ing Jupiter with good telescopes, both reflecting and refracting, for twenty or 

 thirty years past ; and among several hundreds of observations, has never 

 seen above four or five belts at one time. The most -common appearance ob- 

 served, is that of two belts distinctly marked, one on each side 01 the planet's 

 equator, and one at each pole, generally broader, but much fainter than the 

 others. He has never perceived much change in the form or position of the 

 belts during the same season, but in successive years a slight degree of change 

 has been perceptible, some of the belts having either disappeared, or turned 

 much fainter than they were before, or shifted somewhat their relative posi- 

 tions, but has never seen Jupiter without at least two or three beks. Some 

 of the largest of these belts being at least the one eighth part of the diameter 

 of the planet in breadth, must occupy a space at least 11,000 miles broad, and 

 270,000 miles in circumference ; for they run along the whole circumference 

 of the planet, and appear of the same shape during every period of its rotation. 

 It is probable that the smallest belts we can distinctly perceive by our tele- 

 scopes are not much less than a thousand miles in breadth. 



CAUSES OF THE BELTS. 



It is well known that the diurnal motion of the earth, combined with the 

 heat of the sun acting directly on the intertropical regions, produces those at- 

 mospheric currents which blow with a constancy and regularity so singular 

 from east to west in the lower la-titudes of both hemispheres. These currents 

 are attended with others in a contrary direction, wkick entitute their reac- 

 tion, blowing almost as constantly and regularly from west to east in the 

 higher latitudes. Thus the atmosphere covering th surface of the earth is 

 continually swept by systems of currents blowing in either direction parallel to 

 the line and these currents will have a tendency, in proportion to their force 

 and regularity, to produce corresponding arrangements parallel to the line, in 



