Page:Popular Science Monthly Volume 18.djvu/682

664 to 0·0076 millimetre from the unpolished and 0·0085 from the polished granite. That a polished surface of granite should weather more rapidly than a rough one is perhaps hardly what might have been expected. The same observer remarks that, though the polished surface of syenite was still bright at the end of not more than three years, it was less so than at first, and in particular that some figures indicating the date, which he had written on it with a diamond, had become entirely effaced. Granite has been employed for too short a time as a monumental stone in our cemeteries to afford any ready means of measuring even approximately its rate of weathering. Traces of decay in some of its feldspar-crystals may be detected, yet in no case that I have seen is the decay of a polished granite surface sensibly apparent after exposure for fifteen or twenty years. That the polish will disappear, and the surface will gradually roughen as the individual component crystals are more or less easily attacked by the weather, is of course sufficiently evident. Even the most durable granite will probably be far surpassed in permanence by the best of our silicious sandstones. But as yet the data do not exist for making any satisfactory comparison between them.—Nature.

 

F all the institutions which we are proud to call American, none makes so great an expenditure as our system of public education, and none receives so little critical attention from those by whom it is supported. It is seldom referred to except for purposes of flattery. Of all the offspring of American liberty this is the pet, and, as usual, it is the spoiled child. And this will probably remain so as long as indiscriminate praise is more welcome than just criticism.

I purpose, in the few minutes allotted to me, to discover, if possible, the true sphere of the state in reference to the education of the young. I shall use the word state in its broadest sense—a community of persons living within a limited territory and bound together by political ties. If such a community has a right to exist, then it has a right to do anything that is necessary to maintain that existence—to appropriate private property and even to take life itself. But, while the power of the state is thus broad, its duty is proportionally narrow, namely, to protect the person and property of the subject from the violence and fraud of his fellows. While for this purpose no sacrifice is too great, yet to exact from the subject more than is necessary for this purpose is legalized spoliation; for, when you take of a man's property more 