associate justice of the Supreme Court of the United States, resigning in ill-health in 1910.

MOODY, William Vaughan, American poet; b. Spencer, Ind., 3 July 1869; d. 17 Oct. 1910. He was graduated from Harvard in 1893, where he was for a time an instructor in English and afterward an assistant professor in English literature in the University of Chicago. He published The Masque of Judgment' (1900); 'Poems' (1901); and, with R. R. Lovett, a History of English Literature' (1902); The Fire Bringer) (1904); and the dramas, "The Great Divide' and 'The Faith Healer' (1909). His verse is well wrought, not infrequently rising to a sustained high level as in his 'Ode in Time of Hesitation. See FAITH HEALER, THE; GREAT DIVIDE, THE.

MOON, William, English philanthropist : b. Horsemonden, Kent, 1818; d. England, 1894. He was educated for the Church but was com

pelled to abandon this career upon becoming totally blind. He devoted his life to establishing schools and educational helps for blind children and invented a new and simple system of embossed letters for the use of the blind. He established libraries of his books in Eu

rope and United States and greatly furthered

Consult

the facilities for home instruction. Rutherford, William Moon and His Work for the Blind (1898).

MOON, The, from the earliest times, has been the chief object in the sky to attract the attention of the human race. The continual change in its appearance from day to day, its value as a light giver at night, the apparent irregularity of its motions, the curious markings on its face, its connection with the ebb and flow of the ocean, and many a real or supposed influence in terrestrial affairs, have always caused it to be a subject of speculation and inquiry among philosophers of every age. Yet it is only within the last 300 years that the various theories and superstitions connected with it have been put to the test, and that order has been evolved from the chaos of fact and fancy. Even at the present time many a belief, tested by science and found wanting, finds support in otherwise enlightened communities.

Size, Weight, etc. The moon is a nearly spherical body with a diameter of 2,163 miles, a little more than a quarter of that of the earth, moving at an average distance from the earth of 239,000 miles. Its surface is therefore з and its volume 49 that of the earth. It is, however, less dense in the ratio of 10 to 16, or, on the average, its density is the same as that of the rocks on the earth's surface, so that it would require the materials contained in 81 moons to form our globe. Its smaller size and mass cause gravity at the surface to be only % of the terrestrial attraction: the same exertion which would lift a given weight here would raise a weight six times as great there, and a body, instead of falling 16 feet in the first second, would fall only 23 feet. It moves so as to always turn the same face to the earth and therefore rotates on its axis in the same time that it takes to go round the earth- about 27 days. The rotation of the moon about its axis and its motion round the earth is neither quite uniform or circular, as will be seen later; consequently extra portions of the eastern and western faces come successively into view. Further, the

moon's axis is not quite perpendicular to the plane of its orbit, so that the north and south caps are in turn a little inclined toward the earth. These motions are called the librations of the moon, and they permit us to see rather more than half (about three-fifths) the surface.

At

Light and Atmosphere. Like the earth, the moon possesses no light of its own, but receives all from the sun, and its day- the interval from sunrise to sunrise is a month. full moon it sends to us about one 600,000th part of that given by the midday sun. The surface is not nearly so white as its concentrated light would seem to indicate; its brightest portions are nearly of the shade of salt and its darkest that of slate, the average being the color of gray weathered sandstone. The long sunshine for two weeks and the absence of sun for the following two weeks must cause_immense variations of temperature. But Professor Langley of Washington estimates that the tem

perature of the surface, even at the hottest, probably never rises above the freezing point of water; the heat is radiated out nearly as fast as it is received. In the long night the temperature must fall to something like 200° below zero. In spite of this small amount of heat, Professor Langley, by inventing a very

sensitive instrument called a bolometer which would detect the heat from a candle a mile away, succeeded in detecting heat rays coming from the moon. His results depend partly on the many fruitless attempts which have been made to find evidences of the existence of an atmosphere. If air is present its pressure cannot exceed 1-750 that at the earth's surface and it is probably much less, as no refraction has ever been observed when the moon's limb passes over a star. A similar argument applies to the existence of water in any quantity, and no clouds have been certainly seen. It is possible that water-probably in the form of ice — may exist at the bottom of some of the deeper craters, but the low temperature would scarcely permit it to be liquified even when the sun was shining full on it.

Surface Marks.-The well-known resemblance of the full moon to a human face disappears almost immediately if a glass-even the smallest opera glass is trained on to it. When it is looked at through a moderately large telescope, the surface is seen to be broken up into mountain ranges and valleys as well as darker portions, which seem to be comparatively flat. A closer inspection made at more favorable times when the moon is not full so that the shadows cast by the sun can be well seen, puts these features clearly into view. The magnificent telescope in the Lick Observatory in California brings the satellite so near that objects which might be seen with the naked eye if the moon were only 100 miles distant, can be distinguished on the surface under favorable circumstances.

Craters. The most marked feature of the lunar surface is the number of craters which appear in almost every region. These are circular rings with diameters ranging from half a mile to 100 miles, and with exterior walls sometimes as high as 20,000 feet-formations comparatively rare on the earth's surface where they seldom exceed a diameter of a very few miles with much lower walls. In some parts they are scattered in the wildest profusion,

overlapping one another, smaller ones breaking into the walls of the larger and so crowded together that it is difficult to distinguish one from another. In many cases there is a central cone or a group of peaks which often rise as high as the walls of the ring and on which small craters can sometimes be seen. There are also lofty ranges of mountains ten to fifteen thousand feet high, some peaks of the Lunar Appenines rising to 20,000 feet.

Seas. The so-called seas of the moon are simply portions of the surface darker in color than the average and very much less broken up by craters or mountain ranges. These form the main features of the face seen at full moon. They are crossed by thin lines known as rills or clefts which run in all directions, sometimes straight and unbroken for hundreds of miles, even intersecting ranges of mountains and craters and reappearing on the other side. These rills are generally two and rarely exceed 10 miles in width, their depth varying from 100 yards up. A curious feature of a different kind is an absolutely straight cut-the great Alpine valley-some 83 miles long, which crosses a range of mountains and under low magnification looks as if some wandering celestial body had grazed the surface.

White Rays. The most puzzling feature of the surface consists in a series of white rays or streaks which radiate from a few of the principal craters in every direction. In their brightness they mask all other shades of tint on the surface and seem to continue their course, sometimes for hundreds of miles, quite independently of the nature of the country they cross. Prof. W. H. Pickering, however, who has studied the systems carefully, considers that their actual length has been much exaggerated and believes that the apparent length is due to lines of small craters from which they emerge. The most remarkable system is that starting from the crater Tycho, itself of a brilliant whiteness, and giving the whole region the appearance of a globe cracked by internal pressure -a suggestion made by Nasmyth who actually cracked a glass globe in this way and obtained a striking_resemblance.

Origin of the Formations.-The origin of these various formations has been the object of much speculation. That the craters and mountain ranges came into existence after the cooling down of the outer crust and were produced by its contraction and by the enormous tidal disturbances caused by the earth seems a sufficiently probable hypothesis. Objection has been raised to this view on account of the fact that terrestrial volcanoes all show the presence of large quantities of water and that the earth has comparatively few of such formations. But weathering action has undoubtedly had little effect on the moon's surface, while it has been a powerful factor in eliminating such features on the earth. Another theory, that the craters are of the nature of cracked bubbles like those which appear in cooling slag which contains gases, does not require the presence of water, but it has not met with any general acceptance. The rills or clefts are unexplained; some astronomers incline to the idea that they are dried watercourses, others with greater probability that they are fissures produced in cooling. The white streaks or rays are considered by Mon

sieurs Loewy and Puiseux, whose work on the moon accompanies a big atlas of photographs taken lately at Paris, to be formed of volcanic dust or cinders shot out from the craters and carried for considerable distances by currents of air before being deposited on the ground. Prof. W. H. Pickering inclines to the same theory. The rays were the last evidences of activity before the body of the moon became cold and absorbed the small quantities of air and water which at one time were present outside.

Surface Changes. The evidence as to changes in the moon's surface since the first careful observations were made about a century ago is doubtful. One crater, Linné, observed by Beer and Mädler, is given as having a diameter of about six miles. At various times it seems to have appeared and disappeared again - possibly owing to the different circumstances under which it was seen; at present it is scarcely visible. In the absence of air and water such changes must be very rare, the weathering action which takes place on the earth having little or no effect; possibly the enormous differences of temperature every two weeks may in time cause a breaking up of the rock.

Photographs.-The photography of the moon's surface was started by Draper and Bond in America about the middle of the 19th century. The pictures of the latter were shown at the London Exhibition in 1851 and inspired De la Rue in England and others as to its possibilities for the accurate investigation of the lunar surface. The magnificent photographs of Rutherfurd made in New York and published in 1873 have only recently been surpassed by those taken at the Lick, Yerkes and Paris observatories. It is possible that photographs taken 20 or more years from now may, on comparison with these, enable astronomers to detect changes if such occur. The varying aspects of the moon will make this difficult, but the personal element, always present when drawings have to be made, will at any rate be eliminated. At the same time the eye can detect minute details which are absent from photographs.

Periods. The average time occupied by the moon, in moving in its orbit round the earth, is 27d. 7h. 43m., its sidereal period. The synodic period is the interval between successive new moons and it is a little longer owing to the time, 365 days, occupied by the earth in moving round the sun. The moon performs 1/27/3 of its orbit and the earth 1/3654 each day, and therefore the difference between these 1/2731/36541/291⁄2 is the daily fraction of its path which the moon describes with respect to the sun; that is, 291⁄2 days (29d. 12h. 44m.) is the synodic period. If the plane of the moon's orbit coincided with that of the earth's equator, the moon would rise about 50 minutes later each day, but the inclination of these planes to one another varies between 18° and 291⁄2°, so that this retardation is quite different at different times. When full moon occurs near the autumnal equinox, it may, in the latitude of New York, be as small as 23 minutes, while further north it may reduce to nothing, so that for several nights the full moon rises about the same time, soon after sunset. The feature is known as the harvest moon and in countries where the autumn weather is very uncertain, it is a valu