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Take our present problem for example. It is impossible you say that I should deny the ambition to conquer for the sake of the love of my neighbor without killing what is most vital in myself. And it is equally impossible that I should give play to my ambition to conquer without losing my neighbor's love and living a lonely struggle. These things are indeed impossible in the world to which the imagination of the past has been fettered,-this little finite earth the fulness whereof is so easily emptied. If to have all that I can win of such meagre fulness is the only meaning I can give to ambition, either I must kill ambition and love my neighbor across a fence, or I must tear down the fence and kill my neighbor. But what if the fault of all this lay not with the darkness of reality, but with the blindness of untrained imagination? What if we could set before ambition a boundless prospect, so that never, far as conquest might reach, could it find cause to weep for lack of more to conquer? What if, in the very conquering of such a world, the gain of one, so far from being another's loss, were the equal spoil of all, yes, and a weapon forged to the hand of all for new victories? Wherefore then should ambition yield or love be denied?

But perhaps you will say this is but an imagining and a dream. Our humdrum world, the only real one, offers no such object of ambition, and if it did our nature, just human nature, is not such as could understand, still less be fascinated and inspired by it. Does it sound ridiculous to say that our world is one that holds out just such a prospect to all who will but see? Aye, and that many a human eye has seen, and having seen remained single to this vision? I will call the promised land the Kingdom of Nature Subdued: I will call the vision the Vision of Science.

In the beginning, Man was Nature's creature and her plaything. Sometimes she seems to have fondled her toy and been good to it, given it pleasant places to dwell in and let the light of her coutenance shine upon it. Those who think only of these rare moments, may sing O bella età dell'

oro! O Paradise, O Paradise! They forget how rare were these moments and how capriciously bestowed. Elsewhere were many griefs of which man could not so much as guess the reason, and if he dared raise his questioning gaze to God he was mocked for his impotence and nothingness: "Where wast thou when I laid the foundations of the earth? declare, if thou hast understanding."

But need makes for perspicuity. Time passed, and some few caught a glimpse of the vision of science: caught it, widened it, brightened it and passed it on. Perhaps their lives were not very happy in a world where they were much alone; but it is easier to tell of their ostensible hardships than of their enthusiasms,-who knows but that even they found here their compt. Time went on, and that Nature which had begun by being so cruel and capricious a mistress became through man's science more and more his slave. Human eyes were not so often turned to the gods in supplication. A Greek slave called out to his fellows, "Why call ye upon the gods? Ye have hands? Wipe your own nose."

The earth yields; step by step death itself gives ground, and shall we think of the stars only to fear them and to read our fate in them? Shall they forever whisper to us their old, taunting questions: "Canst thou bind the sweet influences of Pleiades, or loose the bands of Orion? Canst thou bring forth Mazaroth in his season? or canst thou guide Arcturus with his sons? Knowest thou the ordinances of heaven? canst thou set the dominion thereof on the earth?"-And shall we always answer, Alas!

But I am dreaming a dream. Is it though so ill a thing to dream, if one does not forget how to laugh the while? Yes, I know, the stars are rather big for our frail hands to play with even as all Nature once played with us. But how else am I to say that there is nothing in Nature that can forever resist the onward march of science? What else am I to say when the same master equations hold in heaven as on the earth, and Arcturus with all his sons is but a falling pebble painted large?

Let us dream then and laugh with Aesop at his frog. It is certain that neither our laughter nor our dreams can hurt our wise neighbor very much, and if we go the toilsome way toward the conquest we dream of, he or one that comes after may sometime look back on us and say, Yes, that was Progress. The measure of man's cooperation with man in the conquest of nature measures progress.

SPECTRUM ANALYSIS

BY ARTHUR W. GOODSPEED

Professor of Physics and Director of the Randal Morgan Laboratory of Physics.

"Spectrum Analysis" denotes the general method of investigation based upon the examination of radiant energy emitted by various sources. Until within about ten years the radiation was studied by means of a prism or diffraction grating. It will be recalled that Newton in 1672 formed the first spectrum and so made the first experiment in spectrum analysis when he showed by means of a triangular glass prism that ordinary sunlight is really composed of many colors, with which we are all familiar, ranged from red to violet. Newton's experiment may easily be made using the electric arc light instead of the sun.

An arrangement of devices into a composite piece of apparatus for examining radiation is called a spectroscope, or for exact measurement a spectrometer. In a simple form it consists of a graduated circular table, for measuring angles, a prism or grating at its center for dispersing the radiation, a collimating tube for rendering the rays parallel and a telescope or photographic camera for viewing or recording the result.

The history of this science may be said to start with the experiments of Wallaston in 1802 and of Fraunhofer in 1814 who noticed in the spectrum of the sun certain dark lines crossing it perpendicular to its length. Fraunhofer mapped nearly 600 of these lines. Eight of the most prominent he designated by the first eight letters of the alphabet the lines A and B lying in the extreme red, C in the orange red, D in the yellow, E in the green, F and G in the blue and H in the violet. Later he added a in the red and b in the green.

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