The correction from to D measured on the line of chords, will reach 4o, calling each degree a mile, will be four miles, which multiply by the given horizontal parallax, and as the first correction falls on the left side of the lunar line, divide by 53, which will give 14' 14" for the second correction, falling on the left side of the lunar line, it is additive to apparent distance, or by proportional logarithms.

First correction 4' prop. log.

Moon's hor. par. 54' 43" prop. log.

1.6532

5172

The dividend 53' prop. log. subt. gives 4′ 8′′

5810

N. B. The apparent zenith distances, are found by subtracting the apparent altitudes from 90°.

On taking a Lunar Observation when there is only one Observer.

A lunar observation may be obtained by only one observer in the following manner :

Suppose the angular distance between the sun and moon to be increasing, lap them sufficiently, so as to allow time to read off the angular distance, and to set it down on the slate, then observe when their limbs are in contact, and as soon as that is done, take the altitude of the sun, with the same sextant, and by having a quadrant at hand, lay down the sextant, and with the quadrant take the altitude of the moon. This operation may be performed in so short a time, that little or no allowance need be made.

N. B. If the distance be decreasing, it may be performed by separating the objects, and waiting till they come in contact.

Since my remarks on the Andes, page 132, went to press, I have ascertained from Mr. Darby, at his lecture-room, Philadelphia, that the Hymmalaya Mountains are the highest in the

known world. Of these there are many peaks, some of which are rated to be 35,000 feet above the level of the sea. Some are actually known by measurement to be 28,000 feet. Of these peaks from twenty to thirty are higher than Chimboraco or Chimborazo, of the Andes, in South America. These mountains are Asia, in lat. about 30° N. and long. 90° east from Greenwich.

Cape Horn, Valparaiso, and Lima.

The following information, though not extensive, may be of importance to those who may happen in a port where directions cannot be procured:

I have been informed by a captain of a whaling ship, who has doubled Cape Horn at all seasons of the year, that the best route in doubling this cape outward bound, is, if possible, to keep out of sight of land, so that advantage may be taken of shifts of wind to sail on either tack, as circumstances require.

CAPE HORN is at the extremity of South America. It is the most southern headland of the Island of Terra del Fuego, round which ships pass in going out of the South Atlantic Ocean, westward, into the South Pacific Ocean. It is in lat. 55° 58' S. and long. 67° 22′ W., and is also situated on a small island, having Nassau Bay within that and Hermit's Islands. It may be known at a distance by a high round hill over it, and two peaked rocks like sugar loaves on its N. W. side, in the direction of N. by W. and S. by E. from each other. There is a point to the W. N. W. which has the appearance not much unlike that of the Cape, but they will be readily known from each other by their situation. There are some straggling low rocks to the west of the Cape, and one at the south, but they are all near the shore. Christmas Sound is 31 leagues W. N. W. 4 W. from the Cape. Between this Cape and Mistaken Cape, there appears to be a passage directly into Nassau Bay; but it has not been correctly explored to affirm it with certainty. The western coast appears to form several good bays and harbours. Cape Horn is said to be the south point of Hermit's Island. False Cape Horn is at the south point of the larger Island of Terra del Fuego, on the east side of which is the entrance to Nassau Bay, which is north of the Hermit's Islands, and turns round to N. W. within this Cape. It is frequently called Mistaken Cape, and lies to the N. E. from the true Cape Horn about three leagues.

VALPARAISO, Port or Bay, on the coast of Chili, is on the South Pacific Ocean, and the west coast of South America. It

is two leagues to the W. N. W. from Cape Curaoma. On turning the point bound for the harbour, range close along a shoal that shows itself within about half a cable's length from the shore, in order to keep to windward. This shoal consists of a ledge of rocks that becomes dry in some parts, but it is pretty bold. Ships that keep off too far are often obliged to make several tacks to recover the road, the anchoring place being high up the river. Bring the point of Valparaiso N. E. by N., the white battery W. S. W., and Cape Caucon N. by E., and a ship will find the best anchoring birth in twenty-seven fathoms, in oozy ground, and sheltered from all winds; its lat. is 33° 1' S., and long. 71° 37′ W. This harbour is well frequented, particularly by coasters, to load corn for Callao and Panama. Pilots may

be had here for almost any part of the coast, especially to the northward; the coasting vessels lie close into the town, and make fast their cables to the shore either to piles or great stones with rings in them; and although so near shore, they have eight or ten fathoms water. On account of the breezes which regularly come about noon from the S. and S. W., and blow so strong that vessels place no dependence on their anchors; this is an excellent way of securing ships; but care inust be taken of a shoal within a cable's length of the shore, near the battery of the White Castle, on which there is only thirteen or fourteen feet at low water, and the sea rises only six feet at most. These are the only dangers in this bay, being in all other respects very safe, and ships may tack in from eight to fifty fathoms, and anchor every where. In turning or beating to the eastward towards the Seite Harmanas, or Seven Sisters, come no nearer the shore than three cables' length, opposite to a running brook, that is crossed by a broad reddish highway, as there is a shoal in that place that has only two fathoms and a half water in it. It must be remembered that ships usually ride in the nook or angle of this road before the battery of Castillo Blanco; this being a very convenient situation for trade, as well as security from pirates and rovers. In winter it is however a bad road, because the north winds blow right in and make such a high sea, that ships are often drove ashore in spite of all their moorings ahead and astern. In summer the south winds are equally violent, but they blow from the land, and therefore make no sea; and if the ship should drive she may put to sea, and return in the evening when the wind always abates.

The river which goes up to the city of St. Jago many leagues inland, is not navigable up to the city, but all the business is done at Valparaiso. Large quantities of hemp, that is brought down the river on rafts formed of bladders and skins, are loaded here.

The point Conception is at N. by E. and partly within the bay, into which the river Aconcagua empties itself. Thisport of Valparaiso has sometimes been called San Tiago, but it has more usually the present name.

LIMA RIVER, on the coast of Peru, and the South Pacific Ocean, has a city of the same name about seven miles from the sea-Callao is the place where all the commerce of the city is transacted, this river consequently cannot be navigable.

Callao is the port town of Lima, situated on a small island opposite to it; is in latitude 12° 3' S. and longitude 77° 1′ W. The river and town of Callao is about three miles S. W. from Lima river, and betwixt them near shore, is from four and a half to five and a half fathoms water, and from Callao to a cape or narrow point of land, also to the S. W. is from five to eight fathoms; on the west side of the cape is but one fathom, and a half, and on the north, three fathoms near the shore, Lorenzo Island is somewhat more than two miles west from Callao cape, and La Laja, a very small island, lies in the midway between them. Round the cape on the south side is shoal water more than a mile from the shore; but two miles east from it is three fathoms; and from thence for four leagues to the southeast the coast forming a kind of a bay, is from four to six fathoms, at two or three miles N. E. from port China, off a point at that distance, there commences a shoal.

The hunch-backed rock is four miles S. by E. from the cape, with the Ordada rock and several smaller ones to the east of that; but there is from nine to sixteen fathoms round them.

Callao Road is the best of any which the South Sea affords ; being safe riding, clear ground, deep water, gradual soundings as well above the town towards Les Piscadores, as below it to St. Lawrence Island, you may turn in or out, as occasion may require, or the wind or weather will permit: to come in from sea, give the cape a good birth of a league at least, because of the winds off shore; for if you be nearer, the wind comes off in strong flaws and gusts-and off the windwardmost point of the capes, is a small ledge of rocks. In coming from the windward channel, between Callao point and the Island of Callao, the Bouqueron must be passed through, the wind always favouring it; small ships go in right before it. Callao Island and port are five leagues from each other, bearing from each other N. E. and S. W. In the passage of Bouqueron, take notice of a break or clift in the high lands of the island, having a white spot on the top of it; then incline a little towards the port of Callao, but still give a birth to the shoal, which in that situation is to the E. or N. E. Come no nearer the point, even in steering in, so as at least to keep the north headland of the island to the westward, this offing will carry a ship safely in, so as to

come to an anchor in the Road in any depth, in oozy ground, the only rock or shoal is about three cables' length from the shore, near a point of St. Lawrence Island, opposite to La Galera point, the most westerly on the same island.

The sea is always so still here, that ships careen at all seasons, without fear of sudden gusts of wind, which are frequent farther to the south, and though the road is open to the N. and N. N. W. these winds so seldom blow here, that no danger is apprehended, because whenever there is such winds, they never exceed a gentle easy breeze, so that it never occasions much swell to do any damage.

The Island of St. Lawrence also breaks off the sea from the S. W. to the S. E. All sorts of convenience are to be had at port Callao, and water is very readily procured in a small river that comes down from Lima, and bears the name of that city, which fall into the sea under the very walls of Callao: from Callao to Lima is about two leagues by land.

An Explanation of the Principal Terms made use of in Astronomy.

A

Aberration, an apparent change of place in the fixed stars, which arises from the motion of the earth combined with the motion of light.

Achronical rising or setting of a planet or star, is when it rises at sunset, or sets at sunrise.

Almicanters, certain imaginary circles, which, in every position of the globe, are supposed to be drawn parallel to the hori

zon.

Altitude, the height of the sun, moon, or stars, above the horizon, reckoned upon a vertical circle, in degrees, minutes, &c.

Amphiscii, a name given to the inhabitants of the torrid zone, on account of their shadows falling at one time of the year towards the north, and at another time towards the south.

Amplitude, an arc of the horizon contained between the east or west point of the heavens, and the centre of the sun or a star, at the time of its rising or setting.

Angle, the inclination or opening of two lines meeting in a point.

Anomaly, (True) the distance of a planet in signs, degrees, ,&c. from that point of its orbit which is the farthest from the

sun.

Anomaly, (Mean) is that which would take place if the planet moved uniformly in the circumference of a circle.