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light which is seen to surround the Sun during a total eclipse. It is an impressive and beautiful phenomenon, and is only visible when the Sun is concealed behind the dark body of the Moon. Professor Young gives the following graphic description of the corona: ‘From behind it [the Moon] stream out on all sides radiant filaments, beams, and sheets of pearly light, which reach to a distance sometimes of several degrees from the solar surface, forming an irregular stellate halo, with the black globe of the Moon in its apparent centre. The portion nearest the Sun is of dazzling brightness, but still less brilliant than the prominences, which blaze through it like carbuncles. Generally this inner corona has a pretty uniform height, forming a ring three or four minutes of arc in width, separated by a somewhat definite outline from the outer corona, which reaches to a much greater distance and is far more irregular in form. Usually there are several “rifts,” as they have been called, like narrow beams of darkness, extending from the very edge of the Sun to the outer night, and much resembling the cloud shadows which radiate from the Sun before a thundershower. But the edges of these rifts are frequently curved, showing them to be something else than real shadows. Sometimes there are narrow bright streamers as long as the rifts, or longer. These are often inclined, or occasionally even nearly tangential to the solar surface, and frequently are curved. On the whole, the corona is usually less extensive and brilliant over the solar poles, and there is a recognisable tendency to accumulation above the middle latitudes, or spot zones; so that, speaking roughly, the corona shows a disposition to assume the form of a quadrilateral or four-rayed star, though in almost every individual case this form is greatly modified by abnormal streamers at some point or other.’ The corona surrounds the Sun and its other envelopes to a depth of many thousands of miles. It consists of various elements which exist in a condition of extreme tenuity; hydrogen, helium, and a substance called coronium appear to predominate, whilst finely divided shining particles of matter and electrical discharges resembling those of an aurora assist in its illumination.
FIG. 7.—The Corona during the Eclipse of May 1883. Fig. 7.—The Corona during the Eclipse of May 1883.

We possess no knowledge of the physical structure of the interior of the Sun, nor have we any terrestrial analogy to guide us as to how matter would behave when subjected to such conditions of extreme temperature and pressure as exist in the interior of the orb. Yet we are justified in concluding that the Sun is mainly a gaseous sphere which is slowly contracting, and that the energy expended in this process is being transformed into heat so extreme as to render the orb a great fountain of light.

Milton in his poem makes more frequent allusion to the Sun than to any of the other orbs of the firmament, and, in all his references to the great luminary, describes him in a manner worthy of his unrivalled splendour, and of his supreme importance in the system which he upholds and governs. After having alighted on Mount Niphates, Satan is described as looking

Sometimes towards Heaven and the full-blazing Sun,
Which now sat high in his meridian tower.—iv. 29-30.

He then addresses him thus:—

O thou that with surpassing glory crowned,
Look’st from thy sole dominion like the god
Of this new World—at whose sight all the stars
Hide their diminished heads—to thee I call,
But with no friendly voice, and add thy name,
O Sun, to tell thee how I hate thy beams,
That bring to my remembrance from what state
I fell, how glorious once above thy sphere.—iv. 32-39.

On another occasion:—

The golden Sun in splendour likest Heaven
Allured his eye.—iii. 572-73.

In describing the different periods of the day, Milton seldom fails to associate the Sun with these times, and rightly so, since they are brought about by the apparent diurnal journey of the orb across the heavens. Commencing with morning, he says:—

Meanwhile,
To re-salute the world with sacred light,
Leucothea waked, and with fresh dews embalmed
The Earth.—xi. 133-36.
Soon as they forth were come to open sight
Of day-spring, and the Sun—who, scarce up-risen,
With wheels yet hovering o’er the ocean-brim,
Shot parallel to the Earth his dewy ray,
Discovering in wide landskip all the east
Of Paradise and Eden’s happy plains.—v. 138-43
or some renowned metropolis
With glistering spires and pinnacles adorned,
Which now the rising Sun gilds with his beams.—iii. 549-51.
while now the mounted Sun
Shot down direct his fervid rays, to warm
Earth’s inmost womb.—v. 300-302.
for scarce the Sun
Hath finished half his journey, and scarce begins
His other half in the great zone of Heaven.—v. 558-60.
To sit and taste, till this meridian heat
Be over, and the Sun more cool decline.—v. 369-70.
And the great Light of Day yet wants to run
Much of his race, though steep. Suspense in Heaven,
Held by thy voice, thy potent voice he hears,
And longer will delay, to hear thee tell
His generation, and the rising birth
Of Nature from the unapparent deep.—vii. 98-103.

The declining day and approach of evening are described as follows:—

Meanwhile in utmost longitude, where Heaven
With Earth and Ocean meets, the setting Sun
Slowly descended, and with right aspect
Against the eastern gate of Paradise
Levelled his evening rays.—iv. 539-43.
the Sun now fallen
Beneath the Azores; whether the Prime Orb,
Incredible how swift, had thither rolled
Diurnal, or this less volubil Earth,
By shorter flight to the east, had left him there
Arraying with reflected purple and gold
The clouds that on his western throne attend.—iv. 591-97.
the parting Sun
Beyond the Earth’s green Cape and verdant Isles
Hesperian sets, my signal to depart.—viii. 630-32.
Now was the Sun in western cadence low
From noon, and gentle airs due at their hour
To fan the Earth now waked, and usher in
The evening cool.—x. 92-95.
for the Sun,
Declined, was hasting now with prone career
To the Ocean Isles, and in the ascending scale
Of Heaven the stars that usher evening rose.—iv. 352-55.

In the combat between Michael and Satan, which ended in the overthrow of the rebel angels, Milton, in his description of their armour, says:—

two broad suns their shields
Blazed opposite.—vi. 305-306,

and in describing the faded splendour of the ruined Archangel, the poet compares him to the Sun when seen under conditions which temporarily deprive him of his dazzling brilliancy and glory:—

as when the Sun new-risen
Looks through the horizontal misty air
Shorn of his beams, or, from behind the Moon
In dim eclipse, disastrous twilight sheds
On half the nations, and with fear of change
Perplexes monarchs.—i. 594-99.

This passage affords us an example of the sublimity of Milton’s imagination and of his skill in adapting the grandest phenomena in Nature to the illustration of his subject.

THE MOON

The Moon is the Earth’s satellite, and next to the Sun is the most important of the celestial orbs so far as its relations with our globe are concerned. Besides affording us light by night, the Moon is the principal cause of the ebb and flow of the tide—a phenomenon of much importance to navigators. The Moon is almost a perfect sphere, and is 2,160 miles in diameter. The form of its orbit is that of an ellipse with the Earth in the lower focus. It revolves round its primary in 27 days 7 hours, at a mean distance of 237,000 miles, and with a velocity of 2,273 miles an hour. Its equatorial velocity of rotation is 10 miles an hour. The density of the Moon is 3·57 that of water, or 0·63 that of the Earth; eighty globes, each of the weight of the Moon, would be required to counterbalance the weight of the Earth, and fifty globes of a similar size to equal it in dimensions. The orb rotates on its axis in the same period of time in which it accomplishes a revolution of its orbit; consequently the same illumined surface of the Moon is always directed towards the Earth. To the naked eye the Moon appears as large as the Sun, and it very rapidly changes its form and position in the sky. Its motions, which are of a very complex character, have been for many ages the subject of investigation by mathematicians and astronomers, but their difficulties may now be regarded as having been finally overcome.

The phases of the Moon are always interesting and very beautiful. The orb is first seen in the west, after sunset, as a delicate slender crescent of pale light; each night it increases in size, whilst it travels eastward, until it attains the figure of a half moon; still growing larger as it pursues its course, it finally becomes a full resplendent globe, rising about the time that the Sun sets and situated directly opposite to him. Then, in a reverse manner, after full moon, it goes through the same phases, until, as a slender crescent, it becomes invisible in the solar rays; afterwards to re-appear in a few days, and, in its monthly round, to undergo the same cycle of changes. The phases of the Moon depend upon the changing position of the orb with regard to the Sun. The Moon shines by reflected light derived from the Sun, and as one half of its surface is always illumined and the other half totally dark, the crescent increases or diminishes when, by the Moon’s change of position, we see more or less of the bright side. Visible at first as a slender crescent near the setting Sun, the angular distance from the orb and the width of the crescent increase daily, until, at the expiration of seven days, the Moon is distant one quarter of the circumference of the heavens from the Sun. The Moon is then a semi-circle, or in quadrature. At the end of other seven days, the distance of the Moon from the Sun is at its greatest—half the circumference of its orbit. It is then visible as a circular disc and we behold the orb as full moon. The waning Moon, as it gradually decreases, presents the same aspects reversed, and, finally, its slender crescent disappears in the Sun’s rays. The convex edge of the crescent is always turned towards the Sun. The rising of the Moon in the east and its setting in the west is an effect due to the diurnal rotation of the Earth on her axis, but the orb can be perceived to have two motions besides: one from west to east, which carries it round the heavens in 29·53 days, and another from north to south. The west to east motion is steady and continuous, but, owing to the Sun’s attractive force, the Moon is made to swerve from its path, giving rise to irregularities of its motion called PERTURBATIONS. The most important of these is the annual equation, discovered by Tycho Brahé—a yearly effect produced by the Sun’s disturbing influence as the Earth approaches or recedes from him in her orbit; another irregularity, called the evection, is a change in the eccentricity of the

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