To-day has been given almost exclusively to the school-children. It was a grand sight to look at the adult chorus, but it was a beautiful sight to look at the children. Eight thousand of them were gathered together from the public schools. The girls were clad in white, and filled the wings, the boys occupying the places of the tenors and bassos. The children arrived promptly--do they ever arrive any other way?--and took their places without a particle of disorder. The white dresses of the girls, trimmed with ribbons of varied colors, their fresh young faces, and the eager, enthusiastic faces of the boys, made up a picture of beauty not often looked upon. It was like a huge garden _parterre_ of flowers, and, as great shafts of sunlight shot in through the windows and bathed them with gold, and fans waved in the happy throng like the wings of a multitude of birds, it made a sight which may be the sight of a lifetime. The audience also was an immense one, completely filling the building, and thus the _coup d'oeil_ was fully as beautiful, if not as imposing, as on any day during the week. The performance commenced with the overture to "William Tell," which was rendered with more animation than on Wednesday. The effects of the cellos, headed by Wulf Fries, were particularly striking. Never before have I heard this noblest of all instruments develop the human voice tones as it has to-day. The applause had hardly subsided when Eichberg rapped the juvenile chorus to attention with his baton. The rising of the children was not like that of the adults. The latter invariably rose slowly and successively, rank after rank. The children, in their impatience, fairly sprang to their feet, and stood, books in hand, eager for the signal. When it was given, they took the beat together grandly, and commenced "Hail Columbia" in unison. As they progressed, however, the instruments were quicker than they, and there was some lagging, but the effect was very novel and striking. Although the girls outnumbered the boys, the latter's voices were much stronger and made themselves most clearly heard. The freshness, purity and clearness of the voices easily rendered them superior to the orchestra, and even the organ seemed to affect them but little. There was no difficulty in hearing them, for each one of the little people was singing for dear life and working with all the zest and enthusiasm of a child's nature. By some process known only to children, they came out together at the end of each stanza, although they sometimes diverged widely in the middle. Think of children singing Mercadante's music! But they did it, and superbly, too. His chorus, "Now the Twilight Softly Stealing," was given by them admirably. It was arranged as a solo for sopranos and altos, and then taken in unison by the full chorus, and I have no musical memory sweeter than the cadences of that chorus, which were given with such beauty and freshness by these children.