The amount of fuel supplied to any one of the motor units can likewise be controlled from a central board, and this is also true of the ballast release apparatus, so that water can be emptied from any one of the ballast tanks at will, thus facilitating ascent or descent by lightening one end or the other. Elevating and steering surfaces are operated by small hand-steering wheels with cables passing around their drums, a member of the crew being stationed at each of these controlling wheels. Owing to the number of motors used, the instrument board is the most formidable appearing piece of apparatus on the bridge, since there is a revolution counter for each power unit in addition to the numerous other instruments required. Some of these instruments are the aneroid barometer for indicating the altitude, transverse and longitudinal clinometers to show the amount of heel and the angle at which the airship is traveling with relation to the horizontal, the anemometer, or air-speed indicator, manometers, or pressure gauges, for each one of the gas bags, fuel and ballast supply gauges, drift indicators, electric bomb releasers, mileage recorders, and the like. In addition to these, there are a large chart and a compass, so the navigating bridge of a Zeppelin combines in small space all the instruments to be found in the engine room and on the bridge of an ocean liner besides several which the latter does not require. That the proper coordination of all the functions mentioned is an exceedingly difficult task for one man seems evident from the numerous Zeppelins that have apparently wrecked themselves. *Crew Carried.* In the various Zeppelins that have been captured or shot down by the British or French, the personnel has varied from fifteen to thirty men but in the majority of instances has not exceeded twenty. The positions and duties are about as follows: The commander, lieutenant-commander, and chief engineer, and possibly a navigating officer are stationed at the bridge. Two or three of the crew are also stationed there to work the manually operated controls. In the cabin just back of the bridge are two wireless operators and one or two engine attendants for the motors in the engine room behind the wireless room. A similar number of engine attendants are stationed in the after engine room and there is at least one attendant for each of the other motor units. One man is stationed at each machine gun, of which there are three to five on the "roof" and two in each car, and at least as many bombers are needed to load the "droppers." As a reserve there are usually an additional gun pointer for each gun and an extra engine attendant, since to run continuously most of the crew would have to stand watch and watch as in marine practice. The sleeping accommodations consist of canvas hammocks slung in the gangway.