key for every day in the month; and if any one key got into wrong hands it would be useless unless it happened to be the one which last locked the lock.
THE CYCLE.
There are a few features of this useful and in some ways wonderful contrivance which should be noticed. First,
THE GEARING OF A CYCLE.
To a good many people the expression "geared to 70 inches," or 65, or 80, as the case may be, conveys nothing except the fact that the higher the gear the faster one ought to be able to travel. Let us therefore examine the meaning of such a phrase before going farther.
The safety cycle is always "geared up"—that is, one turn of the pedals will turn the rear wheel more than once. To get the exact ratio of turning speed we count the teeth on the big chain-wheel,