THE TOTAL ECLIPSE OF AUGUST SEVENTH.
The recent solar discoveries, of which mention has been made in past numbers of this magazine, have on the whole increased the interest attached to the observation of eclipses, though in some respects the importance of these phenomena as opportunities of extending our knowledge of the constitution of the sun has been diminished. It will be remembered that immediately after the total eclipse of last year in India, it was found that the great prominences on the rim of the sun which are never seen with any ordinary appliances, except on these occasions, could be observed at any time with the spectroscope, and that by means of this admirable instrument their shape as well as the spectral lines indicating their chemical composition could be determined; and since that time many observations of them have been made, and interesting conclusions arrived at on both these points, as stated in the article translated in the last number. The principal ones as yet established with certainty are, that they are gaseous, and mainly composed of hydrogen, and that they change their shape with astonishing rapidity, some of their particles perhaps moving with the inconceivable velocity of one hundred miles a second. At any rate, immensely energetic forces and rapid movements must be required to change essentially the shape and position of these masses—which often have ten times the diameter, or a thousand times the volume of the earth—in a quarter of an hour.
So we are not now obliged to wait a year or more and travel several thousand miles to observe for a few minutes these peculiar and still somewhat mysterious bodies; still, it does not follow that they cannot be better examined at the time of an eclipse, or that new appearances may not be noticed on such occasions, now that we are accustomed to these, from which the other more startling phenomena for a long time diverted attention. Success has excited hope of yet greater successes; and eclipses, though affording but a short time for actual observation, are undoubtedly the best occasions for the observer to learn in what direction his labors should be turned. There are also other things, such as the corona, Baily's beads, possible new planets inside of the orbit of Mercury, etc., which can only be seen at these times.
The eclipse of this year, therefore, was by no means neglected by the scientific men of the United States; in fact, it was felt that the reputation of the country depended upon the skill shown in preparing for and in observing it, and a large number of parties were formed, to be stationed at various points of the path of the moon's shadow or line of totality, so that if clouds should prevent success at one place, it might be obtained at another.
The first point touched by the shadow proper, and at which consequently a total eclipse occurred, was in longitude 165° west from Washington, latitude 53° north, being in Siberia; the last, in longitude 10° east, latitude 31° north, being off the coast of North Carolina. At the former the sun rose totally obscured at half-past four, at the latter it set in that condition, at a quarter to seven; and at the intermediate points the eclipse took place at all the intermediate hours of the day. It is rather singular that, owing to the necessary skip of a day in going round the world, it was Sunday morning in Siberia, but Saturday afternoon in the United States; so that the eclipse may be said to have been one of the longest on record. Its actual duration was, however quite short, half-past four A.M. in Siberia, and a quarter to seven P.M. at the ending point, being about four and half-past six P.M. respectively in New York; giving an interval of two and a half hours in which the shadow passed over the long line connecting these points, which it will be perceived are nearly opposite in longitude.
If it had travelled by the shortest route, it would have passed within three degrees of the north pole, and the eclipse would have been invisible in this country; but, fortunately, it lengthened its course, reaching its highest latitude near Behring's Straits, which it crossed, and then swept to the south-east, crossing the territories of Montana and Dakota, and the States of Minnesota, Iowa, Illinois, Indiana, Kentucky, Tennessee, Virginia, and North Carolina. It could hardly have taken a better route for us.
The length of the line was over seven thousand miles, and the consequent average velocity in passing over it about fifty miles a minute, though in the United States it exceeded that amount considerably. The breadth of the belt traversed was somewhat variable; in this country it was about one hundred and fifty miles. Of course, the sun was partially hidden by the moon over a very large portion of the globe; but the region from which its light was at any time completely excluded was comparatively quite small.
Observers stationed themselves at numerous points, even as far west as Alaska and Siberia; but of course most chose positions within the United States. The writer was connected with a party which was established at Shelbyville, Kentucky.
The general diffusion of intelligence, both subjective and objective, as we may say, had of course excited great interest in the eclipse among the people, especially in that part of the country actually within or bordering upon the limits of totality; and though, of course, the nature of the expected event was fully understood by all the educated portion of the community, and by many of the uneducated, still there were some, especially in the rural districts, who vaguely apprehended some great event, to be probably of a disastrous nature, (a hailstorm was the most popular;) and perhaps were as much terrified in anticipation as any entirely ignorant people have ever been at the actual occurrence of this most impressive and sublime spectacle.