Of the many forms of scientific activity which have engaged Professor Egleston during his busy life, only the briefest mention can be made. He was one of the founders of the American Institute of Mining Engineers, was thrice its vice-president, and was chosen president in 1886; and he has published over one hundred articles in its Transactions. He was one of the founders of the American Metrological Society, and of the societies of Mechanical Engineers and of Electrical Engineers, and a member of the society of Civil Engineers and of the Iron and Steel Institute of Great Britain. In the New York Academy of Sciences he was active for many years, and held the vice-presidency from 1869 to 1881. In 1866 Professor Egleston was associated with the Agricultural and Geological Survey of the Union Pacific Railroad; in 1868 was appointed a United States Commissioner to examine the fortifications of the coast; and in 1873 was one of the jurors for the International Exposition at Vienna. From Princeton and Trinity Colleges he received, in 1874, the degrees of Ph. D. and LL. D., respectively, and from the Government of France the rank of a Chevalier of the Legion of Honor in 1890, and the exceptional rank of "Officier" in 1895. His papers, published either separately or in the proceedings of the several engineering societies above mentioned, the Annals of the New York Academy of Sciences, the School of Mines Quarterly, etc., cover a wide range of subjects connected with mineralogy, metallurgy, and mining operations. In mineralogy he was especially devoted to crystallography, and his noble private collection was gathered and arranged with relation to that department. Besides his strictly metallurgical articles and treatises, he has dealt with such topics as rails, in relation to accidents; furnaces and their construction; fire-brick and refractory substances; slags and their utilization, etc.; the decay of building stones, in connection with the Obelisk; technical education, manual training, and improvement in the conditions of workingmen in mining and metallurgical occupations. His chief published works are The Metallurgy of Gold, Silver, and Mercury in the United States, two large volumes, 1887 and 1890, and his Lectures on Mineralogy, to which may be added his Tables for the Determination of Minerals, Metallurgical Tables on Fuels, Iron, and Steel, diagrams and comparisons of crystals and crystal notation, tables of production of many of the metals, report on the Union Pacific Railroad survey of 1868, and many others.