man at different places is made by the “extra duty pay,” and commutation of allowances (rations, quarters, fuel and clothing) when they can not be furnished in kind. The entrance into the service is by an enlistment of five years. Every man must pass a rigid examination into his physical and educational qualifications. The service presents advantages not found in any other branch of the army. The inducements attract a well educated class of men, many of them graduates of colleges, who find in the scientific part of the work at least, a congenial pursuit. The school of instruction is at Fort Myer (formerly Fort Whipple), a military station in Virginia, on the bank of the Potomac river, nearly opposite Washington city. The course embraces the drill and discipline of the soldier, the code of signals, the construction and operation of telegraph lines, the use of meteorological instruments, and the method of taking observations. The central office in Washington occupies an ordinary looking brick building of uncertain age, half a square west of the War Department building. It was originally two two-story dwelling houses, but has received an additional story and “Mansard” roof, and has been fitted for its present use. The plain and dingy exterior escapes critical notice by the display of the mysterious looking machinery and fixtures upon the roof. An immense arrow (anemoscope), with broad feather-tip end, turns its point ever “in the wind’s eye,” and is imitated by two smaller ones at a lower elevation. Several sets of spinning instruments of various sizes stand in different places. These are the anemometers for measuring the velocity of the wind. The part of each visible from the ground is simply a vertical rod with four branches on the top, each branch having a hemispherical shaped cup upon its outer end, so placed as to catch the wind in its convex side. The force of the wind gives the cups a rotary motion in a horizontal plane, which causes the vertical rod to revolve and record by connecting mechanism and dials the velocity of the wind in miles per hour. Near the center of the roof may be seen a vessel with a funnel shaped top into which the rain falls and is measured to ascertain the depth in inches, of which accurate record is kept. Close by is a framework supporting a small cage-like structure with lattice sides and tight roof, within which are hung the thermometers, barometers, and other instruments consulted regularly at intervals, to ascertain the temperature, pressure, and humidity of the atmosphere. These fixtures and instruments are used for the purpose of obtaining indications of the weather, and for the instruction of “Observers,” and serve as well for standards by which instruments to be sent to other places may be tested. Only a portion, however, of the business of the office is done in the building mentioned, a number of others in the vicinity being occupied for the several departments of the work.