MANUAL OF TIDE OBSERVATIONS 



55 



as a protection against the elements when changing the record on the 

 gage. 



180. In selecting the site for a secondary tide station existing facili- 

 ties and the accessibility of the location to an observer must generally 

 be taken into ac- 

 count. For the 



standard tide gage 

 a convenient wharf 

 is especially de- • 

 sired. Otherwise 

 some special plat- 

 form must be con- 

 structed. The port- 

 able gage, partially 

 supported by its 

 own 4-inch iron 

 pipe float well, may 

 be secured to a sin- 

 gle pile, to a fish-net 

 stake, or against a 

 cliff (figs. 20-21). 

 Care should be 

 taken to install the 

 gage at a point 

 where the depth is 

 sufficient to operate 

 the gage at low tide. 



181. The installa- 

 tion of the standard 

 automatic tide gage 

 has already been 

 described on pages 

 32-37 and its opera- 

 tion discussed on 

 pages 41-50. How- 

 ever, all the in- 

 structions given for 

 the guidance of the 

 tide observer at a 

 primary tide station 

 will not necessarily 

 be applicable to a 

 tide observer at a 

 secondary tide sta- 

 tion, who is work- 

 ing under the direc- 

 tion of the chief of party. The installation and operation of the 

 portable automatic tide gage are described on 'the following pages. 



INSTALLATION AND OPERATION OF PORTABLE AUTOMATIC TIDE GAGE 



182. Since the portable tide gage is designed to be set with stylus 

 reading in agreement with the reading on the tide staff, the latter when 

 installed should be so placed that its graduation corresponding to the 

 middle of the height scale of the record paper shall be at approximate 



FIGDHE 20.- 



Installation portable automatic tide gage on 

 fish trap stake. 



