NEW FORM OF INTERMITTENT LIGHT
One advantage of the method that I propose is this, that
while we are able to produce a plain intermittent light; an
intermittent light of variable period, ranging from a brief
flash to a steady illumination of half the revolution ; and
finally, a light combining the immediate occultation of the
intermittent with combination and change of colour, we can
yet preserve comparative lightness in the revolving parts, and
consequent economy in the driving machinery. It must, how-
Fig. 5.
ever, be noticed, that none of these last methods are applicable
to cases where more than one radiant is employed : for these
cases, either my grandfathers or Mr. Wilson's contrivance
must be resorted to.
1871.
12