84 



TABLES OF NEPTUNE. 



take the arguments from Tables I.-IV. more than once in three or four, or even 

 five, years. The intervals of computation are first to be chosen, and need not he 

 less than 180 days for the heliocentric place. Then compute the values of I, y, 0, 

 and the arguments for the first date of the series, and again for a date an integral 

 number of intervals (not generally exceeding ten) later. The longitudes and 

 arguments for the intermediate dates may then be found by continual addition 

 of the differences for 180 days (if this is the interval) from the bottom of Table I. 



39. Examples of (lie use of the tables. 



As a first example, we will compute an ephemeris of the heliocentric positions 

 of Neptune for the years 1865 to 18G8 inclusive. The intervals of computation 

 will be 180 days, and we commence with the date 1864, Oct. 13, and end with 

 1869, March 21, between which are nine of the assumed intervals. We first 

 compute the epochs and arguments for the extreme dates as follows : 



