METEOEOLOGICAL PEEIODICITT. 155 



factory ; but to make assurance doubly sure, I determined to 

 make up a longer period ; this I accordingly did for 140 years, 

 and I was so disappointed at the total disappearance of both ten 

 and twelve-year periods that I cannot say that I have closely scruti- 

 nized the values herein given." Mr. Symonds is also inclined to 

 adopt Mr. Meldrum's theory of wettest years with greatest sun 

 spots. 



But no period has found such general favour as that known as 

 the sun-spots, or eleven-years period. Its advocates assert that 

 meteorological phenomena vary as the area of spots on the sun's 

 surface ; that when they are at a maximum we have the maximum 

 of hurricanes, violent storms, and rainfall. To Mr. Meldrum, of 

 the Mauritius, belongs the honor of first pointing out the coinci- 

 dence of these phenomena, not only for the Mauritius, but also for 

 a large number of stations, so far as maximum rainfall is concerned ; 

 and it appears that out of the stations examined sixty- seven 

 have the maximum rainfall between 1859 and 1862. Amongst these 

 are included two of the Australian stations, Brisbane and Adelaide, 

 which, to a certain extent, agree with this theory, while the other 

 three Australian stations, where a long series of observations have 

 been made, are left out. It is not stated whether the sixty-seven 

 stations were selected, but the three Australian stations omitted do 

 not agree with it, while the two that are taken, to a certain extent do 

 agree. Speaking of these rainfall investigations, Mr. Lockyer 

 grows warm, for he says : — "A most important cycle has been 

 discovered, analogous in most respects to the saros discovered by 

 the astronomers of old. Indeed, in more respects than one may 

 the eleven-yearly period be called the saros of meteorology ; and 

 as the astronomers of old were profoundly ignorant of the true 

 cause of the saros, so meteorologists of the present day are pro- 

 foundly ignorant of the true nature of the connection between 

 the sun and the earth." No doubt this theory has for a time met 

 the growing feeling amongst students of this subject, viz., that 

 we must look outside the earth for the true explanation of its 

 irregular as well as its regular meteorological changes ; but I do 

 not think that we find in it the final answer. In the first place, the 

 sun-spots period is not an eleven years period ; it is generally 

 called such, but if we examine records of the maxima and minima 

 we find a very different result, for the period between maxima 

 actually varies from seven to fifteen years, nay, it is itself subject 

 to variations in intensity as well as in time ; and there is much 

 that indicates an unknown cycle in this phenomenon also.'* 



■•'■ Proctor has shown, page 188, "Science By-ways," that the sun-spot 

 period cannot be traced in the earth's temperature, and the connection, if 

 any, between it and rainfall and wind cannot, up to the present time, be 

 considered proven, if indeed the evidence does not tend the other way. 



I 



