We must now ask our readers to accompany us in one more brief flight across the Atlantic. After a successful observation of the late transit of Venus at Jamaica, Dr. Copeland, the chief astronomer of Lord Crawfords observatory at Dun Echt, took advantage of the railway which now crosses the Western Andes at an elevation of 14,666 feet, to make a high-level tour of exploration in the interests of science. Some of the results communicated by him to the British Association at Southport last year, and published, with more detail, in the astronomical journal Copernicus, are extremely suggestive. At La Paz, in Bolivia, 12,050 feet above the sea, a naked-eye sketch of the immemorially familiar star-groups in Taurus, made in full moonlight, showed seventeen Hyades (two more than are given in Argelanders Uranometria Nova) and ten Pleiades. Now ordinary eyes under ordinary circumstances see six, or at most seven, stars in the latter cluster. Hipparchus censured Aratus who took his facts on trust from Eudoxus for stating the lesser number, on the ground that, in serene weather, and in the absence of the moon, a seventh was discernible.26 On the other hand, several of the ancients reckoned nine Pleiades, and we are assured that Moestlin, the worthy preceptor of Kepler, was able to detect, under the little propitious skies of Wurtemberg, no less than fourteen.27 An instance of keensightedness but slightly inferior is afforded by a contemporary American observer: Mr. Henry Carvil Lewis, of Germantown, Pennsylvania, frequently perceives twelve of this interesting sidereal community.28 The number of Pleiades counted is, then, without some acquaintance with the observers ordinary range of sight, a quite indeterminate criterion of atmospheric clearness; although we readily admit that Dr. Copelands detection of ten in the very front of a full moon gives an exalted idea of visual possibilities at La Paz.
During the season of tempestades from the middle of December to the end of March the weather in the Andes is simply abominable. Mr. Whymper describes everything as bottled up in mist after one brief bright hour in the early morning, and complains, writing from Quito, March 18th, 1880,29 that his exertions had been left unrewarded by a single view from any one of the giant peaks scaled by him. Dr. Copeland adds a lamentable account doubly lamentable to an astronomer in search of improved definition of thunderstorms, torrential rains merging into snow or hail, overcast nocturnal skies, and visible exhalations from the drenched pampas. At Puno, however, towards the end of March, he succeeded in making some valuable observations, notwithstanding the detention as contraband of war, apparently of a large part of his apparatus. Puno is the terminal station on the Andes railway, and is situated at an altitude of 12,540 feet.
Here he not only discovered, with a 6-inch achromatic, mounted as need prescribed, several very close stellar pairs, of which Sir John Herschels 18 inch speculum had given him no intelligence; but in a few nights sweeping with a very small Vogels spectroscope, he just doubled the known number of a restricted, but particularly interesting, class of stars if stars indeed they be. For while in the telescope they exhibit the ordinary stellar appearance of lucid points, they disclose, under the compulsion of prismatic analysis, the characteristic marks of a gaseous constitution; that is to say, the principal part of their light is concentrated in a few bright lines. The only valid distinction at present recognisable by us between stars and nebulæ is thus, if not wholly abolished, at least rendered of a purely conventional character. We may agree to limit the term nebulæ to bodies of a certain chemical constitution; but we cannot limit the doings of Nature, or insist on the maintenance of an arbitrary line of demarcation. From the keen rays of Vega to the undefined lustre of the curdling wisps of cosmical fog clinging round the sword-hilt of Orion, the distance is indeed enormous. But so it is from a horse to an oak tree; yet when we descend to volvoxes and diatoms, it is impossible to pronounce off-hand in which of the two great provinces of the kingdom of life we are treading. It would now seem that the celestial spaces have also their volvoxes and diatoms limiting instances, as Bacon termed such bodies that share the characters, and hang on the borders of two orders of creation.
In 1867, MM. Wolf and Rayet, of Paris, discovered that three yellow stars in the Swan, of about the eighth magnitude possessed the notable peculiarity of a bright-line spectrum. It was found by Raspighi and Le Sueur to be shared by one of the second order of brightness in Argo (γ Argûs), and Professor Pickering, of Harvard, reinforced the species, in 1880-81, with two further specimens. Dr. Copelands necessarily discursive operations on the shores of Lake Titicaca raised the number of its members at once from six to eleven or twelve. Now the smaller planetary nebulæ so named by Sir William Herschel from the planet-like discs presented by the first-known and most conspicuous amongst them are likewise only distinguished from minute stars by their spectra. Their light, when analysed with a prism, instead of running out into a parti-colored line, gathers itself into one or more bright dots. The position on the prismatic scale of those dots, alone serves to mark them off from the Wolf-Rayet family of stars. Hence the obvious inference that both nebulæ and stars (of this type) are bodies similar in character, but dissimilar in constitution that they agree in the general plan of their structure, but differ in the particular quality of the substances glowing in the vast, incandescent atmospheres which display their characteristic bright lines in our almost infinitely remote spectroscopes. Indeed, the fundamental identity of the two species are virtually demonstrated, by the migrations (to use a Baconian phrase) of the new star of 1876, which, as its original conflagration died out, passed through the stages, successively, of a Wolf-Rayet or nebular star (if we may be permitted to coin the term), and of a planetary nebula. So that not all the stars in space are suns at least, not in the sense given to the word by our domestic experience in the solar system.
The investigation of these objects possesses extraordinary interest. As an index to the true nature of the relation undoubtedly subsisting between the lucid orbs and the shining fluid which equally form part of the sidereal system, their hybrid character renders them of peculiar value. Their distribution so far restricted to the Milky Way and its borders may perhaps afford a clue to the organisation of, and processes of change in that stupendous collection of worlds. At present, speculation would be premature; what we want are facts facts regarding the distances of these anomalous objects whether or not they fall within the range of the methods of measurement at present available; facts regarding their apparent motions; facts regarding the specific differences of the light emitted by them: its analogies with that of other bodies; its possible variations in amount or kind. The accumulation of any sufficient information on these points will demand with every external aid, the patient labor of years; under average conditions at the earths surface, it can scarcely be considered as practically feasible. The facility of Dr. Copelands discoveries sufficiently sets off the prerogatives, in this respect, of elevated stations; it is not too much to say that this purpose were it solely in view would fully justify the demand for their establishment.
Towards one other subject which we might easily be tempted to dwell upon, we will barely glance. Most of our readers have heard something of Dr. Hugginss new method of photographing the corona. Its importance consists in the prospect which it seems to offer for substituting for scanty and hurried researches during the brief moments of total eclipse, a leisurely and continuous study of that remarkable solar appendage. The method may be described as a differential one. It depends for its success on the superior intensity of coronal to ordinary sunlight in the extreme violet region. And since it happens that chloride of silver is sensitive to those rays only in which the corona is strongest, the coronal form disengages itself photographically, from the obliterating splendor which effectually shrouds it visually, by the superior vigor of its impression upon a chloride of silver film.
Now if this ingenious mode of procedure is to be rendered of any practical avail, advantage must, above all, be taken of the finer air of the mountains. This for two reasons. First, because the glare which, as it were, smothers the delicate structure we want to obtain records of, is there at a minimum; secondly, because the violet rays by which it impresses itself upon the photographic retina30 are there at a maximum. These, as Professor Langleys experiments show, suffer far more from atmospheric ravages than their less refrangible companions in the spectrum; the gain thus to them, relatively to the general gain, grows with every yard of ascent; the proportion, in other words, of short and quick vibrations in the light received becomes exalted as we press upwards a fact brought into especial prominence by Dr. Copelands solar observations at Vincocaya, 14,360 feet above the sea-level. Indeed, for all the operations of celestial photography, the advantages of great altitudes can hardly be exaggerated; and celestial photography is gradually assuming an importance which its first tentative efforts, thirty-four years ago, gave little reason to expect.
Thus, in three leading departments of modern astronomy solar physics, stellar spectroscopy, and the wide field of photography the aid of mountain observatories may be pronounced indispensable; while in all there is scarcely a doubt that it will prove eminently useful. There are, indeed, difficulties and drawbacks to their maintenance. The choice of a site, in the first place, is a matter requiring the most careful deliberation. Not all elevated points are available for the purpose. Some act persistently as vapor-condensers, and seldom doff their sullen cap of clouds. From any mountain in the United Kingdom, for instance, it would be folly to expect an astronomical benefit. On Ben Nevis, the chief amongst them, a meteorological observatory has recently been established with the best auguries of success; but it would indeed be a sanguine star-gazer who should expect improved telescopic opportunities from its misty summit.
Even in more favored climates, storms commonly prevail on the heights during several months of the year, and vehement winds give more or less annoyance at all seasons; the direct sunbeams sear the skin like a hot iron; the chill air congeals the blood. Dr. Copeland records that at Vincocaya, one afternoon in June, the black bulb thermometer exposed to solar radiation stood at 199°.1 of Fahrenheit actually 13° above the boiling-point of water in that lofty spot while the dry bulb was coated with ice! Still more formidable than these external discomforts is the effect on the human frame itself of transportation into a considerably rarer medium than that for existence in which it was constituted. The head aches; the pulse throbs; every inspiration is a gasp for breath; exertion becomes intolerable. Mr. Whympers example seems to show that these extreme symptoms disappear with the resolute endurance of them, and that the system gradually becomes inured to its altered circumstances. But the probationary course is a severe one; and even though life flow back to its accustomed channels, labor must always be painfully impeded by a diminution of the vital supply. And the minor but very sensible inconveniences caused by the difficulty of cooking with water that boils twenty or thirty degrees (according to the height) below 212°, by the reluctance of fires to burn, and of tobacco to keep alight, and we complete a sufficiently deterrent list of the penalties attendant on literal compliance with the magnanimous motto, Altiora petimus.
That they will, nevertheless, not prove deterrent we may safely predict. Enthusiasm for science will assuredly overbear all difficulties that are not impossibilities. Dr. Copeland, taking all into account, ventures to recommend the occupation during the most favorable season say from October to December of an extra-elevated station 18,500 ft. above the sea, more than one promising site for which might be found in the vicinity of Lake Titicaca. For a permanent mountain observatory, however, he believes that 12,500 ft. would be the outside limit of practical usefulness. It is probable, indeed, that the Rocky Mountains will anticipate the Andes in lending the aid of their broad shoulders to lift astronomers towards the stars. Already a meteorological post has been established on Pikes Peak in Colorado, at an altitude of 14,151 ft. Telescopic vision there is said to be of rare excellence; we shall be surprised if its benefits be not ere long rendered available.
After all, the present strait of optical astronomy is but the inevitable consequence of its astonishing progress. While instruments remained feeble and imperfect, atmospheric troubles were comparatively little felt; they became intolerable when all other obstacles to a vast increase in the range of distinct vision were removed. The arrival of that stage in the history of the telescope, when the advantages to be derived from its further development should be completely neutralised by the more and more sensibly felt disadvantages of our situation on an air-encompassed globe, was only a question of time. The point was a fixed one: it could be reached later only by a more sluggish advance. Both the difficulty and its remedy were foreseen 167 years ago by the greatest of astronomers and opticians.
If the theory of making telescopes, Sir Isaac Newton wrote in 1717,31 could at length be fully brought into practice, yet there would be certain bounds beyond which telescopes could not perform. For the air through which we look upon the stars is in a perpetual tremor as may be seen by the tremulous motion of shadows cast from high towers, and by the twinkling of the fixed stars. The only remedy is a most serene and quiet air, such as may perhaps be found on the tops of the highest mountains above the grosser clouds.
Edinburgh Review.GOETHE
BY PROF. J. R. SEELEYIIIThe highest rank in literature belongs to those who combine the properly poetical with philosophical qualities, and crown both with a certain robust sincerity and common sense. The sovereign poet must be not merely a singer, but also a sage; to passion and music he must add large ideas; he must extend in width as well as in height; but, besides this, he must be no dreamer or fanatic, and must be rooted as firmly in the hard earth as he spreads widely and mounts freely towards the sky. Goethe, as we have described him, satisfies these conditions, and as much can be said of no other man of the modern world but Dante and Shakspeare.
Of this trio each is complete in all the three dimensions. Each feels deeply, each knows and sees clearly, and each has a stout grasp of reality. This completeness is what gives them their universal fame, and makes them interesting in all times and places. Each, however, is less complete in some directions than in others. Dante though no fanatic, yet is less rational than so great a man should have been. Shakspeare wants academic knowledge. Goethe, too, has his defects, but this is rather the place for dwelling on his peculiar merits. In respect of influence upon the world, he has for the present the advantage of being the latest, and therefore the least obsolete and exhausted, of the three. But he is also essentially much more of a teacher than his two predecessors. Alone among them he has a system, a theory of life, which he has thought and worked out for himself.