. Coast artillery drill regulations, United States Army, 1909. The first closing of the circuit starts the watch, thesecond stops it, and the third closing brings the hand back tozero. This operation is repeated continuously, a record of thevelocity of the wind being obtained for every three closings ofthe circuit. There is ample time between the second and thirdclosings to read the velocity of the wind. In case the elec-trical device is not provided, the watch may be started andstopped by hand, the proper instant being indicated by a bellor sounder. The record sent to the fire commanders stat
. Coast artillery drill regulations, United States Army, 1909. The first closing of the circuit starts the watch, thesecond stops it, and the third closing brings the hand back tozero. This operation is repeated continuously, a record of thevelocity of the wind being obtained for every three closings ofthe circuit. There is ample time between the second and thirdclosings to read the velocity of the wind. In case the elec-trical device is not provided, the watch may be started andstopped by hand, the proper instant being indicated by a bellor sounder. The record sent to the fire commanders stationsshould be the mean of ten readings. AZIMUTH INSTRUMENT. 753. Figure 3 illustrates the azimuth instrument. It maybe mounted either upon a tripod, as in the figure, or upon apier mount. It is used for measuring azimuths. 754. The instrument is said to be oriented when it is setup so that it will read azimuths. The operation is as follows: First. Set the graduated circle and index to read the azi-muth of a knovra datum rlEE-CONTROD APPARATUS. 155. 156 riEE-CONTEOLi APPAKATUS. Second. Witli the azimuth clamp screw loosened, set theeyepiece slightly to the left of the reading window and clampthe azimuth clamp. Third. Raise the whole instrument by grasping the top andturn it so that the telescope points in the general direction ofthe datum point with the plumb bob over the home orienting the instrument on a pier mount, the instrumentmay be turned in the proper direction by loosening all of theleveling screws. (Second and third are not essential to the reading of azi-muths, but are provided so that when the adjustment is com-plete the parts of the instrument will be in the most con-venient relative position for operation and reading.) Fourth. Level the instrument. See that all the screwshave a uniform and firm bearing on the leveling plate; setone of the levels exactly over two opposite leveling screws;turn the screws in opposite directions until the bubbles o
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