As seen from Earth, stars are mere points of light, the rays from which in passing to us become subject to various laws, and are also not only refracted, but are affected by the density, humidity and temperature of our atmosphere, coming to us as twinkling lights. Also under the highest telescopic power stars show no appreciable size, and are comparatively fixed in their places, forming such small points in the heavens that their positions can be determined so correctly that the measurements and movements of other stars and planets can be recorded with almost certain accuracy, for keeping the same position themselves with regard to Earth, they define clearly and unmistakably the movements of our world. A star being _one_ point of light, twinkles only, whilst planets, moons, and the sun have so many points and rays of light, all twinkling, that the combination of all the scintillating rays causes a steady light which is quite distinct from the light of a star, the magnitudes of which are classed according to their relative brightness, the first half-dozen or so classes being visible to the naked eye, and the next eighteen or more to the lens of a good telescope. For many centuries it had been thought that the difference in the brilliancy of the stars came from the fact that though they were nearly all equally brilliant, their distances were so remote as more or less to reduce their light, and that ether in space was entirely transparent. The _Regina_, however, had been the cause of considerable modification of these views by enabling many of the difficulties to be removed by actual observation on the spot, when it was found that certain parts of the ether of space were more or less opaque and partially, and often entirely, obliterated certain of the stars by intervening and absorbing some, or all, of their light; also that many, if not all, of these semi-opaque webs of ether were in motion, and sometimes this movement caused the more dense web to pass away from between certain stars and Earth, and thus in the more transparent space certain stars would appear brighter, and the new stars and moons of planets would become visible; at the same time the opaque web of ether having changed position, stars hitherto visible were blotted out of sight from Earth. This accounted for many discoveries of new stars and the loss of many previously observed, also for the periodic loss and reappearance of others, for in certain cases the fog-like stratum of ether was found to move in definite and periodic pulsations which exposed one or more stars beyond, as the veil lifted, or fell, or moved aside. Such stars may then have remained visible for years and would again vanish as the stratum moved back, and in course of time, probably anything from a few hours to thousands of years, it would again expose the hidden star, which would appear and disappear in definite cycles of time. Such stars are called “variables,” of which there