PROCEEDINGS OF THE CANADIAN INSTITUTE. 113 



that particular irregularity. In Toronto there is evidently no settled relation 

 between annual temperatures and sun-spot frequency. Many times sought for, 

 any correspondence whatever has eluded the researches of others besides myself. 

 But this is the worst of places in which to look for periodicities in weather, the 

 areas of low barometric pressure coming from the Rocky Mountain districts may 

 go a hundred miles north or south of us, and thus introduce a disturbing element 

 which battles investigation. Even a slant of wind off the lakes may cool the 

 shores, or its absence heat them, and thus disturb the temperature of any given 

 day. It is in Tropical regions and in places where storms of wind and rain with 

 thunder and lightning are rare, that we may probably discover a periodicity corre- 

 sponding w'ith that of solar rotation, and perhaps even find a temperature curve 

 agreeing with the sun spot cycle ; but such changes must be very slight, on the 

 general average, and it is the height of absurdity to hold the sun responsible for a 

 great excess of heat or cold lasting for a whole season. The excess or defect of 

 mean temperature at Toronto above or below the average is seldom a degree, and 

 has never been known to be four ; vei-y hot seasons here are probably balanced by 

 cool ones in other parts.* We are therefore working on very small margins. This 

 is natural, since the sun and the earth are not in their youth. Lord Kelvin has 

 reduced his estimate of the time the earth has lasted since the first crust covered 

 its surface from a hundred million years to forty, but though I side with the 

 geologists who think a hundred millions are too few, yet in this connection I can 

 be content with the smaller number as an estimate. For, before its crust formed, 

 there were long aeons during which the earth was an agglomeration of mere 

 vapours. Nor is Terra the first born, but, with Venus, is a daughter of the sun's 

 old age, while Mercury is his Benjamin. Mars, Japiter, Saturn, Uranus, Neptune, 

 and probably another, are his elder sons. The sun then has had time to become 

 fairly steady. Being a ball of gas, convection-currents are probably doing their 

 work quietly ; the solar disturbances cannot be of the nature of a terrestrial 

 eruption in which the violence seems to be determined by the resistance to interior 

 forces of an exterior crust. The spots float up from the places which these 

 convection-currents disturb, and as stated at the beginning of this paper they are 

 probably nothing more than large quantities of vapours much attenua,ted on 

 reaching the surface, possibly absorbent of light vibrations, certainly so 

 constituted as to interfere with them. But though these produce the primary 

 effects of solar disturbance but slight secondary effects here, there is something 

 irresistibly attractive in observing them and endeavoring to account for their 

 origin and nature. 



* The average in Toronto since 1840 has been 44°. In 1875, the average was 40°.o7, and in i88q it was 47<'.o2. 



