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.