Photographic Researches and Portraiture 319
of an object. It can indeed be achieved if the object be inanimate by placing it on a reticulated turntable and rotating this turntable through 45° or 90° to obtain the second photograph with the same camera. Of course if we can find the coordinates of one point we can find those of any number, and the
distances between them can then be found in the usual way. Another method is to find a whole series of points T and S or construct plan and elevation drawings of the object from the two photographs.
A paper by Galton entitled "Photographic measurement of Horses and