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Page:Popular Science Monthly Volume 34.djvu/616

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THE POPULAR SCIENCE MONTHLY.

GLASS-MAKING.
By C. HANFORD HENDERSON,

PROFESSOR OF PHYSICS AND CHEMISTRY IN THE PHILADELPHIA MANUAL TRAINING SCHOOL.

I.—A PANE OF GLASS.

"O CARLYLE!" exclaimed Emerson, in his diary, at the time "Sartor Resartus" was being republished in America, "the merit of glass is not to be seen, but to be seen through; but every crystal and lamina of the Carlyle glass shows."

With admirable precision this defines the proper function of a pane of glass. Decorative art, in casting about for new fields of conquest, has too frequently induced a contrary feeling; but, after all, a window-pane at its best is something to be seen through and not to be seen. It is our means of looking out upon the world and letting the sun look in upon us. The more perfectly, then, it fulfills its function, the less evidence will it bear of its evolution from such dull things as sand and lime and soda-cake. Our window-pane is transparent in all things save its own history. It gives no hint of what it is made of, or how it is made. It is, indeed, easier to look through it than it is to look into it. If one look in the right direction, however—and in America this means toward Pittsburgh—he will see, in the cluster of glass-factories which have gravitated toward the natural gas of that neighborhood, a side of industrial activity possessing much interest. The brilliant pane of glass itself tells no stories, but the white-hot furnaces and pots of molten metal, the active, hurried figures, and the movements of rare dexterity that one sees at these places, are far more communicative.

They can well afford to publish their achievements, for about few of its material products can the nineteenth century boast with so much show of justice as about its window-glass. It is true that past ages have produced quite as remarkable technical results in other departments of industry, but in this one product, at least, the present decade appears to be unique. Not even China and Egypt, which have a standing claim of priority on all the arts and sciences, dispute with the modern glass-maker. His triumphs are without rival.

Contrary legends are afloat, but they can be chased into no fact: There is, for instance, a story current about the Queen of Sheba and the wise King Solomon that quite puts into the shade even the deceitfulness of riches. It is related by some gossipy chronicler that, at the time of the famous visit, the royal audience was so arranged that the queen and her suite in approaching were obliged to pass over a floor of glass under which were flowing