Many persons suppose that they are looking on miniatures of the objects represented, when they see them in the stereoscope. They will be surprised to be told that they see most objects as large as they appear in Nature. A few simple experiments will show how what we see in ordinary vision is modified in our perceptions by what we think we see. We made a sham stereoscope, the other day, with no glasses, and an opening in the place where the pictures belong, about the size of one of the common stereoscopic pictures. Through this we got a very ample view of the town of Cambridge, including Mount Auburn and the Colleges, in a single field of vision. We do not recognize how minute distant objects really look to us, without something to bring the fact home to our conceptions. A man does not deceive us as to his real size when we see him at the distance of the length of Cambridge Bridge. But hold a common black pin before the eyes at the distance of distinct vision, and one-twentieth of its length, nearest the point, is enough to cover him so that he cannot be seen. The head of the same pin will cover one of the Cambridge horse-cars at the same distance, and conceal the tower of Mount Auburn, as seen from Boston.
We are near enough to an edifice to see it well, when we can easily read an inscription upon it. The stereoscopic views of the arches of Constantine and of Titus give not only every letter of the old inscriptions, but render the grain of the stone itself. On the pediment of the Pantheon may be read, not only the words traced by Agrippa, but a rough inscription above it, scratched or hacked into the stone by some wanton hand during an insurrectionary tumult.
This distinctness of the lesser details of a building or a landscape often gives us incidental truths which interest us more than the central object of the picture. Here is Alloway Kirk, in the churchyard of which you may read a real story by the side of the ruin that tells of more romantic fiction. There stands the stone "Erected by James Russell, seedsman, Ayr, in memory of his children,"—three little boys, James, and Thomas, and John, all snatched away from him in the space of three successive summer-days, and lying under the matted grass in the shadow of the old witch-haunted walls. It was Burns's Alloway Kirk we paid for, and we find we have bought a share in the griefs of James Russell, seedsman; for is not the stone that tells this blinding sorrow of real life the true centre of the picture, and not the roofless pile which reminds us of an idle legend?
We have often found these incidental glimpses of life and death running away with us from the main object the picture was meant to delineate. The more evidently accidental their introduction, the more trivial they are in themselves, the more they take hold of the imagination. It is common to find an object in one of the twin pictures which we miss in the other; the person or the vehicle having moved in the interval of taking the two photographs. There is before us a view of the Pool of David at Hebron, in which a shadowy figure appears at the water's edge, in the right-hand farther corner of the right-hand picture only. This muffled shape stealing silently into the solemn scene has already written a hundred biographies in our imagination. In the lovely glass stereograph of the Lake of Brienz, on the left-hand side, a vaguely hinted female figure stands by the margin of the fair water; on the other side of the picture she is not seen. This is life; we seem to see her come and go. All the longings, passions, experiences, possibilities of womanhood animate that gliding shadow which has flitted through our consciousness, nameless, dateless, featureless, yet more profoundly real than the sharpest of portraits traced by a human hand. Here is the Fountain of the Ogre, at Berne. In the right picture two women are chatting, with arms akimbo, over its basin; before the plate for the left picture is got ready, "one shall be taken and the other left"; look! on the left side there is but one woman, and you may see the blur where the other is melting into thin air as she fades forever from your eyes.
Oh, infinite volumes of poems that I treasure in this small library of glass and pasteboard! I creep over the vast features of Rameses, on the face of his rock-hewn Nubian temple; I scale the huge mountain-crystal that calls itself the Pyramid of Cheops. I pace the length of the three Titanic stones of the wall of Baalbee,—mightiest masses of quarried rock that man has lifted into the air; and then I dive into some mass of foliage with my microscope, and trace the veinings of a leaf so delicately wrought in the painting not made with hands, that I can almost see its down and the green aphis that sucks its juices. I look into the eyes of the caged tiger, and on the scaly train of the crocodile, stretched on the sands of the river that has mirrored a hundred dynasties. I stroll through Rhenish vineyards, I sit under Roman arches, I walk the streets of once buried cities, I look into the chasms of Alpine glaciers, and on the rush of wasteful cataracts. I pass, in a moment, from the banks of the Charles to the ford of the Jordan, and leave my outward frame in the arm-chair at my table, while in spirit I am looking down upon Jerusalem from the Mount of Olives.
"Give me the full tide of life at Charing Cross," said Dr. Johnson. Here is Charing Cross, but without the full tide of life. A perpetual stream of figures leaves no definite shapes upon the picture. But on one side of this stereoscopic doublet a little London "gent" is leaning pensively against a post; on the other side he is seen sitting at the foot of the next post;—what is the matter with the little "gent"?
The very things which an artist would leave out, or render imperfectly, the photograph takes infinite care with, and so makes its illusions perfect. What is the picture of a drum without the marks on its head where the beating of the sticks has darkened the parchment? In three pictures of the Ann Hathaway Cottage, before us,—the most perfect, perhaps, of all the paper stereographs we have seen,—the door at the farther end of the cottage is open, and we see the marks left by the rubbing of hands and shoulders as the good people came through the entry, or leaned against it, or felt for the latch. It is not impossible that scales from the epidermis of the trembling hand of Ann Hathaway's young suitor, Will Shakspeare, are still adherent about the old latch and door, and that they contribute to the stains we see in our picture.
Among the accidents of life, as delineated in the stereograph, there is one that rarely fails in any extended view which shows us the details of streets and buildings. There may be neither man nor beast nor vehicle to be seen. You may be looking down on a place in such a way that none of the ordinary marks of its being actually inhabited show themselves. But in the rawest Western settlement and the oldest Eastern city, in the midst of the shanties at Pike's Peak and stretching across the court-yards as you look into them from above the clay-plastered roofs of Damascus, wherever man lives with any of the decencies of civilization, you will find the clothes-line. It may be a fence, (in Ireland,)—it may be a tree, (if the Irish license is still allowed us,)—but clothes-drying, or a place to dry clothes on, the stereoscopic photograph insists on finding, wherever it gives us a group of houses. This is the city of Berne. How it brings the people who sleep under that roof before us to see their sheets drying on that fence! and how real it makes the men in that house to look at their shirts hanging, arms down, from yonder line!
The reader will, perhaps, thank us for a few hints as to the choice of stereoscopes and stereoscopic pictures. The only way to be sure of getting a good instrument is to try a number of them, but it may be well to know which are worth trying. Those made with achromatic glasses may be as much better as they are dearer, but we have not been able to satisfy ourselves of the fact. We do not commonly find any trouble from chromatic aberration (or false color in the image). It is an excellent thing to have the glasses adjust by pulling out and pushing in, either by the hand, or, more conveniently, by a screw. The large instruments, holding twenty-five slides, are best adapted to the use of those who wish to show their views often to friends; the owner is a little apt to get tired of the unvarying round in which they present themselves. Perhaps we relish them more for having a little trouble in placing them, as we do nuts that we crack better than those we buy cracked. In optical effect, there is not much difference between them and the best ordinary instruments. We employ one stereoscope with adjusting glasses for the hand, and another common one upon a broad rosewood stand. The stand may be added to any instrument, and is a great convenience.
Some will have none but glass stereoscopic pictures; paper ones are not good enough for them. Wisdom dwells not with such. It is true that there is a brilliancy in a glass picture, with a flood of light pouring through it, which no paper one, with the light necessarily falling on it, can approach. But this brilliancy fatigues the eye much more than the quiet reflected light of the paper stereograph. Twenty-five glass slides, well inspected in a strong light, are good for one headache, if a person is disposed to that trouble.