shallow lake, known as Salton Sea (q.v.). The Southern Pacific Railroad crosses the northern part of this desert and traverses the Coahuila Valley. The Colorado Desert is but a portion of the great desert region of the southwestern United States, which includes also the Yuma and Mohave deserts.

COLORADO, RIO, rēð. A river of Central Argentina, rising in the Andes and flowing southeast. It empties into the Atlantic in about latitude 39° 50' S. (Map: Argentina, E 11). Its entire length is about 700 miles, but it is navigable for light vessels for only a couple of hundred miles. The upper course is through a desert.

bottom of which rushes the river. The length of the Grand Cañon is over 200 miles. After the river emerges from the cañon it turns abruptly south, and, forming the western boundary of Arizona, it flows through a low desert region, receiving almost no tributaries, and diminishing in volume by evaporation and absorption. Leaving United States territory near its The total length of the river is about 900 miles, mouth, it empties into the Gulf of California. and with the Green, 2000 miles. It is navigable for light steamers for several hundred miles from its mouth, but navigation is much impeded by rocks, and sand-bars, as well as by the everchanging volume of its water and the shifting of its bed. The river was discovered in 1540 by Fernando Alarcón, and the perilous descent through the cañon was first made by James White in 1867. See J. W. Powell, Exploration of the Colorado River of the West and its Tributaries; and Dutton, Tertiary History of the Grand Cañon of the Colorado, Monograph II., United States Geological Survey, 1882; Dellenbaugh, Romance of the Colorado River (New York, 1902); James, In and Around the Grand Canyon (Boston, (1902).

COLORADO RIVER. A large river flowing through the plateau region of the southwestern United States. It is formed in the southwestern part of Utah, by the junction of the Green River from the north and the Grand from the northeast, the former rising in southwestern Wyoming and the latter in the north central part of Colorado. Both of these headstreams receive numerous tributaries from the well-watered regions of the Rocky Mountains. Below their junction, the Colorado passes through what is in some respects the most remarkable region on the earth, not only for its natural scenery, but also for the great interest which it possesses for geologists, as it gives on a grand scale the clearest exemplifications of the action of erosive forces in shaping the contour of the land. In the Eocene epoch the whole region of Arizona, Utah, and Nevada was subjected to a vast upheaval, and what was formerly the bottom of the ocean was raised to a height of more than 10,000 feet above sea-level. This region, consisting chiefly of horizontal strata of the Paleozoic and Mesozoic systems, was subjected to extensive denudation by wind and water, and again to successive upheavals accompanied by volcanic action. In the northwestern part the strata were faulted into huge blocks, running north and south, giving the present shape to the mountains of Nevada. The result of the uplifting and erosion was the washing away of the weaker and softer strata, especially to the west of the present course of the Colorado, while those rocks that were protected by harder layers were left standing as extensive plateaus with precipitous escarpments. In some places lavas had been thrust up through the strata by volcanic action, and these localities are now marked by the isolated mesas so characteristic of the country. Since this region is almost or quite rainless below an elevation of 8000 feet, denudation proceeds slowly except along the river-courses, where chasms or ñons are cut deeply into the rock foundations. Such is the case with the Colorado and all the tributaries from its headwaters to the great escarpment called the Grand Wash, on the western boundary of Arizona.

ca

The largest and deepest of these is the famous Grand Cañon, where the Colorado cuts through the Kaibab and Unikaret plateaus, from 7000 to 9000 feet high, in the northern part of Arizona. The cañon is five to six miles wide at the top and 5000 to 6000 feet deep, falling in several successive escarpments, indicating pauses in the upheaval of the plateau. In the middle is the narrow and gloomy cañon proper, with a sheer precipitous depth of 2000 to 3000 feet, at the

COLORADO RIVER. A river rising in the western part of Texas, near the southeastern boundary of New Mexico (Map: Texas, F 5). It flows in a generally southeast direction across the State, and empties into the Gulf of Mexico through Matagorda Bay. It receives a number of tributaries, chiefly from the south; among these are Sulphur Creek, and the Concho, San Saba, and Llano rivers. The chief towns on its course are Bay City, Wharton, Columbus, Lagrange, Bastrop, and Austin. It is about 900 miles long, and in winter is navigable for river steamboats to Austin.

COLORADO SPRINGS. A city and countyseat of El Paso County, Colo., 74 miles south by east of Denver on the Atchison, Topeka and Santa Fe, the Denver and Rio Grande, and other railroads (Map: Colorado, E 2). Its location, 6000 feet above the level of the sea, near the base of Pike's Peak and the celebrated mineral

springs at Manitou, with a healthful climate, have combined to make the place a much-freIt is the seat of Colorado Colquented resort. lege, founded in 1874, and of a State institution for the deaf-mute and blind. Settled in 1870, Colorado Springs was incorporated in 1872, and is governed under a charter of 1878 (revised 1901), which provides for a mayor, chosen biennially, and a city council, elected by wards. Standing and special committees are appointed by the Mayor; also the chief and members of the fire department, members of the police department, market master, street commissioner, and health officer. Other offices are filled by the council. The water-works are owned and operated by the municipality. Population, in 1890, 11,140; in 1900, 21,085; 1906 (local est.), 35,000.

COLORADO STATE AGRICULTURAL COLLEGE. A scientific school of agriculture, situated at Fort Collins, Colo., organized in 1876. The college received 90,000 acres of the lands granted to the State in 1862, and since its inception has been supported chiefly by a State tax.

Its gross income is about $130,000. It offers courses leading to the B.S. and M.S. degrees. Women are admitted on equal terms with

men. The library contains about 25,000 volumes. The attendance in 1906 was over 500.

COLORATION IN ANIMALS. See BIRD;

or

INSECT; PROTECTIVE COLORATION; MIMICRY. COLOR-BLINDNESS, ACHROMATOPSIA, DALTONISM. An incurable defect of vision, owing to which some persons are unable to distinguish certain colors. The name Daltonism is after Dalton, the English chemist, who suffered from the defect. Acquired color-blindness is a symptom of diseases of the optic nerve and retina. Congenital color-blindness usually affects both eyes, and is often hereditary. It is found in from 3 to 4 per cent. of men and less than 1 per cent. of women. It occurs in eyes whose power of vision is otherwise (as to form and distance) perfect. It is usually partial, being a failure to distinguish one or two of the fundamental colors-red, green, and blue. The eyes of persons having this defect of vision have been carefully examined after death without the discovery of any peculiarity. Color-blindness therefore has its seat in the sensorium, not in the visual apparatus. The Hering theory is that the retina contains three pairs of visual materialswhite-black, red-green, and blue-yellow. Colorblindness is accounted for by the supposed absence of one or two of these substances. According to the Young-Helmholtz theory, there are three primary color-perceptions-for red, green, and violet. In the absence of one of these, a color appears composed of the others. The most common forms of color-blindness are red blindness, green blindness, and red-green blindness. To detect the defect, the method of having the patient name colors is not satisfactory, because colors may be differentiated by apparent differences of brightness. Professor Holmgren of Upsala, Sweden, devised a series of test wools which furnish the best means of recognizing defects. These are skeins of wool of certain colors ('test colors'), various tints and shades of the same colors, and so-called 'confusion colors.' When the patient attempts to match the colors with the other skeins, the confusion colors are often added also, and it may be noticed that there is some hesitancy in making the selections.

The question has received serious legislative attention, and in most of the States of the Union stringent laws have been passed regarding the examination of the vision of all who depend on colors for their guidance. It is a crime in colorblind persons to pursue any calling when their defect, known to them, is liable to injure others, and it might be added that it is foolish for a color-blind painter, tailor, or milliner to attempt to compete with those who have perfect vision.

The safety of the traveling public depends in arge measure upon the accuracy with which green or red signals are observed by employees of railways and ships. Yet in but few countries is the matter of examination of color-sense demanded by statute. In Sweden, since 1877, only men with normal color-vision have been employed in the railway service. In Holland the Government controls the matter efficiently. In Italy, while there is no special law, the employees are tested. In France, in the absence of law about examination, Holmgren's test is usually employed. In Germany examination of color-sense is prescribed by law. In Austria, on the State

railroads, examination is made. In England there is no Government regulation, and the tests employed by certain companies are inefficient. Only three of the States of the United States—

Ohio, Massachusetts, and Alabama-have enacted laws to control the matter. In some other States the railroad commissioners formulate regulations requiring the examination of employees, as in New York State. That the traveling public does not demand stringent laws compelling examination of color-sense in all countries is astonishing, and can be explained only by the fact that the prevalence of color-blindness and the possibility of its detection have been understood by the people only since 1875. In 1892 there were employed by the different railroad companies of the United States a total of 821,415 men, while the number of miles of railroad reached 171,563.25. Accepting 3.69 as the percentage of color-blindness among men, the startling number of 30,310 color-blind men were in positions of some sort among the employees mentioned. In some cases the proportion of employees with color-blindness is very small, owing to the adoption by companies of adequate tests and the proper selection of men. In 1880 the officers of the Pennsylvania Railroad invited Dr. William Thomson, professor of ophthalmology in Jefferson Medical College, Philadelphia, to advise and assist them in the examination of the sight of their 40,000 employees, scattered over more than 5000 miles of track, of whom 12,000 were actually dependent upon colored signals for their guidance. A system was devised by which men attached to each division of the road were examined, each in his own locality, by intelligent laymen, with Holmgren's skeins, arranged on what is called "Thomson's stick,' and the coöperation of employees was secured. Reports were sent to the surgical expert, whose decision, after a final examination, was decisive. About 4.2 per cent. were found defective in color-sense. At a later examination, of 25,158 men, only 481, or about 2 per cent., were found color-blind, many men having left the company's employ before being detected, thus being able to secure positions on roads not requiring color-tests. In 1887 the same system of examination was adopted by the Philadelphia and Reading Railroad, with about 15,000 employees on 2200 miles of track, after a serious conflict between officials and employees, which was settled by Dr. Thomson. Of these men, 3.5 per cent. were declared color-blind. The Midland Railway and the London and Southwestern in England adopted the same method. In 1896, from responses to a circular addressed to one hundred of the most important railroad corporations of the country, controlling in all 129,970 miles, inquiring if examinations were made as to color-blindness of employees, it was learned that 35 roads, controlling 54,465 miles, were using Thomson's or other methods; 31 roads, controlling 29,428 miles, were making no test. No reply was received from 34 roads, controlling 46,077 miles. The New York Central Railroad began examining its employees about 1890, requiring them to report for tests of sight at either New York or Buffalo at stated times. This method being found disadvantageous, two physicians were employed about 1899, whose duty it is to travel over the system, examining and reëxamining the men from time to time in their own localities.

This road, in June, 1901, employed about 40,000 men, and controlled 7137.31 miles of track, inclusive of the leased lines, such as the New York and Putnam; West Shore; Fall Brook; Boston and Albany, etc.; but exclusive of the great lines, such as the Lake Shore and Michigan Southern, included in the 'Vanderbilt system.' Consult: Holmgren, De la cécité des couleurs (Sweden, 1877); Joy Jeffries, Color-Blindness (Boston, 1879); Swanzy, Diseases of the Eye, appendix i. (Philadelphia, 1896); and Thomson and Weiland, "Detection of Color-Blindness," in Morris and Oliver's System of Diseases of the Eye, vol. ii. (Philadelphia, 1897).

COLORED HEARING, or CHROMESTHESIA. The anomalous association of colors with sounds. It is the commonest type of synæsthesia, or the formation of unusual connections between sen

sations of different sense departments. While colored hearing is relatively frequent (statistics record one person in eight), it is exhibited in very varied forms. These may, however, be grouped, in the first place with regard to the nature and intensity of the photism (the color which is induced), and secondly with regard to the nature of the inducing sound. The induced color may, in rare cases (see works of Gruber and Whipple, indicated in the bibliography at the end of this article), be of hallucinatory intensity, so as to be seen objectively when the eyes are open. Usually the intensity is less the photism is localized (Flournoy), though not projected. In the third grade the photism is 'imagined' the color is really present as a visual sensation, but has no definite place; e.g. all soprano voices may be white, all tenor voices green. Fourthly, photisms may be simply thought,' no visual sensation being present. Finally, certain persons possess 'negative photisms'-they cannot say what color a sound has, but can say what colors it 'ought not to have. Any auditory impression may serve as the inducing agency. The sources may, therefore, be grouped, for convenience, as (1) musical tones and noises (subdivided into single notes, chords and discords, musical selections, etc., each with further arrangement according to pitch, intensity, clang-tint of instrument), and (2) articulate speech (vowels, consonants, words, sentences).

Can we find any uniform relation between these two series of variables, the inducing sound and the induced color? Certain investigators, using the questionary method, have answered in the affirmative. Thus, Bleuler and Lehmann say that "sharply demarcated, small, bright, or pointed photisms are aroused by high-pitched sounds. Red, yellow, and brown are frequent colors; violet and green are rare; blue stands midway in frequency. The tendency to secondary sensations (synesthesia) is inheritable." Other investigators (e.g. Whipple), who have made detailed experimental studies of a few individuals, contend that the questionary method is inadequate, and that there is a considerable degree of variation, not only between individuals, but also for the same individual at different times, so that "generalization is at present to be avoided."

The explanation of colored hearing is usually found in the persistence in adult life of certain curious and useless connections between sensations. Childhood is characterized by the forma

tion of countless mental combinations. Of these, only the useful or meaningful normally survive. The persistence or recrudescence in the mature individual of anomalous though not abnormal auditory-visual connections is the condition of chromæsthesia. The association may be direct (habitual or specific connection of sensations) or indirect (connections of sensations through the organic complex embodied in a feeling). The absence of abnormality is attested by the facts that colored hearing is no more frequent among neurotic than among normal individuals, and that the associations do not interfere with mental operations. They may, indeed, furnish positive sources of pleasure to their possessor.

Consult: Bleuler and Lehmann, Zwangsmässige Lichtempfindungen durch Schall (Leipzig, 1881); Flournoy, Les phénomènes de synopsie (Paris, 1893); G. M. Whipple, American Journal of Psychology, vol. vi. (Worcester, 1900); Gruber, L'audition colorée et les phénomène similaires (Paris, 1892).

COLORED METHODIST EPISCOPAL CHURCH OF AMERICA. See METHODISM.

COLOR-GUARD.

A military escort for regimental colors. (See COLORS.) Formerly a position of great honor and considerable danger, when on active service; now used only on regimental parades, reviews, and inspections. The United States Infantry Drill Regulations define the composition of a color-guard as "two sergeants, who are the color-bearers, and two experienced soldiers, selected by the colonel."

The colors (National and Regimental) are kept at the office or quarters of the colonel, unless required on parade, in which case they are escorted by the color-guard, marching in one rank, the color-bearers in the centre.

COLOR PHOTOGRAPHY. The reproduction by photography of natural objects in their own colors. There is no means known at present by which, using ordinary photographic processes, this is possible. When a photograph is taken with a camera and a sensitive plate, the developed negative shows an image of the object in various shades of gray, which depend upon the sensitiveness of the photographic plate to the ether-waves characteristic of the colors of the natural object. It is possible so to stain a photographic plate that it is more or less sensitive to all colors; but the developed negative is always gray, except possibly for certain accidental colors which have not the faintest connection with those of the object photographed. To reproduce the colors, therefore, other methods are essential, and there are at the present time two quite distinct processes.

One of these is based upon the work and a suggestion of Prof. J. Clerk Maxwell (1831-79), of the University of Cambridge. He showed that if there were produced simultaneously in the normal eye three sensations-viz. definite shades of blue, green, and red-the eye could be made to perceive any desired color of the spectrum by properly adjusting the intensities of these three component sensations. Thus, if by any means— e.g. by sets of mirrors-the eye can be made to see at one time three ordinary photographs of any natural object, looking at one through a piece of red glass, another through a piece of green glass, and the third through a piece of blue glass, the

eye will see the object in its natural colors, provided the intensity of the deposit of silver on the original three negatives is so adjusted for each negative that the intensities of these red, green, and blue sensations are exactly such as to produce the proper color-sensations. To secure this intensity on the photographic plates, three photographs of the object must be taken, each through such a colored screen as will transmit enough light of all wave-lengths to produce the desired result on the plate. Thus, one plate is exposed in a camera in front of which is a screen which allows to pass a great deal of red and small amounts of yellow and green; the second is exposed with a screen which is transparent to the green and slightly to yellow and blue; the third is exposed with a screen which is transparent to blue and slightly to green and violet. It is a question of the most careful experimenting to find what photographic plates should be used, and what colored screens give the proper intensity with them.

There are three processes of color photography based upon this general idea. In the Ives process, the three photographs of identical sizes are taken simultaneously on three plates, each through its proper 'taking' screen. From these three negatives, three positives are made by contact; and these positives, each with its proper 'viewing screen of pure red, green, or blue, placed in a so-called 'kromskop' in such a manner that sunlight is reflected through them and their screens, and all three pictures are seen superimposed apparently on each other. In another process invented independently by Professor Joly, of Dublin, and Mr. McDonough, of Chicago, the three colored screens through which the photographs are taken are combined by having a series of lines of these three compound colors ruled very closely together on a piece of glass, every fourth line having the same color. A single photograph is taken through this composite screen; a positive is taken of this, and a viewing screen, consisting of a series of lines, one a pure red, the next pure green, the next pure blue, with the same spacing as in the taking screen, is superimposed on the positive, so that the colored lines come in exactly the proper positions; and this compound plate is used as a transparency by holding it up to the light, or by looking through it at a piece of white paper which is brightly illuminated.

Quite a different process, although of the same general principle, has been invented by Professor Wood, of Johns Hopkins University. It depends for the production of the pure colors, red, green, and blue, upon the phenomena of diffraction gratings (q.v.), by means of which white light may be dispersed into pure colors. It is necessary to have three gratings ruled on glass, with grating spaces such that one gives the same deviation for the green as the other two do for the red and blue respectively. Three negatives are taken of the natural object, each through its own compound color screen; on these the three glass gratings are superimposed each on the proper one; positives are then taken through these compound negatives; the three images being superimposed by suitable lenses, thus forming a composite positive of the natural object overlaid with parallel lines suitably spaced and placed. By viewing a source of white light through this plate and using proper optical means, the object will be seen in its natural

colors, the dispersed colors of the three gratings serving in place of the viewing screens of the former processes.

An entirely different physical principle is made use of in the Lippmann method of color photography; it depends upon the fact that the colors seen by the eye are caused by ether-waves of different wave-number; and so, under proper precautions, it is possible to have 'stationary vibrations,' so called, produced. If one vibrates rapidly the end of a long rope, the other end of which is fastened to a wall, waves are sent along the rope; reflected waves are produced; and, as the direct and reflected waves are thus superimposed, there are certain points, regularly spaced, where the two waves neutralize each other's action, while in between these 'nodal' points the string vibrates exactly as if it were an ordinary string stretched between two fixed pegs. This is called a stationary vibration; and the distance between two nodal points equals half the wave-length of the train of waves which is the original cause of the vibration. The same phenomenon may be produced by ether-waves if allowed to fall upon a mirror. In Lippmann's process a photographic plate of particularly fine grain is placed so as to form one side of a bath containing mercury, the film side being away from the mercury. If light of a definite color falls upon the photographic plate, the waves enter the film, reach the mercury, are reflected, and form stationary vibrations. In between the nodes there will be chemical action, which is thus confined to plane surfaces, parallel to each other and very close together, their distance apart depending upon the wave-number of the light. If this photographic plate is now suitably developed, the nodal planes will be dissolved out largely, thus forming of the film a pile of parallel plates at minute intervals. such a pile of plates is viewed with white light, it will appear to be of the same color as that of the light which produces the chemical action, owing to the phenomena of interference (q.v.). Similarly, if the colored light from any natural object falls upon the film in its original condition, each color will produce its own stationary vibration and its own set of parallel planes, where there is chemical action; and so, when developed and viewed in white light, the image will have the proper colors of the object itself. (The above explanation of the Lippmann process is not complete; it offers but a rough idea as to what takes place. In fact, a satisfactory explanation of all the phenomena is not known.)

If

To print in the natural colors the photograph of any colored object is perfectly possible by a simple modification of the method of Ives or of Joly-McDonough, which will be found discussed under THREE-COLOR PROCESS. For additional information see: Wood, Philosophical Magazine, vol. xlvii. (London, 1899); Joly, Nature, vol. liii. (London, 1895-96); Lippmann, Proc. Royal Society of London, vol. Ix. (London, 1896); Wiener, Smithsonian Report (Washington, 1896); Bolas, Tallent, and Senior, A Handbook of Photography in Colors (New York, 1900); Donath, Die Grundlagen der Farbenphotographie (Braunschweig, 1906).

COLOR PRINTING. See THREE-COLOR PROCESS; LITHOGRAPHY.

COLORS, MILITARY AND NAVAL. The term applied to the national flag or ensign wherever

it is displayed and also to other flags, banners, or guidons carried by military bodies, and usually indicating their designation. Emblems, banners, or similar devices have been in use among soldiers and sailors from remotest antiquity. They have been conspicuous in the past for their great moral as well as practical value to the troops carrying them. The older, and more historic the colors, the greater their moral value; for the soldiers of succeeding generations would vie with each other in maintaining their traditions, and adding to their glory, with the result that many of the greatest exploits of military valor have been born of this desire. In practice they were the rallying-point of the organization, the embodiment of its history, and the material symbol of headquarters. They have been in use in every army and in every age up to comparatively recent times, when they have been displaced by the necessities of modern scientific warfare. They still retain their historic value, however, and to a certain extent their moral value also. With the British, infantry colors were originally known as ensigns (q.v.), each company carrying its own color. This soon gave way to the system at present in use, whereby each regiment or battalion is supplied with a royal or King's color, and a regimental color. The former is a Union Jack and the latter a flag of the same color as the facings (q.v.) of the regiment, with the blue union in the corner and the title, number, and honors of the regiment embroidered upon its folds. Both colors are made of silk, measure about three feet nine inches by three feet, and are each mounted on a pole of about eight and a half feet in length. Cavalry regiments of the Guard carry oblong standards, and dragoon regiments, guidons. Both types are made of crimson silk. The Royal Artillery, Royal Engineers, Lancers, Hussars, and Rifle regiments do not carry colors. Since the Zulu War of 1880, British troops no longer take their colors with them when on active service. See ENSIGN.

The colors carried in the United States Army by the various regiments and battalions are two in number, the national flag (see FLAG) and the regimental color, both of which are of prescribed size and form for the various arms of the service. The battalions of engineers carry the national flag, with the title of the battalion embroidered in silver on the centre stripe; and the battalion color, of scarlet silk having in the centre a castle, with the number of the battalion placed above the castle, and the words "U. S. Engineers" below. The artillery corps have similar colors, on which the corps device of two crossed cannon are emblazoned. Infantry regiments have the same national color as artillery and engineers; the regimental color being of blue silk, the coat of arms of the United States embroidered in silk on the centre, beneath the eagle, a red scroll with number and name of regiment embroidered in white; cavalry standards in size are somewhat smaller than those carried by the infantry and consist of a national flag made of silk. The regimental standard is of yellow silk, with the coat of arms of the United States embroidered in silk on the centre, beneath the eagle a red scroll, with number and name of regiment embroidered in yellow, fringe yellow.

According to the United States Army Regulations (1904, sec. 227) the national color will be

The

carried in battle (when it is invariably with the main body or reserve), campaign, and on all occasions of ceremony in which two or more companies participate. The regimental color is carried in like cases in battle and campaign, reviews and inspections. At other ceremonies it is carried only when specially ordered. names of battles in which one or more companies of a regiment, or of the battalions of engineers, or of the artillery corps, have borne a meritorious part are engraved upon silver rings fastened on the pikes or lances of the colors. Each troop of cavalry and battery of field-artillery has a guidon (q.v.) on which the numbers or letters designating the command are inscribed. Camp colors are small flags used to mark the location of some particular corps, post, or other institution.

In naval usage colors play an equally important part. On board old-fashioned ships they are flown at the peak of the spanker gaff, but on recent ships a special flagstaff fitting in sockets at the stern is used for the colors. In port they are hoisted at 8 A.M. and kept hoisted until sunset. On board ships of the United States Navy when the colors are hoisted they are saluted by a call on the bugle, or the band, if there is one on board, plays the "Star-Spangled Banner." While the colors are going up and the bugle or band is playing all officers and men on the upper deck face aft and salute as the colors reach the head of the staff. Dipping the colors (i.e. lowering them a short distance and then hoisting them again) is a species of compliment or salute, but United States naval vessels are forbidden to dip their colors except in returning such a salute. Colors are half-masted to express mourning and hauled down to indicate surrender or submission. When colors are carried in a funeral procession they are draped with black crape.

COLOR-SERGEANT, särʼjent or ser'-. In the United States Army, a non-commissioned officer of the rank of sergeant detailed for the colorguard (q.v.). In the British Army he is the equivalent, in rank, of the United States Army first sergeant, but formerly was one of the noncommissioned officers constituting the color-guard, from which fact the present title is derived.

COLORS OF THIN PLATES. See LIGHT, Interference and Diffraction.

COLOS'SÆ (Lat.. from Gk. Koloooal, Kolossai, also spelled Koλaooal, Kolassai). An ancient city of Phrygia in Asia Minor, on the river Lycus, a tributary of the Mæander. Colossæ was on one of the great ancient trade routes traversing Asia Minor, and is mentioned by Herodotus and Xenophon in such a way as to imply that it was at the time a city of considerable importance. Like its near neighbors, Laodicea and Hierapolis, it probably carried on an extensive trade in the dyed woolen goods for which the region was famed. In Roman times the town had lost a large share of its former importance. Christianity made its way to Colossæ in the days of Paul, not through his personal visitation, but probably through the evangelistic work directed during his long sojourn at Ephesus (cf. Acts xix. 10). During his first imprisonment at Rome Paul sent hither two letters, one addressed to the Church of Colossæ and the other to Philemon, an individual belonging to the church. (See COLOSSIANS; and PHILEMON.) During the third century A.D. the