In preparing the present treatise, I have kept in view the need of collegians and of graduate students in the universities, and endeavored to furnish them with a satisfactory hand-book on Induction. The few pages in popular treatises on Deductive Logic usually allotted to this co-ordinate branch being utterly inadequate and disproportionate, and thereby greatly underrating its extent and importance, should be replaced by a separate treatise comprehending at least the essential elements of Induction, and opening the way for its full investigation and application. In the hope of supplying this want, I offer to students well advanced in the schools the work in hand.<br><br>Special students engaged in the pursuit of physical science, who have not enjoyed a full course in Logic, need a compact hand-book on Induction, in order to gain a clearer insight into the principles of the methods they arc employing, and thus to avoid a waste of energy, and the discouragement of blunders in the dark. To this class of students, also, and to the general reader who desires a clearer knowledge of his own mental processes and of those of the scientist skilled in the discovery of truth, ray work is hopefully addressed.<br><br>With these ends in view, I have earnestly tried, first of all, to be true in matter, then clear and distinct in its treatment.