Page:Popular Science Monthly Volume 79.djvu/182

178 of charts under the title "Meteorographica." He was a member of the Meteorological Committee (later Meteorological Council) formed in 1868 for the purpose of giving storm warning to seaports, for obtaining data for marine charts, and for maintaining a few observatories with self-recording instruments. His service during the thirty years that he was connected with the work of the committee and council may be best expressed in the words of Sir Richard Strachey, in a letter written to Mr. Galton on his retirement from the council in 1901. Only a paragraph can be given.

Composite photography may be mentioned here, although in explaining its origin we must refer to matters more properly belonging to a subsequent section.

The blending of physiognomies by allowing each to make upon the sensitive plate but a fraction of the impression required for a clear picture may in the hands of some be only a harmless amusement for the scientific amateur, but the mother of this invention was the necessity for the securing of greater precision in the determination of family, class or racial types. Composite photography is the mechanicographical method by which its inventor attempted to solve the problem. He points out that human features must show great differences, since we are able to recognize a familiar face among thousands. This is possible because the general expression of a face is the sum of a multitude of small details which are viewed so quickly that they are apparently taken in at a single glance. If any difference from a remembered face be present it immediately looms large before the eye and overshadows all the many points of resemblance. It is impossible to measure these infinitesimal differences between individuals and to determine by statistical means what is the characteristic physiognomy of a race. The selection and photographing of "typical" or "representative" individuals—the course commonly adopted—is altogether untrustworthy, since the judgment of the observer is itself fallaceous, easily swayed by gross and exceptional features rather than by the ordinary ones, so that the carefully chosen typical portrait is more apt to be a caricature.

In a composite photograph family or racial characteristics are strongly impressed upon the film, while the individual idiosyncrasies average out—much as they do in statistical analysis—or to use Galton's own phrase, "leave but a ghost of a trace of individual peculiarities." To discuss in detail the practical applications which have been made,