Of all the ornamental aquatic fowls known in England, the _swan_, though perhaps the commonest, is the noblest; and it has the advantage of being useful in clearing ponds of weeds as well as being ornamental. A swan should generally have a pond at least three acres in extent, and they seldom thrive unless there is an island in the centre overgrown with long grass or underwood, in which they can make their nests. Swans are tolerably hardy, and only require to be taken up in time of frost. They are very fond of rambling over grass when they feel themselves in perfect security; and they eat a great quantity of slugs and snails when thus employed. In the month of May the female swan generally prepares to make her nest, which she does secretly, as, if the cobb or male bird perceives her, he will prevent her if possible. The cygnets, or young swans, are generally hatched about July, and when they first appear their feathers are of a dingy brown instead of being white. When they first go into the water the female, or pen bird, as she is called, only lets them swim a little way, and then, if they appear tired, she takes them on her back. When the cygnets grow bigger, the mother swims round the pond with them following after her like a company of soldiers. As soon as they get about three parts grown, the cobb drives them away from their mother, and forces them to provide for themselves. At this period, if they happen to have been hatched late, they may be fed with boiled barley and bread. They do not become perfectly white till the second year. When two full-grown cobb swans quarrel they fight tremendously; and, though the common species is called the mute swan, they make a loud hissing noise something like that of the goose, but louder and hoarser. A cobb swan will also, when enraged, attack a dog, or even a man, striking tremendous blows with its wings. It is said that a full-grown swan could break a man's arm with a blow of its wing. Swans were formerly considered royal birds; and those upon the river Thames are still the property of the crown, and the young ones are marked every year under the superintendence of the Lord Mayor, the ceremony being called swan-hopping, which is said to be derived from swan-upping, a part of the ceremony being to decide how far up the river the swans have a right to go.