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

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Diagram vii.

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