It was at seven minutes before three that such few stragglers as the streets of York still contained saw a pear-shaped ball of fire traveling across the sky. It drenched the ancient city with a flood of light. The superb front of the minster never before glowed with a more romantic illumination. The unwonted brilliancy streamed through every aperture in every window in the city; every wakeful eye was instantly on the alert; every light sleeper started up suddenly to know what was the matter. Even those whom the blaze of midnight light had failed to awaken were only permitted to protract their slumbers for another minute and a half—only until an awful crash, like a mighty peal of thunder, burst over the town, shaking the doors, the windows, and even the houses themselves. The whole city was thus alarmed. Every one started at the noise. But that noise was not a clap of thunder. Nor was it produced by an earthquake. It was merely the explosion of the fire-ball which flung itself against the atmosphere after its immeasurable voyage through space.
Perhaps the most remarkable instance of the explosion of a meteor is recorded in the case of the great fire-ball so widely observed in America on the 21st of December, 1876. The movements of this superb object have been carefully studied by Professor H. A. Newton and Professor D. Kirkwood. For the prodigious span of a thousand miles this meteor tore over the American continent with a speed of some ten or fifteen miles a second. It first appeared over Kansas at a height of seventy-five miles. Thence it glided over the Mississippi, over the Missouri; it passed to the south of Lake Michigan; it made a short voyage over Lake Erie, and it can not have been very far from the Falls of Niagara, when by becoming invisible all further traces of its movements were lost. While passing a point midway between Chicago and St. Louis a frightful explosion shivered the meteor into a cluster of brilliant balls of fire, which seemed to chase each other across the sky. This cluster must have been about forty miles long and five miles wide. The detonation by which the explosion was accompanied was a specially notable incident of this meteor. It was not only heard with terrific intensity in the neighborhood, but the volume of sound was borne to great distances.
The glory of a meteor is often so evanescent that we just get a glimpse and it is gone. The sky resumes its ordinary aspect; the familiar stars are there, and even the very situation of the brilliant streak has become unrecognizable. But this is not always so; it sometimes happens that the brief career of the meteor leaves a notable trace behind it, so that for seconds and for minutes the sky is diversified by an unwonted spectacle. The path of the meteor leaves a stain of pearly light on the sky to mark the highway pursued by our celestial visitor.
In its fearful career the meteor is often rent to fragments, reduced to dust, dissolved into vapor. The glowing atoms of the wreck lie strewn along the path, just as the ghastly remnants of Napoleon’s mighty army limned out the awful retreat from Moscow.
A pencil-shaped cloud of meteoric débris, perhaps eighty or a hundred miles in length, and four or five miles in diameter, thus hangs poised in air. It is at night. The sun has sunk so far below the horizon that there is no trace of the feeblest twilight glow. An ordinary cloud would, of course, be invisible except as concealing the stars; no beams of light fall upon it; there is nothing to render it luminous. So, too, the meteoric streak will often pass instantly into invisibility, but, as I have said, this is not always the case. There is a well-authenticated instance in which the trail of a superb meteor remained visible for nearly an hour. I have endeavored up to the present to explain the various phenomena presented to us in the fall of a meteor, but here, for the first time, we have to note a circumstance for which it is not easy to account. We can explain why it is that the long meteoric cloud should be there, but we can not so easily explain why we should be able to see it. Whence comes this beautiful pearly luminosity? It seems that the meteoric dust must glow with some intrinsic luminosity.
We have spoken of dazzling fire-balls which generate for a brief moment a light which eye-witnesses, with possibly a pardonable exaggeration, have ventured to compare with the beams of the sun himself. Other meteors are described as being as bright as the full moon. Descending still lower in the scale of splendor, we read of fire-balls as bright as Venus or Jupiter, as bright as Sirius, or as a star of the first magnitude. With each step downward in brilliancy we find the meteors to increase in numerical abundance. Shooting stars as bright as the stars of the second or third magnitude are comparatively frequent; they are still more numerous of the fourth and fifth magnitudes. Every night brings its tale of shooting stars whose brightness is just sufficient to impress the unaided eye. Nor do the shooting stars which even the most attentive eye can detect represent a fraction of their entire number. As there are telescopic stars which the unaided eye can not see, so it might fairly be conjectured that, as we can trace meteors of successive stages of brightness down to the limit of unaided eye visibility, so there may be meteors still and still smaller which would be detected could we only direct a telescope toward them.
If we reflect that for every one that is seen there must be thousands which dart in unseen, we obtain an imposing idea of the myriads of shooting stars that daily rain in upon our globe.
The world is thus pelted on all sides day and night, year after year, century after century, by troops and battalions of shooting stars of every size, from objects not much larger than grains of sand up to mighty masses which can only be expressed in tons. In the lapse of ages our globe must thus be gradually growing by the everlasting deposit of meteoric débris. Looking back through the vistas of time past, it becomes impossible to estimate how much of the solid earth may not owe its origin to this celestial source.
The first and most important truth with regard to the recurrence of the meteors is their occasional appearance in what are known as “meteoric showers.” During such displays it sometimes happens that shooting stars in shoals break forth simultaneously, so as to produce a spectacle which we now regard as of the utmost beauty and interest, but which in earlier times has often been the source of the direst terror and dismay.
Let me, for the sake of illustration, give some account of one of these great showers of shooting stars.