of her oars.

But of all the Antarctic Constellations, the celebrated Southern Cross, by far the most remarkable * * * This constellation, being about thirty degrees from the South Pole, is seen in its whole revolution; and accordingly, when off the Cape, I have observed it in every stage, from its triumphant erect position, between sixty and seventy degrees above the horizon, to that of complete inversion, with the top beneath and almost touching the water.” -Captain Hall's Fragments, 2d. Series, Vol. 2.

CONSTELLATIONS SOUTH OF THE EQUINOCTIAL,

Between Pisces (tail of west Fish) and the South Pole are :

Between Shoulder of Monoceros and South Pole.

The Greater Dog Sirius 1.

Canis Major

31

..

Argo Navis....

64

The Ship Argo

Canopus 1.

8

The Flying Fish

*Piscis Volans

Between Head of Hydra and Sextans and South Pole.

Between Head and Urn of Aquarius and South Pole.

Capricornus .. 51 The Goat

Piscis Australis 24 The

Grus

Southern

Fish

13 The Crane

Fomalhaut 1.

ILLUSTRATIVE EXTRACTS

FROM CAPTAIN BASIL HALL'S FRAGMENTS OF VOYAGES

AND TRAVELS.

LONGITUDE.

"Although it is, undoubtedly, in the fine-weather regions of the globe that the picturesque or poetical beauties of the moon are most felt and seen, her highest utility to seamen lies in the tempestuous latitudes beyond the tropics. Many a stout-souled mariner's heart beats with anxiety and apprehension as he steers his bark round the stormy capes which bound Africa and America, or, worse still, into the British Channel, before a hard south-wester, and prays for the moon to rise. Even to this hour, though many years have passed over my head since then, I remember the joyous feeling with which I blessed the coming of her pale light, when my poor ship was entangled with icebergs off Cape Horn, in the long and dreary nights of the Antarctic July."-Vol. III. 3rd. Series, p. 255.

"But the genuine triumph of the moon, after all, consists in her power, when duly propitiated, of conducting her votaries round the world, and leading them into unknown seas and bays, and far from land, with as much certainty as if they were sailing close to their own shores, familiar to their eyes from infancy."-P. 261.

"The moon is the hand of a great Greenwich clock, seen all over the world, with which you compare the chronometer, to see how it differs and how it goes. You then compare it with the sun as clock of the place. Having by another separate observation determined the latitude.'

"In practice it is easy to press the moon into our service, and make her act as the hand of a Greenwich clock in the sky. The moon, as every one knows, moves, like all the planets and satellites, from west to east, amongst the stars, and performs the complete circuit of the heavens once in every month; that is to say, she moves to the eastward through the heavens at the average rate of about 13 degrees a day, or somewhat more than half a degree an hour. Thus her apparent motion amongst the stars is about one minute of space in two minutes of time; and this, which is a rate of movement distinctly perceptible even to the naked eye under some circumstances, is always observable with the instruments in use at sea. The consequence is, that whenever the sky is clear, and the moon up, we can ascertain, at any given moment of time, by actual observation, her exact place in the heavens relatively to the sun or planets, or stars lying in her path. We then refer to the Nautical Almanac, an Ephemeris in which the moon's place has been previously computed by astronomers, and there we discover the Greenwich time at which it has been predicted that she will reach the point in the heavens we have observed her to occupy, at the moment of taking the lunar,' as it is called. Having likewise ascertained what was the ship's time' at the same instant, by other observations made on board, we ascertain their difference by subtracting one from the other, (precisely as in the case of the chronometer), and we arrive at the difference of longitude between the ship and Greenwich."-P. 266.

LATITUDE.

"In practice, we have merely to watch till the sun, moon, planets, or some one of the numerous bright objects, whose places in the heavens have been well ascertained, comes to the meridian of the ship; we then measure, by a sextant,* its altitude or angular elevation above the horizon, and having applied to that angle the correction due to the star's known distance from the pole, we come at the latitude required. I need not repeat that, were the star which we observe situated actually in the pole, no such correction would be necessary. This may be repeated with other stars throughout the night, though many navigators content themselves with observing the sun's altitude at noon for the latitude. I used always to make my middies determine the ship's latitude in their respective night-watches, and write the result on the log-board, as a current matter of duty.

"The exact moment of noon, it may be thought, is the only one at which the sun's altitude ought to be taken for determining the latitude; and so in strictness it is. But the change of altitude during about half an hour before, or half an hour after noon, is so small, and its rate of variation so well known, that if the ship's time, which is generally known near enough, be only carefully noted by watch, while repeated observations of the sun's altitude are taken, during the twenty minutes before and after noon, the latitude may be determined with nearly as much precision as if the exact meridian observation had been obtained."-P. 270.

"I have seldom remained at sea twenty-four consecutive hours, in any climate, without obtaining the latitude, if I wished anxiously to know the ship's place.

"It is very curious, but very true, that the extreme simplicity of the methods of ascertaining the latitude at sea, both at night and in the day time, compared with the operose and delicate operations necessary for finding the longitude, give to the longitude an importance which it is by no means entitled to claim relatively to the latitude. One is exactly as material as the other, with this great difference in practice, that if the sky be clear, the latitude may easily be determined half-a-dozen times during every hour of the night, whereas the longitude by lunars can be gained only when the moon is above the horizon, and when she is at a particular age. By the help of a chronometer, indeed, the longitude may be corrected almost as often as the latitude; and navigators are much too remiss in using stars for the purpose of determining their time at ship. If advantage be taken of the half hour, or three quarters of an hour, after the sun is well below the horizon, or before he rises again in the morning, the altitude of stars may be observed with great precision by using the inverting telescope of the sextant; and if during the same period the meridian altitude of two or three stars be observed, the ship's place, both in latitude and longitude, may be settled very accurately."-P. 272.

"Sextant," an instrument with two small reflectors, one of them attached to a moveable index, which, being shifted by the hand, is contrived to show the angular distance from the horizon, &c., at which the reflected star is situated.

DEFINITIONS, ETC.

61

9

"We were running for the British Channel before a hard southwest gale, and it was of considerable importance that we should reach some port in England without delay, for we were not only charged with despatches, but were very short of provisions and water. The only chronometer I had on board happened not to be very good, and the sky had been so completely overcast for more than a week before, that we could take no lunars. Thus I felt uncertain of my longitude, to the extent of a degree at least; and all who have tried the experiment know what a nervous thing it is to run in for the land, in the dark, and in stormy weather, when the ship's place is not correctly known. But I felt exceedingly loath to lose so magnificent a wind, before which we spun along at the rate of ten knots,* under a reefed foresail and close-reefed main-topsail. As long as daylight lasted I felt very confident and bold about the matter; but as the night closed in, the doubts and difficulties of the Channel navigation crowded round my thoughts, and almost determined me to bring the ship to,t and wait for the dawn. After poring for a long while over the chart, however, I satisfied myself that if, by any means, I could be sure of keeping in the latitude of 509, or within ten or a dozen miles on either side of that parallel, I should have clear ground to run over for three degrees of longitude at least, greatly within which I felt sure that the error of my chronometer must lie. But how was I to determine this point with any degree of certainty in such weather? The sky had not showed a patch of blue as large as my hand for several days, and though the sun had been seen through the clouds occasionally, we had not succeeded in catching a meridian observation.

"In this dilemma I bethought me of the pole-star, proverbially the mariner's friend, and having fixed my sextant by the cabin light, at the angle about which I knew the latitude must give the altitude of the pole, I cast my boat cloak over my shoulder, and went on deck. There I stationed myself on the larboard‡ side of the quarter-deck, with the instrument sheltered from the rain and spray under the cloak, and grasped in my right hand, while I kept my eye fixed on that part of the heavens in which I hoped, at some momentary opening, to detect the bright star of my night's fortunes. I had to wait more than an hour before there occurred any thing like a chance, by which time my limbs had become cramped and stiffened by the constraint of one posture, while my eye ached and throbbed with its vain attempts to pierce the thick courses of clouds sweeping past.

At last I did get sight of the star, for three or four seconds, and though it glimmered so faintly through the mist, that it could hardly have been identified as Polaris, even by Sir James South himself, I knew by its altitude that it must be the object I was watching for. The horizon was but a shabby one, indistinctly seen in the dark, and hacked by the topping waves like the Sierra Morena. Nevertheless, I succeeded in bringing the star in contact § with the edge of the sea

The left side.

To cease sailing.

* Ten miles per hour. §i.e., by moving the index of the sextant, and its attached reflector, to see the reflected image of the star in the direction of the horizon.

G