In the year 1866 I occupied the position of astronomer to the late Earl of Rosse. The memorable night between November 13th and 14th, 1866, was a very fine one; the moon was absent—a very important consideration in regard to the effectiveness of the display. The stars shone out clearly, and I was diligently examining some faint nebulæ in the eye-piece of the great telescope, when a sudden exclamation from the attendant caused me to look up from the eye-piece just in time to catch a glimpse of a fine shooting star, which, like a great sky-rocket, but without its accompanying noise, shot across the sky over our heads. The great shooting star which had already appeared was merely the herald announcing the advent of a mighty host. At first the meteors came singly, and then, as the hours wore on, they arrived in twos and in threes, in dozens, in scores, in hundreds. Our work at the telescope was forsaken; we went to the top of the castellated walls of the great telescope and abandoned ourselves to the enjoyment of the gorgeous spectacle.
To number the meteors baffled all our arithmetic; while we strove to count on the one side many of them hurried by on the other. The vivid brilliance of the meteors was sharply contrasted with the silence of their flight. We heard on that marvelous night no sounds save those with which we were familiar. The flights of the celestial rockets were attended with no noises that we could hear. The meteors were no doubt somewhat various as to size, but the characteristic feature of this shower, as contrasted with another great shower I have also seen, was the remarkable brilliance of the shooting stars. It was their exceptional splendor even more than their innumerable profusion that gave to the shower its peculiarity. As to the actual brilliancy of the meteors, I am enabled to give the accurate estimate made by Mr. Baxendell at Manchester, where the shower was well seen. Out of every hundred of these meteors ten were brighter than a first magnitude star, and two or three of them were brighter than Sirius. Fifteen out of each hundred were between the first and second magnitudes, and twenty-five were between the second and third magnitudes, while the remainder were smaller.
Some important facts with regard to ancient shooting-star showers have survived the thousand and one casualties to which historical records are exposed. A careful discussion of those which are sufficiently accurate to be intelligible discloses to us the startling fact that in general every thirty-three years a grand shooting-star shower has rained down on our earth. It sometimes happens that two consecutive years are rendered memorable by great showers. At present the day of the year on which this particular shower is wont to appear is about the 13th November; but in earlier ages we find the date to shift slowly toward the commencement of the year. Thus the display which took place in A. D. 1698 was on the 9th of November; while, looking back still further to one of the very earliest records, viz., that of the year 934, we find the date has receded to October 14th. This change of the day on which the shower occurs is of profound theoretical importance in connection with the discovery of the orbit which these meteors pursue. The advance of the date is, however, so slow that for the past few generations, as well as for the next, we may sufficiently define this particular shower by the meteors which enliven the skies between the 12th and the 14th of November. In fact, the poetaster has parodied the well-known lines for the days of the month by a similar effort, which will serve to remind us also of another periodic shower of shooting stars which occurs in August. He writes:
“If you November’s stars would see,
From twelfth to fourteenth watching be.
In August too stars shine from heaven,
On nights between nine and eleven.”
These lines are intended to imply that the days named will usually bring, in every November, a few meteors at all events belonging to the grand shower. These are stragglers, as it were, from the mighty host which visits us three times in the century.
Astronomers have a special name for this group of November meteors. They are called the “Leonids.” To explain why this name has been given, and why it is appropriate, we must dwell on an important part of the phenomena of the shower.
