The Yew Tree.
We use this name, and describe this firework, be cause it is mentioned in all the books on this subject. It is extremely simple to construct, (Fig. 22,) nor is there any thing very particular in its effect. It consists mere ly of a number of cases or gerbes, arranged in succes sive stages ; and in an alternate order, in the form of a pyramid, and the effect of it is easily understood. It admits of being varied with advantage, by placing rows of single lights along the supports of the cases, or by adding a pointed star to the bottom of each case.
The Palm anti the Cy/tress Tree.
This is a very wily of arranging cases of brilliant fire, particularly on a large srale. For this purpose, the frame must be regularly constructed with a support for each case, as the artist must not trust to Iris eye for arranging them, when the beauty of the ef fect depends upon the accuracy of the angles at which they are placed. Nineteen cases will form a regular figure of this knd, in the following manner : Let the perpendicular part of the frame work, (Fig. 23,) be divid ed into nine equal parts, at any distances which the ar tist may think proper, and which may be conveniently a fom, if the cases are to be a foot long. At the lowest point is to be fixed a horizontal bar, capable of support ing a case on each side. At the next point above, the bar must form an angle of ten degrees with the horizon, the following one twenty, the next thirty, and so on to the top ; and the same is to be done on the opposite side of the perpendicular. When the cases arc attached to these, there are of course nine on each side, exactly corresponding in their angles, together with one at the top ; and when it is fired, all these form curves succes sively radiating towards the ground. The artist may, if he pleases, crowd the cases more towards the top than the bottom ; but this must be done in a regularly diminishing manner, by a proper arrangement of the frame work, which is too easily understood to require description.
The effect of this firework may be varied by placing the cases on each side of two posts, inclined in such a manner that they may diverge at the bottom, taking care that the same angles with the perpendicular be nevertheless preserved. In both ways lights, either
single or in the form of stars, may he introduced along the perpendicular, or at the bottom.
This tree may also be doubled, in which case, like the double cascade, it must be exhibited at a consider able elevation. For this purpose, the same operations are repeated below the horizontal cases as above, as may easily be understood. Further, it is varied by making the upper cases, (Fig. 24,) at wide angles upwards, and the lower in small ones successively diminishing and looking downwards, when it is properly the palm tree.
Checkered Fires.
These have also a very brilliant effect, and that in proportion to their numbers and complication.
To produce a simple checkered fire, two perpendi cular posts may be placed at a proper distance, such as three or four feet, for one foot cases, and on these are to be placed as many cases as the artist may choose, in angles of from 40 to 60 degrees, with their mouth open ed, and upwards. Thus, when lighted, the fires inter sect each other so as to produce a network, the nature of which may be varied by altering the angles of the cases, or by placing them at greater or less distances from each other. This is also called a double tree A reticulating fire may also be produced in a differ ent manner, by placing a number of cases in a radiating form upwards, on a horizontal bar, and opposing them to the same number radiating downwards from a bar above.
Such fires as this admit of being multiplied with great effect Thus, instead of two perpendicular or two horizontal bars, there may be four or more, and thus an immense mass of net work may be produced.
But, in these attempts, care must be taken that all the bars are at a sufficient distance, to prevent the several fires from confusing each other. This is a point which the artist must regulate according to his cases ; it being easy; by burning one, to ascertain precisely how far it throws its stream of fie.