Must be a hexagon vertical wheel, fourteen inches diameter; on one
side of the block, whose diameter is two inches and a quarter, is
fixed a tin barrel A, see fig. 53, Nᵒ. 1; this barrel must be a little
less in diameter than the nave; let the length of the barrel and block
be six inches. Having fixed the cases on the wheel, carry a leader
from the tail of the last case into the tin barrel through a hole made
on purpose two inches from the block; at the end of this leader let
there be about an inch or two of loose match, but take care to well
secure the hole wherein the pipe is put, to prevent any sparks falling
in, which would light the second mutation before its time, and confuse
the whole piece.