248

GASTRALGIA-GATLING GUN.

admirably adapted to the cutting of leaves or similar substances holes, from which assailants may be attacked, and is frequently by the action of the lips against a sharp, horny plate. Other overhung by a machicoalted battlement, from which missiles G. have the mouth furnished with two cutting blades, wrought of every description may be poured upon the besiegers. City by powerful muscles. The tongue of some is covered with gates and gates of large castles have in all ages been the subminute recurved hooks, to prevent the possibility of any thing jects of great care in construction; and when from some cause, escaping from the mouth, and the stomach of some is a mus- such as the cessation of constant fighting, or a change in the cular gizzard, provided with cartilaginous or sometimes cal- mode of warfare, Gs. have lost their importance in a military careous projections, or stomachic teeth, to aid in the comminu- point of view, they have maintained their position as important tion of the food. The intestine is generally bent back, so that architectural works, and where no longer useful have become the anus is not far from the head. Very great diversities are ornamental. In very ancient times we read of the "gate" as

found in the reproductive system. In some G. the sexes are dis-
tinct, (G. Diacia;) others are hermaphrodite, (G. Monacia ;)
and while self-impregnation takes place in some of these, others
-as snails-mutually impregnate each other by copulation. In
general, the reproductive organs are largely developed, the
body is unsymmetrical, some of the principal organs-the gills
and nerves-being atrophied; and thus the shell with which
most of them are covered becomes, in the greater number,
spiral, the spire turning toward the unatrophied side, which is
generally the right side, although in some it is the left. The
head and the organ of locomotion are capable of being with-
drawn into the last whorl of the shell, and in the aquatic species
generally the mouth of the shell can be closed by an operculum,
exactly fitting it and attached to the foot, but in which many
varieties of beautiful structure are exhibited, and which is gen-
erally horny, sometimes calcareous. Some shells are simply
conical, and there are numerous diversities of form. The
shell is secreted by the mantle. The organ of locomotion,
called the foot, is in general a muscular disk, developed from
the ventral surface of the body; sometimes, as in limpets,
capable of acting as a sucker, and exhibiting other even more
remarkable modifications, so that in some it becomes an or-
gan of swimming. G. generally creep by means of this disk
adhering to surfaces, and contracting in transverse wrinkles
or undulations, which begin from behind. The G. generally
secrete a peculiar kind of slime. Some of them also produce
other peculiar secretions, of which the Tyrian purple affords
an example.

Gastralgia, (Gr. gaster, "the stomach," and algos, "pain,") pain in the stomach, which occurs in various disorders of the stomach, and which, considered by itself, is not much to be relied on as a sign of disease.

Gas'tric Fe'ver, a popular name for a febrile condition, attended with prominent symptoms connected with the stomach, as well as for typhoid fever.

Gastri'tis, inflammation of the stomach, characterized by fever, great anxiety, heat and pain in the pit of the stomach, increased by taking any food or drink into the stomach, vomiting, and hiccough. Treatment.-Blisters and fomentations externally; diluents internally, with opium (4 to 1 grain) and bismuth subnitrate, (10 to 30 grains,) every three to six hours, in powder.

Gate-way, the passage or opening in which a gate or large door is hung. This may be either an open way with side pillars or a covered way vaulted or roofed over. The G. being a most important point in all fortified places, it is usually protected by various devices. It is flanked by towers with loop

the most prominent part of a city, where proclamations were made, and where the kings administered justice. The Greek and Roman gates were frequently of great magnificence. The Propyle at Athens is a beautiful example, and the triumphal arches of the Romans are the ornamental offspring of their city gates. Gat'ling, (RICHARD JORDAN,) an Amer. inventor, b. in N. C. 1818; the most important of his many inventions is the Gatling gun-a most effective weapon, and one which has been adopted by the U. S. army, and by England and Russia. G. also invented a screw for the propulsion of water-craft, in which, however, he was anticipated by Ericsson; a machine for sowing wheat in drills, a method of transmitting power through compressed air, and also a double-acting hemp-break.

Gatling Gun, a mitrailleuse or repeating machine gun invented by Richard J. Gatling, at Hartford, Conn. It consists

The Gatling Battery Gun.

of a number of breech-loading rifles, revolving around an axis and fired while revolving.

GAUL-GENEVA,

Gaul, (ALFRED ROBERT,) Eng. composer and organist, b, in Norwich 1887; chorister and assistant organist of Norwich Cathedral 1846-59; organist of St. Augustine's Church, Edgbaston, Birmingham; Mus.B., Cambridge, 1861. An oratorio, "Hezekiah," the cantatas "Ruth," (1881) First Psalm, Ninetysixth Palm, "Holy City," (1882,) "Passion Music," "The Ten Virgins," (1890,) dedicated to the choirs of America, and secular part songs have attained success.

249

Madison in the "American Statesmen" series, and at the time of his fatal illness was engaged on a life of Edmund Quincy for the "American Men of Letters" series. D. 1888.

Geck'o, a species of Saurian reptiles. The Gs. are of small size, and generally of repulsive aspect. The colors of most of

Gavazzi, (ALESSANDRO,) a popular Ital. preacher and reformer, distinguished by his patriotic zeal in promoting the civil and religious progress of his country; b. at Bologna 1809. At the age of 16 he became a monk of the Barnabite order, and subsequently was appointed Prof. of Rhetoric at Naples, where he speedily acquired a reputation as an orator. On the ascension of Pius IX. to the papal chair G. was one of the foremost supporters of the liberal policy that inaugurated that pontiff's reign; and having repaired to Rome he devoted himself to the diffusion of political enlightenment and patriotic aspirations among the masses of the Roman population. The pope sanctioned his political labors, and appointed him almoner of a body of about 16,000 Roman troops. To G.'s fervid and patriotic oratory may be attributed, in no slight degree, the uni- them are dull, and the small granular scales with which they versal spirit of self-sacrifice evoked throughout Italy during are covered are in general mingled with tubercles. The legs this period of her history. He was called the Pietro Eremita, or are short, the gait usually slow, measured, and stealthy, although

Common Gecko, (Plactydactylus guttatus.)

Peter the Hermit, of the national crusade. On the establish- Gs. can also run very nimbly when danger presses, and often ment of the republic at Rome he was appointed almoner-inchief to the national army. Under his superintendence efficient military hospitals were organized and attended by a band of Roman ladies, who volunteered their services and co-operation in the care of the wounded. Rome having fallen, G. went to England, where he delivered numerous addresses and lectures illustrative of the political and religious aims of his country. G. twice visited the U. S. He was president of the evangelization committee of the Free Italian Church. D. 1889.

Gay, (SIDNEY HOWARD,) author, was b. at Hingham, Mass., 1814, a descendant of Gov. Bradford, of Plymouth Colony; entered Harvard at the age of 15, and studied law in the office of his father, Ebenezer G. Unwilling to take the oath to support the Constitution of the U. S., which fostered and protected slavery, he gave up a legal career and devoted himself to antislavery journalism and lecturing. He became, in 1842, editor of The Antislavery Standard, a position he retained until he joined, in 1857, the editorial staff of the New York Tribune, of which he was managing editor from 1862 to 1866. From 1867 to 1871 he occupied the same position on the Chicago Tribune, and for another two yrs. was managing editor of the Evening Post. He was the author of Bryant & Gay's Popular History of the United States, and in 1884 wrote the life of James

disappear very suddenly when they seem almost to be struck or caught. The feet are remarkable, being adapted for adher ing to smooth surfaces, so that Gs. readily climb the smoothest trees or walls, or creep inverted on ceilings, or hang on the lower side of the large leaves in which tropical vegetation abounds. The Gs. feed chiefly on insects. They are more or less nocturnal in their habits. They are natives of warm climates, and are very widely distributed over the world. The Gs. have in almost all parts of the world where they are found a bad reputation as venomous, and as imparting injurious qualities to food which they touch, but there is no good evidenco in support of any such opinion; in accordance with which, however, an Egyptian G. is known as "the father of leprosy." Gene'va, a village of Ontario Co., N. Y., at the foot of Seneca Lake. It is an important R.R. junction, and is the northern terminus of the Seneca and Cayuga Canal. Its principal edifices are the Episcopal church, a Gothic structure in stone; the Geneva Medical Coll., and the Hobart Free Coll. This institution, called the Geneva Coll. till 1852, was estab lished here in 1824, and has 10 professors and about 70 students. Pop. about 11,000.

Gene'va, the most populous and flourishing town of Switz erland, situated on the southern extremity of the Lake of

250

GEOLOGICAL SURVEY OF THE UNITED STATES-GEOLOGY.

met with general acceptance in G. In Aug., 1535, the Reformed religion was established by law, and in 1541 Calvin was invited to take up his residence permanently in G. as public teacher of theology. During the 18th c. G. was distracted by a continued feud between the aristocratic and popular parties, until in 1782 Bern, Sardinia, and, in particular, France, interfered in favor of the aristocracy. The French Revolution led to a new crisis; the government was overthrown in July, 1794, equality in the eye of the law was estab lished, a national convention appointed, and a reign of terror commenced. In 1798 G. and its territory were annexed to France and remained so till after the overthrow of the first Napoleon. In 1880 the pop. of the city and suburbs was about 74,453.

ber of the Swiss Confederation. The doctrines of the Reformation, boldly and enthusiastically preached by William Farel,

Geology is the science which treats of the earth in its various relations of form, composi tion, structure, and history. Many of the phenomena and problems connected with the form of the earth are more fully and properly discussed under the sciences of ASTRONOMY and PHYSICS, and GEOGRAPHY appropriately discusses some features of the form and structure of the earth. Other sciences contribute

greatly to the understanding of G. in its various parts: as chem- high as to fuse the most refractory substances under ordinary istry and mineralogy in that part treating of structure and com- pressure, is actually solid and rigid, as above stated. The position, and zoology and botany in the interpretation of the his-history of the earth may be considered under two general tory recorded in its fossils. In the present stage of the science, too, there are specializations of some of the departments of G. into separate sub-sciences. Such are petrography or lithology, treating of the mineral, chemical, and optical properties of rocks; metallurgy, which treats of the methods of taking out and reducing metallic and other ores and minerals; and paleontology, the science of the fossils or organic remains found in the rocks of the earth. The Form of the Earth.-The form of the earth is that of a globe nearly 8,000 m. in diameter. It is not a perfect globe, but has a flattening at the poles, which makes the polar diameter (7,899 m.) about one three-hundredths (264 m.) shorter than the equitorial diameter, (7,925 m.) This form is that which it is believed a globe, originally in a plastic state, revolving about its axis and gradually cooling, would assume. Thus the form records the past history of the globe. The earth is one of the lesser planets of the solar system, and, there. fore, a discussion of its form involves a consideration of its relations to the solar system, its motions on its axis and about the sun, and its specific density. Numerous purely geological problems find their solution in some of these general or cosinical relations of the earth. The formation of climates, of zones of temperature, of ice and the resulting glaciers, of currents of the ocean affecting the distribution of life, of tides

heads: (1) The history through which the earth has passed in reaching its present structure, composition, and surface features; and (2) The history of the inhabitants which it records, with the changes in the conditions of environment which their peculiarities indicate. In the first part are con sidered the materials of which the earth is composed, and the arrangement of these materials, or the structure of the earth. This section of G. is often called Geognosy, or Structural G. Second, the laws, processes, or methods may be considered by which the presen material have received their composition and structure; this section is Dynamical G. Under the second head, the sequence of certain rocks having been ascertained, the organisms whose remains are buried in them are studied in their chronological order, and the deposits containing the fossils are classified in accordance with the faunas or floras they contain; this gives us Historical or Paleontological G., sometimes also called "Stratigraphical G." The Materials of the Earth.-The earth is composed of various materials, which are primarily classified into three groups by their physical states: gaseous, liquid, and solid. Strictly speaking, only the solid part is called the earth, while the liquid and gaseous parts are called envelopes; but it is true that the solid part contains also some liquid and gaseous materials. The solid portions with

affecting the erosion and conformation of coasts-the change of seasons, the gradual increase or decrease over vast periods of time in the average temperature in one or the other hemisphere each of these phenomena is of more or less importance to the geologist, and pertains to the discussion of the form and motion of the earth. The appearance of fossil plants, indicative of warm climate, far toward the North Pole, (a bed of coal 25 to 30 ft. in thickness was reported by Fielding and Herr, Nov., 1877, occurring as far N. as 81° 45',) demonstrates a change of climate not explainable by any of the ordinary seasonal fluctuations recorded by man. The evidence of great ice-sheets covering the land and scouring the sides of the mountains as far S. as the 40th degree of N. latitude, during what is known as the Glacial Age, indicates a change in the other direction which demands knowledge of the astronomical relations of the earth for its explanation. The form of the earth, on the other hand, furnishes evidence as to its interior condition, and it is by the calculations of the astronomers that the geologist reaches the conclusion that the interior of the earth is as rigid as glass or steel, and has not a molten center covered by a comparatively thin crust of rock, as was believed to be the case by the early geologists. By various evidences and methods of calculation the opinion is entertained that the density of the earth, as a whole, is five times that of water, and that the interior mass, though at a degree of temperature so

which science is familiar is the outermost part of the globe, and is composed of rock, stone, sand, soil, etc. The liquid portion is mainly water, and is found in the form of ocean, lake, river, spring, etc., while the gaseous form is chiefly air, and surrounds the others as atmosphere. These physical conditions of the matter of the globe are determined by the temperature and pressure, rather than by the chemical composition, and it is believed that the solid parts of the earth were originally in a vaporous or gaseous condition; these, secondarily, assumed a liquid form, and finally became solid after a very long period of gradual cooling from an intensely heated state. The outer gaseous envelope is called the atmosphere, and is at least 500 m. in thickness. Its composition is normally a mechanical mixture of four volumes of nitrogen and one volume of oxygen, with minute quantities of water-vapor, carbon-dioxide, and slight traces of ozone, ammonia, and acids. The impurities in the atmosphere are chiefly traceable to the chemical changes taking place in nature as to organic phenomena or volcanic outbreaks. Plants in their normal functions absorb carbondioxide and discharge oxygen; air-breathing animals normally absorb oxygen from the air and discharge carbon-dioxide; and wherever men are congregated and fires are kindled oxygen is absorbed and carbon-dioxide set free, and other acids and alkalies are discharged into the atmosphere; thus slight variations result in the proportionate amounts of the several

impurities in the atmosphere. The atmosphere has another skeletons, etc. The solid parts of the earth are known under property important to geologists: with each degree of rise of the general names of rocks, minerals, and soils. Rock is the temperature its capacity to hold water-vapor in suspension more comprehensive term, and is applied more strictly to conis increased, and, inversely, with each degree of fall this solidated masses, while soils are purely superficial and incocapacity is decreased. To this property of the atmosphere herent masses of rock materials. Minerals, metals, and ores, are due the phenomena of clouds, rain, and snow, and the if in a natural state, may be included under the general desigdrying of moisture from soil and rocks. The atmosphere in nation of rocks. Rocks, when analyzed, are found to be comits pure condition would produce slight geological effect, but posed of aggregations of minerals in more or less pure and carrying, as it does, acids and alkalies, it acts upon all rocks crystalline condition, or of fragments of previously solidified with greater or less rapidity as a corrosive agent, gradually and rocks. This physical distinction in the component aggregates very slowly decomposing the surface of the most solid rocks. of which a rock is composed furnishes the basis for a division In association with the changes of temperature upon the sur- of rocks into two groups: (1) crystalline rocks; (2) fragmental face, which produce expansion and contraction of rocks, and rocks. The crystalline rocks are composed of crystallized parabsorption and evaporation of water, and, when the tempera- ticles, each possessing a more or less uniform mineral constituture reaches 32° Fahr., the freezing and well-known expansion tion; the minerals may have assumed the form they possess by of water, the atmosphere becomes a powerful agent for disin- crystallization from an original state of chemical or aqueous tegrating the solid rocks, reducing them to fragments, and solution. In this group are found rock-salt, travertine, some finally, if not carried away by running water, to fine soil. iron-stones, siliceous sinter; and ice, also, may be enumerated These various processes by which the atmospheric and asso- among rocks of this group. Those assuming crystalline form ciated agencies decompose solid rocks to a fine pulverulent state from a fused state are the volcanic and eruptive rocks, includcalled soil go under the technical name of weathering. The ing lava, basalt, and trachyte, and some rocks in which the liquid part of the earth is principally water. Under the name crystalline structure is weakly exhibited or wanting, as the of oceans it covers three fourths of the surface of the earth. vitreous rocks, pitchstone, obsidian, and the cellular type called The average depths of these ocean waters is about 21 m., or pumice. Besides these there are numerous other crystalline 2,500 fathoms. The surface of the ocean is the standard for all rocks exhibiting similar combinations of mineral composition, elevations and depressions on the surface of the globe. The but whose immediate origin is not positively determined. Some

greatest depths at present known are 3,875 fathoms in the of these form the fundamental rocks, so far as known, underAtlantic Ocean, about 100 m. N. of the island of St. Thomas, lying all other kinds. They include granite, syenite, the greenand 4,665 fathoms in the Pacific, E. of the Kurile Islands. stones, etc., which are massive rocks of coarsely granular to Besides the oceans there are numerous basins in the continents finely crystalline structure, showing no lamination, and a series having exits above sea-level, and holding fresh waters; these closely allied to them, but presenting a laminated, schistose, or are inland seas or lakes. The waters of the ocean are heavier gneissoid structure, called the crystalline schists, differing in than the terrestrial waters, the former having an average den- the prominent minerals they contain, suggesting their names, sity of about 1.026, or the ocean water is nearly three one-hun- mica, hornblende, chlorite, etc., schists. A third series, in which dredths heavier than pure water. This greater density is due the rock has evidently assumed a crystalline from an original to the salts which it holds in solution. The average proportion tragmental condition, contains crystalline limestones, dolomites, of these salts to the water is about three and a half per cent. marble, quartzite; and in this group may also be included Twenty-seven of the chemical elements have been detected in clay-slate and roofing-slate, which have had a laminated structappreciable quantities in ocean water by Forchhammer, and ure of the rock and a corresponding readjustment of the ultiit is probable that others might be added if sufficiently deli-mate grains of the rock without full crystallization. The cate tests were applied to their detection. Common metals, Chemical and Mineral Composition of Rocks.-The as silver, copper, lead, zinc, cobalt, nickel, and iron, are crystalline rocks which have assumed the crystalline condiamong the elements detected, and there are found also tion, either directly from a molten state or by metamorphism chlorides of sodium and magnesium, and sulphates of mag- from a solid state, are classified by the minerals they contain. nesia, lime, and potash, as well as some other salts less The component minerals of the fragmental rocks, on account prominent, among the impurities in ocean water. The pres- of their fragmental condition, cannot generally be ascertained ent saltness of ocean waters may be due, in part, to their with precision, and they are necessarily classified by their primeval constitution. Although impurities, in small quanti- chemical composition or by their structure, and the prevail ng ties, are borne into the ocean from the land, it is believed nature of the particles of which they are constituted. The chief that the oceans are less salt than in geologically primitive chemical elements entering into the composition of the known times, the impurities having been removed by the various rocks of the earth are: (1) Oxygen, about 45 per cent. in processes of physical sedimentation, chemical combination weight; (2) silicon, the metalloid basis of quartz and san, and crystallization, and organic secretion in the form of shells, about in weight; (3) aluminium, the metal base of clay, ro