This is the question which has agitated Boston to-day, from the harbor to the Back Bay, and from Bunker Hill to Jamaica Plain. When Boston woke up this morning, notwithstanding her doubts, she dressed herself in festal garments of streamers, flags and bunting, to do honor to the occasion, and to properly impress the strangers within her borders with the fact that she was out for a holiday, and was bound to enjoy herself. And there were strangers enough within her borders. Every other man you met upon the narrow sidewalks was a carpet-bagger, and every other woman had a roll of music in her hands. Band musicians in all sorts of uniforms, carrying all sorts of odd-looking boxes, met you and jostled you at every turn, for it is impossible for two people to pass each other upon a Boston sidewalk, especially if one has a box or a carpet-bag in his hands. Every train and every boat which has arrived to-day was loaded down with musical freight, and all the morning they filed down Boylston street to the Coliseum, in water-proof cloaks with their rolls of music. The hotels are filled with them. The boarding houses are full, both in the city and in the suburbs, and even some of the public halls have been provided with cots, to accommodate the melodious strangers, who have come here to lift up their voices in the grand chorus. And it is a grand chorus. In 1836, Mendelssohn, the great master, led 536 performers, and ten years later led his own "Elijah," with a chorus of 700 before him. In 1862 a chorus of 4,000 voices sang together at the Crystal Palace in London; and last year Costa led 4,500 in the same building. It was considered a great event--an episode in the history of music. Julien, that eccentric little conductor, conceived the idea of increasing upon this number, but the very magnitude of his operations turned his brain, and he died in a mad-house--his disordered mind, even in his dying moments, being occupied with an imaginary orchestra. It has been left for Mr. Gilmore to eclipse them all. What was some time a problem is now a fixed fact; and the annals of music can show no grander triumph than that which this daring, hard working man has achieved this day. When Mr. Gilmore's baton closed the final chord of the massive Martin Luther choral, he had done something which was worth living for. He had a right to be proud of his work.