The pleasure of exercise is due first to a purely physical impression, and secondly to a sense of power in action. The first source of pleasure varies of course with our condition and the state of the surrounding circumstances; the second with the amount and kind of power, and the extent and kind of action. In all forms of active exercise there are three powers simultaneously in action,--the will, the muscles, and the intellect. Each of these predominates in different kinds of exercise. In walking, the will and muscles are so accustomed to work together and perform their task with so little expenditure of force, that the intellect is left comparatively free. The mental pleasure in walking, as such, is in the sense of power over all our moving machinery. But in riding, I have the additional pleasure of governing another will, and my muscles extend to the tips of the animal's ears and to his four hoofs, instead of stopping at my hands and feet. Now in this extension of my volition and my physical frame into another animal, my tyrannical instincts and my desire for heroic strength are at once gratified. When the horse ceases to have a will of his own and his muscles require no special attention on your part, then you may live on horseback as Wesley did, and write sermons or take naps, as you like. But you will observe, that, in riding on horseback, you always have a feeling, that, after all, it is not you that do the work, but the animal, and this prevents the satisfaction from being complete. Now let us look at the conditions of rowing. I won't suppose you to be disgracing yourself in one of those miserable tubs, tugging in which is to rowing the true boat what riding a cow is to bestriding an Arab. You know the Esquimaux kayak, (if that is the name of it,) don't you? Look at that model of one over my door. Sharp, rather?--On the contrary, it is a lubber to the one you and I must have; a Dutch fish-wife to Psyche, contrasted with what I will tell you about.--Our boat, then, is something of the shape of a pickerel, as you look down upon his back, he lying in the sunshine just where the sharp edge of the water cuts in among the lily-pads. It is a kind of a giant pod, as one may say,--tight everywhere, except in a little place in the middle, where you sit. Its length is from seven to ten yards, and as it is only from sixteen to thirty inches wide in its widest part, you understand why you want those "outriggers," or projecting iron frames with the rowlocks in which the oars play. My rowlocks are five feet apart; double the greatest width of the boat.