We visited the new fort which the government is erecting on the lake, a little to the north of the town, commanding the entrance of Niagara river. It is small, but of wonderful apparent strength, with walls of prodigious thickness, and so sturdy in its defences that it seemed to me one might as well think of cannonading the cliffs of Weehawken. It is curious to see how, as we grow more ingenious in the means of attack, we devise more effectual means of defence. A castle of the middle ages, in which a grim warrior of that time would hold his enemies at bay for years, would now be battered down before breakfast. The finest old forts of the last century are now found to be unsafe against attack. That which we have at St. Augustine was an uncommonly good sample of its kind, but when I was in Florida, three or four years since, an engineer of the United States was engaged in reconstructing it. Do mankind gain any thing by these improvements, as they are called, in the art of war? Do not these more dreadful engines of attack on the one side, and these more perfect means of protection on the other, leave the balance just where it was before? On Tuesday evening, at seven o'clock, we took passage in the steamer Oregon, for Chicago, and soon lost sight of the roofs and spires of Buffalo. A lady of Buffalo on her way to Cleveland placed herself at the piano, and sang several songs with such uncommon sweetness and expression that I saw no occasion to be surprised at what I heard of the concert of Leopold de Meyer, at Buffalo, the night before. The concert room was crowded with people clinging to each other like bees when they swarm, and the whole affair seemed an outbreak of popular enthusiasm. A veteran teacher of music in Buffalo, famous for being hard to be pleased by any public musical entertainment, found himself unable to sit still during the first piece played by De Meyer, but rose, in the fullness of his delight, and continued standing. When the music ceased, he ran to him and shook both of his hands, again and again, with most uncomfortable energy. At the end of the next performance he sprang again on the platform and hugged the artist so rapturously that the room rang with laughter. De Meyer was to give another concert on Tuesday evening at Niagara Falls, and the people of Buffalo were preparing to follow him. The tastes of our people are certainly much changed within the last twenty years. A friend of ours used to relate, as a good joke, the conversation of two men, who came to the conclusion that Paganini was the greatest man in the world. They were only a little in advance of their age. If such are the honors reaped by De Meyer, we shall not be astonished if Sivori, when he comes over, passes for the greatest man of his time.