Those who follow the "southern" route, take their departure from St John's, (Staten Land,) and steer to the southward to lat. 63°, where they expect to find the wind from the eastward, which will carry then as far as 850 or 87° of W. lon. They make this longitude, before they cross the parallel of 610, whence, as those who go the other route, they steer directly north to lat. 40°.

Independently of personal observation, other means of acquiring information, relative to the navigation around Cape Horn, have been resorted to. Besides access to numerous log books and notes, information has been obtained on the subject, from masters of vessels, who have been sailing to and from the west coast of South America, for many years. The opinions of some, derived from an attentive observation, and strengthened by the experience of twenty voyages, have the highest claims to respect. The advice of these men urges the propriety of yielding to circumstances in doubling Cape Horn, and of being guided by the winds, in giving preference to either the "inshore" or the "southern" passage.

The former is to be pursued always, when the winds are favorable, keeping close into the land, never passing to the southward of Diego Ramirez, more than ten or twelve leagues. It is better to go to the northward of it, when it can be done without loss of time. The "inshore" passage being nearer in point of distance, when the winds are ahead, if the sea be smooth enough to allow a vessel to beat to windward without losing by leeway; but when this can no longer be done in a breeze that is freshening, the route should immediately be abandoned by standing to the south, until the wind shall be found to be more favorable for getting to the west, which frequently happens by running a few leagues to the southward of Diego Ramirez. The westerly winds, for the most part, come in a sweep around the land, without stretching many degrees in breadth, towards the south.

The longitude of 85° should be gained, without going to the northward of the parallel on which the land is cleared. The latitude of 40° S. as in the other route, is made on the meridian of 85°. This is always done to clear the gales and currents, which blow and set on shore in the vicinity of the Island of Mocha, and the outlet to the straits of Magellan.

Vessels bound from the U. States around Cape Horn, are recommended to cross the line, between lon. 23° and 26°, so that with the south east trades, they can fetch Cape Frio, which should always be done; then to run the coast down on soundings and to pass between the Falklands and the Main.

If driven off the coast before reaching the Islands, it is better to beat up to it, to the northward, than to pass down south, to the eastward of them, after the gale abates. There are circumstances under which the outside passage would prove the more expeditious, but their presence cannot be known by description; the situation of the vessel, the direction of the winds, the appearance of the weather, etc. are the guides for pointing out the proper time for the outside passage, and they frequently deceive seamen, who have never made a voyage around Cape Horn.

The probability of meeting westerly gales to the south, after having passed to the east of the Islands, and the sufferings to which the ship's company is liable in them, are sufficient reasons why preference should be given to the passage between the Islands and the Main. The coast and the soundings along it, are clear and regular.

When the wind is fair, Cape St. John's should be doubled close around, and all canvass crowded on the ship, to carry her to the west as fast as possible. The difficulty of the passage consists in getting from Staten Land to 85° west.

If on clearing St. John's, or making Hermit's Island, a gale be met from the westward, the vessel, unless she could clear all danger by standing to the northward and westward, should be kept constantly on the starboard tack, until she either forges out of the range of the gale, or arrives in lat. 63°. With the easterly winds to the south, she can run to 85° west, whence she can steer north to 40° as previously directed.

If it be necessary to go to 63° south, before the winds will allow the vessel to stand to the westward, she should make her westing to the southward of 60°; if she gets out of the strength of the gale, before she reaches 63°, she can run up her westing on the parallel upon which she may be, or as near it, as the breeze will allow. It is always advisable to be in lon. 85° before attempting to pass to the northward of Cape Horn.

The U. S. S. Falmouth, and H. B. M. S. Volage, doubled Cape Horn in Oct. 1831; the latter had thirty eight the former twenty four days from the Cape to the lat. of Talcahuana. Both of them took a

westerly gale off the pitch of the Cape. The Falmouth stood down on the starboard tack to 62° 5′ S. and found the winds more favorable. The Volage, persisting in the attempt to gain the "inshore" passage, lay to on either tack, to preserve her relative position with regard to the lat. of the Cape, and was drifted off to the east

ward. When this gale abated, she stood up to the Cape again, and took another, in which she was also driven to the eastward. In the third attempt she succeeded in doubling the Cape. She put into Talcahuana, to repair the damages which she had sustained while riding out the gales from the westward. The Falmouth arrived in Valparaiso in excellent order.

In May 1829, the U. S. S. Guerriere, sailed around Cape Horn into the Pacific; she encountered a gale from the northward and westward, before she passed Diego Ramirez, she received it in the starboard tack, and forged to the southward: she got clear of it in lat. 58° 37′ near which parallel she stood to the west, she was twenty one days from the Cape to the latitude of Talcahuana.

The U. S. S. Brandywine, made the same passage in seventeen days, she passed the Cape in December, 1826; she found the winds varying from N. W. to S. W.; she ran up the usual westing without crossing the parallel of 57° 30'. When the winds freshened so that she could not beat to windward, she lay to with her head to the south, giving the land a wider berth.

The American whale ship Enterprise, and the English whaler Sussex, encountered a gale off the Cape, near the same time. The former, by forging to the southward cleared the gale in lat. 58° and in fifteen days after first crossing the parallel of the Cape, she was in the latitude of Talcahuana. The Englishman had thirty six days to the same parallel; she lay to, close to the cape in order that when the gale should abate, she might hug the land around. Before she cleared the Cape, she was twice driven by gales off to the eastward. Short passages are made by hugging the land when the wind is fair or moderate from the westward, but seldom by waiting first to ride out a gale from that quarter. Many instances could be cited shewing the advantage of steering to the southward under such circumstances. But to prove what is here recommended is not pertinent to the object in view, reasons must suffice. Common practice teaches that good passages are more frequently made by those vessels, which finding contrary gales off the Cape, stand boldly to the south, than by those, that lie to in them, keeping near the parallel of the Cape. The barometer has not been found to be of much practical utility off Cape Horn, how useful soever it may be in middle latitudes, by indicating the approach of hurricanes; it is no index to the winds in the high latitudes to the south of Cape Horn.

He, who in the China seas, is warned by the barometer, of the approaching Typhoon, and can foretell the coming of a gale by the height of the mercury in it, finds that off Cape Horn, the same indications are frequently followed by moderate breezes and even by calms. Here the mercury, below the mean height of lower latitudes, becomes very unsteady, falling and rising several inches in a few hours. During the strength of a gale, sometimes it is observed to rise, at other times it falls or remains in statu quo. Its mean height south of the latitude of Cape Horn is 29.03 in.

As the Pacific coast of Tierra del Fuego and Patagonia is approached with the wind from the westward, the mercury in the barometer ascends. When the wind is strong, it rises above thirty inches, and close under the land with fresh westerly gales it frequently stands above 30-50 in.

From lat. 45°, embracing a region towards the south of twelve or thirteen degrees in breadth, the most prevalent winds are from the westward. Vessels entering this region from the south have a rise in the barometer, when the wind is on the land. The rise is generally observed to commence about the latitude of the Cape, continuing to increase as the land is neared; and when the winds are fresh, a greater accumulation of atmosphere is shown by a higher range of the mercury.

The result of my own barometrical observations compared with others to which I have had access, shews that within this region, the barometer stands higher when the winds are from the westward, than it does, cæteris paribus, between the same parallels in the Atlantic. The difference is nearly as twenty nine to thirty, and increases as the land is approached. This accumulation of atmosphere is caused from the obstruction which the mountains of Patagonia, and the highlands of Tierra del Fuego affix to the winds in their passage across the continent towards the Atlantic. The air thus obstructed is compressed by that coming after it, and according to the force of the wind, and the distance from the land, the barometer indicates a greater or less superincumbent pressure. The disturbing cause which first destroyed the atmospheric equilibrium towards the East, continuing to act, the density of the obstructed air is increased by the increased tendency to restore the equilibrium from the west. The air thus forced, rushes around the southern extremity of the land, with an impetuosity that is known only to those, who experience the effects of its violence. This current of air, as it sweeps around

Cape Horn is confined to a channel, which is widened towards the south in proportion to the latitudinal breadth of the column, that is rushing to the east. Near the southern borders of this channel, the easterly winds commence, returning in eddies towards the west whence they are again carried eastwardly, in the current that rushes around Cape Horn.

ART. VI.-Plan of an Instrument for finding the true Lunar Distance; invented by M. F. MAURY, Passed Midshipman, U. S. Navy.

GF HE, is a great circle of brass, standing upon three legs X y Z; it represents the horizon. AE, A F and BC, are arcs of great circles; they also are of brass, and their planes pass through O, a com

mon centre.

The periphery of GFHE, the middle curvature PQ, of A E, the concave circumference of B C, and the convex of A F, have equal radii centering in O.

A E, describes half of a hemisphere on the hinge at A, the axis of which, is that of the zenith and nadir, and of course passes through O. The extremity F, of the arc A F, is fixed in the plane of GF HE, and the extremity E, of A E, revolves in the plane of G F H E, and along its circumference, describing arcs of equal circles, from the centre O, until it stands in the plane of AF, the two then represent a semicircle. By means of the screw S, which presses E to GFHE, E is placed and fixed at any distance from F. The hinge at A, is of brass turning against steel, which lessens friction.

AE and AF, are arcs of the azimuth circles, in which the sun or a star and the moon are at the time of taking a lunar observation. Each is 90° and graduated to every 10' or 15' on a slip of finer metal, let in for that purpose.

BC, is an arc of the geocentric circle, in the plane of which, the sun and moon appear, when the observation is taken; it is graduated as the other arcs are, but from 20° to 120°. It is intended first to set off the apparent, and then to measure the true lunar distance. To assist in transferring the altitudes and distance with exactness, from the sextants with which they are taken, to the arcs of the instrument, each of them is provided with a vernier scale, a, b, c, having a tangent and a fixture screw respectively attached to them. The extremity m, of BC, is hinged to zero of the vernier c; the axis of this hinge