A. MATHEMATICS AND ASTRONOMY. 17 



was already known that all the more important spots and 

 groups of spots only occur where faculse had already been 

 found. From the great intensity of the flame-like protuber- 

 ances, he concludes that the faculre must be looked upon as 

 the hot portions of the surface; thence it follows at once 

 that, above them, ascending currents of air must exist, and 

 that from all sides the cooler air must stream toward these 

 hot portions. If the ascending currents reach to the colder 

 strata of air, the resulting precipitation brings about dark 

 clouds. Even after the formation of these clouds the as- 

 cending; and horizontal currents still continue, giving; rise to 

 the intense bright veins that are seen running through groups 

 of spots. The only indication of storms in the lowest stra- 

 ta to which he gives any weight is found in the observed 

 deviations of the tips of the chromospheric flames. If, he 

 states, an upward current is instituted in the solar atmos- 

 phere, some of the higher masses of air must necessarily de- 

 scend ; therefore there must somewhere, at some altitude, oc- 

 cur a contest of currents giving rise to horizontal currents, 

 such as he has observed in at least four instances. Astron. 

 Midi., LXXXIIL, 90. 



THE CONSTITUTION OF THE SUN. 



Messrs. Wilson and Seabroke, having made a long series 

 of observations, at Rugby, on the solar protuberances, and 

 finding that they preponderate greatly in the equatorial re- 

 gion of the sun, where the spots also predominate, have ofler- 

 ed some brief remarks on a new theory of protuberances and 

 spots. Their theory assumes that, at some distance below 

 the sun's surface, the pressure is such that substances, such as 

 some metals, are in a liquid state, though at a temperature 

 far exceeding their boiling-point under ordinary pressure. 

 In this case the compressed liquids will, on the whole, ar- 

 range themselves in the order of density. If the pressure be 

 diminished, these will burst into vapor. The equilibrium is, 

 therefore, unstable. Consequently it is assumed that there 

 may exist in the sun two or more liquids, so related that the 

 denser has the lower boiling-point. If these disturbances of 

 pressure occur, they will produce vertical eruptions through 

 the upper layers of the sun, throwing up the chromosphere 

 and photosphere into jets, such as are observed. The sub- 



