Page 475 - 89 history of astronomy_opt

lines in the spots, such as would be pro-
duced by a rapid motion in the line of sight.
It has been found that both uprushes and
downrushes occur, but there is no marked
predominance of either in a sun-spot. The
velocity of motion thus indicated in the line
of sight sometimes appears to amount to
320 miles a second. But it must be remem-
bered that pressure of a gas has some effect
475