Methode Jacotot. Choix de propositions mathematiques. Par P. Y. Sepres.[607] 2nde edition. Paris, 1830, 8vo. (pp. 82). Of Jacotot's method, which had some vogue in Paris, the principle was _Tout est dans tout_,[608] and the process _Apprendre quelque chose, et a y rapporter tout le reste_.[609] The first tract has a proposition in conic sections and its preliminaries: the second has twenty exercises, of which the first is finding the greatest common measure of two numbers, and the last is the motion of a point on a surface, acted on by given forces. This is topped up with the problem of sound in a tube, and a slice of Laplace's theory of the tides. All to be studied until known by heart, and all the rest will come, or at least join on easily when it comes. There is much truth in the assertion that new knowledge {279} hooks on easily to a little of the old, thoroughly mastered. The day is coming when it will be found out that crammed erudition, got up for examinations, does not cast out any hooks for more. Lettre a MM. les Membres de l'Academie Royale des Sciences, contenant un developpement de la refutation du systeme de la gravitation universelle, qui leur a ete presentee le 30 aout, 1830. Par Felix Passot.[610] Paris, 1830, 8vo. Works of this sort are less common in France than in England. In France there is only the Academy of Sciences to go to: in England there is a reading public out of the Royal Society, &c. A DISCOURSE ON PROBABILITY. About 1830 was published, in the _Library of Useful Knowledge_, the tract on _Probability_, the joint work of the late Sir John Lubbock[611] and Mr. Drinkwater (Bethune).[612] It is one of the best elementary openings of the subject. A binder put my name on the outside (the work was anonymous) and the consequence was that nothing could drive out of people's heads that it was written by me. I do not know how many denials I have made, from a passage in one of my own works to a letter in the _Times_: and I am not sure that I have succeeded in establishing the truth, even now. I accordingly note the fact once more. But as a book has no right here unless it contain a paradox--or thing counter to general opinion or practice--I will produce two small ones. Sir John Lubbock, with whom lay the executive arrangement, had a strong objection to the last word in "Theory of Probabilities," he maintained that the singular _probability_, should be used; and I hold him quite right. {280}