[CHAPTER XI.]
Fire-works, which are exhibited on water, have a very pleasing effect. Water rockets, in particular, are much admired.
Sec. I. Of Water Rockets.
Water rockets are generally small, from four ounces to two pounds. When large, they are difficult to be kept above water without a cork float. When this is used, it is tied to the neck of the case. They will not dive as well with as without floats.
The cases for water rockets are made in the same proportion as for sky-rockets, but the paper is thicker. For those which are driven solid, put in at first a ladle full of slow-fire, and 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 the case is filled within three diameters. Then drive on the composition one ladleful of clay, through which make a small hole to the charge. 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 thus filled the rockets, dip their ends in melted rosin or sealing wax, or secure them with grease. When they are fired, six or eight may be thrown in at once; but if they are all to swim or sink at the same time, they must all have an equal quantity of composition and be fired together.
In the rockets which burn in the water, there must be a considerable variation in the construction of the mould, and also in the materials of which they are composed. The composition should consist of three materials mixed together, viz. three ounces of meal-powder, one pound of saltpetre, and eight ounces of sulphur. If the rocket is to appear on the water with a beautiful tail, the composition must consist of eight ounces of gunpowder, one pound of saltpetre, eight ounces of sulphur, and two ounces of charcoal. When the composition has been prepared according to these proportions, and the rocket been filled, apply a saucisson to the end of it, and having covered the rocket with wax, pitch, &c. as before mentioned, attach it to a small rod of white willow, about two feet in length, that the rocket may conveniently float. Cork may be used, as we observed, for the same purpose. A certain quantity of meal-powder, without any mixture, put at certain distances, must be used, if it is required that these rockets should plunge down and again rise up.
Sec. II. Of Pipes of Communication.