As this firework is transitory, its effect may be im proved and prolonged in various ways. We shall de scribe a few of these. Many. Roman candles may be fired together, in a vertical direction ; but, to produce a good effect from this method, all that are to burn at once must be so far different in the proportional dis tances of the stars in their composition, that there may always be a star or two in the air; a matter easily ac complished. Many may be made to fire at the same time in a different way, so as to produce a pleasing of feet. In this way a number are arranged above each other on an upright post, at an angle of 50 or 60 de grees, and a similar number is placed in the same way on a post at some distance, so that the orifices are op posed to each other. Thus, when they are all lighted at once, as they must be by a single leader, they ap pear to carry on an engagement, throwing stars at each other, which, thus crossing. form beautiful curves in the air. In these contrivances also, the disposition of the stars should be dissimilar in the different cases, that there may be always a few stars in the air at the same time We beg to caution pyrotcchnists against suffer ing their stars to tall among the spectators, as they pe netrate like musket balls, and as we Julie seen an in stance of death from this accident.
As the Roman candle is not durable, and as it may be often desirable to keep up this kind of fire for a long time, this may be done indefinitely, even for a whole night were it required, by means of a succession of them placed together. For this purpose they must be connected in succession by leaders from the end of one to the beginning of another, taking care that these may be so well secured that no accidental fire from one may dischin ge any of the chain out of its turn.
Single Roman candles may also be varied in other ways, independently of their combinations, with wheels or complicated pieces. Thus, they may be caused to discharge•serpents as well as stars, by attaching these outside the cases, and causing them to communicate with the composition at different periods of its burn ing, by means of a very small orifice. The serpent must, in this attempt, be secured to the case by a piece of quick match, which, by burning, will allow it easily to disengage itself; and thus, by making these holes in proper places, this firework may be caused to dis charge a serpent and a star alternately. Crackers may also be attached to the sides of the cases in the same manner, so as very much to increase the effect; and it is further easy to make this more amusing by adopting the folded crackers which fly off, and continue their successions of reports after they are disengaged. Last ly, as the greatest defect of. a single Roman candle is the quiet way in which it expires it may be connected at the bottom with a separate magazine of stars or ser pents, or crackers, or all united so as to terminate in a lively and brilliant manner.
Of Water Rockets.
Many kinds of complicated fireworks may be exhi bited in the water without difficulty ; a circumstance always surprising to the populace, who imagine a ne cessity antipathy between fire and water. But we shall only here describe the simpler water rocket, as the complicated kinds will come more in a proper place hereafter.
The principle of these is exactly the same as that of the sky rocket, or rather of the line rocket, as they re quire no sticks The compositions may also be select ed in the same manner. so that we need not dwell on this part of the subject. They should be furnished with bounces or crackers at the end, as it is to no pur pose to provide star• on other ornaments, which would immcoiately be distinguished by coming into contact with tl e water. This cannot happen to the case, as the current ul air issuing from it prevents the ail from entering. But it is to no purpose to allow them to burn under the water, though they may be permitted to explode Oct e with a good eW'ct, as they only send sup smoke, and appear to the spectators to be a failure when this happens Hence they must be made just capable of floating on their sides, by means of a bit of cork or wood, it that is necessary Thus, when fired, they recoil, and as this cannot be done in a straight line owing to the unequal resistance of the water, they wander about in serpentine directions, sometimes even sinking for a short space. It may happen that they will sink, and not rise again, by sticking in the mud, which must be considered as a failure ; and as there is no advantage in this, we do not recommend the use of what is called a sinking charge.
If the water is large enough to afford room for a di rect flight, this may be produced by means of a stick. That should be flat, so that at the extremity it take a good hold of the water, and thus direct the steerage. If very long, the steerage will be so correct that it will advance in a straight line ; but an irregular line, which is perhaps more amusing, may be produced by making the stick not much longer than the rocket itself.
The simpler water rocket may be caused to perform another motion, which is also entertaining. For this purpose, it is also to be provided with a stick, so form ed, that when the wh'ile is placed in the water, the rocket may lie at an angle of from five to ten degrees. In this case its mouth will be immersed ; but that is of no moment, as a proper leader, well secured, to pre vent the entrance of the water, must be brought from it towards the upper end of the case. When this rocket is fired, it rises out of the water, and falls again repeatedly so as to perform a ricochet-movement in its flight, or what is commonly called duck and drake.