In a series of arches, or an arcade, the spandrils may also be marked by a pointed star, (Fig.11,) and the same ornament may generally be freely used throughout pieces of architecture, as it does not interfere with the general designs.
Columns of any order are defined by lines in their margin, (Fig. 13,)and capitals of a fanciful kind are easily formed for them, by means of stars and lines of lights. A sort of excuse for the Ionic volutes may be produced by two larger lights. To represent twisted columns is extremely easy, and these are very ornamental,(Fig. 14,) and if the building is extensive, windows and doors may be defined in the same manner.
The necessary tranquillity of architecture does not admit of the introduction of sparkling fires, except in the form of mutations or additional parts. But in this way gerbes and Roman candles may be introduced on the tops of buildings, with feathers, stars, wheels, Ste. Wheels may also be introduced on the faces of the building, taking care to place them in such positions, and to make them of such sizes, that they may coincide with the general architectural design, without which their effects are unpleasing, instead of being ornamental. They may, for example, represent marigold windows. \V here gerbes are introduced, they stand with most effect on the summits of columns, or on Gothic pin nacles; and in single pinnacles or steeples, rows of brilliant fire may also be introduced with good effect in the place of the crockets ; as triple combinations on a small scale may be adopteel to represent finials. But on this subject it is endless to dwell, as the artist must, after all, be guided by the draughtsman, who will dis pose of his ornaments for him on proper principles, and without whose assistance it is in vain to attempt works of this nature.
Of 21ILVeable These also admit of great variety ; but we must, for the same reasons, be satisfied with describing a few. In general, it is a good rule that whatever motions they arc to receive should be given by means of wheels; but, as we formerly remarked in our observations on machinery, this is sometimes not possible, owing to their great weight and complication. Proper machinery
must then he adopted ; yet there should always be wheels attached, that the firework may at least have the credit, in the spectator's eyes, of being able to produce its own motions.
One of the most common and pleasing of these is a ,spiral cone. (Plate CCCCLXXI1I, Figs. 29, 30 ) The frame for this is attached to a horizontal wheel revolving freely on its centre, and is provided with a spiral line. to which the lights arc fixed at a short distance. It may be of any dimension which the artist chooses; but a height of four feet, with an angle of about thirty de grees for the cone, forms a very convenient figure. The horizontal wheel below is driven by horizontal brilliant fires, or by oblique ones, in any of the modes formerly mentioned when treating of horizontal wheels. Some times the cone is terminated by a star, or by a single gerbe. The figure of an inverted cone is not pleasing, nor is that of a double one; but both may be used in large displays where variety is required.
A cylinder may also be constructed in a similar man ner, and this may be very agreeably varied, by attaching a horizontal wheel both above and below, (Figs. 32,) by which means also some additional revolving lorce is gained. Cylinders, revolving in this manner, may form a very beautiful firework alone, if on the upper part there is fixed a fountain of fire, so as to spread over on all sides.
In all these figures, which have lights spirally dis posed, and which revolve at the same time, the effect produced is that of a screw in motion, and hen e they arc applicable to architecture, or in other combinations, in a variety of ways. They may also be made to re volve hotizontally ; and, for this purpose, two wheels must be attached to the ends of a cylinder. Thus, However, the particular effect of the wheel is lost to the spectators, otherwise titan as they will represent a stream of fire at each end directed towards them. Such a firework may, however, be rendered beautiful, by add ing to it sonic fixed cases that may throw their fires upwards, so as to intersect above in the manner of a Gothic arch.