28 
MR. C. CHAMBERS OH LUNI-SOLAR VARIATION'S OF 
17. Regarding these numbers as the amplitudes of the eight simple waves whose 
periods are specified in paragraph 13, we see that generally B 3 , and in a less degree 
A 1 —which refer to the lunar half-day and the lunar day respectively—form important 
elements of the whole luni-solar variation ; and scarcely less important are the 
elements that have the A 3 ’s for their amplitudes : the numbers for the remaining five 
periods are generally smaller, though for none of them are they so small as to 
approach general insignificance. 
18. Up to this point we have, in comparing our formula with observation, had to 
adapt to the purpose variations obtained for the period of the lunar day. It would 
obviously be a more direct procedure to arrange the so-called lunar differences of a 
given season in solar days, according to the age of the moon, and, although the labour 
of copying out the numbers so arranged, and of re-computing, is considerable, we 
have thought the verification of the results obtained by the indirect mode of pro¬ 
cedure of sufficient importance to justify the undertaking of the task, at least in 
respect of the element of declination, and for that season, November to January, 
when the luni-solar variations at Bombay have the largest range. Accordingly, 
abstract sheets were prepared for the 1st, 2nd, 3rd, &c., solar days after new moon, 
embracing all such days in the months November to January of the years 1846 to 
1870. The hourly sums and means and the diurnal variations were then taken on 
each abstract sheet, with the results shown in Table 23. 
