amputation of several of their organs, and of consequence must possess a strong princi. ple of vitality. They are fond of basking in the sun, cannot well dispense with water for any considerable time, and are incapable of sustaining rigorous cold. See Amphibia Plate II. fig. 1..

R. esculenta, or green frog, is much larger than the last species, and abounds in many countries of Europe, though but rarely to be found in England. These animals croak so loudly as to be heard at a very great distance, and to produce great annoy ance. They are extremely voracious, and will occasionally seize small birds, and chickens and ducks when very young, swallowing them entire. They are in some places much used for food, particularly in France, and thought fittest for the table in the month of June.

R. catesbeiana, or the bull-frog, is found in many regions of North America, and grows to the length of eighteen inches from the nose to the hind feet. Its sounds resemble the lowing of a bull. In Virginia these frogs are supposed to be great puri. fiers of the water, and a pair of them may generally be seen by any person approaching the public fountains common in that country; but on being thus surprised by the traveller, they make two or three leaps, and plunge into the mouth of the spring, where they are secure from molestation. They are highly rapacious, often commit great depredations on the poultry, swallowing even young geese without considerable difficulty.

R. paradoxa, or the paradoxical frog, is of the size of the common frog of Europe, and is found chiefly in America, and par ticularly in Surinam. It is remarkable for the circumstance of the tadpole, bearing a greater proportion to the size of the parent animal than in any other species. This proportion, indeed, is truly extraordinary and curious.

R. zebra, or the zebra frog, is a native of Carolina and Virginia, and is by far the largest of the slender bodied frogs. It is of a pale reddish brown, and beautifully marked, transversely, on the back and limbs, with bars of a chesnut colour.

R. arborea, or tree frog, is not found in Great Britain, but is met with in various other parts of Europe, and in elegance and activity is superior to every other European species. In summer it resides in the woods, and haunts the trees in quest of insects, which it approaches on its belly, in the

same manner as a cat to a mouse, and at length seizes with an elastic and instantaneous spring. It is particularly noisy on the approach of rain. In winter it takes up its abode in the bottoms of the waters, remaining till the spring in a state of torpor.

RANCIDITY, in chemistry; fixed oils are liable, by keeping, to undergo a change well known by the name of rancidity. They become thick; acquire a brown colour, an acrid taste, and a disagreeable smell. The oil thus altered converts vegetable blues into red, and of course contains an acid. It is believed that this change is owing to the alteration of the foreign substances present in oils, or to the action of those foreign bodies upon the oily matter itself. Several of the fixed oils, when newly extracted, let fall, on standing, a quantity of mucilaginous matter; and from the experiments of Scheele, it appears probable that they always retain less or more of a similar principle.

RANDOM shot, in gunnery, is a shot made when the muzzle of a gùn is raised above the horizontal line, and is not designed to shoot directly, or point blank. The utmost random of any piece is about ten times as far as the bullet will go point blank. The bullet will go furthest when the piece is mounted to about forty-five degrees above the level range.

RANGE, in gunnery, the path of a bul let, or the line it describes from the mouth of the piece to the point where it lodges. If the piece lie in a line parallel to the horizon, it is called the right or level range: if it be mounted to forty-five degrees, it is said to have the utmost range, all others between 00 and 45o are called the intermediate ranges.

RANK, the order or place allotted a person, suitable to his quality or merit. See PRECEDENCE.

RANK, in war, is a row of soldiers, placed side by side. To double the ranks, is to put two ranks into one. To close the ranks, is to bring the men nearer; and to open them, is to set them further apart.

RANSOM, was the sum formerly given by captains or passengers for the redemption of a vessel captured by pirates. This is now prohibited by statute.

RANUNCULUS, in botany, crowfoot, a genus of the Polyandria Polygynia class and order. Natural order of Multisilique, Linnæus. Ranunculaceæ, Jussieu. Essential character: calyx five-leaved; petals five to eight, with a honied pore at the

claw; seeds naked. There arè fifty-nine species. R. aconitifolius, aconite leaved crowfoot, is a very handsome species, about three or four feet in height, branched; stems hollow within; leaves large, digitate, three-lobed, divided to the base; segments lanceolate, hirsute, especially at the base; flowers white, terminating each branch; petals roundly serrate. Native of the Alps of Europe. The double flowering variety has been obtained by seeds, and is preserved in many gardens for the beauty of its flowers. By some gardeners it is called fair-maid of France. The Persian crowfoot, or garden ranunculus, has been greatly improved by culture, and many new flowers obtained from seeds, amongst which are several with semidouble flowers, which produce seeds; and from these there are such prodigious varieties of new flowers annually obtained, which are large and of such variety of beautiful colours, as to exceed all other flowers of that season; many of them are finely scented; the roots, when strong, generally produce twenty or thirty flowers upon each; it is a native of the Levant.

RAPE of women, is where a man has carnal knowledge of a woman by force, and against her will, which is by our law a capital felony, and subjects the offender to the punishment of death, which is never remitted. By 18 Elizabeth, c. 7, if any person shall, unlawfully and carnally, know and abuse any woman child under the age of ten years, whether with her consent or against it, he shall be punished as for a rape. And it is not a sufficient excuse in the ravisher to prove that she is a common strumpet; for she is still under the protection of the law, and may not be forced. Nor is the offence of a rape mitigated, by showing that the woman at last yielded to the violence, if such her consent were forced by fear of death or duress; nor is it any excuse that she consented after the fact.

RAPE is also a name given to a division of a county, and sometimes means the same as a hundred, and at other times signifies a division consisting of several hundreds ; thus Sussex is divided into six rapes, every one of which, besides its hundreds, has a castle, a river, and a forest belonging to it. The like parts in other counties are called tithings, lathes, or wapentakes.

RAPHANUS, in botany, radish, a genus of the Tetradynamia Siliquosa class and order. Nataral order of Siliquosæ, Cru

ciformes, or Cruciferæ. Essential charac. ter: calyx closed; silique torose, subarticulate, cylindrical; glands four, two between each shorter stamen and the pistil, and two between the longer stamens and the calyx. There are six species, R. sativus, common garden radish, has a large fleshy, fusiform, annual root; stem upright, thick, much branched and diffused, rough with pellucid bristles; leaves rough; calyx green, rough haired; petals pale violet, with large veins running over them. It is a native of China. There are four varieties of the common radish, viz. the long-rooted radish; the small white turnep-rooted or Naples radish; the black Spanish radish; and the large turnep-rooted, or white Spanish radish. The first variety is that which is commonly cultivated in our kitchen gardens for its roots; of this there are seve ral subordinate variations.

RAPHIDIA, in natural history, a genus of insects of the order Neuroptera. Gene ric character: mouth with a curved toothed horny mandible; thorax long, cylindrical; three stemmata; wings deflected; antennæ filiform, as long as the thorax, the anterior part elongated and cylindrical; four feelers very short, filiform; tail of the female terminated by a large recurved bristle. There are two species, viz. the R. ophiosis, a smallish fly with rather large transparent wings, and a narrow thorax, stretching for. wards in a remarkable manner; it is found on trees in summer, though but seldom; the pupa resembles the complete insect, except being destitute of wings. R. rotata, mentioned by Gmelin has, by other naturalists, been supposed to be a mere variety of the ophiosis. Dr. Shaw mentions two other species, viz. R. cornuta, which in size is equal to one of the larger dragon flies, and is distinguished by its very long horn-like jaws, which extend far beyond the thorax, and are terminated by a bifid tip; the wings are large, reticulated, and semi-transparent. It is a native of North America. R. mantispa, a small species that has the habits of the genus Mantis, and is sup posed by some to belong to that genus.

RAREFACTION, in physics, is the making a body to expand or occupy more room or space, without the accession of new matter. It is by rarefaction that gunpowder takes effect; and to the same prin ciple also we owe eolipiles, thermometers, &c. The degree to which air is rarefiable exceeds all imagination; perhaps indeed its degree of expansion is absolutely beyond

all limits. Upon the rarefaction of the air is founded the method of measuring altitudes by the barometer; in all cases of which the rarity of the air is found to be inversely as the force that compresses it, or inversely as the weight of all the air above it at any place.

The open air, in which we breathe, says Sir Isaac Newton, is 8 or 900 times lighter than water, and by consequence 8 or 900 times rarer. And since the air is compressed by the weight of the incumbent atmosphere, and the density of the air is proportionable to the compressing force, it follows by computation, that at the height of about seven English miles from the earth, the air is four times rarer than at the surface of the earth; and at the height of 14 miles, it is 16 times rarer than at the surface of the earth; and at the height of 21, 28, or 35 miles, it is respectively 64, 256, or 1024 times rarer, or thereabouts; and at the height of 70, 140, and 210 miles, it is about 1,000,000, 1,000,000,000,000, or 1,000,000,000,000,000,000, &c.

Mr. Cotes has found, from experiments made with a thermometer, that linseed-oil is rarified in the proportion of 40 to 39 in the heat of the human body; in that of to 15 to 14, in that degree of heat wherein water is made to boil; in the proportion of 15 to 13, in that degree of heat wherein melted tin begins to harden; and finally, in the proportion of 23 to 20, in that degree wherein melted tin arrives at a perfect solidity. The same author discovered, that the rarefaction of the air, in the same degree of heat, is ten times greater than that of the linseed-oil; and the rarefaction of the oil, about fifteen times greater than that of the spirit of wine.

RASANT, or RAZANT, in fortification. Rasant-flank, or line, is that part of the curtain or flank whence the shot exploded rase, or glance, along the surface of the opposite bastion.

RAT. See Mus.

RATCH, or RASH, in clock-work, a sort of wheel having twelve fangs, which serve to lift up the detents every hour, and make the clock strike.

RATCHETS, in a watch, are the small teeth at the bottom of the fusy, or barrel, which stops it in winding up.

RATE, a standard or proportion, by which either the quantity or value of a thing is adjusted.

RATE of a ship of war is its order, degree, or distinction, as to magnitude, bur

den, &c. The rate is usually accounted by the length and breadth of the gun-deck, the number of tons, and the number of men and guns the vessel carries. Of these there are six rates. A first-rate man of war has its gun-deck from 159 to 174 feet in length, and from 44 to 50 feet broad; it contains from 1313 to 1882 tons, has from 706 to 800 men, and carries from 96 to 100 guns. Second rate ships have their gun-decks from 153 to 165 feet long, and from 41 to 46 feet broad; they contain from 1086 to 1482 tons, and carry from 524 to 640 men, and from 84 to 90 guns. Third rates liave their gun-decks from 140 to 158 feet in length, from 37 to 42 feet broad; they contain from 871 to 1262 tons; carry from 389 to 476 men, and from 64 to 80 guns. Fourth rates are in length on the gun-decks from 118 to 146 feet, and from 29 to 38 broad; they contain from 448 to 915 tons; carry from 226 to 346 men, and from 48 to 60 guns. Fifth rates have their gun-decks from 100 to 120 feet long, and from 24 to 3f broad; they contain from 259 to 542 tons, and carry from 145 to 190 meu, and from 26 to 44 guns. Sixth rates have their gun-decks from 87 to 95 feet long, and from 22 to 25 feet broad; they contain from 152 to 256 tons, carry from 50 to 110 men, and from 16 to 24 guns.

It is to be observed, that the new-builtships are much larger, as well as better, than the old ones of the same rate; whence they double numbers all along; the larger of which express the proportions of the new-built ships, as the less those of the old ones.

RATIO, in mathematics, is the relation which one quantity bears to another in respect of magnitude, the comparison being made by considering how often one contains, or is contained by, the other. Thus, in comparing 6 with 3, we observe that it has a certain magnitude with respect to 3, which it contains twice; again, in comparing it with 2, we see that it has a different relative magnitude, for it contains 2 three times, or it is greater when compared with 2 than it is when compared with 3. The ratio of a to b is usually expressed by two points placed between them, thus, a:b; and the former is called the antecedent of the ratio, the latter the consequent. When one antecedent is the same multiple, part, or parts, of it's consequent, that another antecedent is of its consequent, the ratios are equal. Thus, the ratio of 4 6 is equal to the ratio of