The Free Academy will fulfil the reasonable expectations of its founders. It is admirably designed, and its appointments and administration have thus far been judicious. We lack yet a University: there is no school in America deserving this title; all our colleges should be regarded as _gymnasia_, sifting the classes of the common schools and preparing their more advanced and ingenious pupils for such an institution; and the Free Academy may be accepted as a model by which they can be reshaped for their less ambitious but more appropriate duties. This is a subject ably and properly treated in Professor Tappan's recent volume on Education, (published by Mr. Putnam,) to which we beg attention. The whole number of students now attending the Free Academy is three hundred and twenty-nine, of whom one hundred and five were admitted at the last examination, in February. The number for whom the building is designed is about six hundred. Authors and Books. A book which we cannot too highly recommend is the _Briefe ueber Humboldt's Kosmos_ (Letters on Humboldt's Cosmos), published at Leipzic, in two octavo volumes, from the pens of Professor COTTA and Professor SCHALLER. It is intended to serve as a commentary upon that work, which it is well worthy to accompany. Without attempting an exhaustive treatise on the details of the various topics touched on by Humboldt, the writers have expanded some of the leading points of his work into scientific essays, whose practical utility is none the smaller for an elegant and attractive style, and a genial enthusiasm, of which Humboldt need not be ashamed. The first volume, by Professor Cotta, contains forty letters on the following themes: The enjoyment of nature; matter and forces, growth and existence; natural philosophy; the fixed stars, their parallaxes, groups, movements, nebulae; double stars, structure of the universe, resisting medium; the solar system; the laws of motion, Kepler and Newton; density of the heavenly bodies; our moon, its orbit, no atmosphere, no water; comets; meteors, and meteoric stones; form of the earth; magnetism; volcanic activity; gas-springs; geysers; internal structure of the earth; history of organisms, their first origin, and developments; the surface, its forms, and their influence on animated life; the gradual rising and sinking of the surface in Sweden; the tides; circulation of water on the earth--springs, cold, warm, mineral, artesian--rivers, seas, ocean currents, evaporation and condensation; glaciers; the atmosphere, climate, weather, winds, storm-clouds; organic life on the earth, its nature, differences, origin of the differences, original production, creation, first appearance; man, his origin, races, forms, phrenology, &c. These letters offer, as we have already said, in a pleasing and attractive form, a condensed and comprehensive view of what is now known with reference to the sciences treated. The letter upon Man is especially interesting.