The well-known private library of the late Rev. Dr. SAMUEL FARMER JARVIS is to be sold in this city, by Messrs. Lyman & Rawdon, about the beginning of October. In several departments of sacred and classical literature it is one of the finest collections in America, and it will probably attract large numbers of buyers, especially from among the lovers of mediæval scholarship and theology. * * * * * MR. MITCHELL'S new book, the _Diary of a Dreamer_, is in press by Charles Scribner, and the same publisher will issue for the holidays an edition of the _Reveries of a Bachelor_, admirably illustrated by Darley, who seems indeed never to have done better than in some of his designs for it. * * * * * MR. LONGFELLOW has in the press of Ticknor, Reed and Fields, of Boston, a new poem, entitled _The Golden Legend_. It is the longest of his poetical works, making some 350 pages, and will soon be given to the public. * * * * * There is this year a very remarkable number of new books illustrative of the applications of science to mechanics. Every man seems determined to master the learning which can be turned to account in his vocation, and the booksellers are quite willing to aid them. We suppose the most generally and importantly useful work of this kind ever printed is Appleton's _Dictionary of Machinery, Mechanics, Engine Work, and Engineering_, just completed in two very large compactly printed and profusely illustrated octavo volumes. In this great work are gathered the best results of the study and experiment of the workers of the world. It is a cyclopedia of inventions, in which one may be sure of finding described the best processes yet discovered for doing every thing that is to be done by means of mechanics. The benefits conferred on the country by this publication must be very great; its general circulation would mark a new period in our physical advancement, and to a degree influence our civilization, since there is no country in the world in which every resource is so readily applied to purposes of comfort and culture. If knowledge is power, as, misquoting Lord Bacon, it is every day asserted, the truth is most conspicuous in the range of those arts and occupations illustrated by these incomparable volumes, which should be in the house of every man who has already provided himself with the Bible and Shakspere. The Appletons also publish a _Mechanics' Magazine_, edited in a very admirable manner, and we understand it is largely sold.