be
produced by the star or by any other figure where the fire is not to
appear as proceeding from the circumference of the centre.

These two pieces, as well as those that follow, may be of any size,
provided you observe the proportion between the parts of the figure
and the spiral, which must be wider in larger figures than in small.
If the sun, for example, have from six to twelve inches diameter, the
width of the strokes that form the spiral need not be more than
one-twentieth part of an inch, and the spaces between them, that form
transparent parts, about two-tenths of an inch. If the sun be two feet
diameter, the strokes should be one-eighth of an inch, and the space
between, one quarter of an inch; and if the figure be six feet
diameter, the strokes should be one quarter of an inch and the spaces
five-twelfths of an inch. These pieces have a pleasing effect, when
represented of a small size, but the deception is more striking when
they are of large dimensions.

It will be proper to place those pieces, when of a small size, in a
box quite closed on every side, that none of the light may be diffused
in the chamber: for which purpose it will be convenient to have a tin
door behind the box, to which the candlesticks may be soldered, and
the candles more easily lighted.

The several figures cut out should be placed in frames, that they may
be put, alternately, in a groove in the forepart of the box; or there
may be two grooves, that the second piece may be put in before the
first is taken out.

The wheel must be carefully concealed from the eye of the spectator.

Where there is an opportunity of representing these artificial fires
by a hole in the partition, they will doubtless have a much more
striking effect, as the spectator cannot then conjecture by what means
they are produced.

It is easy to conceive that by extending this method, wheels may be
constructed with three or four spirals, to which may be given
different directions. It is manifest also that, on the same principle,
a great variety of transparent figures may be contrived, and which may
be all placed before the spiral lines.

_To represent Cascades of Fire._

In cutting out cascades, you must take care to preserve a natural
inequality in the parts cut out; for if, to save time, you should make
all the holes with the same pointed tool, the uniformity of the parts
will not fail to produce a disagreeable effect. As these cascades are
very pleasi