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was remarkably rainy, it scarcely ceased for eight or nine months, and llie weather was not settled before the middle of January 1803.*
It is observed that within these few years more rain has fallen than formerly. The Spaniards attribute it to the presence of heretical English 1
One remarkable circumstance attends the rain in (he Gulf; which is, that it begins in the morning, increases with the sun, till its greatest violence is at noon: decreasing towards the evening; and generally leaving the night, clear, serene, and tolerably cool. In 1803, a moderate quantity of rain fell in June, July, and August; but in general it was so dry that there could not be said to be any rainy season, and in the spring of 1801 the drought was so long, that every building being thoroughly parched up, and ready to catch fire by the smallest spark, some plantation houses, many huts, and a few patches of cane and cotton were destroyed. Even the woods whose smaller underwood and grassy vegetation were almost burnt up by the sun, easily caught tire in many parts either by accidental sparks, or by design to assist in clearing the land. Much of the northern mountainous ridge was in this slate, and exhibited at night a magnificent spectacle; particularly at Chaguaranius, where both the opposite mountains were in a blaze; and the valley itself filled and covered with thick smoke far above their summits. The additional heat was plainly perceptible on board the ship near a mile and a half distant.
[The effects of exposure from surveying were tolerably severe in this instance. Out of seven, two died, and nunc of the rest escaped a dangerous illness on a toast reckoned remarkably healthy !—Ed.]
( To be concluded in our next. J
There are two subjects in navigation which have obtruded themselves of late years, on the attention of certain careful navigators, but which, by the majority of our seamen, are considered of loo trifling a nature to be worth thinking about. The effects of local attraction on the compass remain still unattended to, and the management of a ship in meeting a hurricane, so as to adopt the proper course for avoiding it soonest, is yet we fear little understood; and yet these two points are fraught with danger, and have, it is well known, caused the destruction of many a goodly ship. Eotb of these subjects have been largely treated on in the Nautical Magazine, and although we may incur the risk of being considered tedious, we shall not let slip any favourable opportunities as they present themselves, of illustrating their dangerous tendency, until we find them take that place in ships' reckonings which they ought to have. The former of these subjects is well illustrated, in the following letter from her Majesty's harbour-master at Plymouth. This talented gentleman has alluded to ample directions for fouling the amount of local attraction, which we published in our volume for 1837,
* Thunder and lightning denote the approach of the rainy season, during which they are sometime* very severe. At other parts of the jear they seldom liaupuu,
(p. 247,) which, if they be properly followed, are quite sufficient; for we hold, that let the amount of local attraction on each point be what it may, it is only necessary that it should be known, so that a proper allowance may be made for it. Mr. Walker has instanced some remarkable cases of steam-vessels being led astray by it, and undoubtedly they are the vessels likely to suffer most from its effects, in consequence of the masses of iron on board. A very remarkable instance of local attraction will also be found in the escape of her Majesty's ship Hastings, from shipwreck, in the river St. Lawrence, recorded in our volume for 1839, (p. 279,) in which ship it amounted to two points! These, and many other instances which we have recorded in this work, along with the following, adduced by Mr. Walker, should operate as timely warnings to our seamen to grapple with the subject in earnest, and not to allow their vessels to be led from their courses, perhaps into danger without knowing it,—in fact, to know at all times the real course which they may be steering.
Bovisand, June 4, 1841. Sir.—If the extensive application of iron to the formation and equipment of ships has improved their form, augmented their strength, and accelerated their speed, its magnetic action upon the steering compasses has increased the difficulty of coast navigation, l'he general use of chronometers in the open sea, in rendering navigation comparatively easy, has made the majority of navigators indifferent about heaving the log, taking lunars, and making those nice calculations and allowances upon which the accuracy of a ship's dead-reckoning depends. The fact is, that by means of chronometers, ships now traverse the ocean with less difficulty and more speed than formerly; but in consequence of more iron entering into the fabric of our ships, and our navigators becoming less expert in the art of keeping a dead-reckoning in narrow seas, and foggy weather, the risk of shipwreck arising from errors in the reckoning has rather been increased.
Ingenious men have attempted to devise means for correcting the local attraction. You, sir, have given very excellent and plain directions for finding the amount of local attraction on a ship's compass. It appears to me desirable, that a popular explanation of the causes and consequences of local attraction iu a ship, might turn the attention of seamen to the subject, and teach them how to guard against errors in their reckoning, although the actual amount of the local attraction of the compass on its different points be not ascertained.
Although thousands may deny, there are but few seamen who know that every substance entering into the fabric of a ship, or contained within her, is actually susceptible of magnetic action. Among the metals, iron is by far the most powerful j every nail, bulk-bar, or shot, is in fact a magnet possessing a north and south pole by induction from the globe itself. Take for example any article of iron whatever,—as a pig of ballast, a crow bar, or even a ring, and on applying a small compass, it will be found that the north point of the compass-needle will be attracted by the upper part of the iron, and repelled by the lower part. If the iron be turned upside downwards, the same result will be obtained, and it will be found that the part of the metal that formerly attracted the compass-needle, will now repel it,^in a word, that the polarity of a piece of iron is instantly inverted by the invertion of the iron itself.
If a piece of iron be placed across the deck, or laid at right angles to the keel, the polarity of the iron will be changed with every roll the ship takes. The elevation or depression of a gun will do the same, the breech now attracting and then repelling the compass-needle, and hence, the reason why the compass-card swims, or rather swings, on each side of the course when a man-ofwar is rolling from side to side.
Every separate article of iron in a ship is from position, and by induction from that great magnet the globe, a magnet possessing a north aud south pole, and that change of position in the ship will change the polarity in the iron. I am convinced I need only mention this fact, in order to induce masters and mates of merchant ships to try by experiment, and thereby convince themselves how dangerous it must be to stow large masses of iron in a vertical or transverse position in the hold! When long and heavy iron things are received on board, they should be stowed horizontally and in a fore and aft direction.
In ships-of-war, or in yachts, the necessary weights may be regarded as constant, and the local attraction on the compass should be ascertained on all points and under every condition; but in merchant ships, whose cargoes vary, those who have charge should remember the following axioms:—
1st. That all iron is from position magnetical.
2nd. That a ship's rudder is at the stern, and the steering compass near the helmsman, and on the upper deck.
3rd. That the greater part of the iron in a ship is before, and also below the place of the steering compass.
4th. That the upper parts of all the iron in a ship are therefore nearer to the compass-needle than the lower parts.
Hence it follows, that the upper parts of all the iron articles on board, excite a greater influence upon the compass than do the lower and more remote parts! The north point of the compass-needle is, therefore, drawn forward in north magnetic latitude, but driven aft in the southern hemisphere. The south point is repelled by the upper part of any piece of iron here—but it would be attracted at the Cape of Good Hope!
Without enlarging on these magnetic properties of iron, in a cast or wrought state, let us enquire what takes place in practical navigation. If a ship were built entirely of wood, the local attraction of the ship upon her compass would be very small. If this ship were placed in an east and west direction when empty, her compass would indicate the true magnetic direction of her keel; if now, a cargo of hard-ware be put on board, the north point of the compass (placed in the binnacle,) may be drawn forward by the local attraction of the cargo, and instead of the ship's head being east or west, it may now be E.b.N. or W.b.N., atid therefore the compass would indicate a course one point too far to the northward,—and if at sea, the ship would be every day to the southward of her reckoning, and the nearer the course steered to the magnetic east or west, the greater would the error in the reckoning be.—Permit me to offer a few illustrations in support of my position.
On the 30th of December, 1818, being in command of a King's store-ship, laden with iron tanks, and bound to Plymouth, and knowing that these tanks would excite an influence upon the compasses, a course was steered W.N. W. from St. Catharines point for the Start:—there was a fresh breeze at east, and clear weather, but at daylight the Start bore N.N E. twenty-one miles! In this case, the ship was at least eight leagues farther to the southward than she ought to have been by steering W.N.W. I was not then aware of the fact, that an iron tank would exert a magnetic influence equal to a solid cube of the same dimensions.
On the 26th of March, 1803, her Majesty's ship Apollo sailed from Cove of Cork, with a convoy of seventy sail of merchant ships; on the 2nd of April, at three in the morning, the frigate and forty sail of her convoy, went on shore on the coast of Portugal, ot a time they imagined themselves three degrees to the westward. The loss of these ships may be ascribed to the local attraction of the frigate upon her compasses, for about thirty sail of the convoy had during the night wore to the north-west, and escaped destruction. This convoy had been steering for several days in a south-west direction, the north point of the frigate's compass would be drawn forward, thereby indicating a course further to the westward than the ships were really steering, and hence the melancholy loss of so many ships!
Being in charge of her Majesty's ship Royal William, recently launched and equipped at Pembroke, I was directed not to put to sea without two steamfrigates, ordered to accompany me to Plymouth: they arrived and towed the ship down Milford haven, and out to sea :—sail was then made with a fresh breeze from north-west; there were, however, symptoms of the wind drawing lo the westward, and I shaped a course for Scilly, instead of for the Lands End. Cnpt. Oliver, of the Dee, hailed, "how long do you intend steering on this course?'1 I replied, "till I make Scilly light." The wind freshened,—the ship increased her pace to eleven or twelve knots, and the steam-frigates were left far behind. We made Scilly light, and bore up for the Longships, passing between them and the Seven Stones,—passed up Channel, and ran into Hamoazc, the wind having drawn to the southward. The steamers had continued their course with sail and steam, and made breakers under their bows on the north side of Scilly, the light being eclipsed by St. Martins head. They backed their engines, shortened sail, and stood to the north-west till daylight, when no three-decker was to be found 1 They searched the rocks in vain, and proceeded to Plymouth, alarmed for the safety of the Royal William. It now turned out that their compasses indicated a course that ought to have carried the steamers far to the westward of the Scilly islands :—the north point of the compass was drawn forward by the influence of their machinery.
I had occasion to return to Pembroke to bring round another line-of-battle ■hip, taking a passage in the steam-frigate Salamander, commanded by Capt. Austin. The adventure of the "Royal William" induced us to make many observations upon the local attraction of the steamer during the passage. A dockyard sailing vessel was taken in tow, and after rounding the Lands End, we shaped a course for St. Anns Point, with a firm conviction on my part of making St. Govans Head. The wind shifted to south-west, with thick weather, and as we neared the Welch coast, we were amused as well as instructed, by the master of the vessel astern, standing up and waving his hat to steer more to port. He actually ca.st off the tow rape and hauled up two or three points! We went on as before, and as was expected, made St. Govans Head, south-east from St. Anns Point.
The master of the lighter knew by his compass that we were steering too far to the eastward. Our object was to prove how little dependanee may be placed in the compass of a steam-vessel, when the local attraction is not known.
The steamer " San Juan," ran on shore on the coast of Portugal, aud more recently the "Thames," instead of making the Longships,—made Scilly and was lost. It is only a few days since the "Great Liverpool," returning from the Mediterranean, in steering for the Lizard, made the Start, and I am informed, that in going up the Mediterranean on a course intended to carry her to I he northward of Galita, she actually passed between that island and the African shore in the night I
Instances might be multiplied to shew that in north magnetic latitude ships will almost always be to the southward and eastward of their reckoning, by reason of the north point of the compass being drawn forward, and the south point drawn at't by local magnetism; but in the southern magnetic hemisphere things will be_ inverted, and ships will generally be found to the northward and westward of their dead-reckoning !_
II.M.S. Thetis left Rio for England, and ran upon Cape Frio, steering a course which ought to have cleared the land. The north point of her compass needle was repelled aft, and the south point drawn forward by the frigate's local attraction; her compass indicated a course more easterly than the ship was really making.
In conclusion, I invite the mariner to watch the "effects of local magnetism upon his compasses! Let him make frequent experiments with his compasses, and avoid the stowage of large masses of iron in a vertical or transverse position. Compasses too, are often placed too close to each other, n single compass is to be preferred near the binnacle, but that one should be narrowly watched I
I am. &c.
To the Editor of the Nautical Magazine. William Walked
Tllli VoYtGE OF THE SlIlP Fl.ORENTIA.
( Continued from p. 453.,)
Mry 3rd.— At 3 P.m. came to anchor in Manila roads, in five and a half fathoms,—veered to sixty fathom?; the light-hoiisj on the river point E.N.E. distant from the shore about two miles:—only five vessels in the roads, two American, one Spanish, and two English. On entering the bay, we were boarded by a Spanish row gun-boat for a report. At 7 in the evening were visited by the port-captain, and received permission to go on shore. We now learnt the intelligence that disturbances continued in China.
May \lh.—On Monday, (English time,^ great was my surprise, wheu on arriving at the house of Messrs. Halliday, Wise, and Co., to whom I consigned the ship, to find that it was Sunday in Manila! these people having kept their time as given by the earliest navigators, who discovered these islands from the eastward.
Manila, the celebrated city, which in the year 1740 contained only from 6 to 7,000 inhabitants, in the city and suburbs now contains 80,000! The population of the island is estimated by the government returns at 4,390,000 souls. The houses in the city, as well as the mercantile houses in the suburbs, are built substantially of stone, having a verandah or balcony along the upper story. The lower fronts of a great many houses are disposed of to different persons, Chinamen and others, and converted into shops, and the upper part of the house is reserved for the use of the family, occupying the building. The back part of the loner or ground floor is U3ed for stores, stables, coach-house, &c. The rooms are generally large and lofty, the sala or drawing-room bring the principal room for visiters: the comeda or comedor is the next, and which is used for meals, and from these two rooms the quartos, cameras or sleeping apartments, are entered. These rooms are splendidly furnished, and with great taste, many having elegant prints and pictures framed and glazed. Glass hanging lamps, and many ornaments of bronze, gilt glass, artificial flowers, fancy clocks, &c, chiefly French, are found on the different tables and niches in the rooms. Even the Chinese and the richer class of Mestizos imitate the same style; the Mestizos generally having images of the crucifixion, patron saints, and the Virgin Mary, tastefully yet laudrily dressed, and placed in very handsome gilt arid ornamented glass cases. 'J he houses of the lower classes and Indianos in the suburbs, and generally in the country, are built of bamboo, and are raised on posts a few feet from the ground, the sides sometimes run up with plank boarding, but more generally with a thatch, called by the natives nerpal.
The principal streets are tolerably wide, but in the city and chief suburbs there are many very narrow, and yon might hold a conversation with your opposite neighbour with great ease, and which is oftentimes done by the senoritas and their nubios, as they call them here. The Spanish and higher classes of people dress in European costume, and the Chinese according to their own custom, but the male natives invariably appear in a light shirt, worn outside their trowsers, and the
ENLARGED SERIES.—NO. 8.—VOL. FOR 1841. 3 Z