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Page:Popular Science Monthly Volume 19.djvu/533

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The thought had not then occurred to him. Now his wife's fanciful challenge awakened a desire to paint the moon in colors; for, as the most exquisite portrait in black and white can not express the bloom of lip and cheek, or the burnished gold of sunny tresses, neither could the various astronomical drawings now in existence express the beautiful gradations of light, the delicate tinting of the gray-green plains, the brilliant peaks and sunlit edge that make the telescopic moon the most interesting of celestial bodies.

Hitherto the human face and form had engaged his pencil: he could command sittings of his subject where and when he chose; direct the light and shade; arrange the drapery, select the pose: but here was to be another order of affairs; a willful, fitful queen, subject to no human wishes, obedient to no mortal command. There were only two evenings in the month in which to study the chosen phase—on one of them or both her Majesty might command the vapors of the air and veil herself in impenetrable cloud. Another month she might summon the forces of the winds, and dance with them a demon's dance upon the telescopic mirror; and, on the next night, when the chosen phase was past, appear serenely beautiful upon a field of stainless blue.

It may be fairly asked how the artist, contending with so many difficulties, could paint a faithful portrait at all. As it would be impossible in the moon's short sittings, if one may use the term, to catch and fix accurately the varied details that crowd its surface with the pencil alone, Mr. Harrison resorted, as a first step, to photographic aid. Taking Rutherfurd's negative of the three-days-old crescent, he enlarged it to the desired size by means of an oxyhydrogen light, throwing the image from the glass to his canvas. Thereon he sketched the outlines of the craters, plains, and mountain-ranges, as the enlarged negative indistinctly presented them. Then, by the light of a lantern suspended from the observatory roof, from time to time consulting the image of the moon mirrored in the telescope, he sharpened every detail, marking out the intensely black shadows and the equally intense high lights on the topmost peaks of the terminator, the dazzling edge, and the gradations of tint on the far-stretching plains.

Slowly—for eighteen months rolled by before the first phase was finished—pencil and pigment, guided by artist eye and hand, did their work, and there stood a faithful portrait of the three-days-old crescent, twenty-one inches in diameter, showing the terminator at Messier.

The edge toward the left is brilliantly illuminated by the sun, whose proximity casts a yellowish tint over the plains, that gradually fades into grayish-green in the shadows of night on the right edge or terminator. On the remainder of the disk, faintly illumined by earthlight, may be dimly seen outlines of the Apennine ranges, and the craters of Copernicus and Tycho.

The brilliant convexity of the moon is well thrown out by the clear