This is a process of combining a number of images in such a way that the result obtained is an aggregate of its components. Francis Galton was one of the first to employ this system. In the appendix to his "Inquiries into Human Faculty," Galton has described the very elaborate and perfect form of apparatus which he has used in his studies; but entirely satisfactory results may be obtained with much more simple contrivances. The instrument used by Prof. Bowditch[7] is merely an old-fashioned box camera, with a hole cut in the top for the reception of the ground-glass plate upon which the image is to be reflected for purposes of adjustment. The reflection is effected by a mirror set at an angle of 45 degrees in the axis of the camera, and pivoted on its upper border so that, after the adjustment of the image, the mirror can be turned against the upper side of the box, and the image allowed to fall on the sensitive plate at the back of the camera. The original negatives are used as components, and are placed in succession in a small wooden frame which is pressed by elliptical springs against a sheet of glass fastened vertically in front of the camera. By means of this arrangement it is possible to place each negative in succession in any desired position in a plane perpendicular to the axis of the camera, and thus to adjust it so that the eyes and the mouth of its optical image shall fall upon the fiducial lines drawn upon the ground-glass plate at the top of the camera. An Argand gas burner with a condensing lens furnishes the necessary illumination.
[7] From McClure's Magazine, September, 1894.
"For our amateur photographers," writes Prof. Bowditch, "who are constantly seeking new worlds to conquer, the opportunity of doing useful work in developing the possibilities of composite photography ought to be very welcome. Not only will the science of ethnology profit by their labors, but by making composites of persons nearly related to each other, a new and very interesting kind of family portrait may be produced. The effect of occupation on the physiognomy may also be studied in this way. By comparing, for instance, the composite of a group of doctors with that of a group of lawyers, we may hope to ascertain whether there is such a thing as a distinct legal or medical physiognomy."
By Prof. Bowditch.
FIG. 84.—COMPOSITE PORTRAITS OF BOSTON PHYSICIANS AND SAXON SOLDIERS.
[TELEPHOTO PICTURES.]
FIG. 85.—CAMERA WITH OPERA GLASS ATTACHED.
During the last few years many so-called telephotographic lenses have been placed upon the market. These instruments enable one to photograph objects in the distance and obtain images very much larger than those given by the ordinary photographic lens. These lenses are, however, very costly. In an article by Mr. O. G. Mason, published in The Photographic Times for June, 1895, that gentleman described a simple method of obtaining telephoto pictures by replacing the ordinary lens with an opera glass. He says: "Several devices have been brought forward with a view of decreasing the expense of telephoto lenses, but I have seen no others so satisfactory, cheap and simple, as the utilization of the ordinary opera glass for the camera objective, which was described, figured and finally constructed for me about a year ago by Mr. Alvin Lawrence, the horologist of Lowell, Mass. An opera or field glass is a convenient and useful instrument in the kit of any touring photographer; and when he can easily and quickly attach it to his camera-box as an objective its great value is at once made apparent. Mr. Lawrence's method of doing this at little cost is a good illustration of Yankee ingenuity. It is not claimed that such a device will do all or as well as a telephotographic lens costing ten times as much; but it will do far more than most people could or would expect. Of course the field is quite limited, which, in fact, is the case with the most expensive telephotographic objective, and the sharpness of the image depends much upon the quality of the opera or field glass used. The accompanying views show the relative size and character of image by a forty-five dollar rapid rectilinear view lens and a four-dollar opera glass attached to the same camera and used at the same point. The other illustrations show the camera as used and the method of opera glass attachment to the lens-board. It will be seen that the eye end of the opera glass is placed against the lens-board, one eye-piece in a slight depression around the hole through the centre, and by a quarter turn the brace between the two barrels passes behind a projecting arm on the board, the focusing barrel resting in a slot in this arm, where it is firmly held in position by friction alone.