Or, take one-third of the grain of fulminating silver; fold it up in a small piece of paper, and wrap it up in another piece, and paste it round a pin. These pins stuck in the wick of a candle make a very loud noise. Fulminating silver may be also used in the following manner:--Put half a grain in a piece of glass-paper, and enclose it in a piece of foil; put it then at the bottom or side of a drawer, and on opening or shutting it, it will immediately go off. Put a quarter of a grain of fulminating silver into a piece of paper, and place in the snuffers when quite cold; when the candle is snuffed, it will go off. AQUATIC FIRE-WORKS. Works that sport in the water are much esteemed by most admirers of fire-works, particularly water-rockets; and as they seem of a very extraordinary nature to those who are unacquainted with this art, they merit a particular explanation. _Water-Rockets._ They may be made from four ounces to two pounds. If larger, they are too heavy; so that it will be difficult to make them keep above water without a cork float, which must be tied to the neck of the case; but the rockets will not dive so well with as without floats. Cases for these are made in the same manner and proportion as sky-rockets, only a little thicker of paper. When you fill those which are driven solid, put in first one ladleful of slow fire, then two of the proper charge, and on that one or two ladles of sinking charge, then the proper charge, then the sinking charge again, and so on, till you have filled the case within three diameters; then drive on the composition one ladleful of clay; through which make a small hole to the charge; then fill the case, within half a diameter, with corn-powder, on which turn down two or three rounds of the case in the inside; then pinch and tie the end very tight; having filled the rockets, (according to the above directions,) dip their ends in melted resin or sealing-wax, or else secure them well with grease. When you fire those rockets, throw in six or eight at a time; but, if you would have them all sink, or swim, at the same time, you must fill them with an equal quantity of composition, and fire them together. _Pipes of Communication for Water._ They may be used under water, but must be a little thicker in the paper than those for land. Having rolled a sufficient number of pipes, and kept them till dry, wash them over with drying oil, and set them to dry; but when you oil them, leave about an inch and a half at each end dry, for joints; as, if they were oiled all over, when you come to join them, the paste will not stick where the paper is greasy: after the leaders are joined, and the paste dry, oil the joints. These pipes will lie many hours under water, without receiving any damage. _Horizontal Water-Wheels._