STRANGE NEWS ABOUT THE SOLAR PROMINENCES. 
47 
Some of the jets are small, quickly variable in shape, and 
last but a short time. They resemble, in fact, as pictured by 
Secchi, a mere development and extension of the irregularities 
seen in the fourth form of the chromatosphere. 
Next in order are jets such as are shown in fig. 1 of the 
illustrative plate. Such jets are not often met with on a great 
scale. Secchi terms them cones. Such cones often extend 
themselves into curved shapes such as are shown in fig. 2 ; the 
transformation from the form shown in fig. 1 to that of fig. 2 
occupying only about twenty minutes. Nor is the transforma- 
tion gradual, but one form passes quickly into the other after a 
short interval of seeming tranquillity. “The luminosity of 
jets is always very great,” says Secchi, “ their roots being more 
luminous than the rest of the solar surface.* Their appear- 
ance is extremely beautiful ; the most splendid display of fire- 
works would fall far short of realising to the imagination the 
magnificent glory of the sublime spectacle they present. Some- 
times the branches fall in the shape of parabolas more or less 
inclined ; at other times they are like the .heads of immense 
palms with the most graceful curving branches.” In figs. 
3 and 4 of the plate are shown some of the forms assumed by 
these jets. “ The branches,” says Secchi, “incline sometimes 
in the direction of the jet, sometimes recoil upon the stalk 
from which they spring. This kind of jet is always compact, 
filamentary to the base, and terminated at the apex without 
any clear, decided outlines. Their light is so bright that they 
can be seen through the light clouds into which the chroma- 
tosphere breaks up. Their spectrum indicates besides hydrogen 
the presence of many other substances .” (The italics are mine, 
and I invite special attention to the statement here made by 
Fr. Secchi.) “ These I call sheaves. I frequently observe in 
sheaves a great variability in the refrangibility of the rays ” 
( that is , the indications of very rapid motions). “ Frequently 
also, when they have attained a certain height, they cease to 
grow, and become transformed into exceedingly brilliant masses, 
which after a time separate and form fiery clouds. A cha- 
racteristic of sheaves as of the flames is their short duration ; 
they rarely last an hour, frequently only a few minutes.” 
The prominences of the third class — called plumes by 
Secchi — resemble the jets in some respects, but differ from 
them in being less bright, and in remaining longer visible ; in 
having their extremities sometimes surmounted by or resolved 
* Secchi here refers, of course, to the appearance presented in the spectro- 
scope. If the jets were in any part of their extent actually brighter than 
the sun’s surface, they would he visible without spectroscopic aid ; which 
has never happened. 
