APPLICATION OF THE STEREOSCOPE TO EDUCATIONAL PURPOSES.
The observations contained in the preceding chapters prepare us for
appreciating the value of the stereoscope as an indispensable auxiliary
in elementary as well as in professional education. When the scholar
has learned to read, to write, and to count, he has obtained only the
tools of instruction. To acquire a general knowledge of the works of
God and of man—of things common and uncommon—of the miracles of nature
and of art, is the first step in the education of the people. Without
such knowledge, the humblest of our race is unfit for any place in the
social scale. He may have learned to read his Bible, and he may have
read it after he had learned to read;—he may have committed to memory
every sentence in the Decalogue;—he may have packed into the storehouse
of his brain all the wisdom of Solomon, and all the divine precepts
of a greater than Solomon, while he is utterly ignorant of everything
above him, around him, and within him,—ignorant, too, of the form, the
magnitude, and the motions of his terrestrial home,—ignorant of the
gigantic structures which constitute the material universe,—ignorant of
the fabrics which industry prepares for his use, and of the luxuries
which commerce brings from the ends of the earth and places at his
door,—ignorant even of the wonderful operations of that beneficent
commissariat, which is every moment, while he sleeps and dreams,
elaborating the materials by which he is fed and clothed.
Were we to say, though we do not say it, that in our own country the
teachers, so penuriously endowed by the State, are not much in advance
of their pupils, we should err only in stating what is not universally
true; and yet there are men of influence and character insisting upon
the imposition of sectarian tests, and thus barricading our schools
against the admission of the wisest and the fittest masters! And while
every civilized community in the world is eagerly teaching their
people, irrespective of religious creeds, the same bigots, civil and
ecclesiastical, in our own country, have combined to resist the only
system of education which can stem the tide of vice and crime which is
desolating the land.
Missionary labour and reformatory institutions, valuable as they are,
presuppose an educated community. To instruct and reform a race that
can neither read their Bible nor derive knowledge from books, is a
task beyond human achievement. The dearest interests of society,
therefore, call loudly for _Secular Education_,—the greatest boon which
philanthropy ever demanded from the State. The minister who, in the
face of sectarian factions, dares not identify himself with a large
legislative measure for the education of the people, and resigns office
when he fails to carry it, prefers power to duty, and, if he ever
possessed it, divests himself of the character of a statesman and a
patriot. He may be justified in punishing the law-breaker who cannot
read his statutes, but he is himself the breaker of laws of a higher
order, and sanctioned by a higher tribunal.
If the education of the people is to be attempted either by partial or
comprehensive legislation, the existing system is utterly inefficient.
The teacher, however wisely chosen and well qualified, has not at his
command the means of imparting knowledge. He may pour it in by the
ear, or extract it from the printed page, or exhibit it in caricature
in the miserable embellishments of the school-book, but unless he
teaches through the eye, the great instrument of knowledge, by means
of truthful pictures, or instruments, or models, or by the direct
exhibition of the products of nature and of art, which can be submitted
to the scrutiny of the senses, no satisfactory instruction can be
conveyed.[65] Every school, indeed, should have a museum, however
limited and humble. Even from within its narrow sphere objects of
natural history and antiquities might be collected, and duplicates
exchanged; and we are sure that many a chimney-piece in the district
would surrender a tithe of its curiosities for the public use. Were
the British Museum, and other overflowing collections, to distribute
among provincial museums the numerous duplicates which they possess,
they would gradually pass into the schools, and before a quarter of a
century elapsed, museums would be found in every proper locality.
[65] “The importance of establishing a _permanent Museum of Education_
in this country, with the view of _introducing improvements in the
existing methods of instruction_, and specially directing public
attention in a practical manner to the question of National Education,
has been of late generally recognised.”—_Third Report of the
Commissioners for the Exhibition of 1851_, presented to both Houses of
Parliament, p. 37. Lond., 1856.
As we cannot indulge in the hope that any such boon will be conferred
on our educational institutions, it becomes an important question how
far it is possible to supply the defect by the means within our reach.
The photographic process may be advantageously employed in producing
accurate representations of those objects, both of nature and of art,
which it would be desirable to describe and explain in the instruction
of youth; but as experience has not yet taught us that such pictures
will be permanent, and capable of resisting the action of time and the
elements, it would be hazardous to employ them in the illustration
of popular works. It is fortunate, however, that the new art of
galvanography enables us, by a cheap process, to give to photographs
the permanence of engravings, and to employ them in the illustration of
educational works.[66]
[66] This fine invention we owe to Mr. Paul Pretsch, late director of
the Imperial Printing Office at Vienna. It is secured by patent, and is
now in practical operation in Holloway Place, Islington.
But however much we may value such an auxiliary, representations or
drawings, on a plane, of solids or combinations of solids at different
distances from the eye, are in many cases unintelligible even to
persons well informed; so that, on this ground alone, we cannot but
appreciate the advantages to be derived from binocular pictures and
their stereoscopic relievo, not only in the instruction of youth, but
in the diffusion of knowledge among all ranks of society.
One of the most palpable advantages to be derived from the illustration
of school-books by pictures in relief, is the communication of correct
knowledge of the various objects of natural history. If, as we have
already shewn, the naturalist derives important assistance in his
studies from correct representations of animated nature, how much more
valuable must they be to the scholar who never saw, and may never see
the objects themselves. In the department of zoology, the picture
might frequently be taken from the living animal, standing before the
camera in vigorous life and transcendent beauty; or when this cannot
be done, from the fine specimens of zoological forms which adorn our
metropolitan and provincial museums. The trees and plants, too, of
distant zones, whether naked in their osteology, or luxurious in their
foliage, would shew themselves in full relief;—the banyan, clinging
with its hundred roots to the ground,—the bread-fruit tree, with its
beneficent burden,—the cow tree, with its wholesome beverage,—the
caoutchouc tree, yielding its valuable juice,—or the deadly upas,
preparing its poison for the arrow of the savage or the poniard of the
assassin.
With no less interest will the schoolboy gaze on the forms of insect
life, which will almost flutter before him, and on the tenants of
the air and of the ocean, defective only in the colours which adorn
them. The structures of the inorganic world will equally command
his admiration. The minerals which have grown in the earth beneath
his feet, and the crystals which chemistry has conjured into being,
will display to him their geometric forms, infinite in variety, and
interesting from their rarity and value. Painted by the very light
which streamed from them, he will see, in their retiring and advancing
facets, the Kohinoor and other diamonds, and the huge rubies, and
sapphires, and emeralds, which have adorned the chaplet of beauty, or
sparkled in the diadem of kings. The gigantic productions of the earth
will appeal to him with equal power,—the colossal granites, which have
travelled in chariots of ice, and the rounded boulders, which have
been transported in torrents of mud; and while he admires, in their
strong relief, the precipices of ancient lava—the Doric colonnades
of basalt—the upheaved and contorted strata beside them, and the
undisturbed beds which no internal convulsions have shaken, he will
stand appalled before the fossil giants of the primeval world that trod
the earth during its preparation for man, and have been embalmed in
stone to instruct and to humble him.
In acquiring a knowledge of physical geography, in which the
grander aspects of nature arrest our attention, their stereoscopic
representations will be particularly instructive. The mountain range,
whether abrupt in its elevation, or retiring from our view,—whether
scarred with peaks or undulating in outline,—the insulated mountain
tipped with snow or glowing with fire,—the volcano ejecting its burning
missiles,[67]—the iceberg fixed in the shore, or floating on the
deep,—the deafening cataract,—the glacier and its moraines, sinking
gently to the plains,—and even the colossal wave with its foaming
crest, will be portrayed in the binocular camera, and exhibited in all
the grandeur and life of nature.
[67] An accomplished traveller, the Rev. Mr. Bridges, who ascended
Mount Etna for the purpose of taking Talbotype drawings of its scenery,
placed his camera on the edge of the crater to obtain a representation
of it. No sooner was the camera fixed and the sensitive paper
introduced, than an eruption took place, which forced Mr. Bridges to
quit his camera in order to save his life. When the eruption closed, he
returned to collect the fragments of his instrument, when, to his great
surprise and delight, he found that his camera was not only uninjured,
but contained a picture of the crater and its eruption.
The works of human hands,—the structures of civilisation, will stand
before the historian and the antiquary, as well as the student, in
their pristine solidity, or in their ruined grandeur,—the monuments by
which sovereigns and nations have sought to perpetuate their names,—the
gorgeous palaces of kings,—the garish temples of superstition,—the
humbler edifices of Christian faith,—the bastions and strongholds of
war, will display themselves in the stereoscope as if the observer were
placed at their base, and warmed by the very sun which shone upon their
walls.
Although few of our village youth may become sculptors, yet the
exhibition of ancient statues in their actual relief, and real apparent
magnitude, cannot fail to give them salutary instruction and rational
pleasure. To gaze upon the Apollo Belvidere,—the Venus de Medici,—the
Laocoon, and the other masterpieces of ancient art, standing in the
very halls which they now occupy; or to see the _chef d’œuvres_ of
Canova, Thorvaldsen, and Chantrey, or the productions of living artists
in their own studio, with the sculptor himself standing by their side,
will excite an interest of no ordinary kind.
From the works of the architect, the engineer, and the mechanist,
as exhibited in full relief, the student, whether at our schools or
colleges, will derive the most valuable instruction. The gigantic
aqueducts of ancient and modern times,—the viaducts and bridges which
span our valleys and our rivers, and the machinery in our arsenals,
factories, and workshops, will be objects of deep interest to the
general as well as the professional inquirer.
There is yet another application of the stereoscope to educational
purposes, not less important than those which have been mentioned.
In the production of diagram representing instruments and apparatus,
which cannot be understood from drawings of them on a plane, it will
be of incalculable use to the teacher to have stereoscopic pictures
of them. In every branch of physical science, diagrams of this kind
are required. When they are intended to represent apparatus and
instruments, either for illustrating known truths, or carrying on
physical researches, binocular pictures can be easily obtained; but
when the diagrams have not been taken from apparatus, but are merely
combinations of lines, we can obtain binocular photographs of them only
from models constructed on purpose. These models will give binocular
representations in various azimuths, so that the true position of
planes at different inclinations, and lines at various angles with
each other, and at different distances from the eye, will be readily
apprehended. Astronomical diagrams, in which orbits, &c., may be
represented by wires, and optical figures, in which the rays may be
formed by threads or wires, would be thus easily executed.
Among the binocular diagrams, consisting of white lines upon a black
ground, which have been executed in Paris, there is one representing
the apparatus in which a ray of light, polarized by reflexion from a
glass plate, passes through a crystallized film perpendicular to the
plane of the paper, and is subsequently analysed by reflexion from
another plate at right angle to the following plate. This diagram, when
placed in relief by the stereoscope, gives as correct an idea of the
process as the apparatus itself.
As an auxiliary in the investigation of questions of difficulty and
importance, both in physics and metaphysics, the stereoscope is
peculiarly valuable. It enables us to place in its true light the
celebrated theory of vision on which Bishop Berkeley reared the ideal
philosophy, of which he was the founder, and it gives us powerful aid
in explaining many physical phenomena which have long baffled the
ingenuity of philosophers. It would be out of place to give any account
of these in a work like this, but there is one so remarkable, and at
the same time so instructive, as to merit special notice. In order to
exhibit, by means of _three_ diagrams, a solid in relief and hollow at
the same time, which had not been previously done, I executed three
drawings of the frustum of a cone, resembling those in Fig. 31, so
that the _left_-hand one and the middle one gave the _hollow_ cone,
while the _middle_ one and the _right_-hand one gave the _raised_
cone. Having their summits truncated, as in the figure, the cones
exhibit, in the one case, a circle at the bottom of the hollow cone,
and in the other, a circle on the summit of the raised cone. When these
three diagrams[68] are placed in an open lenticular stereoscope, or
are united by the convergency of the optical axes, so that we can not
only see the _hollow_ and the _raised_ cones, but the flat drawing on
each side of them, we are enabled to give an ocular and experimental
proof of the cause of the large size of the horizontal moon, of her
small size when in the meridian or at a great altitude, and of her
intermediate apparent magnitude at intermediate altitudes,—phenomena
which had long perplexed astronomers, and which Dr. Berkeley, rejecting
previous and well-founded explanations, ascribed to the different
degrees of brightness of the moon in these different positions.
[68] A binocular slide, copied from the one originally designed by
myself, forms No. 27 of the Series of white-lined diagrams upon a black
ground executed in Paris. The drawings, however, are too large for the
common stereoscope.
As the circular summit of the _raised_ cone _appears_ to be _nearest_
the eye of the observer, the summit of the _hollow_ cone _farthest_
off, and the similar central circle in the flat drawing on each side,
at an intermediate distance, the apparent distances from the eye of
different and equal circles will represent the apparent distance of
the moon in the _zenith_, or very high in the elliptical celestial
vault,—the same distance when she is in the _horizon_, and the same
when at an intermediate altitude. Being in reality of exactly the same
size, and at the same distance from the eye, these circular summits, or
sections of the cone, are precisely in the same circumstances as the
moon in the three positions already mentioned. If we now contemplate
them in the lenticular stereoscope, we shall see the circular summit of
the _hollow_ cone the _largest_, like the _horizontal_ moon, because
it _seems_ to be at the _greatest_ distance from the eye,—the circular
summit of the _raised_ cone the _smallest_, because it appears at
the _least_ distance, like the _zenith_ or culminating moon,—and the
circular summits of the flat cones on each side, of an _intermediate_
size, like the moon at an _intermediate_ altitude, because their
distance from the eye is intermediate. The same effect will be equally
well seen by placing three small wafers of the same size and colour on
the square summits of the drawings of the quadrangular pyramids, or
more simply, by observing the larger size of the square summit of the
hollow pyramid.
This explanation of the cause of the increased size of the horizontal
moon is rigorously correct. If any person should suspect that the
circles which represent the moon are unequal in size, or are at
different distances from the eye, they have only to cut the diagram
into three parts, and make each drawing of the frustum of the cone
occupy a different place in the binocular slide, and they will obtain
the very same results. Hence we place beyond a doubt the incorrectness
of Dr. Berkeley’s theory of the size of the horizontal moon,—a theory
to which the stereoscope enables us to apply another test, for if we
make one or more of these circles less bright than the rest, no change
whatever will be produced in their apparent magnitude.