807)
• NEWTON, JOHN (1823-1895)
• NEWTON, SIR CHARLES THOMAS (1816-1894)
• NEWTON, SIR ISAAC (1642-1727)

Newton's See also:

• TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
• TIME, MEASUREMENT OF
• TIME, STANDARD

time, this was the prevailing See also:

• OPINION (Lat. opinio, from opinari, to think)

opinion . Newton, however, showed that white light could be decomposed by a prism into the spectral colours red, See also:

• ORANGE
• ORANGE (Citrus Aurantium)
• ORANGE, HOUSE OF

orange, yellow, See also:

• GREEN, A
• GREEN, ALEXANDER HENRY (1832—1896)
• GREEN, DUFF (1791—1875)
• GREEN, JOHN RICHARD (1837—1883)
• GREEN, MATTHEW (1696-1737)
• GREEN, THOMAS HILL (1836-1882)
• GREEN, VALENTINE (1739–1813)
• GREEN, WILLIAM HENRY (.1825–1900)

green, See also:

• BLUE (common in different forms to most European languages)

blue, See also:

• INDIGO (earlier indico, from Lat. indicum, the Indian sub-stance or dye; the Sans. name was niti, from nila, dark blue, and this through Arab. al-nil, annil, gives " aniline ")

indigo and See also:

• VIOLET

violet; the colours appearing in this See also:

• ORDER
• ORDER (through Fr. ordre, for earlier ordene, from Lat. ordo, ordinis, rank, service, arrangement; the ultimate source is generally taken to be the root seen in Lat. oriri, rise, arise, begin; cf. " origin ")
• ORDER, HOLY

order and passing gradually into each other without abrupt transitions . White is therefore not a simple colour, but is merely the colour of sunlight, and probably owes its apparently homogeneous character to the fact that it is the See also:

• AVERAGE

average colour of the light which fills the eye when at See also:

• REST (O. Eng. rest, reste, bed, cognate with other Teutonic forms, e.g. Ger. Rast, Riiste, rest, and probably Gothic Rasta, league, i.e. resting or stopping place)

rest . The colours of the various objects which we see around us are not due (with the exception of self-luminous and fluorescent bodies) to any See also:

• POWER [WILLIAM GRATTAN] TYRONE (1797-1841)

power possessed by these objects of creating the colours which they exhibit, but merely to the exercise of a selective See also:

• ACTION

action on the light of the See also:

• SUN
• SUN (0. Eng. sonne, Ger. sonne. Fr. soleil, Lat. sol, Gr. ijXior, from which comes helio- in various English compounds)

sun, some of the constituent rays of the white light with which they are illuminated being absorbed, while the rest are reflected or scattered in all directions, or, in the See also:

• CASE
• CASE, JOHN (d. 1600)

case of transparent bodies, transmitted . White light is thus the basis of all other colours, which are derived from it by the suppression of some one or more of its parts . A red See also:

• FLOWER (Lat. flos, floris; Fr. fleur)
• FLOWER, SIB

flower, for instance, absorbs the blue and green rays and most of the yellow, while the red rays and usually some yellow are scattered .

If a red See also:

• POPPY

poppy is illuminated successively by red, yellow, green and blue light it will appear a brilliant red in the red light, yellow in the yellow light, but less brilliant if the red colour is pure; and See also:

• BLACK
• BLACK, ADAM (1784-1874)
• BLACK, JEREMIAH SULLIVAN (1810–1883)
• BLACK, WILLIAM (1841-1898)

black in the other colours, the blackness being due to the almost See also:

• COMPLETE

complete absorption of the corresponding colour . Bodies may be classified as regards colour according to the nature of the action they exert on white light . In the case of See also:

• ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

ordinary opaque bodies a certain proportion of the incident light is irregularly reflected or scattered from their surfaces . A white See also:

• OBJECT

object is one which reflects nearly all the light of all colours; a black object absorbs nearly all . A See also:

• BODY

body which reflects only a portion of the light, but which exhibits no predominance in any particular See also:

• HUE

hue, is called See also:

• GREY, CHARLES GREY, 2ND EARL (1764-1845)
• GREY, HENRY GREY, 3RD EARL (1802-1894)
• GREY, LADY JANE (1537-1554)
• GREY, SIR EDWARD
• GREY, SIR GEORGE (1812–1898)

grey . A white See also:

• SURFACE

surface looks grey beside a similar surface more brilliantly illuminated . The next class is that of most transparent bodies, which owe their colour to the light which is transmitted, either directly through, or reflected back again at the farther surface . A body which transmits all the visible rays equally well is said to be colourless; pure See also:

• WATER

water, for example, is nearly quite colourless, though in large masses it appears bluish-green . A translucent substance is one which partially transmits light . Translucency is due to the light being scattered by See also:

• MINUTE
• MINUTE (Lat. minutes, small; minuere, to make less)

minute embedded particles or minute irregularities of structure . Some fibrous specimens of See also:

• TREMOLITE

tremolite and See also:

• GYPSUM

gypsum are translucent in the direction of the See also:

• FIBRES
• FIBRES (or FIBERS, in American spelling; from Lat. fibra, apparently connected either with filum, thread, or findere, to split)

fibres, and practically opaque in a transverse direction . Coloured transparent objects vary in shade and hue according to their size; thus, a conical See also:

• GLASS
• GLASS (O.E. glees, cf. Ger. Glas, perhaps derived from an old Teutonic root gla-, a variant of glo-, having the general sense of shining, cf. " glare," " glow ")
• GLASS, STAINED

glass filled with a red liquid commonly appears yellow at the bottom, varying through orange up to red at the upper See also:

• PART

part .

A coloured See also:

• POWDER (through O. Fr. puldre, modern poudre, from Lat. pulvis, pulveris, dust)

powder is usually of a much lighter tint than the substance in bulk, as the light is reflected back after transmission through only a few thin layers . For the same See also:

• REASON (Lat. ratio, through French raison)

reason the powders of transparent substances are opaque . Polished bodies, whether opaque or transparent, when illuminated with white light and viewed at the proper See also:

• ANGLE (from the Lat. angulus, a corner, a diminutive, of which the primitive form, angus, does not occur in Latin; cognate are the Lat. angere, to compress into a bend or to strangle, and the Gr. ayKOS, a bend; both connected with the Aryan root ank-, to

angle, reflect the incident light regularly and appear white, without showing much of their distinctive colours . Some bodies reflect light of one colour and transmit that of another; such bodies nearly always possess the properties of selective or metallic reflection and anomalous See also:

• DISPERSION
• DISPERSION (from Lat. dispergere, to scatter)

dispersion . Most of the See also:

• COAL

coal-See also:

• TAR

tar dyes belong to this See also:

• CATEGORY (Gr. Karrlyopia, " accusation ")

category . Solid eosin, for example, reflects a yellowish-green and transmits a red light . See also:

• GOLD
• GOLD [symbol Au, atomic weight 195.7(H = 1),197.2(0 =16)]

Gold appears yellow under ordinary circumstances, but if the light is reflected many times from the surface it appears a See also:

• RUBY (Lat. rubeus, red)

ruby colour . On the other See also:

• HAND
• HAND (a word common to Teutonic languages; cf. Ger. Hand, Goth. handus)
• HAND, FERDINAND GOTTHELF (1786-185r)

hand, a powerful See also:

• BEAM
• BEAM (from the O. Eng. beam, cf. Ger. Baum, a tree, to which sense may be referred the use of " beam " as meaning the rood or crucifix, and the survival in certain names of trees, as horn-beam)

beam of light transmitted through a thin gold-See also:

• LEAF (O. Eng. leaf, cf. Dutch loof, Ger. Laub, Swed. lof, &c.; possibly to be referred to the root seen in Gr. Ma-eta, to peel, strip)

leaf appears green . Some solutions exhibit the curious phenomenon of dichromalism (from &-, See also:

• DOUBLE
• DOUBLE (from the Mid. Eng. duble, the form which gives the present pronunciation, through the Old Er. duble, from Lat. duplus, twice as much)

double, and xpWaa, colour), that is, they appear of one colour when viewed in strata of moderate thickness, but of a different colour in greater thicknesses (see ABSORPTION OE LIGHT) . The blue colour of the See also:

• SKY (M. Eng. skie, cloud; O. Eng. skua, shade; connected with an Indo-European root sku, cover, whence " scum," Lat. obscurus, dark, &c.)

sky (q.v.) has been explained by See also:

• LORD
• LORD (O. Eng. hldford, i.e. hldfweard, the warder or keeper of bread, hlIf, loaf; the word is not represented in any other Teutonic language)
• LORD, JOHN (1810-1894)

Lord See also:

• RAYLEIGH, JOHN WILLIAM STRUTT

Rayleigh as due to the scattering of light by small suspended particles and See also:

• AIR (from an Indo-European root meaning " breathe," " blow ")
• AIR, or ASBEN

air molecules, which is most effective in the case of the shorter waves (blue) . J . See also:

• TYNDALL, JOHN (182o-1893)

Tyndall produced similar effects in the laboratory .

The green colour of See also:

• SEA (in O. Eng. sae, a common Teutonic word; cf. Ger. See, Dutch Zee, &c.; the ultimate source is uncertain)
• SEA, COMMAND OF THE

sea-water near the See also:

• SHORE

shore is also due to a scattering of light . The colours of bodies which are gradually heated to white incandescence occur in the order—red, orange, yellow, white . This is because the longer waves of red light are first emitted, then the yellow as well, so that orange results, then so much green that the See also:

• TOTAL

total effect is yellow, and lastly all the colours, compounding to produce white . Fluorescent bodies have the power of converting light of one colour into that of another (See See also:

• FLUORESCENCE

FLUORESCENCE) . Besides the foregoing kinds of colorization, a body may exhibit, under certain circumstances, a colouring due to some See also:

• SPECIAL

special physical conditions rather than to the specific properties of the material; such as the colour of a white object when illuminated by light of some particular colour; the colours seen in a film of oil on water or in See also:

• MOTHER

mother-of-See also:

• PEARL
• PEARL, THE

pearl, or See also:

• SOAP

soap-bubbles, due to interference (q.v.); the colours seen through the eyelashes or through a thin handkerchief held up to the light, due to diffraction (q.v.); and the colours caused by ordinary See also:

• REFRACTION
• REFRACTION (Lat. refringere, to break open or apart)

refraction, as in the See also:

• RAINBOW

rainbow, double refraction and polarization (qq.v.) . See also:

• COMPOSITION
• COMPOSITION (Lat. compositio, from componere, to put together)

Composition of Colours.—It has been already pointed out that white light is a See also:

• COMBINATION (Lat. combinare, to combine)

combination of all the colours in the spectrum . This was shown by Newton, who recombined the spectral colours and produced white . Newton also remarks that if a froth be made on the surface of water thickened a little with soap, and examined closely, it will be seen to be coloured with all the" colours of the spectrum, but at a little distance it looks white owing to the combined effect on the eye of all the colours . The question of the composition of colours is largely a physiological one, since it is possible, by mixing colours, say red and yellow, to produce a new colour, orange, which appears identical with the pure orange of the spectrum, but is physically quite different, since it can be resolved by a prism into red and yellow again . There is no doubt that the sensation of colour-vision is threefold, in the sense that any colour can be produced by the combination, in proper proportions, of three See also:

• STANDARD
• STANDARD, BATTLE OF THE

standard colours . The question then arises, what are the three See also:

• PRIMARY

primary colours ? Sir See also:

• DAVID
• DAVID (a Hebrew name meaning probably beloved 1)
• DAVID, FELICIEN (1810—1876)
• DAVID, GERARD [GHEERAERT DAVIT], (?=1523)
• DAVID, PIERRE JEAN (1789–1856)
• DAVID, ST (Dewi, Sant)

David See also:

• BREWSTER, SIR DAVID (1781–1868)
• BREWSTER, WILLIAM (c. 1566–1644)

Brewster considered that they were red, yellow and blue; and this view has been commonly held by painters and others, since all the known brilliant hues can be derived from the admixture of red, yellow and blue See also:

• PIGMENTS (Lat. pigmentum, from pingere, to paint)

pigments .

For instance, See also:

• VERMILION

vermilion and chrome yellow will give an orange, chrome yellow and See also:

• ULTRAMARINE

ultramarine a green, and vermilion and ultramarine a See also:

• PURPLE

purple mixture . But if we superpose the pure spectral colours on a See also:

• SCREEN (usually, but very doubtfully, connected with Lat. scrinium, a box for holding books, from scribere, to write; a connexion with Ger. Schranke, barrier, has been suggested)

screen, the resulting colours are quite different . This is especially the case with yellow and blue, which on the screen combine to produce white, generally with a See also:

• PINK

pink tint, but cannot be made to give green . The reason of this difference in the two results is that in the former case we do not get a true combination of the colours at all . When the mixed pigments are illuminated by white light, the yellow particles absorb the red and blue rays, but reflect the, yellow along with a See also:

• GOOD, JOHN MASON (1764-1827)

good See also:

• DEAL

deal of the neighbouring green and orange . The blue particles, on the other hand, absorb the red, orange and yellow, but reflect the blue and a good deal of green and violet . As much of the light is affected by several particles, most of the rays are absorbed except green, which is reflected by both pigments . Thus, the colour of the mixture is not a mixture of the colours yellow and blue, but the See also:

• REMAINDER, REVERSION

remainder of white light after the yellow and blue pigments have absorbed all they can . The effect can also be seen in coloured solutions . If two equal beams of white light are transmitted respectively through a yellow See also:

• SOLUTION (from Lat. solvere, to loosen, dissolve)

solution of See also:

• POTASSIUM [symbol K (from kalium), atomic weight 39.114 0=16)]

potassium bichromate and a blue solution of See also:

• COPPER (symbol Cu, atomic weight 63.1, H=1, or 63.6, O = 16)

copper sulphate in proper thicknesses, they can be compounded on a screen to an approximately white colour; but a single beam transmitted through both solutions appears green . Blue and yellow pigments would produce the effect of white only if very sparsely distributed . This fact is made use of in laundries, where See also:

• COBALT (symbol Co, atomic weight 59)

cobalt blue is used to correct the yellow colour of See also:

• LINEN

linen after washing .

See also:

• THOMAS
• THOMAS (c. 1654-1720)
• THOMAS (d. 110o)
• THOMAS, ARTHUR GORING (1850-1892)
• THOMAS, CHARLES LOUIS AMBROISE (1811-1896)
• THOMAS, GEORGE (c. 1756-1802)
• THOMAS, GEORGE HENRY (1816-187o)
• THOMAS, ISAIAH (1749-1831)
• THOMAS, PIERRE (1634-1698)
• THOMAS, SIDNEY GILCHRIST (1850-1885)
• THOMAS, ST
• THOMAS, THEODORE (1835-1905)
• THOMAS, WILLIAM (d. 1554)

Thomas See also:

• YOUNG
• YOUNG, A
• YOUNG, ARTHUR (1741-1820)
• YOUNG, BRIGHAM (1801-1877)
• YOUNG, CHARLES MAYNE (1777–1856)
• YOUNG, EDWARD (1683–1765)
• YOUNG, JAMES (1811-1883)
• YOUNG, THOMAS (1773-1829)

Young suggested red, green and violet as the primary colours, but the subsequent experiments of J . Clerk See also:

• MAXWELL
• MAXWELL, JAMES CLERK (1831–1879)

Maxwell appear to show that they should be red, green and blue . Sir See also:

• WILLIAM
• WILLIAM (1143-1214)
• WILLIAM (1227-1256)
• WILLIAM (1J33-1584)
• WILLIAM (A.S. Wilhelm, O. Norse Vilhidlmr; O. H. Ger. Willahelm, Willahalm, M. H. Ger. Willehelm, Willehalm, Mod.Ger. Wilhelm; Du. Willem; O. Fr. Villalme, Mod. Fr. Guillaume; from " will," Goth. vilja, and " helm," Goth. hilms, Old Norse hidlmr, meaning
• WILLIAM (c. 1130-C. 1190)
• WILLIAM, 13TH

William Abney, however, assigns somewhat different places in the spectrum to the primary colours, and, like Young, considers that they should be red, green and violet . All other hues can be obtained by combining the three primaries in proper proportions . Yellow is derived from red and green . This can be done by superposition on a screen or by making a solution which will transmit only red and green rays . For this purpose Lord Rayleigh recommends a mixture of solutions of blue See also:

• LITMUS (apparently a corruption of lacmus, Dutch lacmoes, lac, lac, and moes, pulp, due to association with " lit," an obsolete word for dye, colour; the Ger. equivalent is Lac/emus, Fr tournesol)

litmus and yellow potassium chromate . The litmus stops the yellow and orange light, while the potassium chromate stops the blue and violet . Thus only red and green are transmitted, and the result is a full See also:

• COMPOUND
• COMPOUND (from Lat. componere, to combine or put together)

compound yellow which resembles the simple yellow of the spectrum in See also:

• APPEARANCE (from Lat. apparere, to appear)

appearance, but is resolved into red and green by a prism . The brightest yellow pigments are those which give both the pure and compound yellow . Since red and green produce yellow, and yellow and blue produce white, it follows that red, green and blue can be compounded into white . H. von See also:

• HELMHOLTZ, HERMANN LUDWIG FERDINAND VON (1821-1894)

Helmholtz has shown that the only pair of simple spectral colours capable of compounding to white are a greenish-yellow and blue .

Just as musical sounds differ in pitch, loudness and quality, so may colours differ in three respects, which Maxwell calls hue, shade and tint . All hues can be produced by combining every pair of primaries in every proportion . The addition of white alters the tint without affecting the hue . If the colour be darkened by adding black or by diminishing the See also:

• ILLUMINATION

illumination, g a variation in shade is produced . Thus the hue red includes every variation in tint from red to white, and every variation in shade from red to black, and similarly for other hues . We can represent every hue and tint on a See also:

• DIAGRAM

diagram in a manner proposed by Young, following a very similar See also:

• SUGGESTION

suggestion S B of Newton's . Let RGB (fig. r) be an MILITARY 729 through W . To vary the shade, the whole triangle must be uniformly darkened . The simplest way of compounding colours is by means of Maxwell's colour See also:

• TOP (cf. Dan. top, Ger. Topf, also meaning pot)

top, which is a broad See also:

• SPINNING (from O. Eng. spinnen, to spin, cf. Ger. spinnen, &c., the Teut. root is seen, to draw out, cf. span, spider)

spinning-top over the spindle of which coloured disks can be slipped (fig . 2) . The disks are slit radially so that they can be slipped partially over each other and the surfaces exposed in any desired ratio . Three disks are used together, and a match is obtained between these and a pair of smaller ones mounted on the same spindle .

If any five colours are taken, two of which may be black and white, a match can be got between them by suitable See also:

• ADJUSTMENT (from late Lat. ad juxtare, derived from juxta, near, but early confounded with a supposed derivation from justus, right)

adjustment . This shows that a relation exists between any four colours (the black being only needed to obtain the proper intensity) and that consequently the number of See also:

• INDEPENDENT

independent colours is three . A still better See also:

• INSTRUMENT (Lat. instrumentum, from insincere, to build up, furnish, arrange, prepare)

instrument for FIG . 2 . combining colours is Maxwell's colour See also:

• BOX
• BOX (Gr. irl or, Lat. buxus, box-wood; cf. 2r6Eir, a pyx)

box, in which the colours of the spectrum are combined by means of prisms . Sir W . Abney has also invented an apparatus for the same purpose, which is much the same in principle as Maxwell's colour box . Several methods of colour See also:

• PHOTOGRAPHY (Gr. bias, light, and ypa w, to write)
• PHOTOGRAPHY, CELESTIAL

photography depend on the fact that all varieties of colour can be compounded from red, green and blue in proper proportions . Any two colours which together give white are called complementary colours . Greenish-yellow and blue are a pair of complementaries, as already men- tioned . Any number of pairs may be obtained by a simple See also:

• DEVICE

device due to Helmholtz and represented in fig . 3 .

A beam of white light, decomposed by the prism P, is recompounded into white light by the See also:

• LENS
• LENS (from Lat. lens, lentil, on account of the similarity of the form of a lens to that of a lentil seed)

lens 1 and focussed on a screen at f . If the thin prism p is inserted near the lens, any set of colours may be deflected to another point n, thus producing two coloured and complementary images of the source of light . Nature of White Light.—The question as to whether white light actually consists of trains of waves of See also:

• REGULAR

regular frequency has been discussed in See also:

• RECENT

recent years by A . Schuster, Lord Rayleigh and others, and it has been shown that even if it consisted of a See also:

• SUCCESSION (Lat. successio, from succedere, to follow after)

succession of somewhat irregular impulses, it would still be resolved, by the dispersive See also:

• PROPERTY

property of a prism or grating, into trains of regular frequency . We may still, however, speak of white light as compounded of the rays of the spectrum, provided we mean only that the two systems are mathematically See also:

• EQUIVALENT

equivalent, and not that the homogeneous trains exist as such in the See also:

• ORIGINAL

original light . See also Newton's Opticks, bk. i. pt. ii.; Maxwell's Scientific Papers; Helmholtz's papers in Poggendorf's Annalen; Sir G . G . See also:

• STOKES, SIR G
• STOKES, SIR GEORGE GABRIEL, BART
• STOKES, WHITLEY (1830-1909)

Stokes, See also:

• BURNETT, FRANCES ELIZA HODGSON (1849– )

Burnett Lectures for 884—5—6; Abney's Colour Vision (1895) . (J . R .