ON THE RELATION OF NATURAL SCIENCE TO ART. 671 
the origin of the modern schools of painting and in the manner of 
impressionists and pleinairists. It further taught landscape painters 
to depict rocks and vegetation with geological and botanical accuracy, 
and to represent glaciers, which hitherto had been but rarely and never 
successfully attempted. It caught and fixed the changing aspect of 
the clouds, though only yielding a somewhat restricted survey of the 
heavens. It aided portrait painters, without exciting their jealousy; 
for, unable to rival them in representing the average aspect of persons, 
it only seized single, often strained and weary, expressions, rendering 
almost proverbial the comparison between a bad portrait and a photo- 
graphed face; nevertheless it supplied them on many occasions with 
an invaluable groundwork, lacking nothing but the animating touch 
of an artist’s hand. 
However, the recent progress of photographic portraiture claims the 
attention of artists in more than one respect. Duchenne and Darwin 
called into existence a new doctrine of the expression of the emotions; 
the former by galvanizing the muscles of the face, in order to imitate 
different expressions, the latter by inquiring into their phylogenetic 
development in the animal series. Both presented artists with photo- 
graphs which quickly consigned to oblivion the copies hitherto employed 
for purposes of study in schools of art, dating chiefly from Lebrun; 
even the sketches in Signor Mantegazza’s new work on “ Physiognomy 
and Mimics” will scarcely enter into competition. On Mr. Herbert 
Spencer’s suggestion Mr. Francis Galton subsequently solved by the 
aid of photography a problem which was previously quite as inac- 
cessible to painters as the representation of an average expression to 
photographers. He combined the average features of the face and 
skull of a sufficient number of persons of the same age, sex, profession, 
culture, or disposition to disease or vice in one typical portrait, which 
exhibits only those characteristic forms common to their various dis- 
positions. This was effected by blending on one negative the faint 
images of a series of persons belonging to the same descriptiom In 
the same manner Prof. Bowditch, of Harvard Medical School, Boston, 
obtained the representative face or type of American students of both 
sexes and of tramway conductors and drivers. In the latter instance 
the intellectual superiority of the conductors over the drivers is plainly 
visible. How Lavater and Gall would have relished this! 
Of course the average expression of a single person might be pro- 
cured by similar means, if it were worth while summing up on the same 
plate repeated photographs of different expressions. Instantaneous 
photography, however, furnishes a welcome substitute for the average 
expression, by seizing with lightning swiftness the changing phases of 
the human countenance in their full vivacity. Here again pathology 
places itself at the disposal of art. M. Charcot has found that photo- 
graphs of the convulsions and facial distortions of hysterical patients 
resemble our classical representations of the possessed. Raphael’s 
