1878.] 



Declination at Trevandrum. 



87 



them occurred at Kew (the Trevandrum observations having been 

 discontinued) on August 15, 1867. The period is thus one of eleven 

 years and six months. 



On the other hand, the sun-spot period is that between September 

 15, 1855, and March 15, 1867, being likewise eleven years and six 

 months. 



C. Variations ivhich seem to depend on Planetary Configurations. 



8. In a paper on the Kew declination-range already alluded to, it 

 was shown that the planetary periods of most frequent occurrence 

 appear to be well indicated by the results of sixteen years' observa- 

 tions. Indeed, for the two periods of shortest length — that of 

 Mercury about the sun, and that of Mercury and Jupiter, it was found 

 that half of the observations gave a result of the same character as 

 the whole sixteen years. 



From this we might conclude that these periods will probably (if 

 they have a real existence) be indicated by the Trevandrum observa- 

 tions. 



It will be seen from the following tables that the Trevandrum 

 declination-ranges give results for these two planetary periods very 

 similar to those given by the Kew observations. 



Table Y. — Period of Mercury about the Sun. 

 (0° denoting Perihelion — 65 sets for Kew — 47 for Trevandrum.) 



o 





O 



Kew. 



Trevandrum. 







and 



30 



+ 429 



+ 263 



30 



»? 



60 



+ 433 



+ 223 



60 



5) 



90 



+ 256 



+ 237 



90 



55 



120 



+ 5 



+ 300 



120 



55 



150 



-280 



+ 150 



150 



5) 



180 



-439 



-433 



180 



■>■) 



210 



-413 



-879 



210 



55 



240 



-279 



-740 



240 



55 



270 



-140 



-263 



270 



55 



300 



+ 13 



+ 333 



300 



55 



330 



+ 158 



+ 680 



330 



55 



360 



+ 278 



+ 506 



