Now, take the slim fellow, and set him to making so many efforts a day with any given muscle or muscles, say those of his upper left arm, for instance. Put some reward before him which he would like greatly to have--say a hundred thousand dollars--if in one year from date he will increase the girth of that same upper left arm two honest inches. Now, watch him, if he has any spirit and stuff, as thin fellows very often have, and see what he does. Insist, too, that whatever he does shall in no way interfere with his business or regular duties, whatever they may be, but that he must find other time for it. And what will he do? Why, he will leave no stone unturned to find just what work uses the muscles in question, and at that work he will go, with a resolution which no obstacle will balk. He is simply showing the truth of Emerson's broad rule, that "in all human action those faculties will be strong which are used;" and of Maclaren's, "Where the activity is, there will be the development." The new work flushes the muscles in question with far more blood than before, while the wear and tear being greater, the call for new material corresponds, and more and more hearty food is eaten and assimilated. The quarter-inch or more of gain the first fortnight often becomes the whole inch in less than two months, and long before the year is out the coveted two inches have come. And, in acquiring them, his whole left arm and shoulder have had correspondingly new strength added, quite going past his right, though it was the larger at first, if meanwhile he has practically let it alone. There are some men, either at the college or city gymnasiums, every year, who are practically getting to themselves such an increase in the strength and size of some particular muscles. We knew one at college who, on entering, stood hardly five feet four, weighed but about one hundred and fifteen pounds, and was small and rather spare. For four years he worked with great steadiness in the gymnasium, afoot and on the water, and he graduated a five-foot-eight man, splendidly built, and weighing a hundred and sixty-eight pounds--every pound a good one, for he was one of the best bow-oarsmen his university ever saw.