21 



the extensive computations required when the ordi- 

 nary type of measuring machine is used. Their 

 change of position from day to day yielded a new 

 determination of the law of the solar rotation, 

 which was found to differ at the calcium and 

 hydrogen levels. At the lower level of the calcium 

 flocculi the period of rotation at the sun's equator 

 is 24.8 days, increasing gradually to 26.8 days at 

 45 latitude. In other words, the gaseous sun 



FIG. 14. Solar Prominence 80,000 miles high. 



does not rotate like the solid earth, on which points 

 in all latitudes complete a rotation in 24 hours. 

 It turns more and more slowly as the poles are 

 approached, points in high latitudes lagging behind 

 those nearer the equator. If this could happen on 

 the earth, Jacksonville, which is almost due south 

 of Cleveland, would be far to the east of it 24 

 hours hence. In the higher levels of the solar 



