There is another and a smaller lake near the Fifth Avenue entrance. It is near the wall on Fifty-ninth street, and lies down in a deep hollow, formed by high, rocky sides, which give it a wild, mountainous appearance. PLEASURE SEEKERS. In fair weather the Park Commissioners cause free concerts to be given on the mall every Saturday afternoon, by one of the best bands in the city. The music is of a high character, and thousands flock there to hear it. The Park is full of visitors on fine afternoons, and the boats on the lake are crowded. The horses and equipages of the wealthier classes form one of its greatest attractions on such occasions. They come in great numbers. All the celebrities of the city, and many from other parts of the world, are to be seen here, and the horses now compare favorably with those of any other American city. Previous to the opening of the Park, there were no drives around or in New York, and the horse-flesh of the Metropolis was the laughing-stock of the country. Now the case is different. In the winter season, when the lake and ponds are frozen over, the skating is the great attraction. Large sheds are erected at the principal points, containing private apartments for the sexes, restaurants, cloak-rooms, and places for warming and putting on or removing skates. The ice is carefully examined, and the dangerous localities are plainly marked. Every precaution is taken to prevent accidents, and means of assistance are always at hand. When the ice is in good condition, a large ball is hoisted on the Arsenal, and little flags are fastened to the various street cars running to the Park. In this way the news is soon scattered through the city, and crowds of persons flock to the Park to enjoy the sport. The scene is both brilliant and exhilarating. The Commissioners prepare a code of liberal rules for the government of skaters, and place them at conspicuous points. All persons going on the ice are required to comply with them, on pain of exclusion from the sport. Good sleighing is rare in the Metropolis, but when it is to be had, the best is always in the Park. THE ARSENAL. This building is situated on Fifth Avenue, just within the Park enclosure. It was originally used for the purpose designated by the name it bears, but is now a free museum of natural history and art. It contains the nucleus of the Zoological Garden, which is now in course of construction near the centre of the Park, on the line of Eighth Avenue, and though the collection of animals, birds, etc., is small, it is very interesting. In the upper part of the building are the models of the sculptor Crawford, presented to the city by his widow, and many other interesting specimens of art. THE CROTON RESERVOIRS.