298 Mr. C. Meldrum on a connexion [May 15, 



With this idea, it was some time ago determined to discuss the cyclones 

 that had occurred during the last twenty-five years in the Southern Indian 

 Ocean, and it was found, what had been often surmised, that they were 

 more frequent and more violent in the maxima than in the minima sun- 

 spot years. 



It is well known that the cyclones of the Indian Ocean are attended 

 with much rain, which is not confined to the body of the storm, but ex- 

 tends over wide areas. Years remarkable for cyclones, therefore, should 

 be also years remarkable for rain ; but to test this inference, with regard 

 to the Indian Ocean, we had no rainfall statistics, except eighteen years' 

 observations at Mauritius : and these were in every respect favourable, 

 the rainiest years having been those in which cyclones were most abun- 

 dant. In the absence of other data, the Brisbane and Adelaide rainfalls 

 were consulted ; and it was found that, like the Mauritius rainfall, they indi- 

 cated a periodicity. It was then surmised that there might be a rainfall 

 periodicity generally, and that, if such was the case, both it and the cy- 

 clone periodicity were concomitant effects of one and the same cause. 

 This supposition haying been strengthened by the results of an examina- 

 tion of the rainfall of England, it was resolved to examine all the rainfall- 

 tables (containing one or more sun-spot periods) that could be obtained. 



The first step was to ascertain whether there was any marked differ- 

 ence in the amount of rainfall at or about the turning-points of the sun- 

 spot period. This has been done for eighteen stations by adding the 

 rainfall in the three principal years of maxima, and in the three principal 

 years of minima sun-spots, and then comparing the results. The follow- 

 ing Table gives the stations and the years of observation :- — 



Table I. 











Yea 



rs of 





Stations. 



Lat. 



Long. 



Observation. 











From 



To 



I. 





59 55 N- 



/ 

 10 43 E. 



1839 



1863 



2. 





57 09 N. 



2 06 W. 



1829 



1867 



3- 





56 34 N. 



2 35 w. 



1843 



1868 



4- 



Deanston House, Perthshire ... 



i837 



1865 



5- 





55 56 N. 



3 03 w. 



1852 



1865 



6. 



Carbeth-Griithrie, near Glasgow 





1815 



1859 



7- 









1836 



1864 





Greenwich (Observatory) 



51 29 N. 







1815 



1869 



I: 





50 51 N. 



4 22 E. 



1833 



1861 



IO. 





43 29 N. 



75 04 W. 



1854 



1869 



II. 





22 33 N. 



88 21 E. 



1853 



1871 



12. 





13 64 N. 



80 14 E. 



1843 



1849 



13- 





6 49 N. 



58 15 W. 



1846 



1856 



14. 



Mauritius (Observatory) 



20 ic S. 



57 3 oE - 



1854 



1872 



15- 



Brisbane (Observatory) 



27 28 S. 



153 c6 E. 



i860 



1871 



16. 





29 30 s. 



38 02 E. 



1858 



1867 



17. 





33 56 S. 



18 49 E. 



1842 



1869 



18. 



South Australia (Adelaide) 



34 54 S. 



138 38 E. 



1839 



i860 



