Page:Popular Science Monthly Volume 5.djvu/77

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ACTION OF SUNLIGHT ON GLASS.

sphere does his best to alter it, by insisting on the improvement of secondary schools.

Your present responsibility is of another, though not less serious, kind. Institutions do not make men, any more than organization makes life; and even the ideal university we have been dreaming about will be but a superior piece of mechanism, unless each student strive after the ideal of the scholar. And that ideal, it seems to me, has never been better embodied than by the great poet, who, though lapped in luxury, the favorite of a court, and the idol of his country-men, remained, through all the length of his honored years, a scholar in art, in science, and in life:

Wouldst shape a noble life? Then cast

No backward glances toward the past:
And though somewhat be lost and gone,
Yet do thou act as one new-born.
What each day needs, that shalt thou ask;
Each day will set its proper task.
Give others' work just share of praise;
Not of thine own the merits raise.
Beware no fellow-man thou hate:
And so in God's hands leave thy fate."

Contemporary Review.

 

ACTION OF SUNLIGHT ON GLASS.
By E. S. DRONE.

IN a quiet street at the "West End" of Boston, there stands a house, the window-sills and roof of which, for more than ten years, have been covered with hundreds of pieces of glass, exposed to the full force of the sun's rays during the whole or greater portion of every day, only being protected by covers in the event of snow-storms. The results of these experiments, instituted to show a change produced in the color of glass by the actinic rays of the sun, have been discussed in this country and in Europe, but as yet the cause of this remarkable phenomenon has not been fully explained.

As early as 1825, Prof. Faraday noticed a change of color in glass containing oxide of manganese, due to the action of solar light, and it was thought that advantage might in some cases be taken of this action for the removal of color in glass. Prof. Faraday found that glass of a pale color, or even colorless at first, became pink by long exposure to solar rays, while portions of the same glass, not so exposed, were apparently unaltered. This effect he attributed to the solar light acting upon the manganese. In 1839 Splittgerber recorded the following interesting fact in Poggendorf's Annalen, published in