Two Observers of the Skies.
Edward Emerson Barnard, of the Yerkes Observatory, Williams Bay, Wisconsin, is in the first rank of living astronomers. Among his many discoveries the most remarkable is that of the fifth satellite of Jupiter at the Lick Observatory. His early work at the Vanderbilt Observatory, Nashville, gave full promise of his later achievements. One evening in November, 1883, he was observing an occultation of the well-known star Beta Capricorni by the moon. He had patiently waited for his opportunity; such an occultation is best seen when the moon is a small crescent, the star disappearing at the dark curve of the moon where its beams do not overpower the feeble stellar ray. When the moon passes between the eye and a fixed star, the disappearance of the star is instantaneous. At the distance from which we look at it the star is a point only, and as the moon has no atmosphere, the instant the edge of the lunar surface touches the line joining the eye of the observer with the star, it vanishes from sight. When the moon passed in front of Beta Capricorni Mr. Barnard noticed that instead of disappearing at once, there was a sudden partial diminution of the light of the star, then a total extinction of the remaining point. The interval between the diminution and complete extinction of the light occupied only a few tenths of a second, but it was long enough to put his keen mind upon inquiry. Mr. Barnard in an astronomical journal called attention to the phenomenon and suggested that instead of there being only one star, as formerly supposed, there were really two stars so close together that in an ordinary six-inch telescope, such as he had used, they appeared to be one. He inferred also that one of the pair must be a good deal brighter than the other, because at the beginning the change in brightness was less than at the end. This surmise was soon afterward fully verified by Mr. S. W. Burnham with the eighteen and one half inch equatorial of the Dearborn Observatory at Chicago, revealing a close and unequal double star which would have remained unresolved had he used a less powerful instrument.
This Sherburne Wesley Burnham is the most successful discoverer of double stars who has ever lived. “The extreme acuteness of vision,” says Professor John Fraser, “which enables one to prosecute such research with the highest success is a very rare gift; and the discovery of close doubles, as in his case, is its severest test. To measure a star—that is, to ascertain by means of the micrometer the distance and position angle of the companion with reference to the principal star—is one thing, and to find new and close doubles is a very different thing. Baron Dembowski, the most noted measurer of double stars, had no success as a discoverer, and confessed his inability to find new doubles. When, however, a new double had been found by another observer, and the distance and position angle of the companion approximately estimated, he could readily find and accurately measure it. When Mr. Asaph Hall, in 1877, had found the two satellites of Mars and described their positions, it was not difficult for any astronomer who had access to a large Clark telescope to find them and see all that Mr. Hall had seen. The whole difficulty was in seeing them for the first time. Besides the ability to see a difficult object, there is required an intelligence and experimental knowledge of the subject, which are as rare as the visual faculty itself. Some of the lower animals have more acute vision than human beings; but they do not know all they see, or understand relations to other facts. They have plenty of sight, but they lack insight. Mr. Burnham’s powers in both these respects is extraordinary.”
At the Cape of Good Hope Observatory remarkable observations of double stars have been recorded. Sir David Gill, the director, says:—“At the Cape Observatory, as has always been the case elsewhere, the subject of double star measurement on any great scale waited for the proper man to undertake it. There is no instance, so far as I know, of a long and valuable series of double star discovery and observation made by a mere assistant acting under orders. It is a special faculty, an inborn capacity, a delight in the exercise of exceptional acuteness of eyesight and natural dexterity, coupled with the gift of imagination as to the true meaning of what he observes, that imparts to the observer the requisite enthusiasm for double star observing. No amount of training or direction could have created the Struves, a Dawes or a Dembowski. The great double star observer is born, not made, and I believe that no extensive series of double star discovery and measurement will ever emanate from a regular observatory through successive directorates unless men are specially selected who have previously distinguished themselves in that field of work, and who were originally driven to it from sheer compulsion of inborn taste.”
The Eye of a Naturalist.
It is sometimes said that the faculty of observation is a special gift with limitations, that the naturalist sees bones, feathers, shells because he is looking for them, while the armorer or the engineer but seldom gives a second glance to anything but guns, girders, or machinery.
To this rule we find striking exceptions. Edward S. Morse, of Salem, Massachusetts, is the foremost American expert in Japanese pottery. As a youth he was a railroad draughtsman in Portland, Maine, where his ambidexterity with the pencil and his discoveries in natural history brought him to the notice of Louis Agassiz. As a boy he was greatly interested in the shells of his native State; before he left school he had discovered and described a new species of land snail, Helix asteriscus, which the older naturalists had regarded as the young state of another and well-known species. At the same time he determined the distinct character of a most minute species, Helix minutissima, which had been described as such thirty years before, but which the later authorities had believed to be the young of another species. This faculty for discrimination led him to demonstrate a new bone in the ankle of birds which Huxley, and others, had supposed to be a process and not a separate bone. This discovery added another to the many reptilian characters which have been disclosed in the anatomy of birds. He also established beyond question that the brachiopods, always believed to be mollusks, are not mollusks at all, but are related to the worms. In Mr. Morse’s case we have either a man with a universal power of observation, or enjoying distinct faculties of perception, each usually appearing alone in an observer. Noticing a Japanese shooting a bow and arrow one day he took up the study of the attitude of the hand in pulling the bow. His memoir on this subject, with illustrations, has attracted world-wide interest. Pursuing this theme he examined an ancient object of bronze having three prongs, labeled as a bow-puller in European museums, showing that it had no relation whatever with the bow. Keenly susceptible to the beauty and variety of roofing tiles in Europe and the East, he has for the first time given them classification, and shown their ethnological significance. While teaching natural history at the University of Tokio he brought together the Japanese pottery now exhibited at the Museum of Fine Arts in Boston, unsurpassed as a collection in the world. His eye was as sharp in reading a potter’s mark, however worn and blurred, as when as a boy in Maine he defined minute species of land shells.
The Value of Collections.
Altogether commendable is the spirit which leads a boy or girl to collect and arrange shells, common wildflowers, seaweeds, and the diverse minerals brought to light in a railroad cutting. What is thus gathered, compared, and studied will leave a much deeper impression on the memory than what is seen for a moment in a museum or a public garden. And yet, to the profound student the museum is indispensable: he gives weeks or months to the contents of its cases, supplementing what he has learned in the field, by the seashore, in the woods. Take, for example, protective resemblances, one of the most fascinating provinces of natural history. Here is a hornet clear-wing moth. What has made it look like a wasp? Both share the same field of life, and while the wasp does not prey on the moth or in any perceptible way compete with it, the two insects have a vital bond. In its sting the wasp has so formidable and thoroughly advertised a weapon that by closely resembling the wasp the moth, though stingless, is able to live on its neighbor’s reputation, and escape attack from the birds and insects which would devour it if they did not fear that it is a stinging wasp. So far is the resemblance carried that when the moth is caught in the hand it curves its body with an attitude so wasplike as seriously to strain the nerves of its captor.
How came about so elaborate a masquerade? At first, ages ago, there was a faint likeness between the moth and the wasp; any moth in which that likeness was unusually decided had therein an advantage and tended to be in some measure left alone by enemies. In thus escaping it could transmit in an ever-increasing degree, its peculiarities of form and hue to its progeny, until in the rapid succession of insect generations, amid the equally rapid destruction of comparatively unprotected moths, the present striking similarity arose. Instances of this kind abound, forming some of the most attractive exhibits in the American Museum of Natural History of New York, and other great museums. Mr. W. H. Bates, who first explained these resemblances, did so as the result of comparing many various examples preserved in his cabinets at home, although, of course, his memory of habits observed in the field was indispensable. His ample collections enabled him to bring into view at once many captures separated by wide intervals of time and space. It was the opportunity thus afforded of taking a comprehensive survey of resemblances as a whole that led him to think out the underlying reason.