A fixed sun is an assembly of jets, charged with sparkling fire, or with Chinese fire, which are arranged about the support so as to form rays, and equipped with a fuse communicating from one to another so that all are kindled at the same time. (PL VIII, figs. 1 and 2.)
A fixed sun of one row is ordinarily composed of 12 jets. The artificer rounds a piece of wood having a suitable thick-ness, and 12 holes are pierced in the rim, after the fashion of those to receive the spokes in the hub of a wheel. The holes are provided with a thread to hold the screw end of sticks to which the jets are to be fastened. These sticks have a length two-thirds that of the jets. A groove is made along each, in which the jet lies, being tied to the stick at two points. A touch of glue to the knot on each string prevents its loosening. (PL VIII, fig. 2.)
After the sticks with the jets attached have been screwed in position on the hub, a port fire is laid circularly over the end of the jets, so that it. is in contact with the throat of each, which has already been primed. The port fire is then opened with scissors at the point of contact, in such a manner that the inclosed match touches directly on the throat, where it is fastened by means of two threads, which are knotted into the choke and tied crosswise over the port fire. A strip of paper is then pasted over each one of these points of communication.
The center of the rounded wood support, or hub, is also pierced with a screw hole, in order to fasten it to a wooden rod, which is to hold it in a vertical position. Sometimes the hole is made square, and the piece of wood has a corresponding form, when a key-pin is used for fastening. A small sun is commonly used to garnish with fire the space from the center of the hub to the throat of the jets. This is oftenest charged with white fire. The sun should carry three jets of good size, such that they will increase the effect of the display, yet will go out quickly, so that their flames shall by no means continue longer than the burning of the fixed sun.
Suns are also constructed with spiral parallel rows of jets. For placing a second row, it is necessary to tie a light wooden hoop on the jets of the first row in the middle of their length, to which the new jets are fastened. Likewise, a third row of jets is mounted by attaching them to a circular hoop placed midway in the length of the second row of jets; and so on to any desired extent. All the additional jets are supplied with port fires as were those of the first row, and the communication reaches from one row to another, so that all take fire at the same time. (PL IX, fig. 11.)
It is a common practice to charge the jets with two sorts of fire; the first half of Chinese fire and the second half of sparkling fire. Such variation increases the beauty of the sun's effect.