This device for making exposures in the photographic studio has
proved to be so useful and popular as to have secured almost general
recognition and adoption among the photographers of America.
The possibility of making exposures in the studio, unknown to the
subject, placed a very decided advantage in the hands of the
operator, who, standing at any point, could watch the expression of
the subject and seize the right moment to secure the impression
desired; so that the pneumatic shutter seemed to be the proper
complement to the lightning dry plate.
There is a great variety of these shutters exhibited and for sale,
and the number continually increases.
The earliest example of this style of shutter that we know of is the
Cadett, an English invention, which, in its introduction into this
country, served as a stimulus to the inventive genius of Americans,
and, as a consequence, we have the great variety that now may be
selected from. An effort was made to apply electricity to use in
working a shutter, but it did not succeed, and so the rubber tube
and bulb became the accepted means for applying the force necessary
to open and shut the slides or doors constituting the shutter.
An attempt has been made to apply a time regulator to the pneumatic
exposer that shall keep the lens uncovered for a period of time at
the will of the operator, which shall be regulated by an index
pointing at a figure representing a definite period of time. By
turning the index to any figure, from 1 to 20 or more, representing
seconds, the shutter is held open for that time, and then closes
automatically. This shutter is opened, in the first instance, by
pressure upon a bulb, [p125] in the same manner as any of the
pneumatic devices. We may enumerate, among the various shutters,
those giving the most satisfaction in use,