Having made all these corrections, which many 1mariners despatch summarily by an addition of twelve minutes, he has the true meridian altitude of the sun. Taking this from a quadrant, or ninety degrees, gives its zenith distance, or distance from the point in the heavens which is 'immediately over the head of the observer, and would be met by a straight line passing from the centre of the earth through his position.

Now if the sun were for ever on the equator, the zenith distance would always be the latitude; but as the sun is only twice a year upon the equinoctial, and as his distance from it at times increases more than twenty degrees, it becomes necessary to take this distance, called his declination, into the estimate.

The sun's declination is given in the almanack for the noon of each day by correcting it for the time anticipated or elapsed, according as the sun comes first to him, or the first meridian by his position east or west of it, the observer obtains the declination for noon at its own position. This declination applied to the zenith distance, by adding when the sun is on the same side of the equator, by subtracting when on the opposite side, gives the true latitude.

Thus a daily and accurate knowledge of the latitude is to the mariner a desideratum of easy attainment, and hence the value attached by seamen to an accurate knowledge of it, and hence too the saw of latitude, lead, and look out.

It frequently happens that at the time when the sun or moon is on the meridian, clouds prevent the observing of its meridional altitude; the latitude may then be obtained by observing two altitudes out of the meridian at different times, and noting the interval of time which elapses between the times of observation.

1. Vide Root. captain.

2. A nautical saying indicating the three important cares of a

LAPLAND, NORWAY, AND DENMARK. LAPLAND is the most northern country of Europe, and is divided between Russia and Sweden. The country is so cold that the hot liquor we call brandy sometimes freezes there. It is to be feared, however, that the Lapps find means of thawing more of it than is good for them.

The people have a great many reindeer, whose flesh. supplies food, and whose skins furnish clothing. They also take the place of horses, and drag the people over the snow in sledges, at a rapid rate. These people have no history that is worthy of being related.

Norway is an extensive country, bounded on the west by the Atlantic Ocean, and on the east by Sweden. It is a cold, bleak and barren region, but the inhabitants live pretty comfortably. They have very fine cows, from which they make the best butter in the world.

Bergen is the largest city, and has twenty thousand inhabitants. The houses are small, and generally built of wood. Fires sometimes do great damage, and therefore there are a good many watchmen who walk about the streets at night, muffled up in thick great coats. Every hour they cry out, "God preserve our good city of Bergen!"

2 Norway was early inhabited by rough tribes, who were adventurous seamen. There seems to have been now and then a pirate among them, for in 860, a pirate, named Nadody, discovered Iceland, which was afterwards settled by the Norwegians.

Norway was conquered by Canute, king of Denmark, in 1030; but six years after, it became independent, and for many years it was governed by its own king. In

1. Vide Root. 2. In the ninth and tenth centuries the inhabitants of Norway, Sweden, and Denmark were terrible to the southern parts of Europe by their piracies. 3. All the Scandinavian governments were monarchical: the first king of Denmark was Dan, a native of the island of Zealand.

1397, it was incorporated with Denmark, and continued a part of that kingdom till 1814, when it was transferred to Sweden.

Denmark is a little kingdom lying between Sweden and Germany. It is a level country, nearly surrounded by the sea. Copenhagen, the capital, has one hundred and twenty thousand inhabitants. The whole population of the kingdom is two millions. The Danish language is spoken both in Denmark and Norway.

The three kingdoms of Denmark, Sweden, and Norway were anciently called Scandinavia. In very early times these were occupied by tribes of Finns and Germans; afterwards the Goths conquered these countries. They were led by Odin, of whom many marvellous tales are told, and who seems to have been worshipped as a kind of Jupiter, among these northern tribes. Skiold, the son of Odin, is said to have been the first king of Denmark,

All that we really know of Denmark at this early period, is, that the people were composed of wild, adventurous warriors, who were generally considered by the more southern nations of Europe as pirates. About the time that the Roman empire fell, the Danes, Swedes, and Norwegians were known by the general name of Normans.

In 920, the several Danish tribes appear to have been united under one government. Canute conquered England and a part of Scotland in 1016, and subdued Norway in 1030. Since his time, Denmark has had a great many sovereigns, and been engaged in several wars, but its history offers little that is interesting.

GEOGRAPHICAL.-Area, 310,000 square miles. Population, four millions.
How is Denmark bounded, and of what parts does it consist?

What are the principal towns of Norway, and of Denmark?

What islands belong to Denmark, and what is Hecla remarkable for?
What are the latitude and longitude of Copenhagen and Christiana?
CHRONOLOGICAL.-Iceland discovered by the Norwegians A.D. 860.

The Goths and Swedes, Teutonic tribes, having conquered Sweden, the Finns and the Laplanders were united into one nation A.D. 1250. They had previously to this date embraced Christianity.

ASTRONOMY.

Finding the Longitude.

VARIOUS ways have been devised to find the longitude, in all of which the great element is Time. Inasmuch as the earth performs her diurnal revolution in twenty-four hours from the time any given meridian is brought under the sun, until it reaches it again, it follows that 24 hours and 360 degrees are both equal to a circle, and that the equator, and other circles of longitude, may be indifferently estimated by either of these divisions. Hence the

difference of time between two places is no other than the difference between the sun's coming to their respective meridians, or in a word their difference in longitude; and it follows that if we by any means simultanously ascertain the time of the first meridian, and the time at ship, we shall have ascertained the longitude.

The easiest mode of solving this problem is by means of the 'chronometer. This is a watch so nicely constructed as to go with perfect uniformity in any climate. To find the longitude by means of it, the mariner has merely to take an observation of the sun or other star, when rising or falling rapidly, and deduce the time of ship: this compared with the time at the first meridian 'simultaneously given by the chronometer, determines the longitude. Several chronometers concurring with each other may make the mariner sure of his position, but a single one, unchecked by other data, and liable from its fineness of construction to easy derangement, is a dangerous guide.

The most certain way of ascertaining the longitude is by the eclipses of Jupiter's satellites. Their times. of 'immersion and 1emersion at the first meridian are noted down in the almanack, and these compared with the times at which the 'telescope shows the observer the

occurrence of the same phenomena, determine the longitude. But the unsteadiness of a ship at sea, deprives the mariner of this expeditious method.

There yet remains open to him another, of sufficient accuracy: this is by observing the distance of the moon from the sun, and other particular fixed stars, and comparing the time of observation with that time at which the almanac shows a similar difference for the first 1meridian. The only difficulty attending this beautiful method, which the rapid movement of the moon in her 1orbit, and her consequent change of distance from the stars, renders proportionably correct, consists in the first place in nicely observing the distance, and then in correcting it trigonometrically for the errors occasioned by 1parallax and refraction. A single lunar observation, like a single chronometer, has been confided in, to the loss of many a noble ship; but a series of them taken from day to day, with stars on different sides of the moon, and concurring to show the same longitude, are worthy of all confidence.

Our meridians are reckoned from Greenwich, the first meridian in all English maps and charts being drawn through Greenwich. This is a purely arbitrary decision of Charles the Second, who ordered the observatory to be erected there. In consequence of this, the difference of time between Greenwich and any place on the globe will, by reckoning four minutes for every degree, give the degree of longitude of the place as shown on English maps. By this then, alone, the longitude may be ascertained, the difficulty being in obtaining chronometers which will keep accurate time in all climates. The immense importance of such a chronometer was manifested some years since, when Parliament offered ten thousand, fifteen thousand, and subsequently twenty thousand pounds, to any person who would construct one. Mr. Har ́rison partially succeeded, and was rewarded accordingly.

1. Vide Root.