MANUAL OF TIDE OBSERVATIONS 



23 



its driving gear, then take out the six screws holding the cover plate 

 (31, fig, 13) and remove it from the face of the drum. Slide the drum 

 away from the standard toward the gear train and remove the screw 

 which fastens the inner end of the spring to the fixed shaft. (This 

 screw is slotted in its shank instead of in its head.) Take out the 

 screw holding the other end of the spring in the drum and remove 

 broken spring. Now, put in the screw, which is slotted in its shank, 

 through the round hole in the inner end of the new spring and fasten 

 this end of the spring in place to the fixed shaft, wind the spring so 

 that it will fit into its recess in the drum and attach its outer end in 

 the drum case by means of the screw provided for that purpose, and 

 reassemble. About a teaspoonful of fine watch oil should be put in- 

 side the case through the charging hole, which is closed by means of 

 one of the six small screws (32, fig. 13) holding the cover plate in 

 place. 



50. Fair leader. — This is a pulley mounted on a brass arm attached 

 to the bottom of the base of the instrument and extending down 

 inside the short section of float pipe. It is secured in place by a 

 clamping screw (26, fig. 13). Its purpose is to guide the float wire 

 from its drum to the center of the float well. 



51. Gears. — The float wire drum actuates the stylus screw through 

 a train of three gears (11, 8, 6, fig. 11). The two gears (11, 6) are 

 interchangeable with other gears furnished with the instrument to 

 obtain different scale ratios. The middle gear (8) is an idler used 

 for all scale ratios and provision is made for an adjustment of its 

 position to properly mesh with the other gears in use. Each gea«r has 

 the number of teeth stamped in the metal and the combinations to be 

 used are shown in the accompanying table : 



52. Scale of gage. — By changing the combination of gears as indi- 

 cated in the table above, five different height scales may be obtained 

 ranging from 1 : II14 to 1 : 45. The maximum range of tide which 

 can be recorded as a continuous curve with the different scales is also 

 indicated in the table. However, if an unexpected extreme high or 

 low water does carry the stylus to one end of the stylus screw beyond 

 the limit, evidence is usually left which will enable an experienced 

 tabulator to determine the approximate height reached by the tide. 

 The absolute limit of range which can be recorded by the present 

 gage, operating under usual conditions, is fixed by the length of wire 



