160 U. S. COAST AND GEODETIC SURVEY. 



made for the given year. It lias been the recent practice to enter 

 the ampHtude settings to the nearest 0.05 foot as being sufficiently- 

 close for all practical purposes. 



For the dial settings for January 1 , hour, the Greenwich equilib- 

 rium arguments of {Vo + u)'s from Table 15 are to be applied, ac- 

 cording to the indicated sign, to the angles of column C or Z> of Form 

 444, using the angle in column D if it is less than the argument, 

 ■otherwise using the angle in column C. For the application of the 

 (Vo + u)'s a strip similar to that used for the factors / should be pre- 

 pared. The same strip will serve for all stations for the given year. 

 For the dial settings it is customary to use whole degrees, except for 

 component Mj, for which the setting is carried to the first decimal 

 of a degree. 



The settings for February 1 and December 31 are used for checking 

 purposes to ascertain whether there have been any slipping of the 

 gears during the operation of the machine. ■ To obtain the dial set- 

 tings for February 1, 0*", and December 31, 24^, prepare strips similar 

 to those for the/'s and (Vo + u)'s. On one enter the angular motion 

 of the components from January 1, O'^ to February 1,0"^; on a second 

 and a third strip, the angular motion for February 1, 0*^ to December 

 31, 24*^, for a common and leap year, respectively. For checking 

 purposes a fourth and fifth strip may contain the angular changes 

 lor a complete common and a complete leap 3"ear, respectively. 

 The values for these strips may be obtained from Table 36. These 

 strips will be found more convenient if arranged with two columns 

 each, one column containing the values in a positive form and the 

 other column containing the equivalent negative value which is 

 obtained by subtracting the first from 360. These strips are good 

 for all years, distinction being made between the common and leap 

 years. By applying the first strip to the dial settings for January 

 1 the values for Februar}^ 1 are readily obtained, and by appl}dng 

 the second or third strip to the latter settings those for the end of 

 the year are obtained. The values obtained by applying the fourth 

 or fifth strips to the settings for January 1 should also give the correct 

 setting for the end of the year, and thus serve as a check. The 

 angular changes for computing the settings for any day of the year 

 may be obtained from Tables 16 and 17. 



