58 U. S. COAST AND GEODETIC SURVEY 



to the stylus screw and the float-drum axle are easily removed after 

 taking off the nuts (7, 12, fig. 11) holding them in place. 



188. Record cylinder. — The record cylinder with the clock move- 

 ment inside is now installed in its supports. The clockwork rotates 

 the cylinder in such a direction that its top moves toward the stylus 

 screw, and when installing the cylinder it should be placed in its sup- 

 ports with the capstan nut (4, fig. 11) on the same side of the instru- 

 ment as the train of gear wheels, this being designated as the front 

 of the gage. 



189. Record paper. — Five different scales of record paper are pro- 

 vided and care must be taken to select the scale desired and to see 

 that the ^ears printed on the sheet are the same as the corresponding 

 gears on the gage. With the capstan nut (4, fig. 11) loosened, the 

 paper is placed on the cylinder with the zero of the height scale 

 toward the front of the instrument ; that is, at the same end of the 

 cylinder as the capstan nut. The paper is held in place by a metal 

 clip (24, fig. 12), this clip being released at one end when installing 

 the paper. After the paper is in place, the cylinder is turned until 

 the stylus reading on the paper scale corresponds approximately to 

 the correct time and the nut at the end is then tightened to secure 

 the cylinder in this position. 



190. Two days of record are traced on the sheet of paper for each 

 revolution of the cylinder. Since the times of high and low water 

 occur about 50 minutes later each day, the tide curve traced on the 

 same sheet during several revolutions of the cylinder separates suffi- 

 ciently to be distinctive unless the range of tide is very small. Al- 

 though a singe sheet of record paper might serve for an entire week, 

 it is recommended that a new sheet be placed on the gage every 3 or 

 4 days. 



191. Setting stylus. — To set the stylus to the approximate height of 

 the tide as read on the tide staff, the nut (7, fig. 11) holding the upper 

 gear to the stylus screw is undamped, and the stylus screw may then 

 be turned freely to bring the stylus to the reading desired. The gear 

 is then again clamped in position. A finer adjustment for height may 

 now be obtained by means of the slow-motion screw (25, fig. 12) pro- 

 vided for the purpose. The stylus should be reset to agree with the 

 staff reading each time the record paper is renewed. 



192. While the approximate time setting of the stylus is obtained 

 by the turning of the record cylinder as described in paragraph 

 189, a finer adjustment is secured by means of the slow-motion screw 

 (34, fig. 13). When setting the stylus for time, whatever slack there 

 may be in the record cylinder due to lost motion in the gears should 

 first be taken out by lightly placing the hand on top of the cylinder 

 and drawing it in a direction away from the stylus. 



193. Care of clock. — Although the clock enclosed in the record 

 cylinder has an 8-day movement, it is recommended that it be wound 

 semiweekly. The clock is regulated by means of the small end of the 

 clock key inserted in the small keyhole in the front end of the cylin- 

 der. When regulating the clock, however, the record cylinder should 

 be allowed a full 48-hour revolution and the clock movement adjusted 

 according to the amount that it fails or overruns a complete revolu- 

 tion of the cylinder and not for any particular hour on the cross- 

 section paper. 



