1898-99.] MAGNETIC INFLUENCE OF SUN ON THE EARTH AND ON COMETS. 357 
place at the date mentioned. I exhibit the curve drawn from the data 
there given as to the Horizontal Force, where you can see this depres- 
sion, and I may add that the vertical force was more marked on 
October 3rd than on any other day in the whole year. 
Mag. Hor. Foree, Bombay. 
5 lo 15 20 
It seems then that if, while a comet is near perihelion, a great solar 
outburst takes place on the side of the sun which faces it, or if the out- 
burst, as is usually the case, remains magnetically active until by rota- 
tion it is brought to face the comet, the vagrant body is thrown into a 
state of excitation, and is in danger of disruption. 
This strange, yet quite to be expected connection, is a new discovery, 
so far as we here know, and if on further observation and enquiry it 
proves unchallengeable, it will have interesting consequences. 
Having thus shewn that solar activity has an effect which we can see, 
on bodies other than the earth, it will be in order to examine if it influ- 
ences the belts on Jupiter. If Mr. Stupart will have Venus examined 
with care when there is a magnetic storm, he may find traces of aurora 
there, and the occasional vision we get of the unillumined part of her 
disc may be accounted for with reasonable certainty. 
Magnetology has for a long time been stationary, but signs are not 
wanting that it is about to take higher rank among the sciences. It may 
be that another branch is being added to it, and that celestial magnetism 
may occupy some pages in the book of knowledge. 
The science has been hitherto in a position comparable to that of 
astronomy in pre-Copernican times. The ever-varying curves, which 
when superimposed in any way—by solar rotations, by sun-spot periods, 
or by aliquot parts of the Terrestrial calendar—interlace in apparently 
inextricable confusion, are like the motions of the planets under the 
