THE POPULAR SCIENCE MONTHLY.
the acquired color of the glass. Among the gathered specimens was one of crown-glass, set in a church in Lexington, Mass., in 1794, from which the windows were removed in 1846, and afterward used as covers for hot-beds. The original color, ascertained by removing the putty from the edges, was a light green, and that produced by seventy-three years' exposure, a purple. Mr. Gaffield's efforts have also been directed toward examining the old cathedral-glass of Europe, where such observation is practicable. He still continues with great enthusiasm the experiments begun eleven years ago, and carefully records the results of his observations on a well-known phenomenon, "in the hopes that they may add some mite to the sum of human knowledge, and may stimulate and aid those who are better versed in scientific studies, to ascertain the causes and exact operations of this interesting power of the sun's rays to paint the products of art, as they do so beautifully and wonderfully the works of Nature on the mountain, in the forest and field."
|MEASURES OF MENTAL CAPACITY.|
SCIENCE cannot look otherwise than favorably upon every attempt to determine the quantitative relations of mind and body; and much ingenuity has been expended in the effort to arrive at a geometrical expression of it. Aristotle, "the father of Natural History," as Prof. Agassiz calls him, speaks of an angle of the forehead to an horizontal line of the face as an indication of intelligence, and it is evident that the Greek sculptors designedly represented the superhuman attributes of the gods by an angle exceeding that of the highest human. It is not strange, therefore, that, when Camper restored the lost science and art of the measurement of psychological development, under the name of the Facial Angle, in 1784, the scientific world gave it a cordial welcome. But of course it could not be accepted as veritable scientific truth without running the gantlet of the severest criticism. Its most vulnerable point was a claim to be something more than a mere general rule, applicable to the designation of the rank of a species or of a race in the scale of intellectual and moral elevation. It claimed to be applicable to the distinction between nationalities, and even between individuals of the same class of society, both as to facial and as to mental characteristics. This was too much, and on this ground Blumenbach and others attempted to demolish it as a rule altogether, and by very many were supposed to have succeeded. Like other favorites, it had the misfortune to be made too much of, the consequence being that it came to be treated as of little worth. And yet nearly all comparative anatomists and physiologists make use of it as a