26 



NA TURE 



\_May 2, 1878 



Kew observations not having then begun) on February 15, 1856, 

 and the second of them occurred at Kew (the Trevandrum ob- 

 servations 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 Sep- 

 tember 15, 1855, and March 15, 1867, being likewise eleven 

 years and six months. 



d. Variations which seem to defend on Planetary Configurations, 



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

 it was shown that the planetary periods of most frequent occur- 



rence appear to be well indicated by the results of sixteen years 

 observations. 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 

 observations. 



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. 





,7ront3 .1' 



Period of Mercury about the Sun. 

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



Between 



