We recently observed a very striking example of these warm and cold appearances of light; it was at the theater: a beam of red light shone brightly upon an actor, whose shadow was absolutely green. Some of the people around us were astonished at the phenomenon, which they could perceive very plainly. Phenomena of this kind are produced every instant in a nature illuminated by the sun; nearly all the shadows are colored in hues which we can distinguish with a little attention where the unpracticed eye sees nothing but gray. Thus in a mountainous country, exposed to the warm light of the sun, the mountains in the horizon appear blue through the haze; then, as evening draws on, the sun appears a deeper orange, more reddish, while the sky seems green by contrast, and the red rays of the sun falling on the mountains turn them violet, in those beautiful tints which give so much glory to those countries of large shadows and bright lights.
However intense the light of day may be, it is therefore always colored, and gives those colored shadows which painters do not always observe. The painter, in fact, should make an analysis of the complex light around him, and should repeat the result in synthesis on his canvas. Upon hardly any other condition can he represent the transparency of the atmosphere, or the luminosity of a subject or a landscape. These colored shadows are not, therefore, false colors, as often seems to be believed, or optical illusions; they are really existent, but our eyes are hardly ever practiced enough to discern them; we are deficient in education of the color sense. This education is not hard to attain. There are persons who have special aptitudes and are consequently remarkable colorists, just as some persons have an admirably organized ear for music; but, besides these, it is possible for all persons endowed with the faculty of observing and capable of attention to acquire with considerable rapidity the faculty of discerning colors, where they at present hardly see anything but confused gray masses. (The epithet gray, we may observe, is used as applied to many things the color of which is not susceptible of exact determination.) Such attentive observation of colors is, however, attended with some danger to painters. Every person prefers some one color, is influenced by a particular shade. When we examine the works of the painters we see that there are many differences in the way of seeing. Some see blue, red, green; others see clear, others obscure. In the analysis of a complex color it happens that there is sometimes an auto-suggestion. Where there is a hardly defined violet, the painter will exaggerate it on his canvas, and will be obliged, in order to keep up the right tone, to increase the intensity of the colors next to it. Hence arises a common error with painters, who start with a true principle, but are not able to apply it properly, and give their picture a tonic violet, green, or yellow, beyond all reason.—Translated for the Popular Science Monthly from the Revue Scientifique.
SKETCH OF THOMAS EGLESTON.
By Prof. DANIEL S. MARTIN.
As a general rule, the work of the scientist is not of a kind to attract conspicuous notice from the public, especially in great cities, filled and thrilled with commercial and political activity; and so it comes to pass that men of rare attainments and untiring energy, in the highest walks of life and thought, may spend their whole life-time in such an environment, and be scarcely known outside of a limited circle of kindred minds. They may confer lasting benefits on the community, render important services to the whole country, and be widely known and honored in other lands, and yet receive but little general recognition in the place of their abode.
Such a man, in such a community, is Prof. Thomas Egleston, of the city of New York. He has been too busy and too modest to seek prominence in the public eye, and his scientific work has been of a kind that does not lend itself readily to popular lectures or startling announcements; but as a mineralogist, a metallurgist, and a mining engineer, and as the planner and founder of the great School of Mines of Columbia University, he has made a deep and permanent impress on the history of science in the United States.
Professor Egleston is of New England stock, his ancestors having been among the first settlers of Dorchester, Massachusetts, in 1635. Thence they came by a toilsome and perilous journey to Connecticut, and founded Windsor, which was thenceforward their home, and whence his father came to New York. The removal to Connecticut arose from a desire for greater freedom of life and worship than they found in Massachusetts; and Professor Egleston has been deeply interested in studying the little-known records of this movement, and the influence which it exerted, as an almost unwritten chapter in American history. He proposes to publish these researches, together with much other material relating to our colonial history, in which he is an enthusiastic student.
He was born in New York, on December 9, 1832. As a boy he took considerable interest in certain aspects of science, and at the age of thirteen had gathered a collection of minerals and rocks. He attended Yale College, and in the later years of his course took special elective work in chemistry. After graduating there in 1854, he was for a time an assistant to Prof. Benjamin Silliman, Jr. Subsequently he went abroad, partly for his health, and was advised to spend some time in Paris. With no special professional purpose, but from a general desire to improve his time, he began attending lectures on geology and chemistry at the Jardin des Plantes, under D'Orbigny (a brother of the eminent writer) and Hilgard, and he worked with much energy in the laboratories of those departments at the Jardin. He thus attracted the attention of some of the faculty of the École des Mines, who offered him larger facilities in that institution, which he at once accepted. After much very interesting study in the paleontological laboratory there, he decided to go regularly through the entire course, and accomplished that purpose with notable success and honor, graduating in 1860. He had worked as an assistant in every laboratory of the school, and in the summers had traveled through much of France, becoming familiar with its geology, mineral resources, mining works and processes, and gaining a mastery at first hand of all branches of those subjects. Those years were to him full of interest and enjoyment; friendships were formed that have enriched his whole life; and in it all the man was being remarkably prepared for the work of developing those forms of science and of industrial progress in our own country. Professor Egleston has always retained a strong feeling of attachment toward the École des Mines, which has likewise been warmly reciprocated. He has shown his interest by two gifts to the institution, of five thousand dollars each.
Returning hither in 1861, just as the war cloud was darkening over the land, he received almost immediately an appointment at Washington, to take charge of the mineralogical collections and laboratory of the Smithsonian Institution. After two years there he conceived the purpose that determined his whole career, and has so greatly influenced both American science and American mineral development—that of a school of mines at New York.