The three volumes already published embrace the progress of Spanish conquest from the first discoveries of Columbus to Pizarro's incursion into Peru. It is sincerely to be hoped that Mr. Helps may continue his work, at least to the period when the Spanish conquest and colonization were met and limited by the conquest and the colonization of the other European nations. Its importance, as a wise, thoughtful, unpolemic investigation of the origin and the results of Slavery, is hardly to be overestimated. The space allowed to a critical notice does not permit us to render it full justice. We can do little more than recommend it warmly to the readers of history and to the students of the most difficult and the darkest social problem of the age. _Handbook of Railroad Construction, for the Use of American Engineers. Containing the Necessary Rules, Tables, and Formulae for the Location, Construction, Equipment, and Management of Railroads, as built in the United States_. With 158 Illustrations. By GEORGE L. VOSE, Civil Engineer. Boston: James Munroe & Co. 1857. 12 mo. pp. 480. All who trust their persons to railroad cars, or their estates to railroad stocks, will welcome every effort to enlighten that irresponsible body of railroad builders and managers in whose wits we put our faith. The work which we here notice is intended for uneducated American engineers, of whom there are unfortunately too many. The rapidity with which our railroads have been built, and the experimental character of this new branch of engineering, have obliged us to resort to such native ability and mother wit as our people could afford. The great body of our railroad engineers have had no training but the experience they have blundered through; and even our railroad financiers are men more distinguished for courage and energy than for experimental skill. Mr. Vose's book will doubtless be of great service in remedying these evils, by bringing within the reach of every intelligent man a valuable and very carefully prepared summary of such rules, formulas, and statistics as our railroad experiences have furnished and proved. Railroad engineering and management have united almost every branch of mechanical and financial science, and have developed several new and peculiar arts; so that the successful construction, equipment, and management of a railroad require a rare combination of accomplishments. Managers hitherto have been too little acquainted with their business to settle many questions of economy, but they are now beginning to look upon their enterprises with cooler judgments.