PROCEEDINGS OF THE CANADIAN INSTITUTE. 115 



Sun-Spots and Weather Cycles. By A. Elvins. 



{Read isth February, l()02.) 



We all feel interested in the weather, our personal comfort and the prosperity 

 of our country depend very much on it. Some seasons are early, some late : 

 some ivet, some dry : our farms and gardens are productive or the reverse, as the 

 weather is favourable or unfavourable ; the opening or closing of navigation, 

 whether it is early or late, depends on the weather, and this is important to our 

 sailors, and to trade and commerce generally. If we could foretell the general 

 character of a coming season we could act, so far as possible, to meet coming 

 conditions. 



Nations have seen the importance of knowing the climate of the different ' 

 parts of the earth's surface and have erected and maintained observatories where 

 observations are made and preserved. From these records the mean meteoro- 

 logical conditions existing at such localities are known. 



But the extremes, rather than the mean conditions, are what is needful to be 

 known. Every one knows that we sometimes get a wet spring, and on other 

 years a dry one. Our pastures are some years green in summer, at others dry and 

 parched. In 1843 and again in 1878 Ave had above 4' inches of rain at Toronto, 

 and less than 18 in 187-4 and 1887. What can be the cause of these changes? 



We know that our summer results from the northern hemisphere of the earth 

 being then turned sunward, and our winter from the same hemisphere being turned 

 from the sun, and we naturally turn to the sun and try to find an answer to our 

 question from it. 



Ever since the invention of the telescope the sun has been an object of great 

 interest to astronomical observers ; sometimes it is a spotless globe of light, and at 

 others, one or more spots are seen on its surface. They break out unexpectedly, 

 exist for a short time, occasionally two or three nionths, and graduallj' disappear. 

 Some of those spots are of great magnitude. I have seen some more than 100,000 

 miles in length, or rather the group has been that long. In and around these 

 spots the sun's surface seems very much disturbed, and with the aid of the 

 spectroscope great uprushes of gases can be seen rising to an enormous height ; 

 and we are led to ask if those great solar outbursts, sun-spots, etc., are not the 

 cause of our weather changes. 



I shall have to return to those sun-spots, but here I shall diverge a little to 

 refer to another fact. When a magnet is suspended so as to move freely on a 

 pivot as in surveying instruments, and properly protected from local disturbances, 

 it points in a definite northerly direction and is as a rule stationary. But it is 

 not always without motion ; sometimes it vibrates from side to side of the main 

 line, and this continues for a time, and then disappears. This is known as a 

 magnetic storm. 



Such magnetic storms are found to be more frequent when the sun is much 

 spotted than at other times, and it has been thought that these sto7-ms are caused 

 by the disturbance on the sun, which disturbs the ether of space, and the 

 magnetism of the solar system ; that is, that magnetic storms are the result of the 

 outbreak of sun-spots, or as Mr. Harvey thinks, of the disturbance to which the 

 spots themselves are due. 



There is also another phenomenon which must not be overlooked, that is, 

 auroral displays. We at Toronto have had good opportunities of studying these, 

 for we have been well situated for their observation during the past century, and 

 the displays have been frequent and very grand. Like the disturbance of the 

 magnetic needle, the auroral displays are more frequent and brilliant when the 

 sun is most spotted, and when we plot the number of occurrences in a curve for 

 many years we find the sun-spot curve, the curve of magnetic disturbance, and 



