METEOEOLOGICAL PEEIOBICITr. 157 



Maximum period 1859-60-61 ... 183 inelies of rain.. 

 Minimiim „ 1866-67-68 ... 140 

 Maximum „ 1869-70-71 ... 165 



A period of twelve years has by some been thought to exist and 



be connected with Jupiter's revolution about the sun. Xo doubt 



this planet has a great influence on the solar system, and controls 



some of its meteor streams ; but althougji I am fully prepared to 



admit the possibility of this action directly aifecting our climate 



' — and some confirmation appears to be found in such series as 



1866) or— 1865") 



1854 [ dry 1853 [ 



1842) 1329 3 



(the intermediate year 1841 was very wet) — yet it fails altogether 

 when extended to other series, and rainfall measurements show 

 no trace of it. We are therefore compelled to feel, like Mr. 

 Symonds, disappointment that it cannot be traced. 



A period of thirteen years is said to be recognised by the 

 majority of observers in Ceylon, and that the intensity of the 

 •monsoons, rainfall, and cloudy weather, vary in this cycle. 



In America there are some indications of a period of seventeen 

 years, and it is said that one of the marked features is the regular 

 return of a plague of locusts. 



In the British Association Eeport for 1842, page 24, Luke 

 Howard, P.R.S., attempted to prove a period of eighteen years 

 in the climate of England, from his own observations at Ack- 

 worth, in Yorkshire ; but when he afterwards (1845) attempted 

 to predict the weather on this theory, he stated that his lunar 

 period was modified by the facts then taking place, and I am not 

 aware that this period has been advocated by any one else. 



The next period, " nineteen years," we will pass over for the 

 present, to mention an opinion expressed by Mr. Jevons, whose 

 valuable investigation into the climate of Australia gave him every 

 facility for forming a correct estimate of our climate. He says 

 (at page 81 of his work) : — 



" I think it will appear pretty plain from the table of floods 

 and droughts that the history of the Australian Colonies compre- 

 hends only two complete and two incomplete climatic periods, 

 thus) : — 



Period. Commencing. Terminating. Characterised by 



1. 



2. ... 1799 



3. ... 1822 



4. ... 1842 



1798 ... Drought 



1821 ... Elood 



1841 ... Drought 



Not terminated Flood, 

 in 1858 



There can be no doubt that, taken as a whole, the second 

 period, 1799 to 1821, was one of great floods ; but 1808, 1810, 



