Most long-period variables are red stars of the Antarian or of the carbon star classes with banded spectra, but they differ from ordinary red stars by occasionally showing bright lines, which indicate an uprush of intensely hot hydrogen gas in their atmospheres. These bright lines always appear at times of maximum, and prove that the star periodically undergoes some physical change: but what is the nature and the cause of this change? It can scarcely be due to the near approach of a satellite, because of the irregularity in the time of maximum. There is a certain resemblance between the way in which the light waxes and wanes and the waxing and waning in the number of sunspots on the sun, and spectra of these Mira stars also somewhat resemble sunspot spectra: can it be that our sun is an incipient variable star with a period of about eleven years? It is true that sunspots seem to be cooler rather than hotter regions on the sun, but a time of maximum spots is also a time of maximum activity; slightly more heat is actually radiating, the corona is brighter and larger, and the bright scarlet flames of hydrogen and calcium which we call prominences are larger and more abundant. Possibly it is a tremendous display of these on Mira which makes the hydrogen lines bright at maximum. SOME SOUTHERN VARIABLE STARS OF LONG PERIOD +------------+----------+----------+---------+----------------------+ | Name. | Maximum | Minimum | Period. | Remarks. | | |Magnitude.|Magnitude.| | | +------------+----------+----------+---------+----------------------+ | | | | Days. | | |Mira | 1.7 | 9.6 | 331½ | Discovered in | | | | | |1596. Large irregular-| | | | | |ities in period | | | | | |and max. brightness. | | | | | | | |R Sculptoris| 6.2 | 8.8 | 376½ | A red “carbon | | | | | |star.” | | | | | | | |R Leporis | 6.1 | 9.7 | 436 | Crimson. A | | | | | |“carbon star.” | | | | | | Observed from 1852 | | | | | |to 1883, but very | | | | | |few observations | | | | | |published since, so | | | | | |new work would | | | | | |be valuable. | | | | | | |