The officers of the marine artillery are liable to be sent on board ship to study naval gunnery, so as to be in a position to report upon alterations or improvements in this science. NAVAL ARCHITECTS.--(_Génie Maritime._) The naval architects are charged with the construction and repair of vessels of war, and with the manufacture of all the machinery required in the ports and dockyards. The factories of Indret and La Chaussade are under their direction. The pupils of the Polytechnic enter the corps of naval architects with the rank of _élève du Génie Maritime_. They are sent to the School of Application of Naval Architects at L’Orient. After two years’ instruction they undergo an examination, and, if successful, they are promoted to the rank of sub-architect of the third class, so far as vacancies admit. They may be advanced to the second class after a service of two years. HYDROGRAPHERS.--(_Ingénieurs Hydrographes._) The hydrographers are stationed at Paris. They are sent to the coast to make surveys, and the time so spent reckons as a campaign in determining their pension. On their return to Paris they are employed in the construction of maps and charts. The hydrographers have the same rank and advantage as the naval architects. On leaving the Polytechnic, the pupils enter the corps of hydrographers with the rank of _élève hydrographe_. After two years’ service, and one season employed on the coast, they become sub-hydrographers without further examination. ROADS AND BRIDGES.--GOVERNMENT CIVIL ENGINEERS.--(_Fonts et Chaussées._) The Polytechnic furnishes exclusively the pupils for the Government Civil Engineer Corps. On leaving the Polytechnic, the pupils enter the School of Application in Paris. The course of instruction here extends over a period of three years. It commences each year on the first of November, and lasts till the 1st of April. After the final examination, the pupils are arranged according to the results of the examination and the amount of work performed. The pupils enter the college with the rank of _élève de troisième classe_. They rise successively to the second and to the first class, on making the requisite progress in their studies. From the 1st of May to the 1st of November the _élèves_ of the second and the third class are sent on duty into the provinces. The _élèves_ of the first class who have completed their three years’ course of instruction, are employed in the duties of ordinary engineers, or are detached on special missions. In about three years after quitting the college, they may be appointed ordinary engineers of the second class.