are considerably over a thousand, and others are being added as time goes on; some have definite periods of visibility and invisibility, and some change erratically, being seldom equal, all depending on the size, movement and density of the particular semi-transparent web of intervening ether, which, although appearing to be bound by no known law, yet has a certain law of movement of its own, because it may be timed and its passage anticipated with accuracy. One of the chief of these periodical stars is Mira Ceti, the “wonderful star,” which was visible from Earth when the travellers left, but in a few days they passed through a great bank of dense, semi-opaque ether, thousands of miles in thickness and extent. This was almost imperceptible when they were in it, but as they had approached it had appeared like a faint cloud, the mass of which was sufficient to hide the star from Earth when intervening. The magnitude of Mira—in common with that of all other such stars—varies according to the density and opacity of the intervening stratum, undergoing many ‘wonderful’ changes. Its period is less than an Earth-year by about thirty-four days, thus going through about twelve changes in eleven Earth-years, or thereabouts. Its brightness, which is fiery red, causes it to be classed in the second magnitude, in which it remains about fifteen days, when it diminishes in brightness till, in about three months’ time, the full bulk of the bank of ether hides it altogether from the naked eye, and only through powerful telescopes can it be seen for a little under five months, when a more transparent portion of the web of ether gradually pulsates before it. In the course of a little under three months the belt has lifted, or become so thin as to be wholly transparent, and the “wonderful star” comes into view again without anything intervening. She has thus regained her original brilliancy as a star of the second magnitude, and Mira has now gone through her average changes, but even these are subject to much variation. The movements of the ether follow a law at present unknown, to discover which the _Regina_ would have been obliged to stay close at hand, probably for years, which was scarcely advisable, so the scientists left the definition of the law of ether-movement to some future occasion, contenting themselves with the elucidation of the cause of the variability of stars, and particularly of this “wonderful star,” which has been the source of so much controversy and speculation since its discovery in Cetus in 1596 by David Fabricius. It was also found that the ether pulsated and moved in such a manner as to cause the star to appear of varying brightness, and to alter its period to a longer or shorter time—probably a matter of twenty to thirty days either way. They, however, noticed that at the eleventh maximum of brilliancy, which was then approaching, the star was completely exposed to view from Earth, thus causing it to appear at that particular time far