1866.] Prof. Phillips on a Zone of Spots on the Sun. 



67 



spots, there would appear reason for expectation that spots of like cha- 

 racter may be expected to recur again in the same parts of the sun's 

 surface. In the great work of Mr. Carrington we find several examples 

 of the appearance of new spots in nearly the same places as those which 

 had been so occupied before. Those who think with M. Chacornac that 

 sun-spots are due to volcanic eruptions, and regard their changes of ap- 

 pearance as effects of the displacement of solid and gaseous bodies about 

 the region of disturbance, must naturally look for repetitions of these phe- 

 nomena in the same parts of the solar surface. 



The greater frequency of spots between the parallels of 10° and 30° 

 lat. N. and S., the comparative rarity of them on the equator, and the 

 almost entire absence of them from the circumpolar regions is well esta- 

 blished. If we take the data from Mr. Carrington' s register and suppose 

 in all 1000 spots to be observed, 1/8 will be found between the parallels of 

 0° and 10° from the equator, 450 between 10° and 20°, 324 between 

 20° and 30°, and 48 above 30°. 



The proportionate numbers for the northern and southern hemispheres 

 are 450 in North latitude, 550 in South latitude. 



If now we inquire, by the aid of the same invaluable book, as to the re- 

 lative frequency of spots in different longitudes, we shall obtain a result of 

 considerable interest in reference to the question of the place of the 

 eruptions. Mr. Carrington has registered his observations through 99 

 rotations, and has arranged them in groups which can be tabulated for 

 longitude. Assuming the rotation-period to be exact enough for fixing 

 the longitudes in the course of seven years and 142 days, we may repre- 

 sent the relative frequency of the spots on different meridians as follows : — 



o o 



Longitude 10 to 20 

 ^„ 60 to 70 

 100 to 110 

 160 to 170 

 190 to 200 

 300 to 310 



320 maximum ; 

 220 minimum ; 

 313 maximum ; 

 250 minimum ; 

 366 maximum ; 

 1 73 minimum ; 



showing three maxima at intervals of 90°, 90°, and 180°, and three mi- 

 nima at intervals of 100°, 140°, and 120°. Or if we take the circumference 

 of the sun in three meridional compartments of 120° each, and suppose 

 1000 spots in all, we shall find 



to 120 .... 357 

 120 to 240 .... 368 

 240 to 360 274 



I am at present of opinion that this result may be trusted so far as to 

 show that certain tracts of the sun's surface are more liable to eruption 

 than other tracts, by reason of local peculiarity only. 



