Plate CCCCLXXIV. Fig. 32 This is not so much calculated to stand alone as to form a part of some other general design The spiral columns carry the sort of illuminated globes formerly described ; and they may be extended to more. When pairs of spiral columns are made to revolve in this way, it has a better effect if the direction of their motions are reversed. This piece is particularly adapted for mutations, but we need not encumber our figure with them.
Fig. 33. This represents another variety of architec ture, in which the forms of trees are combined with those of a building The simplest idea is here repre sented, but it may be multiplied and varied with great ease. The cases which are to form the branches of the palm tree should not be lighted till the end, so that it will first represent a piece of simple architecture.
Plate CCCCLXXV. Fig. 28. This is another speci men in an oriental style, of which the very simplest idea alone is given. It requires no other explanation than such as have been given for the preceding ones.
Plate CCCCLXXV Fig. 29. This is intended to represent a Chinese pagoda, but is only applicable to works on a very large scale. The whole of the archi tectural lines must. be defined by rows of lights ; and the bells which ornament the extremities of the interme diate roofs must consist of large ones. Wheels of diminishing sizes upwards may be introduced into the several stories. It may also terminate by discharges of brilliant fire from various parts of the building, and very t-ariveniently by sky rockets ; but we have not thought it neccQsary to crowd the figure with these.
Plate CLCCLXXV. Fig. 30. This is intended to represent the mode in which a light colonnade may be managed ; but we need not describe the variety of fire and ornaments which it admits, as our intention has only been to give a general notice of the nature of the design. lights should appear to hang upon lines, so as to form the catenarian curves. But, as this cannot actually be done upon real lines, on account of their unsteadi ness, these curves should be drawn upon the frames; which is easily done by following with a bit of chalk the line which a heavy rope makes upon them when sus pended in the proper places.
Plate CCCCLXXIII. Fig. 25. This is a complicated figure with wheels, intended to act as a mutation piece. The lights are succeeded by the wheels, and these by the diverging cases. It requires a great deal of room ;
and the wheels on the stem should be small, that they may not interfere too much with the illuminations.
Plate CCCCLXXIII. Fig. 26. This is a combina don of wheels with stars and brilliant cases, which is also intended to show three changes. The stars are first lighted, then the wheels, and lastly the cases. On one of the arms, which is prolonged for that purpose, lights are placed, by adopting which plan a distinct lire wo.dc is produced ; and it this be used, all the lights and stars must be fired at the same time ; and the others as before, in succession.
Plate CCCCLXXIII. Fig. 27. This -is intended to represent one of numerous modes that might have been given, of forming a single mutable column, which may conveniently be exhibited alone, or may form a centre kr other smaller uorks. All the lines of the pillar, the capital, and the pedestal, are formed by lights; and two large lights, with an intermediate star or not, may be used for the volutes of the capital. In this way the pillar is first lighted. The first mutation consists in lighting a wheel upon the pedestal, and the last in firing the fixed cases on its angles. and the fountain upon its summit.
Plate CCCCLXXIII. Fig 28. We shall terminate this section,•hich might have been indefinitely prolong ed, by a plan for a simple colonnade, which also per forms three mutations. It explains itself without assist ance. The lights are succeeded by the wheels, and these by the cases at the summit ; and single cases are here used for the purpose of producing a piece of light appearance. In all these mutations, care must be taken that the lights may continue till c% ery thing else is burnt out. These are, of course, measured to burn the whole wheel, and somewhat more ; while the light ing of the last case of the wheel gives the signal to the artist to apply the fire to the last mutation, for which there must be always a separate leader. The wheels are lighted from a hole made in some case of light, which is near at hand ; the time of which has been pre viously so calculated that all which remains unburut from that point may exactly equal the whole wheel in duration. Thus the artist will have nci further trouble during the burning than to watch the time when the last case of the wheel takes fire.