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Serpents and Frogs. SERPENT-LIKE REPTILES compose the third order of the class. They are distinguished principally by having no 'external organs of motion ; a few of them, however, have rudimentary limbs concealed beneath the skin. Though destitute of wings and feet, the motions of some, at times, are so rapid that the eye can scarcely follow them. The spine, or back-bone, consists of from two to three hundred small bones united by a ball-and-socket joint, admitting of free motion in every direction. In moving, the serpent first rests on a joint of its body near the head, and then draws itself up into one or more arches; then, resting on a joint near the tail, it shoots forward and straightens itself. These movements are performed so quickly, that the serpent appears to glide over the earth almost without touching it.
The two venomous teeth with which some of this order are provided, are long and sharp-pointed, and have a deep groove on one side. At the root of each there is a gland that secretes a poison. When not in use, the fangs lie down close under the upper jaw, so as to offer no resistance to the passage of the food ; but when required as instruments of offence or defence, they are made to stand erect downwards, and by biting not only are wounds made, but the poison is ejected into them through the grooves.
Some serpents can swallow animals that are much thicker than themselves. This is owing to the jaws consisting of several separable and moveable pieces, and to the peculiar manner in which they are united to the skull. Like worms and spiders, serpents shed their skin periodically. This order is divided into three families--snakes, true serpents, and naked serpents.
Snakes have small shoulder-bones, and the scales with which they are covered, both on the upper and under sides, are extremely small. The blind worm or brittle snake, is a well-known example of this family.
The true serpents have neither breast-bone nor shoulderbones, and the ribs nearly reach round the body; many of them have indication of 1 posterior limbs, the ends of which appear in some externally in the form of little crooks. This, by far the most numerous family, is again divided into double-walking serpents (those that can move either backwards or forwards with equal facility), non-venomous serpents, venomous serpents with fangs only, and venomous serpents with fangs and other teeth. Naked serpents, of which there are few, have very small eyes, and no scales on the skin.?
FROG-LIKE REPTILEs compose the fourth and last order. The skin is without clothing of any kind, and with few exceptions, the toes have no nails. The first three orders of reptiles undergo no important change after leaving the egg. It is otherwise with the frog tribe. Their eggs are deposited in the water, where they remain till the young burst forth, having very much the appearance and structure of fish; moving by means of the tail, and breathing water by gills. In a few weeks, however, feet gradually make their appearance; the tail becomes shorter, and at last disappears; the gills close, and the reptile assumes its perfect form, breathing air by means of lungs. A few of this order, as the proteus and siren, retain their gills through life, and yet possess lungs; these only are true
amphibious animals, being at all times capable of breath, ing either on land or in water.
2. The most extraordinary fossil known belongs to this order, and is called the pterodactylus, from pteron, and dactulos, a finger. It was a lizard, yet could fly. Its head and neck resembled a bird's; its bones and teeth a lizard's; its wings the bat's; and its body and tail were like the present mammalia. It formed the connecting link between birds and reptiles. The iguanodon, an herbivorous fossil lizard, of seventy feet long, also belougs to this class.
SWEDEN. Not much is known about the early history of Sweden. În ancient times it was under the government of Denmark. A Danish queen, called Margarét, ruled over Denmark, Sweden, and Norway, in 1387.
In 1518, the Danish king Christian II. caused ninetyfour Swedish senators to be 'massacred in the city of Stockholm. Gustavus Vasa, the son of one of these 'senators, 'incited the Swedes to 'revolt against Denmark.
Gustavus Vasa succeeded in freeing his country, and was 'elected king. The next. sovereign of Sweden who is worth mentioning, was Gustavus Adolphus. He began to reign in 1611, at the age of eighteen.
In 1633, he won the battle of Lutzen, but was killed at the moment of victory.
Gustavus Adolphus left a daughter named Christiana, who was then only six years old. She was thought to possess remarkable talents, and great pains were taken with her education. But she was neither a good woman nor a good queen.
After reigning a considerable time, queen Christiana became weary of the cares of government. She therefore 'abdicated the throne, and set out to seek a 'residence in some pleasanter country than Sweden.
The most famous sovereign that Sweden ever had, and
1. Vide Root. 2. About 50 B.C. Odin or Woden reigned over it, the same who after death being worshipped by the northern nations on Wednesday, gave name to the day Woden's day or Wednesday. 3. Margaret formed the Union of Calmar in 1397 ; by it Denmark, Sweden, and Norway, were to be ever under one sovereign, and each was to elect the sovereign in turn. 4. Christian II. the Nero of the north, was ten years king, nine banished, twenty-seven a prisoner in a cell into which no one entered, his food being given him through a door, and he then regained his liberty, but not his throne. 5. He established the Lutheran form of worship in Sweden. 6. Charles XII. warred against Denmark, Poland, and Russia. By the battle of Paltowa in 1709, Charles lost all he had gained by the battle of Narva in 1700.
one of the most famous in the world, was Charles the Twelfth. He began to reign in 1697, at 15 years of age.
Charles the Twelfth was a scourge to all Europe, and to his own kingdom more than 10 any other. He delighted in war for its own sake.
During the first few years of his reign, Charles was constantly successful; but in 1709, the czar of Russia gained a great victory over him, at Pultowa. Charles then made his escape into Turkey.
In 1714, he left Turkey, and returned to Sweden. His first business was to make war again. But his warfare was now drawing to a close,
One night, while besieging a fortress in Norway, he advanced in front of his troops to see how the siege was going on. A cannon-shot struck him on the head, and killed him. He was found grasping his sword, which was half drawn from the scabbard. Historians seem hardly decided whether to call Charles a hero or a madman.
One of his 'successors, named Gustavus the Third, was shot at a masquerade, in 1792. Gustavus the Fourth behaved in such a manner that his subjects were compelled to dethrone him. This took place in 1809.
The next king was Charles the Thirteenth. The emperor Napoleon caused a French general, named Bernadotte, to be declared Crowy-prince of Sweden, and heir to the throne. In 1818, when Charles the Thirteenth died, Bernadotte succeeded him,
GEOGRAPHICAL.-Area, 172,189 square miles. Population, three millions.
part is in the frigid zone ?
Finding the Latitude. To find the latitude of a place is of the highest importance in navigation. For this essential performance we have abundant data. All the heavenly bodies are, by the revolution of the earth, daily brought to the meridian, at which time, if their 'altitude could be measured, their declination or distance from the equator being known, the latitude is readily deducible. It may also be ' deduced from single or double altitudes of bodies not in the meridian, the time being accurately known. But the meridian altitude of the sun furnishes at once the easiest and most correct method of finding the latitude.
Furnished with a 'sextant, circle, or "octant, the observer goes upon deck, and having examined the adjustment of his instrument, proceeds to bring down the image of the sun reflected by its mirror, until the lower limb just sweeps the horizon. He continues to follow and measure its ascent until it ceases to rise. The moment that it begins to fall, and the lower limb dips in the horizon, the sun has passed the meridian. The altitude marked by the index being read off, it is next corrected in the following manner.
First, the observer adds the semi-diameter, in order to make the altitude apply to the centre of the object; next he subtracts the dip to meet the error caused by the extension of the horizon in consequence of the rotundity of the earth, and the elevation of his eye above its surface, also the refraction of the atmosphere, by which the object when not vertical is made to appear higher than its true place; lastly he adds the parallax, a small correction inconsiderable from the sun's distance, in order to reduce the calculation for the centre of the earth, from which point all calculations are made, and which is ever supposed to be the station of the observer.