8

STUDYING THE HEAVENS.

Both possible and easy, provided the sky be clear and cloudless.

But this condition is as necessary by day as by night. How can we determine in which direction lies the south, if the sun be hidden from our gaze by an uniformly opaque atmosphere, and if objects, lit up by a diffuse light, project no shadow at any time of the day?

Endeavour to group together the stars which more particularly strike your gaze; and be careful, in these groupings, to define every fantastic figure which is suggested by your vivid imagination. Undoubtedly, our earliest ancestors, the "world's gray forefathers," proceeded in this manner, in their anxiety to lay hold of some definite guiding-marks in yonder ocean of sparkling atoms. And to study a science by its history is to follow up its successive development.

THE GREAT AND THE LITTLE BEAR.

Observe yonder very remarkable group of seven stars ; nearly all are of the same splendour, and they are so arranged as to figure an antique chariot, provided with a somewhat curved axle pole.

Observe it carefully. And not far from this group you will detect another, by no means so conspicuous, but exactly resembling it in form. This second chariot is turned in an inverse direction, and the stars composing it, with three exceptions, are much less brilliant.

Here, then, are two groups of stars, clearly distinguished by their configuration-two constellations, for such is the scientific name given to all the stellar groups.

THE GREAT BEAR.

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It has been the fortune of the first of these two groups to strike the eye of the most indifferent observer from the remotest antiquity; and its likeness to a quadriga early procured it the name of a car or chariot. For those Christians who pleased themselves in studding the sky with Biblical personages, it is David's

David "

was the female of the Bear, an ursa, or agurus. Whence came this transfiguration? Listen to the fanciful old myth.

Callisto was the most beautiful of the daughters of the King Lycaon. Jupiter, who may appropriately be styled the "Don Juan" or "Lovelace" of the heathen Olympus, fell in love with her; and she bore him a son, named Arcas, who gave his name to Arcadia, that land of song and fable, groves and streams, where Lycaon exercised his sovereign sway.

ΙΟ

THE "SEVEN STARS.”

Juno, the queen of heaven, and wife of the so-called king of gods and men, transported by her jealous rage, changed Callisto into a she-bear; who, one day, would have been unwittingly slain by Arcas, if Jupiter, opportunely appearing on the scene, had not metamorphosed the hunter into another animal, Ursa Minor, or the Little Bear. According to this myth, the Little Bear will be but a transformation of the former, who was the Great Bear, or, before all and above all, the Bear.

It is somewhat surprising, according to certain writers, that Homer should refer to only one of these constellations :

*Αρκτοιθ ̓ ἦν καὶ ἅμαξαν ἐπίκλησιν καλέουσιν.*

(The Bear, which men the Chariot also name).

:

But the learned commentators who have censured the poet for making no distinction between Ursa Major and Ursa Minor, probably never looked at the starry vault with an attentive eye; otherwise, like all the world, they might have convinced themselves that the seven stars, septem triones (whence the word "septentrion "), forming the beautiful constellation, which, undoubtedly, long before Homer's time, was known as "The Bear" or The Celestial Chariot," were all that could be seen. With a single exception, these stars are of the second magnitude-that is to say, they, so far as regards their brilliancy, rank next to the most brilliant stars of the firmament. The least conspicuous star in the group

* Homer, "Odyssey," v. 273.

"URSA MINOR."

II

one of the third magnitude-occupies the base of the pole of the Celestial Chariot, or of the Bear's tail; it is the fourth star counting from the extremity of the tail. On celestial charts, it is particularised by the fourth letter of the Greek alphabet, (delta).

Observe, in passing, that the first of these charts, wherein the stars of a constellation were indicated by Greek characters, appeared in 1603, at Augsburg, under the title of "Uranometria." Its author, Jean Bayer, an amateur astronomer, who died in 1660, conceived the idea of designating by the first letters of the Greek alphabet—a, ß, y, d, and so on—the most noticeable stars. The animals bearing the names of the constellations are drawn in this map with very considerable care; but it requires, let us hasten to add, much imagination and good-will to recognise, in the form of a stellar group, the animal shown in the drawing.

Thus far Ursa Major. The four stars of the quadriga, or chariot, have been employed to form the dorso-lumbar region of the animal; the three others define its tail; and, finally, twenty-four little stars, some of which are hardly visible to the naked eye, compose the head and paws of the celestial "plantigrade."

As for Ursa Minor, it is impossible to distinguish it immediately when you are unaccustomed to surveying or examining the celestial vault. To detect its position, you require to be forewarned of it; to know, in the first place, that there exists in the vicinity of the Bear an exactly similar stellar group. The point of the tail-a in Ursa Minor-alone possesses a

12

SEEING AND NOT SEEING.

splendour comparable to that of the principal stars in Ursa Major. But how construct a figure with one star? The four other stars, two of which mark the anterior part of the animal's body, and two others the tail, properly so called, are only of the third magnitude: they are marked ß, y, d, ɛ. Finally, the stars which define the posterior portion, marked Bayer's chart, are only of the fourth magnitude-in other words, are scarcely visible. The eye, to detect them, must be wholly free from any gleam of light.

and ʼn on

Many generations passed before they succeeded in discovering what a single individual solved during his brief career. All Homer's contemporaries, and, prior to these, tens of millions of mortals, had contemplated the sky, and yet none of them had detected the difference between Ursa Major and Ursa Minor. The distinction, therefore, is of a comparatively recent date; probably does not date back earlier than the sixth century before the Christian era.

Let us recall ourselves, now, to the question propounded. The first impression produced by the aspect of the sky during a beautiful winter night is, we repeat, that the number of the stars is infinite. This wholly spontaneous thought, which, to some extent, imposes itself on the mind long before the reason attempts any calculation, is, strange to say, both false and true.

But how can a thought be both false and true? Nothing is easier than to explain the seeming contradiction. We shall return to it hereafter, after we have indulged in some indispensable digressions.