Vertical Scroll Wheel.
15. Vertical Scroll Wheel.
A wheel of this kind may be made of any diameter. The nave may be of moderate size, and to it fix four spokes at right angles to each other, and united to the fell or circumference; round the latter you are to fix any number of port-fires: on the front of the spokes form, with some strong iron wire, a scroll or volute, in dimensions proportionate to the wheel, beginning at the centre; on this scroll tie cases of brilliant fire, which should not be too large, and placed head to tail, as in other similar arrangements. The case nearest the circumference must be fired first, which being farthest from the centre has most power to set the wheel in motion. The port-fires may be before, at the same time, or after the scroll.
This wheel may be wrought into one far more ornamented and complex. A double scroll might be formed on the spokes, as well as a double set of port-fires on the circumference; a pot of some kind at the centre would readily suggest itself.