Wondrous gymnasts are some of the Seventh, and after evening parade they often give exhibitions of their prowess to circles of admirers. Muscle has not gone out, nor nerve, nor activity, if these athletes are to be taken as the types or even as the leaders of the young city-bred men of our time. All the feats of strength and grace of the gymnasiums are to be seen here, and show to double advantage in the open air. Then comes sweet evening. The moon rises. It seems always full moon at Camp Cameron. Every tent becomes a little illuminated pyramid. Cooking-fires burn bright along the alleys. The boys lark, sing, shout, do all those merry things that make the entertainment of volunteer service. The gentle moon looks on, mild and amused, the fairest lady of all that visit us. At last, when the songs have been sung and the hundred rumors of the day discussed, at ten the intrusive drums and scolding fifes get together and stir up a concert, always premature, called tattoo. The Seventh Regiment begins to peel for bed: at all events, Private W. does; for said W. takes, when he can, precious good care of his cuticle, and never yields to the lazy and unwholesome habit of soldiers,--sleeping in the clothes. At taps--half-past ten--out go the lights. If they do not, presently comes the sentry's peremptory command to put them out. Then, and until the dawn of another day, a cordon of snorers inside of a cordon of sentries surrounds our national capital. The outer cordon sounds its "All's well"; and the inner cordon, slumbering, echoes it. And that is the history of any day at Camp Cameron. It is monotonous, it is not monotonous, it is laborious, it is lazy, it is a bore, it is a lark, it is half war, half peace, and totally attractive, and not to be dispensed with from one's experience in the nineteenth century. OUR ADVANCE INTO VIRGINIA. Meantime the weeks went on. May 23d arrived. Lovely creatures with their taper fingers had been brewing a flag for us. Shall I say that its red stripes were celestial rosy as their cheeks, its white stripes virgin white as their brows, its blue field cerulean as their eyes, and its stars scintillating as the beams of the said peepers? Shall I say this? If I were a poet, like Jeff. Davis and each and every editor of each and every newspaper in our misbehaving States, I might say it. And involuntarily I have said it. So the young ladies of New York--including, I hope, her who made my sandwiches for the march hither--had been making us a flag, as they have made us havelocks, pots of jelly, bundles of lint, flannel dressing-gowns, embroidered slippers for a rainy day in camp, and other necessaries of the soldier's life.