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Composite Portraiture
now be effected by means of the three converging magic-lanterns and the result may be
accepted as generic in respect of this particular type of criminals.
The process of composite portraiture is one of pictorial statistics. It is a familiar fact
that the average height of even a dozen men of the same race, taken at hazard, varies so
little, that for ordinary statistical purposes it may be considered constant. The same may be
said of the measurement of every separate feature and limb, and of every tint, whether of
skin, hair, or eyes. Consequently a pictorial combination of any one of these separate traits
would lead to results no less constant than the statistical averages. In a portrait, there is
another factor to be considered besides the measurement of the separate traits, namely,
their relative position; but this, too, in a sufficiently large group, would necessarily have a
statistical constancy. As a matter of observation, the resemblance between persons of the
same “genus” (in the sense of “generic,” as already explained) is sufficiently great to
admit of making good pictorial composites out of even small groups, as has been
abundantly shown.
Composite pictures, are, however, much more than averages; they are rather the
equivalents of those large statistical tables whose totals, divided by the number of cases,
and entered in the bottom line, are the averages. They are real generalisations, because
they include the whole of the material under consideration. The blur of their outlines,
which is never great in truly generic composites, except in unimportant details, measures
the tendency of individuals to deviate from the central type. My argument is, that the
generic images that arise before the mind’s eye, and the general impressions which are
faint and faulty editions of them, are the analogues of these composite pictures which we
have the advantage of examining at leisure, and whose peculiarities and character we can
investigate, and from which we may draw conclusions that shall throw much light on the
nature of certain mental processes which are too mobile and evanescent to be directly dealt
[Read before the Photographic Society, 24th June, 1881.]
I propose to draw attention to-night to the results of recent experiments and
considerable improvements in a process of which I published the principles three years
ago, and which I have subsequently exhibited more than once.
I have shown that, if we have the portraits of two or more different persons, taken in
the same aspect and under the same Previous page Top Next page