Had Mr. Wheatstone combined pictures, each of which was a correct monocular picture, as seen with each eye, and as taken with a small aperture or a small lens, he would have found no discrepancy between the results of observation and of science. From the same cause, we presume, namely, the use of multocular pictures, Mr. Alfred Smee[52] has been led to a singular method of taking binocular ones. In one place he implicitly adopts Mr. Wheatstone’s erroneous rule. “The pictures for the stereoscope,” he says, “are taken at two stations, at a greater or less distance apart, according to the distance at which they are to be viewed. For a distance of 8 inches the two pictures are taken at angles of 18°, for 13 inches 10°, for 18 inches 8°, and for 4 feet 4°.” But when he comes to describe his own method he seems to know and to follow the true method, if we rightly understand his meaning. “To obtain a binocular picture of anybody,” he says, “the camera must be employed to take half the impression, and then it must be moved in the arc of a circle of which the distance from the camera to the _point of sight_[53] is the radius for about 2½ inches when a second picture is taken, and the two impressions conjointly form one binocular picture. There are many ways by which this result may be obtained. A spot may be placed on the ground-glass on which the point of sight should be made exactly to fall. The camera may then be moved 2½ inches, and adjusted till the point of sight falls again upon the same spot on the ground-glass, when, if the camera has been moved in a true horizontal plane _the effect of the double picture will be perfect_.” This is precisely the true method of taking binocular pictures which we had given long before, but it is true only when small lenses are used. In order to obtain this motion in the true arc of a circle the camera was moved on two cones which converged to the point of sight, and Mr. Smee thus obtained pictures of the usual character. But in making these experiments he was led to take pictures _when the camera was in continual motion backwards and forwards for 2½ inches_, and he remarks that “_in this case the picture was even more beautiful than when the two images were superimposed_!” “This experiment,” he adds, “is very remarkable, for who would have thought formerly that a picture could possibly have been made with a camera in continual motion? Nevertheless we accomplish it every day with ease, and the character of the likeness is wonderfully improved by it.” We have now left the regions of science, and have to adjudicate on a matter of opinion and taste. Mr. Smee has been so kind as to send me a picture thus taken. It is a good photograph with features enlarged in all azimuths, but it has no other relief than that which we have described as monocular. [52] _The Eye in Health and Disease_, by Alfred Smee, 2d edit. 1854, pp. 85-95.