156 



METEOROLOGICAL PEEIODICITY. 



In tlie next place, in the tropical limits of hurricanes, where 

 the cycle is said to be most conspicuous, the truth of the theory 

 Jias been denied by other observers, and I do not think that we 

 can be satisfied with such an uncertain cause or coincident 

 phenomena as the solution of our difficulty. It is true that the 

 increase of sun-spots can be seen year by year, and to a certain 

 extent the approach of a maximum can be detected in this way ; 

 but the sun-spot curve is a most irregular one — sometimes re- 

 maining almost stationary, and then, with a great outburst, 

 running rapidly upwards. Besides, the great charm of a period 

 is gone, if it may be seven or fifteen years long, as the case may 

 be. Eor convenience I will here give the recorded dates of 

 maxima and minima of sun-spots from " Loomis' Meteorology :" — 



Su:s^-spoT Periods. 







o 



==s 















f^ 



WH 



Remarks. 





Remarks. 



93 





Year. 



1778 



111 



11 



1789 



73 



15 



1804 



44 



12 



1816 



58 



14 



1830 



111 



7 



1837 



101 



11 



1848 



98 



12 



1860 



140 



10 



1870 



Slight rise in cui've — year 1781 

 Rapid fall to 1791, then gradual 

 Quick fall to 1806, then gradual 

 Gradual fall to 1820, then slow 

 Quick fall 



Verj' quick fall to 1838, then 



quick fall. 

 Rapid fall to 1850, then a stop, 



and again a quick fall. 

 Quick fall to 1863, then rise, 



and again quick fall. 

 Rapid fall 



Year. 



1784 





1798 



14 



1810 



12 



1823 



13 



1833 



10 



1845 



12 



1856 



11 



1867 



11 



Rose nearly to max. by 1787. 



Gradual I'ise. 



SlovvT rise. 



Steady rise until 1828, then 

 slight fall, and again a rise. 

 Very rapid rise. 



Rapid rise. 



Very i-apid rise. 



Very i*apid rise. 



The duration of this period has been variously stated as 11, 111-, 

 and Hi years, with how much regard to observations we have 

 already seen. Taking the rainfall at Sydney, 1860 had the great- 

 est recorded rainfall here ; but another year given as one of the 

 limits of maximum, 1862, was, with one exception, the driest on 

 record, while the nearest approach in rainfall here to 1860 was 

 1841, which was not a year of maximum or minimum sun-spots, 

 but is exactly nineteen years from 1860. 



Using our rainfall observations, as has been done in Mr. Meld- 

 riim's discussion of the results at other places — that is, taking 

 three years together, one on each side of the maxima and minima, 

 we get the following results : — 



Minimum period 1843-44-45 

 Maximum „ 1847-48-49 

 Minimum „ 1855-56-57 



195 inches of rain. 



115 



147 



