CONTENTS. On the Foundations of the Theory of Probabilities On the Method of Least Squares Some Remarks on the Theory of Matter Remarks on the Fundamental Principle of the Theory of Probabilities 12 38 49 53 62 63 68 On the Existence of a Relation among the Co-efficients of the Equation of the Squares of the Differences of the Roots of an Equation On the Achromatism of Eye-Pieces of Telescopes and Microscopes On the Condition of Equilibrium of a System of Mutually Attractive Variation of Node and Inclination Investigation of the Aberration in Right Ascension and Declination 81, 92, 130, 142, 149, 157, 191, 223 82 84 86 Sur les Intégrales aux Différences Finies Report on the Recent Progress of Analysis (Theory of the Comparison ERRATUM. p. 1, 4, 5. For Bernouilli, read Bernoulli. BIOGRAPHICAL MEMOIR OF ROBERT LESLIE ELLIS, M.A. LATE FELLOW OF TRINITY COLLEGE, CAMBRIDGE. BY HARVEY GOODWIN, D.D. DEAN OF ELY. α "Il avait une promptitude infinie à tout saisir, une mémoire prodigieuse et une faculté méthodique et rectifiante pour tirer, comme par une chimie naturelle, quelque chose de précieux de tout ce qui s'offrait à lui, soit dans la conversation, soit dans la lecture. Tout sujet d'entretien lui était bon; il acceptait volontiers celui qu'on mettait sur le tapis, et il étonnait les indifférents par les trésors qu'il tirait à l'instant de la mine qu'ils lui avaient offerte sans y songer. Son esprit était comme une bibliothèque encyclopédique bien ordonnée, qu'il suffisait d'ouvrir à la lettre qu'on voulait, pour en faire sortir des richesses." BIOGRAPHICAL MEMOIR OF ROBERT LESLIE ELLIS. THE publication in a collected form of the papers which this volume contains is to be regarded, to a certain extent, as a tribute of affection. From this point of view the work would hardly seem to be complete without some notice of the life and character of the author. That he was a man of no ordinary attainments, in at least one field of knowledge, will be sufficiently evident to those who know no more of him than they can gather from this portion of his writings; that he had powers distinct from those of mathematical research, is evident from what he has done as the editor of the philosophical works of Bacon; but even these published records of his intellect will perhaps fail to convey to readers that impression of remarkable and various ability which was made, I believe, upon all those who were brought into personal contact with him. It may therefore be interesting to the general reader, besides completing the memorial character of the volume, if an attempt be made by one of his contemporaries to give some account of what he was. The mere facts of the life are few and simple. The external picture of it may be very easily drawn. It was short, |