these months a merchant vessel can gain to windward thirty-five miles a day in working up between Mocha and Suez.

In the Red Sea during June, July, and August the wind is stronger at night than in the day.

In that portion of the sea called the Sea of Suez a misty horizon is generally the forerunner of wind, however this does not always follow. The same remark applies to the little fleecy clouds observed over the mountains of Toor or Sinai seen at the South entrance of the Strait of Jubal.

During the winter months the northerly winds bring dry weather throughout the whole extent of the Red Sea, and the southerly winds wet weather. A change of wind is found thus previous to any change being observed. During the summer months the atmosphere is generally moist over the whole extent of the Red Sea. The sky is, however, very clear in the zenith. The wind rarely blows in sudden gusts in this sea; sometimes, however, it is strong from the North.

Each monsoon takes a month before it becomes completely established. At Mocha, from September to May, the wind varies from E.S.E. to S.E.b.E., and from the beginning of April to the end of August it frequently blows from S.S.W. to S.W. In November and December, along the coast between Mocha and Aden, the breeze is very strong; in June and July it is variable and moderate.

The rainy season in the Red Sea lasts from April to September. When the N.E. monsoon penetrates into the Red Sea, it assumes the direction from S.E. And enclosed as it is by the high lands of Africa, in a narrow strait, it gains considerable force, inclining slightly towards the coast of Arabia. Indeed it is probably stronger on this coast than on that of Abyssinia, even in the lower part of the Red Sea. It begins to diminish in force towards the parallel of 14° N. lat., and in proportion as it reaches the widest part of this sea, it gradually becomes a light breeze, turning west of the shores and islands of the coast of Africa, and meeting the Northerly winds of these parts.

South Coast of Arabia.-On the South coast of Arabia beyond the gulf of Aden, that is, West of the meridian of Cape Guardafui, as far as Ras-el-Gat, in December, January, February, and the first fifteen days of March, the N.E. monsoon prevails along the coast, its direction depending on the formation of the shore. At sea, it varies from N.E. to E.b.S., with fine clear weather, without any squalls or rain.

Bay of Koorya-Moorya.-The same winds prevail on the whole extent of this coast, excepting between Ras-Seger and Ras-Karwan; and in the great bay of Koorya-Moorya, where the weather differs greatly from that of the rest of the coast. Sudden changes in the wind are often found there, and its violence is occasionally dangerous, especially as there are no indications of it. A cloud appears over the mountains of the bay, the fine clear weather becomes suddenly cloudy, five minutes afterwards it blows heavily from the Northward. Arabs call these winds belaats, and dread them very much. Belaats. During the belaats one breeze follows another at intervals of eight or ten days, blowing heavily, sometimes in gusts and squalls,

The

varying from N.N.E. to N.N.W. These winds never last less than three days, and sometimes continue for seven and even ten days. They are equally dangerous to vessels near the coast. Sometimes towards evening the wind falls entirely, and a calm lasts for an hour or two; then down come heavy gusts from the mountains, at intervals of several minutes between, without any other warning than the whistling of the wind and the noise of the sea made by them. These breezes are heavy enough to blow the sails away from the yards, and even to carry away masts and all. They last for five or six hours, and follow each other at greater or less intervals. The belaat is often followed by strong winds from S.E., producing a heavy sea. At other times,

in the same bay, gusts of wind from S.S.W. are found, often lasting for five days together, but are not dangerous, because they blow along the coast.

Northerly winds are not felt at any great distance out at sea, and appear to prevail on that part of the South coast of Arabia only above-mentioned. After passing the bay of Koorya-Moorya, they follow the direction of the coast, yielding to the influence of the high mountain chain of the Subban. The South winds only appear to blow on this portion of the Arabian coast, rarely extending over the Southern part; and the S.W. monsoon only reaches Socotra from the 1st to the 10th of May. Heavy rains then occur; but the S.S.W. winds, which blow in February and March, must not be confounded with the S.W. monsoon.

From the middle of March to April the winds are weak and variable over the whole of the coast under consideration, and have a tendency to draw to the Southward. Alternate land and sea breezes are then found. The sky is generally clear at this time, and during the night a heavy dew.

In May the weather is uncertain, and when the monsoon is strong it comes from S. W., with fine weather.

In June, July, and August, the S. W. monsoon is in full force; it is especially violent in July, at least it is then most frequent. In the beginning of June the passage is made from the Red Sea or Persian Gulf; but the end of August is preferred, as then the height of the monsoon is over.

In September the wind is moderate, varying from West to South. The Arabs call these damauro. These winds continue from the 1st of September to the establishment of the N.E. monsoon.

In October light and variable winds prevail, with frequent calms. The land breeze is found near the coast, and sometimes alternately with the sea breeze. During the night the sky is cloudy, sometimes with rain.

From the 18th to the 20th of November the N.E. monsoon generally blows on the South coast of Arabia. After this period, the winds, taking the direction of the coast, prevail between North and East. Previous to the monsoon the weather is the same as during the preceding month, and is also rainy.

On the South coast of Arabia the regularity of the seasons must

not be depended on, for sometimes at the same period in one year the winds will be quite opposite to those of another. Besides, on the whole of this coast, especially where the land is low, the wind is subject to the sun's influence, and hence atmospheric variations, an influence even which operates on strong winds. Thus to the N.E. of Ras-Fartak the N.E. monsoon frequently lasts only three months (during a part of November, December, January, and part of February). The S.W. monsoon generally terminates in the middle or towards the end of August, and merchant ships sail for the Red Sea in the beginning of September. In March Southerly winds sometimes blow fresh E.N.E. off Ras-Fartak, especially in the bay of KooryaMoorya. April and May are considered by the Arabs as a separate season, which they call bayn el autern. The wind is then changeable and principally blows from Southward, so that vessels come from all parts. Almost all those which go down the coast at the commencement of the N.E. monsoon, return during these months. In August, when it blows fresh from S.W. to the Southward of Ras-el-Gat, to the Northward of it this wind gradually changes, and becomes S.E. From this cape to Muskat we find variable winds and alternate land and sea breezes. Sometimes a N.W. wind, coming from the Persian Gulf, extends as far as Muskat, and occasionally S.E. winds lasting a few days.

In September and onwards to the end of March, the prevailing wind is East and moderate. The wind is seldom strong at this season, but when alternate land and sea breezes prevail, they are tolerably fresh.

The S.W. monsoon begins at the end of March, and lasts till the middle of September.

Persian Gulf.-N. W. winds prevail during nearly all the year in the Persian Gulf, and a Southerly wind is only met with in December, January, and February, but even then does not last.

With the exception of these three months, when heavy squalls from S.S.W. and S.W. occur, Southerly winds are only occasionally met with in the Persian Gulf. When they freshen up and last two or three days, it is pretty nearly certain that the N.W. winds will then return with more violence than before. It will even happen that in those months, when Southerly winds generally prevail, vessels will suddenly encounter heavy squalls from the Northward, and perhaps become disabled. It has also been observed, that the N.W. winds which follow these Southern breezes, are generally stronger and last longer than the former.

Those which

Shemaal.-The North winds are called shemaal. occur once in a year, in about June or July, and last forty days, interrupted only by intervals of calm and light airs, are called the great shemaal, at which time it is useless to attempt beating up the gulf from the Southward.

In March and April there is also a little shemaal, which sometimes lasts for twenty days without any change in its force or direction. About four or five days before it sets in, the currents of the Persian

Gulf set rapidly to the Northward, so that vessels beating to windward make about twenty miles a day. The winds in the gulf are neither so regular nor contiuue so long as those in the Red Sea. They frequently interrupt each other, the land breeze or a strong S.W. wind, principally at the entrance of the gulf.

The N.W. and S.E. winds are those which last; all others are always weak and variable.

During the winter months, southerly winds are accompanied by rain. The following observations apply more especially to the Southern part of the Persian Gulf. In October the winds are variable; sometimes from West and South, accompanied with fine weather.

In November the winds vary from N.E. to S.E. and S.W. At the time of new moon there is generally a strong N.E. wind continuing for three days, with a cloudy sky, after which it becomes very fine.

In December moderate Northerly winds are found, freshening only at the time of the new moon. At which time it blows fresh from N.E., and the weather is fine and pleasant.

In January the wind varies between N.E. and West; prevailing mostly from North and East, and blowing fresh. At the time of the

new moon from NE. Snow appears then on the mountains.

In February the winds generally vary from N.N.E. to S.W., perhaps to N.W. Occasionally there is stormy weather and strong land breezes from the coast of Arabia. There is little rain on this coast, but on the coast of Persia it falls in abundance.

During the month of March, strong breezes prevail from North and West, accompanied with rain, particularly about the time of new

moon.

In April, moderate westerly winds prevail, but attended with squalls, which at the time of new moon become stormy. Towards the end of this month we sometimes find Easterly winds, lasting for two or three days.

During the month of May we find the winds from the West and South, bringing fine weather. At the end of this months fogs are very thick. The atmosphere is then loaded with sand, which is kept at a great height by reason of its rarity, a phenomenon which especially occurs in the Northern part of the gulf, and along the coasts bordering the desert.

In the months of June and July we have the great shemaal, blowing strongly from N.W.

In August and September the wind is variable, with a tendency to West.

(To be continued.)

NO. 9.-VOL. XXV.

3 s

COMPASS EXPERIMENTS AND OBSERVATIONS ON MAGNETIC CHANGES IN THE "ROYAL CHARTER."-By the Rev. Dr. Scoresby.

At a special meeting of the Liverpool Compass Committee, held in their rooms, on Saturday the 16th of August, the Rev. Dr. Scoresby gave a comprehensive account of his magnetic researches during the voyage of the Royal Charter to Australia, and round the world. The Royal Charter, it should be noted, is an iron ship, of the clipper class, with auxiliary steam power, belonging to the Liverpool and Australian Navigation Company, and commanded by Capt. F. Boyce. She is 324 feet in length on deck, and 42 feet in breadth, and 2,780 tons

measurement.

The compasses of the Royal Charter, observations on which was one important object of Dr. Scoresby's inquiries, were four in number; the steering compass, adjusted by magnets on Mr. Airy's principles, 68 feet from the stern; another adjusted compass, called the "companion compass," 89 feet; a standard compass on the deck house, unadjusted, 181 feet from the stern, and a compass aloft, 42 feet above the poop deck. The leading objects contemplated by Dr. Scoresby in his recent undertaking, were to verify or test his theoretic views and results of inductive magnetism, with relation to the compass, especially as to the "retentive quality so highly developed in iron ships, in the process of construction, with the changes in such magnetism,-views which he had first placed before the public at the meeting of the British Association at Oxford, in 1847, and since then, in his "Magnetical Investigations," published in 1852, and in various other forms; and to test also his plan of a compass aloft, first proposed in his account of discoveries on the eastern coast of Greenland, in 1822, for the avoidance of the ship's attraction, and for obtaining correct compass guidance, so essential to safety in navigation.

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Four plans or processes were adopted by Dr. Scoresby for the determination of the facts, as to the nature and changes of the ship's magnetic condition, viz. :-comparisons almost daily, of the four compasses described; experiments on the ship's external magnetism, as indicated by her deviating action on a compass, placed first near the upper edge of the top plating, and then gradually let down towards the water's edge,-such experiments being made in different parts of the ship's length, on the poop, and forecastle; the determination, from time to time, of the polarity of iron bars, standards, &c., having an upright position; and, finally, the ascertaining the position taken by a Foxe's dipping needle in different stations about the deck, and comparing the results with the known terrestrial dip. By these several applications, the whole of the objects contemplated in the voyage were satisfactorily and completely attained, and to Dr. Scoresby it was necessarily most gratifying to find that not one of the conclusions he had been led to by inductive researches was in any measure controverted; bat, on the contrary, all the leading propositions he had been urging