The Polytechnic College of Philadelphia, now in its ninth year, is a truly excellent institution, the practical results of which are shown in the fact that its students, immediately on graduating, have generally received appointments as civil and mechanical engineers, or otherwise stepped at once into active and remunerative employment. Its object, as we are told, is to afford to the young civil, mining, or mechanical engineer, chemist, architect, metallurgist, or student of applied science, every facility whereby he may perfect himself in his destined calling. It is, in fact, a collection of technical schools, or schools of instruction in the several departments of learned industry. It comprises the school of mines, for professional training in mine-engineering, in the best methods of determining the value of mineral lands and of analyzing and manufacturing mine products. Also the schools of civil engineering, of practical chemistry, of mechanical engineering, architecture, general science, and agriculture. To these is added a military department, now under superintendence of a former instructor in West-Point, with the use of the State armory near the college, generously granted by the State, with a supply of arms. We are glad to say that in all these schools the instruction is thorough, not only in theory but in actual _practice_. The course of the school of chemistry, for instance, comprehends the principles of the science and their actual application to agriculture, to the arts, and to analysis; to the examination and smelting of ores; to the alloying, refining, and working of metals; to the arts of dyeing and pottery; to the starch, lime, and glass manufacture; to the preparation and durability of mortars and cements; to means of disinfecting, ventilating, heating, and lighting. Its students are also practiced in manipulations, testing in the arts qualitative and quantitative; in analysis of minerals and soils, and in many other important practical matters.