And yet it requires no great gift of prophecy to see that what has been accomplished is only an earnest of what is to come in the not distant future. In every direction eager experimenters are on the track of new discoveries. Any day a chance observation may open new and important fields of exploration, just as Hall's observation about the power of cryolite to absorb aluminum pointed the way to the new aluminum industry; and as Birkeland's chance observation of the electric arc in a magnetic field unlocked the secret of the unresponsive nitrogen. It will probably not be long, for example, before a way will be found to produce electric light without heat--in imitation of the wonderful lamp of the glow-worm. Then in due course we must learn to use fuel without the appalling waste that at present seems unavoidable. A modern steam-engine makes available only five to ten per cent. of the energy that the burning fuel gives out as heat--the rest is dissipated without serving man the slightest useful purpose. Moreover, the new studies in radio-activity have taught us that every molecule of matter locks up among its whirling atoms and corpuscles a store of energy compared with which the energy of heat is but a bagatelle. It is estimated that a little pea-sized fragment of radium has energy enough in store--could we but learn to use it--to drive the largest steamship across the ocean--taking the place of hundreds of tons of coal as now employed. The mechanics of the future must learn how to unlock this treasury of the molecule; how to get at these atomic and corpuscular forces, the very existence of which was unknown to science until yesterday. The generation that has learned that secret will look back upon the fuel problems of our day somewhat as we regard the flint and steel and the open fire of the barbarian. If problems of energy offer such alluring possibilities as this, problems of matter are even more inspiring. The new synthetic chemistry sets no bounds to its ambitions. It has succeeded in manufacturing madder, indigo, and a multitude of minor compounds. It hopes some day to manufacture rubber, starch, sugar--even albumen itself, the very basis of life. Rubber is a relatively simple compound of hydrogen and carbon; starch and sugar are composed of hydrogen, carbon, and oxygen; albumen has the same constituents, plus nitrogen. The raw materials for building up these substances lie everywhere about us in abundance. A lump of coal, a glass of water, and a whiff of atmosphere contain all the nutritive elements, could we properly mix them, of a loaf of bread or a beefsteak. And science will never rest content until it has learned how to make the combination. It is a long road to travel, even from the relatively advanced standpoint of to-day; but sooner or later science will surely travel it.