evidence that man has present power to influence the quality of
future humanity, we soon discover that his past influence in that
direction has been very large indeed. It has been exerted hitherto
for other ends than that which is now contemplated, such as for
conquest or emigration, also through social conditions whose effects
upon race were imperfectly foreseen. There can be no doubt that the
hitherto unused means of his influence are also numerous and great.
I have not cared to go much into detail concerning these, but
restricted myself to a few broad considerations, as by showing how
largely the balance of population becomes affected by the earlier
marriages of some of its classes, and by pointing out the great
influence that endowments have had in checking the marriage of monks
and scholars, and therefore the yet larger influence they might be
expected to have if they were directed not to thwart but to
harmonise with natural inclination, by promoting early marriages in
the classes to be favoured. I also showed that a powerful influence
might flow from a public recognition in early life of the true value
of the probability of future performance, as based on the past
performance of the ancestors of the child. It is an element of
forecast, in addition to that of present personal merit, which has
yet to be appraised and recognised. Its recognition would attract
assistance in various ways, impossible now to specify, to the young
families of those who were most likely to stock the world with
healthy, moral, intelligent, and fair-natured citizens. The stream
of charity is not unlimited, and it is requisite for the speedier
evolution of a more perfect humanity that it should be so
distributed as to favour the best-adapted races. I have not spoken
of the repression of the rest, believing that it would ensue
indirectly as a matter of course; but I may add that few would
deserve better of their country than those who determine to live
celibate lives, through a reasonable conviction that their issue
would probably be less fitted than the generality to play their part
as citizens.
It would be easy to add to the number of possible agencies by which
the evolution of a higher humanity might be furthered, but it is
premature to do so until the importance of attending to the
improvement of our race shall have been so well established in the
popular mind that a discussion of them would be likely to receive
serious consideration.
It is hardly necessary to insist on the certainty that our present
imperfect knowledge of the limitations and conditions of hereditary
transmission will be steadily added to; but I would call attention
again to the serious want of adequate materials for study in the
form of life-histories. It is fortunately the case that many of the
rising medical practitioners of the foremost rank are become strongly
impressed with the necessity of possessing them, not only for the
better knowledge of the theory of disease, but for the personal
advantage of their patients, whom they now have to treat less
appropriately than they otherwise would, through ignorance of their
hereditary tendencies and of their illnesses in past years, the
medical details of which are rarely remembered by the patient, even
if he ever knew them. With the help of so powerful a personal motive
for keeping life-histories, and of so influential a body as the
medical profession to advocate its being done,[21] and to show how
to do it, there is considerable hope that the want of materials to
which I have alluded will gradually be supplied.
[Footnote 21: See an address on the Collective Investigation of
Disease, by Sir William Gull, _British Medical Journal_, January 27,
1883, p. 143; also the following address by Sir James Paget, p. 144.]
To sum up in a few words. The chief result of these Inquiries has
been to elicit the religious significance of the doctrine of
evolution. It suggests an alteration in our mental attitude, and
imposes a new moral duty. The new mental attitude is one of a
greater sense of moral freedom, responsibility, and opportunity; the
new duty which is supposed to be exercised concurrently with, and
not in opposition to the old ones upon which the social fabric
depends, is an endeavour to further evolution, especially that of
the human race.
APPENDIX
A.--COMPOSITE PORTRAITURE.
The object and methods of Composite Portraiture will be best
explained by the following extracts from memoirs describing its
successive stages, published in 1878, 1879, and 1881 respectively:--
I. COMPOSITE PORTRAITS, MADE BY COMBINING
THOSE OF MANY DIFFERENT PERSONS INTO A SINGLE RESULTANT FIGURE.
[_Extract from Memoir read before the Anthropological Institute,
in 1878_.]
I submit to the Anthropological Institute my first results in
carrying out a process that I suggested last August [1877] in my
presidential address to the Anthropological Subsection of the
British Association at Plymouth, in the following words:--
"Having obtained drawings or photographs of several persons alike in
most respects, but differing in minor details, what sure method is
there of extracting the typical characteristics from them? I may
mention a plan which had occurred both to Mr. Herbert Spencer and
myself, the principle of which is to superimpose optically the
various drawings, and to accept the aggregate result. Mr. Spencer
suggested to me in conversation that the drawings reduced to the
same scale might be traced on separate pieces of transparent paper
and secured one upon another, and then held between the eye and the
light. I have attempted this with some success. My own idea was to
throw faint images of the several portraits, in succession, upon the
same sensitised photographic plate. I may add that it is perfectly
easy to superimpose optically two portraits by means of a stereoscope,
and that a person who is used to handle instruments will find a
common double eyeglass fitted with stereoscopic lenses to be almost
as effectual and far handier than the boxes sold in shops."
Mr. Spencer, as he informed me, had actually devised an instrument,
many years ago, for tracing mechanically, longitudinal, transverse,
and horizontal sections of heads on transparent paper, intending to
superimpose them, and to obtain an average result by transmitted
light.
Since my address was published, I have caused trials to be made, and
have found, as a matter of fact, that the photographic process of
which I there spoke enables us to obtain with mechanical precision a
generalised picture; one that represents no man in particular, but
portrays an imaginary figure possessing the average features of any
given group of men. These ideal faces have a surprising air of
reality. Nobody who glanced at one of them for the first time would
doubt its being the likeness of a living person, yet, as I have said,
it is no such thing; it is the portrait of a type and not of an
individual.
I begin by collecting photographs of the persons with whom I propose
to deal. They must be similar in attitude and size, but no exactness
is necessary in either of these respects. Then, by a simple
contrivance, I make two pinholes in each of them, to enable me to
hang them up one in front of the other, like a pack of cards, upon
the same pair of pins, in such a way that the eyes of all the
portraits shall be as nearly as possible superimposed; in which case
the remainder of the features will also be superimposed nearly enough.
These pinholes correspond to what are technically known to printers
as "register marks." They are easily made: A slip of brass or card
has an aperture cut out of its middle, and threads are stretched
from opposite sides, making a cross.[22] Two small holes are drilled
in the plate, one on either side of the aperture. The slip of brass
is laid on the portrait with the aperture over its face. It is turned
about until one of the cross threads cuts the pupils of both the eyes,
and it is further adjusted until the other thread divides the
interval between the pupils in two equal parts. Then it is held
firmly, and a prick is made through each of the holes.
[Footnote 22: I am indebted for the woodcuts to the Editor of
_Nature_, in which journal this memoir first appeared.]
[Illustration: ]
The portraits being thus arranged, a photographic camera is directed
upon them. Suppose there are eight portraits in the pack, and
that under existing circumstances it would require an exposure of
eighty seconds to give an exact photographic copy of any one
of them. The general principle of proceeding is this, subject in
practice to some variations of detail, depending on the different
brightness of the several portraits. We throw the image of each of
the eight portraits in turn upon the same part of the sensitised
plate for ten seconds. Thus, portrait No. 1 is in the front of the
pack; we take the cap off the object glass of the camera for ten
seconds, and afterwards replace it. We then remove No. 1 from the
pins, and No. 2 appears in the front; we take off the cap a second
time for ten seconds, and again replace it. Next we remove No. 2,
and No. 3 appears in the front, which we treat as its predecessors,
and so we go on to the last of the pack. The sensitised plate will
now have had its total exposure of eighty seconds; it is then
developed, and the print taken from it is the generalised picture of
which I speak. It is a composite of eight component portraits. Those
of its outlines are sharpest and darkest that are common to the
largest number of the components; the purely individual
peculiarities leave little or no visible trace. The latter being
necessarily disposed equally on both sides of the average, the
outline of the composite is the average of all the components. It is
a band and not a fine line, because the outlines of the components
are seldom exactly superimposed. The band will be darkest in its
middle whenever the component portraits have the same general type
of features, and its breadth, or amount of blur, will measure the
tendency of the components to deviate from the common type. This is
so for the very same reason that the shot-marks on a target are more
thickly disposed near the bull's-eye than away from it, and in a
greater degree as the marksmen are more skilful. All that has been
said of the outlines is equally true as regards the shadows; the
result being that the composite represents an averaged figure, whose
lineaments have been softly drawn. The eyes come out with
appropriate distinctness, owing to the mechanical conditions under
which the components are hung.
[Illustration: ]
A composite portrait represents the picture that would rise before
the mind's eye of a man who had the gift of pictorial imagination in
an exalted degree. But the imaginative power even of the highest
artists is far from precise, and is so apt to be biassed by special
cases that may have struck their fancies, that no two artists agree
in any of their typical forms. The merit of the photographic
composite is its mechanical precision, being subject to no errors
beyond those incidental to all photographic productions.
I submit several composites made for me by Mr. H. Reynolds. The
first set of portraits are those of criminals convicted of murder,
manslaughter, or robbery accompanied with violence. It will be
observed that the features of the composites are much better looking
than those of the components. The special villainous irregularities
in the latter have disappeared, and the common humanity that
underlies them has prevailed. They represent, not the criminal, but
the man who is liable to fall into crime. All composites are better
looking than their components, because the averaged portrait of many
persons is free from the irregularities that variously blemish the
looks of each of them.
I selected these for my first trials because I happened to possess a
large collection of photographs of criminals, through the kindness
of Sir Edmund Du Cane, the Director-General of Prisons, for the
purpose of investigating criminal types. They were peculiarly
adapted to my present purpose, being all made of about the same size,
and taken in much the same attitudes. It was while endeavouring to
elicit the principal criminal types by methods of optical
superimposition of the portraits, such as I had frequently employed
with maps and meteorological traces,[23] that the idea of composite
figures first occurred to me.
[Footnote 23: _Conference at the Loan Exhibition of Scientific
Instruments_, 1878. Chapman and Hall. Physical Geography Section, p.
312, _On Means of Combining Various Data in Maps and Diagrams_, by
Francis Galton, F.R.S.]
The other set of composites are made from pairs of components. They
are selected to show the extraordinary facility of combining almost
any two faces whose proportions are in any way similar.
It will, I am sure, surprise most persons to see how well defined
these composites are. When we deal with faces of the same type, the
points of similarity far outnumber those of dissimilarity, and there
is a much greater resemblance between faces generally than we who
turn our attention to individual differences are apt to appreciate.
A traveller on his first arrival among people of a race very
different to his own thinks them closely alike, and a Hindu has much
difficulty in distinguishing one Englishman from another.
The fairness with which photographic composites represent their
components is shown by six of the specimens. I wished to learn
whether the order in which the components were photographed made any
material difference in the result, so I had three of the portraits
arranged successively in each of their six possible combinations. It
will be observed that four at least of the six composites are
closely alike. I should say that in each of this set (which was made
by the wet process) the last of the three components was always
allowed a longer exposure than the second, and the second than the
first, but it is found better to allow an equal time to all of them.
[Illustration: The accompanying woodcut is as fair a representation
of one of the composites as is practicable in ordinary printing. It
was photographically transferred to the wood, and the engraver has
used his best endeavour to translate the shades into line engraving.
This composite is made out of only three components, and its
threefold origin is to be traced in the ears, and in the buttons to
the vest. To the best of my judgment, the original photograph is a
very exact average of its components; not one feature in it appears
identical with that of any one of them, but it contains a
resemblance to all, and is not more like to one of them than to
another. However, the judgment of the wood engraver is different.
His rendering of the composite has made it exactly like one of its
components, which it must be borne in mind he had never seen. It is
just as though an artist drawing a child had produced a portrait
closely resembling its deceased father, having overlooked an equally
strong likeness to its deceased mother, which was apparent to its
relatives. This is to me a most striking proof that the composite is
a true combination.]
The stereoscope, as I stated last August in my address at Plymouth,
affords a very easy method of optically superimposing two portraits,
and I have much pleasure in quoting the following letter, pointing
out this fact as well as some other conclusions to which I also had
arrived. The letter was kindly forwarded to me by Mr. Darwin; it is
dated last November, and was written to him by Mr. A.L. Austin, from
New Zealand, thus affording another of the many curious instances of
two persons being independently engaged in the same novel inquiry at
nearly the same time, and coming to similar results:--
INVERCARGILL, NEW ZEALAND,
_November 6th_, 1877.
To CHARLES DARWIN, Esq.
SIR,--Although a perfect stranger to you, and living on the reverse
side of the globe, I have taken the liberty of writing to you on a
small discovery I have made in binocular vision in the stereoscope.
I find by taking two ordinary carre-de-visite photos of two
different persons' faces, the portraits being about the same sizes,
and looking about the same direction, and placing them in a
stereoscope, the faces blend into one in a most remarkable manner,
producing in the case of some ladies' portraits, in every instance,
a _decided improvement_ in beauty. The pictures were not taken in a
binocular camera, and therefore do not stand out well, but by moving
one or both until the eyes coincide in the stereoscope the pictures
blend perfectly. If taken in a binocular camera for the purpose,
each person being taken on one half of the negative, I am sure the
results would be still more striking. Perhaps something might be
made of this in regard to the expression of emotions in man and the
lower animals, &c. I have not time or opportunities to make
experiments, but it seems to me something might be made of this by
photographing the faces of different animals, different races of
mankind, &c. I think a stereoscopic view of one of the ape tribe and
some low-caste human face would make a very curious mixture; also in
the matter of crossing of animals and the resulting offspring. It
seems to me something also might result in photos of husband and
wife and children, &c. In any case, the results are curious, if it
leads to nothing else. Should this come to anything you will no
doubt acknowledge myself as suggesting the experiment, and perhaps
send me some of the results. If not likely to come to anything, a
reply would much oblige me.
Yours very truly,
A.L. AUSTIN, C.E., F.R.A.S.
Dr. Carpenter informs me that the late Mr. Appold, the mechanician,
used to combine two portraits of himself under the stereoscope. The
one had been taken with an assumed stern expression, the other with
a smile, and this combination produced a curious and effective
blending of the two.
Convenient as the stereoscope is, owing to its accessibility, for
determining whether any two portraits are suitable in size and
attitude to form a good composite, it is nevertheless a makeshift
and imperfect way of attaining the required result. It cannot of
itself combine two images; it can only place them so that the office
of attempting to combine them may be undertaken by the brain. Now
the two separate impressions received by the brain through the
stereoscope do not seem to me to be relatively constant in their
vividness, but sometimes the image seen by the left eye prevails
over that seen by the right, and _vice versâ_. All the other
instruments I am about to describe accomplish that which the
stereoscope fails to do; they create true optical combinations. As
regards other points in Mr. Austin's letter, I cannot think that the
use of a binocular camera for taking the two portraits intended to
be combined into one by the stereoscope would be of importance. All
that is wanted is that the portraits should be nearly of the same
size. In every other respect I cordially agree with Mr. Austin.
The best instrument I have as yet contrived and used for optical
superimposition is a "double-image prism" of Iceland spar (see Fig.,
p. 228), formerly procured for me by the late Mr. Tisley, optician,
Brompton Road. They have a clear aperture of a square, half an inch
in the side, and when held at right angles to the line of sight will
separate the ordinary and extraordinary images to the amount of two
inches, when the object viewed is held at seventeen inches from the
eye. This is quite sufficient for working with carte-de-visite
portraits. One image is quite achromatic, the other shows a little
colour. The divergence may be varied and adjusted by inclining the
prism to the line of sight. By its means the ordinary image of one
component is thrown upon the extraordinary image of the other, and
the composite may be viewed by the naked eye, or through a lens of
long focus, or through an opera-glass (a telescope is not so good)
fitted with a sufficiently long draw-tube to see an object at that
short distance with distinctness. Portraits of somewhat different
sizes may be combined by placing the larger one farther from the eye,
and a long face may be fitted to a short one by inclining and
foreshortening the former. The slight fault of focus thereby
occasioned produces little or no sensible ill effect on the
appearance of the composite.
The front, or the profile, faces of two living persons sitting side
by side or one behind the other, can be easily superimposed by a
double-image prism. Two such prisms set one behind the other can be
made to give four images of equal brightness, occupying the four
corners of a rhombus whose acute angles are 45°. Three prisms will
give eight images, but this is practically not a good combination;
the images fail in distinctness, and are too near together for use.
Again, each lens of a stereoscope of long focus can have one or a
pair of these prisms attached to it, and four or eight images may be
thus combined.
[Illustration: Fig. 1 shows the simple apparatus which carries the
prism and on which the photograph is mounted. The former is set in a
round box which can be rotated in the ring at the end of the arm and
can be clamped when adjusted. The arm can be rotated and can also be
pulled out or in if desired, and clamped. The floor of the
instrument is overlaid with cork covered with black cloth, on which
the components can easily be fixed by drawing-pins. When using it,
one portrait is pinned down and the other is moved near to it,
overlapping its margin if necessary, until the eye looking through
the prism sees the required combination; then the second portrait is
pinned down also. It may now receive its register-marks from needles
fixed in a hinged arm, and this is a more generally applicable
method than the plan with cross threads, already described, as any
desired feature--the nose, the ear, or the hand, may thus be
selected for composite purposes. Let A, B, C, ... Y, Z, be the
components. A is pinned down, and B, C, ... Y, Z, are successfully
combined with A, and registered. Then before removing Z, take away A
and substitute any other of the already registered portraits, say B,
by combining it with Z; lastly, remove Z and substitute A by
combining it with B, and register it. Fig. 2 shows one of three
similarly jointed arms, which clamp on to the vertical covered with
cork and cloth, and the other carries Fig. 3, which is a frame
having lenses of different powers set into it, and on which, or on
the third frame, a small mirror inclined at 45º may be laid. When a
portrait requires foreshortening it can be pinned on one of these
frames and be inclined to the line of sight; when it is smaller than
its fellow it can be brought nearer to the eye and an appropriate
lens interposed; when a right-sided profile has to be combined with a
left-handed one, it must be pinned on one of the frames and viewed by
reflection from the mirror in the other. The apparatus I have drawn
is roughly made, and being chiefly of wood is rather clumsy, but it
acts well.]
Another instrument I have made consists of a piece of glass inclined
at a very acute angle to the line of sight, and of a mirror beyond it,
also inclined, but in the opposite direction to the line of sight.
Two rays of light will therefore reach the eye from each point of
the glass; the one has been reflected from its surface, and the
other has been first reflected from the mirror, and then transmitted
through the glass. The glass used should be extremely thin, to avoid
the blur due to double reflections; it may be a selected piece from
those made to cover microscopic specimens. The principle of the
instrument may be yet further developed by interposing additional
pieces of glass, successively less inclined to the line of sight,
and each reflecting a different portrait.
I have tried many other plans; indeed the possible methods of
optically superimposing two or more images are very numerous. Thus I
have used a sextant (with its telescope attached); also strips of
mirrors placed at different angles, their several reflections being
simultaneously viewed through a telescope. I have also used a
divided lens, like two stereoscopic lenses brought close together,
in front of the object glass of a telescope.
II. GENERIC IMAGES.
[_Extract from Proceedings Royal Institution, 25th April 1879_]
Our general impressions are founded upon blended memories, and these
latter will be the chief topic of the present discourse. An analogy
will be pointed out between these and the blended portraits first
described by myself a year ago under the name of "Composite Portraits,"
and specimens of the latter will be exhibited.