Vol. XI, No. 9.] Sunspots and Prominences. 295. 
[V.S.] 
Unlike sunspots, prominences are found all over the sun, 
from the equator to the poles, and they are most frequent in 
regions where no spots form. Large massive prominences, 
even when occurring in sunspot regions, are seldom found 
very near spots, and in fact seem to avoid their neighbourhood. 
me of the smaller types, on the other hand, are never found 
surface in the form of arches (fig. 3) but curiously enough the 
arch often becomes narrower at the base, a form which could 
not be taken by a stream of gas acted on by gravity alone. 
On July 3ist, 1908, a very remarkable prominence in. the 
form of a single arch or ring stood over a sunspot (fig. 
o m 
Sometimes they are like pillars or pyramids, sometimes 
trees or sheaves of corn, sometimes a cloudy mass hovers above 
the sun’s surface, or is attached to it only by a few fine 
filaments. One was photographed on February 18th, 1908, 
which gradually rose to an immense height (figs. 5, 6). It 
was scarcely visible on the first plate taken at 8h. 23m., but 
was a very bright compact mass at 9h. 38m. Throughout the 
day it rose higher and higher, and at last the upper edge was 
60,000 miles above the sun’s surface, that is to say more 
distant from it than the moon is from the earth. The 
P.M. at over 6 km.: and 6 P.M. the 
“tid km. and sian book perth as oo sun was getting low, 
® speed attained . per second. 
It is evident, sheer chat gome repulsive force acts on 
n comets’ tails, and light-pressure very 
bably is concerned in this. But we are not yet able to 
*xplain what forces cause prominences to 
“range and varied shapes which our photographs reveal, 
