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POPULAR SCIENCE REVIEW. 
oblique, and very bright and well defined. This jet rising to a 
great height is seen to bend back again, falling upon the sun 
like the jets of our fountains, and presently the sinking matter 
is seen to assume the shape of gigantic trees, more or less rich 
in branches and foliage. Gradually the whole sinks down upon 
the sun, sometimes forming isolated clouds before reaching the 
solar surface. It is in the upper portions of such prominences 
that the most remarkable and rapid transformations are wit- 
nessed; but a great difference is observed in the rate with 
which prominences change in figure. Their duration, also, is 
very variable. Some develope and disappear in a few minutes, 
while others remain visible for several successive days.” 
Eespighi agrees with Zollner in considering that the well- 
marked bases of the eruptive jets 44 proves that the eruption 
takes place through some compact substance forming a species 
of solar crust,” and also in believing 44 that the enormous velo- 
city with which these gaseous masses rush through the solar 
atmosphere implies that the latter is of excessive tenuity.” 
The highest prominence observed by Eespighi had an elevation 
of no less than 1 60,000 miles. 
Secchi’s recent researches, or the researches he has recently 
completed, result in a classification of the whole series of phe- 
nomena presented by the sierra and the prominences. In the 
first place, he remarks that the sierra or chromatosphere pre- 
sents four distinct aspects. At times it has a perfectly smooth 
and well-defined outline, and is very little less brilliant at the 
edge than throughout the remaining portion of its depth. At 
other times, though the chromato sphere is quite smooth, and as 
it were calm, its brilliancy diminishes outwards so gradually 
that no limit can be distinguished ; more frequently the sierra 
is surmounted by filaments all sloped in the same direction. 
And lastly, and most frequently of all, the chromatosphere has 
an irregular outline, and is fringed with small tongues of flame 
having no specific direction. 
The prominences may be divided into three general orders — 
heaps , jets , and plumes. 
The heaped prominences are of three kinds. First, there 
are slight elevations of the corona rarely more than 15 or 20 
seconds in height, and having an outline either diffuse like the 
second form of the chromatosphere, or fringed like the third 
or fourth forms of that layer. Secondly, there are brilliant 
masses resembling our cumulus clouds. Thirdly, there are large 
diffuse masses suspended above or attached to the tops of the 
larger prominences. 
Next in order are the jets, the most interesting of all the 
prominences on account of the evidence they afford of mighty 
repulsive or eruptive forces. 
