494 Dr. P. Lowell on Photographs of Jupiter 



Introducing this correction we have : 



Antarctic belt -38°'5 



South Temperate belt -28°-9 



South edge of S. Tropic belt .... -20°'8 



dark line in ,, „ .... —17°' 2 



North edge of „ . . . . - 8°'l 



North Tropic belt + 8°-l 



North stripe of S. Tropic belt .... + 16°' 5 



North Temperate belt + 33°*7 



From this we see that the belts near the equator are here 

 symmetrically disposed with regard to that line and regard- 

 less of the declination of the Sun at the time. Hence they 

 cannot be caused by him but by Jupiter himself. Jupiter's 

 cloud envelope is therefore totally unlike our own, and is a 

 self-raised, not a sun-raised phenomenon. This state of 

 things can only be due to great internal heat setting up 

 currents which are persistent in their main features for long- 

 intervals of time. At other longitudes their latitudes differ ; a 

 feature, interesting as it is, into which I do not propose here 

 to enter, and unaffeeting apparently the present conclusion. 



The latitudes we have deduced are those on a sphere of 

 radius equal to the polar radius. To correct these to the 

 apparent latitude on the planet we proceed as follows. In 

 an oblate spheroid any meridianal plane cuts out an ellipse 

 in which all lines perpendicular to the polar axis are in- 

 creased over those of the sphere with that axis as diameter 



in the proportion of j to b where 



a = equatorial diameter, 

 b = polar „ 



If, then, cc = colatitude measured on the sphere, 



a'= „ „ „ ellipse, 



we have tan a' = T tan a. 

 b 



This gives for the apparent latitude on the planet for the 

 several belts : — 



Antarctic - 36°'7 



South Temperate — 27°\3 



South edge of S. Tropic ...... — 19°'7 



dark line in „ — 16°*2 



North edge of „ - 7 a 6 



North Tropic + 7°'6 



North stripe of N. Tropic -f-15 c, 5 



North Temperate + 32°'0 



