humanfaculty4 - page 255 of 305

Composite Portraiture

the common family traits are clearly marked. Ghosts of portions of male and female attire,

due to the peculiarities of the separate portraits, are seen about and around the composite,

but they are not sufficiently vivid to distract the attention. If the number of combined

portraits had been large, these ghostly accessories would have become too faint to be

The next step is to compare this portrait of two brothers and their sister which has been

composed by optical means before the eyes of the audience, and concerning the

truthfulness of which there can be no doubt, with a photographic composite of the same

group. The latter is now placed in a fourth magic-lantern with a brighter light behind it,

and its image is thrown on the screen by the side of the composite produced by direct

optical superposition. It will be observed that the two processes lead to almost exactly the

same result, and therefore the fairness of the photographic process may be taken for

granted. However, two other comparisons will be made for the sake of verification,

namely, between the optical and photographic composites of two children, and again

between those of two Roman contadini.

The composite portraits that will next be exhibited are made by the photographic

process, and it will now be understood that they are truly composite, notwithstanding their

definition and apparent individuality. Attention is, however, first directed to a convenient

instrument not more than 18 inches in length, which is, in fact, a photographic camera with

six converging lenses and an attached screen, on which six pictures can be adjusted and

brilliantly illuminated by artificial light. The effect of their optical combination can thus be

easily studied; any errors of adjustment can be rectified, and the composite may be

photographed at once.

It must not be supposed that any one of the components fails to leave its due trace in

the photographic composite, much less in the optical one. In order to allay misgivings on

the subject, a small apparatus is laid on the table together with some of the results obtained

by it. It is a cardboard frame, with a spring shutter closing an aperture of the size of a

wafer, that springs open on the pressure of a finger, and shuts again as suddenly when the

pressure is withdrawn. A chronograph is held in the other hand, whose index begins to

travel the moment the finger presses a spring, and stops instantly on lifting the finger. The

two instruments are worked simultaneously; the chronograph checking the time allowed

for each exposure and summing all the times. It appears from several trials that the effect

of 1000 brief exposures is practically identical with that of a single exposure of 1000 times

the duration of any one of them. Therefore each of a thousand components leaves its due