It so chanced that on the evenings of 18th and 19th February two photographs of the very spot where three days later the new star appeared were taken at Harvard Observatory. On neither of these photographs is there the slightest evidence of the star’s existence. It was, therefore, on these dates non-existent so far as our earth was concerned. On the evening of 20th February a well-known English observer, Mr. Stanley Williams, had also taken a photograph of the same portion of the sky; and again there was no trace of the star. Mr. Williams’s photograph was taken twenty-eight hours before Dr. Anderson saw it. Still more strange is the fact that on the evening of 21st February three observers on the Continent testify that they had the constellation Perseus under observation from seven o’clock to eleven, and had the new star then been visible they could not have failed to see it. The star, therefore, blazed out some time between eleven o’clock and three on the night of its discovery. Now, what does this mean? It means this: that by some cause a star, quite dark before, or so faint that it could not be seen even by means of a powerful telescope, in a few hours, or perhaps in a few minutes, blazed forth as a star of conspicuous brightness. In this brief space of time a dark and probably chill globe became a seething mass of fire, a million times hotter than it was before. Fierce, fervent heat lit up the orb with a glow that reached from rim to rim of the stellar universe. We have here a catastrophe that goes beyond our wildest conceptions: the conflagration of a world, the ruin of a star. What guarantee have we for an assumption of this kind? What of certitude is there in our vision of such a Day of Doom for any part of our universe? Let us consider the salient facts regarding the recent changes in the appearance and structure of this star. We shall relate only those facts that are beyond controversy, as far as our present knowledge goes. Nova Persei did not reach its maximum brightness till the evening of 25th February, when it was probably the most conspicuous object in the midnight sky. It was then at least six times brighter than at the time of its discovery. After this date it began to wane slowly. At intervals there were spurts of brightness lasting for two or three days, as if the fires had not exhausted themselves. On the whole, however, the light of the star waned, and by the end of the year its enfeebled light was just bright enough to be evident to the naked eye; twelve months after its appearance it could only be seen with the aid of a telescope.