u 



The mass of Jupiter being great, his influence is con- 

 siderable in disturbing the other planets, the disturbance 

 produced by him is the reciprocal effect produced in the 

 motions of himself and Saturn. The mutual action of these 

 immense bodies is of such a nature that if one be by the 

 disturbance put before its mean place, the other will be behind 

 its mean place. This inequality is of such a magnitude as 

 at its maximum to advance or retard Saturn by 0-49" in longi- 

 tude, and to retard or advance Jupiter by 0-21'. This great 

 inequality goes through all its changes of magnitude in 

 about 918 years. 



At a meeting of the R.A.S., Lieut. Col. Strange, F.R.S., in 

 following the Astronomer Royal as to the iiuiifficiency of existing 

 physical observatories, or what is more recognised as physical 

 astronomy, said if the study of the sun only was in question, 

 that alone would justify such a measure. There can hardly 

 be a doubt that almost every natural phenomenon connected 

 with climate can be distinctly traced to the sun as the great 

 dominant force. " It is my conviction," says Col. Strange, 

 " that of all the fields now open for scientific cultivation, 

 there is not one which promises results of such high utili- 

 tarian value as the exhaustive systematic study of the sun." 



No one who has studied the combined sciences of astronomy 

 and meteorology will deny that Col. Strange's suggestion is a 

 step in the right direction. 



The connection of planetary configurations and solar spots, 

 with terrestrial magnetism and auroral phenomena, must tend 

 to establish a connection between sun-spots and solar radiation. 

 So long ago as August 1612, Galileo wrote, in the second of 

 his three celebrated letters, that it was his oj)inion solar 

 spots have some relation to the planets. 



This principle has been made all but clear from a paper read 

 by Mr. Meldrum at the meeting of the British Association, 

 showing that cyclones of the Indian Ocean have a periodicity cor- 

 responding with sun-spots. Mr. A. Elvins, at Toronto, has fo 

 many years recorded such astronomical phenomena and storm 

 periods, the result of which, from his registered tables, is 

 that storm periods usually occur at sun-spot maxima. 



We may gather from these remarks that every solar dis- 

 turbance receives an immediate response from the earth, and 

 that the magnetic impulse travels sensibly with the velocity 

 of light. There is a counterpart of such cyclones and lateral 

 movements in the body of the sun, by which the wave-lengths 

 of luminous vibrations of light are measured in passing from 

 one colour of the spectrum to another, and by which means not 

 only the rate at which solar storms travel over the sun, but 



