mensuration, and the stereometricon (a mode of cubing all solids by one and the same rule, thus reducing the study and labour of a year to that of a day or an hour), which he had then but recently invented, and for which he was made honorary member of several learned societies, and received the numerous medals and diplomas already alluded to. The following letter from the Ministry of Public Instruction, Russia, is worthy of insertion as explanatory of the advantages of the stereometricon: DEPARTMENT OF PUBLIC INSTRUCTION, St. Petersburg, Feb. 14th, 1877. To M. BAILLAIRGÉ, architect, Quebec, SIR,—The Committee on Science of the Department of Public Instruction (of Russia) recognizing the unquestionable usefulness of your “Tableau Stéréométrique,” for the teaching of geometry in general, as well as its practical application to other sciences, is particularly pleased to add its unrestricted approbation to the testimony of the _savants_ of Europe and America, by informing you that the above “Tableau,” with all its appliances, will be recommended in the primary and middle schools, in order to complete the cabinets and mathematical collections, and inscribed in the catalogues of works approved of by the Department of Public Instruction. Accept, sir, the assurance of my high consideration. E. DE BRADKER, Chief of the Department of Public Instruction.