BIRDIE HAIGHT.--1. The American swan breeds in the northern parts of America, and its migrations extend only to North Carolina. Another American species is the Trumpeter Swan, breeding chiefly within the Arctic Circle, but of which large flocks are seen in winter as far south as Texas. It is smaller than the common swan, which is found in its wild state in Asia and the eastern parts of Europe. In a half-domesticated state it has long been a common ornament in lakes and ponds in this country and Europe, more especially the latter. The black swan is a native of Australia. 2. Varicose veins, it is said, may be radically cured by a surgical operation, but the disease may reappear in some other portion of the body, there being no way to prevent it. 3. Papua, or New Guinea, is the largest island in the world. Australia now ranks as one of the grand divisions of the earth. S.A.M.--Eighteen articles on electricity have been published in this and previous volumes. They were: "A Cheap Electrical Machine," Vol. II, No. 22; "How to Make a Simple Electrical Machine," Vol. VI, No. 3; "Experiments of Various Kinds," Vol. VI, No. 4; "A Storm in a Teacup," Vol. VI, No. 9; "The Leyden Jar and How to Make It," Vol. VI, No. 20; "The Electrician at Home," Vol. VII, No. 16: "A Mysterious Alarm," Vol. VIII, No. 14; "Studies in Static Electricity," Vol. IX. No. 30, "How to Make an Electrical Machine," Vol. IX, No. 20; "How to Make an Electric Battery," Vol. X, No. 8; "The Induction Coil and How to Make It," Vol. X, No. 28; "A Simple Electrical Machine," Vol. XI, No. 6: "Simple Electrical Experiments." Vol. XI, No. 15; "An Electric Bell Outfit," Vol. XI, No. 20; "How to Make a Storage Battery," Vol. XI, No. 25; "Induction Coil Condenser," Vol. XI, No. 47; "Electric Lamps and How to Work Them," Vol. XII, Nos. 1 and 2; and "Electro-Motors and How to Make Them," Vol. XII, No. 3. BIAS EYES.--1. Letters relating to business matters connected with this paper--such as inquiries relating to advertising rates--are the only ones answered by mail. They must invariably contain a stamp to pay postage on such reply. 2. Any reader complying with the rules governing the exchange department is entitled to its privileges. 3. He is an Englishman by birth. 4. The principal use of the bell on board ships is to denote the time of the day or night, which is done by 1, 2, 3, and so on, up to eight strokes of the bell. The twelve hours between midnight and noon, or noon and midnight, are divided into three portions of eight bells each, the duration of time between bells being half an hour. Consequently, during the course of each twelve hours, the same number of strokes of the bell will necessarily be used to denote three different hours or periods of time, as follows: