H

A

By close hauling, or bracing up the yards as it is termed, a vessel may be made to move towards a point very different from that to which the wind is travelling; thus, suppose the wind to blow in the direction from C to D, and a sail to be placed in the direction D E; let CD represent the force of the wind, and complete the parallelogram, having the side ED parallel to the sail, and DF perpendicular to it. The force of the wind represented by CD is equal by the laws of mechanics to two forces, one applied in the direction and represented in amount by CE, or FD, and one by CF or ED. Now it is evident that E D does not help to push the ship forward; all the progress must depend upon the force exerted by FD, but FD is itself SAILING ON A WIND. not in the line in which it is desired the vessel should move, and by the same law of mechanics the force (FD) may be resolved into two-one as F H thrusting the ship sideway, the other FG (or HD, equal to FG) propelling the vessel in the line BA; and thus F G or HD represents the whole beneficial result from the force of wind represented by CD.

B

But should the wind be more adverse, recourse is had to tacking, and a great deal of sailing results in very little progress. Let us see how this occurs.

Should the wind be coming from A to B it cannot fall upon the sail D so as to cause it to propel the ship forward; but by altering the vessel's direction from B A to B I, the wind may so blow upon D as to move the ship onward to I; on arrival at which point, by again tacking, and sailing to K, the wind now striking the ship and sails from the other side, and so continuing to change the tacks, the point A may be at length reached, but only after much extra distance has been traversed and time lost.

The interest created by this lecture was kept up by the doctor's subsequently conducting a class for the study of his favourite science; and with the aid of the ingenious ship's carpenter, he constructed several apparatus to illustrate his instructions; and before landing many of the passengers had acquired much valuable knowledge of the leading principles and facts of chemistry, electricity, and galvanism.

NOTE TO PAGE 67.-Strictly speaking, steam generated at 212° under the ordinary pressure of the atmosphere, occupies about 1700 times the space it filled when in the form of water. The experiments of Watt gave the result of one cubic inch of water yielding one cubic foot of steam, or 1728 inches.

"In me the spirit of the Cape behold,

That rock by you the Cape of Torments named,
By Neptune's rage in horrid earthquake framed,
When Jove's red bolts o'er Titan's offspring flamed.
With wide-stretched piles I guard the pathless strand,
And Afric's southern mound unmoved I stand;

Nor Roman prow, nor daring Tyrian oar,
E'er dashed the white wave foaming to my shore.

Nor Greece nor Carthage ever spread the sail

On these, my seas, to catch the trading gale.

You, you alone have dared to plough my main,
And with the human voice disturb my lonesome reign."

LUSIAD.

AT noon we were, by observation, sixty miles distant from Cape Town, and two hours afterwards the pleasant sound of "land ho!" passed through the ship; and scanning the horizon we de

scried far off on the lee bow the dim mountains, looming out of the sea, in form as of a crouching lion, guarding its native domain.

Gradually becoming more distinct, the two high lands, so well known as the Lion's Head and Rump, were approached; and the broad flat Table Mountain, against which Cape Town rests in quiet repose, opened out to view between the Lion's Head and the bold craggy cliffs of the Devil's Peak.

Piloting our way by lead and eye, for night rapidly advanced, the good ship rounded the Lion's tail, formed by the long low slip of land called Green Point, jutting out into the sea, and the Petrel's anchor was dropped about a mile from the shore, on which the many twinkling lights told of the habitations of man; and we seemed as by a resurrection to have returned to the world of our fellows.

Far up on the right of Cape Town other thousand glowing lamps suggested that a new city had arisen unknown to former visitors. It was the Mahometan city of the dead, whither, at the festival of the Ramazan, the living resort in grateful recollection of the departed faithful, and illuminate their tombs with lamps, and anoint the headstones with oil.

Off Cape Town we lay for some days, during which we several times witnessed that curious appearance exhibited by Table Bay, of one portion being calm and quiet as a lake of glass, while at a few yards distance a hurricane may be blowing in all its fury.

This phenomenon arises from portions of the Bay being protected from the influence of violent inland winds by the mountains immediately surrounding Cape Town; whereas the gullies or openings between the mountains form outlets or tubes through which the wind rushes with accelerated force, the line of demarcation between heavy squall and dead calm, being almost mathematically defined. To prevent ships drifting to sea a second

anchor is frequently dropped, royal masts housed, and the lower yards pointed to the wind.

Cape Town, with its hot dusty streets, running formally at right angles to one another, walled in with lines of whitewashed houses on either hand, is less agreeable on close acquaintance than pleas ing from its water view, or as seen from one of the neighbouring mountains, the Lion's Rump for instance, whence a noble prospect is obtained of Table Bay and the town, the sweep of ocean to the horizon, the distant mountains far off in the interior, and at the rear of Cape Town the nearer Table Mountain, on whose summit or adown whose sides the white mist and rain clouds linger, or roll in masses, becoming to the practised residents, as it puts on or removes its cloudy table-cloth, or stands uncovered, a grand natural indicator, by observing which the approaching weather is known. "The cloth is on the mountain," they will say; "we cannot do so and so to-day."

The mingled population of English, Dutch, Malays, and Africans, with their different customs, manners, and modes of dress, affords a large fund of amusement and instruction to the resting voyager.

Not cognizant of the rotundity of the globe, the ancients believed, from the increase of temperature as they advanced towards the south, that the limit of endurance would be arrived at, and imagination conjured up vast impassable regions of flame, in which only salamanders could exist. By slow degrees adventurous navigators dispelled these phantasies, and pushed their researches further and further along the African coast, until they resulted in the discovery of its limits by Bartholomew Diaz, in 1486, and the weathering of its most southerly point by Vasco de Gama, in 1497.

This sailing round the much dreaded Cape of Storms, or Lion of the Sea, as it was termed, solved the problem of an eastern sea route to India, and the Portuguese monarch gave to the land