Part 29

The Iceland geysers, mentioned by Saxo Grammaticus, are situated about 30 m. N.W. of Hecla, in a broad valley at the foot of a range of hills from 300 to 400 ft. in height. Within a circuit of about 2 m., upwards of one hundred hot springs may be counted, varying greatly both in character and dimensions. The Great Geyser in its calm periods appears as a circular pool about 60 ft. in diameter and 4 ft. in depth, occupying a basin on the summit of a mound of siliceous concretion; and in the centre of the basin is a shaft, about 10 ft. in diameter and 70 ft. in depth, lined with the same siliceous material. The clear sea-green water flows over the eastern rim of the basin in little runnels. On the surface it has a temperature of from 76 deg. to 89 deg. C., or from 168 deg. to 188 deg. F. Within the shaft there is of course a continual shifting both of the average temperature of the column and of the relative temperatures of the several strata. The results of the observations of Bunsen and A. L. O. Descloizeaux in 1847 were as follows (cf. _Pogg. Ann._, vol. 72 and _Comptes rendus_, vol. 19): About three hours after a great eruption on July 6, the temperature 6 metres from the bottom of the shaft was 121.6 deg. C; at 9.50 metres, 121.1 deg.; at 16.50 metres, 109 deg. (?); and at 19.70 metres, 95 deg. (?). About nine hours after a great eruption on July 6, at about 0.3 metres from the bottom, it was 123 deg.; at 4.8 metres it was 122.7 deg.; at 9.6 metres, 113 deg.; at 14.4 metres, 85.8 deg.; at 19.2 metres, 82.6 deg. On the 7th, there having been no eruption since the previous forenoon, the temperature at the bottom was 127.5 deg.; at 5 metres from the bottom, 123 deg.; at 9 metres, 120.4 deg.; at 14.75 metres, 106.4 deg.; and at 19 metres, 55 deg. About three hours after a small eruption, which took place at forty minutes past three o'clock in the afternoon of the 7th, the temperature at the bottom was 126.5 deg.; at 6.85 metres up it was 121.8 deg.; at 14.75 metres, 110 deg.; and at 19 metres, 55 deg. Thus, continues Bunsen, it is evident that the temperature of the column diminishes from the bottom upwards; that, leaving out of view small irregularities, the temperature in all parts of the column is found to be steadily on the increase in proportion to the time that has elapsed since the previous eruption; that even a few minutes before the great eruption the temperature at no point of the water column reached the boiling point corresponding to the atmospheric pressure at that part; and finally, that the temperature about half-way up the shaft made the nearest approach to the appropriate boiling point, and that this approach was closer in proportion as an eruption was at hand. The Great Geyser has varied very much in the nature and frequency of its eruptions since it began to be observed. In 1809 and 1810, according to Sir W. J. Hooker and Sir George S. Mackenzie, its columns were 100 or 90 ft. high, and rose at intervals of 30 hours, while, according to Henderson, in 1815 the intervals were of 6 hours and the altitude from 80 to 150 ft.

About 100 paces from the Great Geyser is the _Strokkr_ or churn, which was first described by Stanlay in 1789. The shaft in this case is about 44 ft. deep, and, instead of being cylindrical, is funnel-shaped, having a width of about 8 ft. at the mouth, but contracting to about 10 in. near the centre. By casting stones or turf into the shaft so as to stopper the narrow neck, eruptions can be accelerated, and they often exceed in magnitude those of the Great Geyser itself. During quiescence the column of water fills only the lower part of the shaft, its surface usually lying from 9 to 12 ft. below the level of the soil. Unlike that of the Great Geyser, it is always in ebullition, and its temperature is subject to comparatively slight differences. On the 8th of July 1847 Bunsen found the temperature at the bottom 112.9 deg. C; at 3 metres from the bottom, 111.4 deg.; and at 6 metres, 108 deg.; the whole depth of water was on that occasion 10.15 metres. On the 6th, at 2.90 metres from the bottom it was 114.2 deg.; and at 6.20 metres, 109.3 deg. On the 10th, at 0.35 metres from the bottom, the reading gave 113.9 deg.; at 4.65 metres, 113.7 deg.; and at 8.85 metres, 99.9 deg.

[Illustration: FIG. 1.]

The great geyser-district of New Zealand is situated in the south of the province of Auckland in or near the upper basin of the Waikato river, to the N.E. of Lake Taupo. The scene presented in various parts of the districts is far more striking and beautiful than anything of the same kind to be found in Iceland, but this is due not so much to the grandeur of the geysers proper as to the bewildering profusion of boiling springs, steam-jets and mud-volcanoes, and to the fantastic effects produced on the rocks by the siliceous deposits and by the action of the boiling water. In about 1880 the geysers were no longer active, and this condition prevailed until the Tarawera eruption of 1886, when seven gigantic geysers came into existence; water, steam, mud and stones were discharged to a height of 600 to 800 ft. for a period of about four hours, when quieter conditions set in. Waikite near Lake Rotorua throws the column to a height of 30 or 35 ft.

[Illustration: FIG. 2.]

In the Yellowstone National Park, in the north-west corner of Wyoming, the various phenomena of the geysers can be observed on the most portentous scale. The geysers proper are about one hundred in number; the non-eruptive hot springs are much more numerous, there being more than 3000. The dimensions and activity of several of the geysers render those of Iceland and New Zealand almost insignificant in comparison. The principal groups are situated along the course of that tributary of the Upper Madison which bears the name of Fire Hole River. Many of the individual geysers have very distinctive characteristics in the form and colour of the mound, in the style of the eruption and in the shape of the column. The "Giantess" lifts the main column to a height of only 50 or 60 ft., but shoots a thin spire to no less than 250 ft. The "Castle" varies in height from 10 or 15 to 250 ft.; and on the occasions of greatest effort the noise is appalling, and shakes the ground like an earthquake. "Old Faithful" owes its name to the regularity of its

## action. Its eruptions, which raise the water to a height of 100 or 150

ft., last for about five minutes, and recur every hour or thereabouts. The "Beehive" sometimes attains a height of 219 it.; and the water, instead of falling back into the basin, is dissipated in spray and vapour. Very various accounts are given of the "Giant." F. V. Hayden saw it playing for an hour and twenty minutes, and reaching a height of 140 ft., and Doane says it continued in action for three hours and a half, and had a maximum of 200 ft.; but at the earl of Dunraven's visit the eruption lasted only a few minutes.

_Theory of Geysers._--No satisfactory explanation of the phenomena of geysers was advanced till near the middle of the 19th century, when Bunsen elucidated their nature. Sir George Mackenzie, in his _Travels in Iceland_ (2nd ed., 1812), submitted a theory which partially explained the phenomena met with. "Let us suppose a cavity C (fig. 1), communicating with the pipe PQ, filled with boiling water to the height AB, and that the steam above this line is confined so that it sustains the water to the height P. If we suppose a sudden addition of heat to be applied under the cavity C, a quantity of steam will be produced which, owing to the great pressure, will be evolved in starts, causing the noises like discharges of artillery and the shaking of the ground." He admitted that this could be only a partial explanation of the facts of the case, and that he was unable to account for the frequent and periodical production of the necessary heat; but he has the credit of hitting on what is certainly the proximate cause--the sudden evolution of steam. By Bunsen's theory the whole difficulty is solved, as is beautifully demonstrated by the artificial geyser designed by J. H. J. Muller of Freiburg (fig. 2). If the tube ab be filled with water and heated at two points, first at a and then at b, the following succession of changes is produced. The water at a beginning to boil, the superincumbent column is consequently raised, and the stratum of water which was on the point of boiling at b being raised to d is there subjected to a diminished pressure; a sudden evolution of steam accordingly takes place at d, and the superincumbent water is violently ejected. Received in the basin c, the air-cooled water sinks back into the tube, and the temperature of the whole column is consequently lowered; but the under strata of water are naturally those which are least affected by the cooling process; the boiling begins again at a, and the same succession of events is the result (see R. Bunsen, "Physikalische Beobachtungen uber die hauptsachlichsten Geisire Islands," _Pogg. Ann._, 1847, vol. 72; and Muller, "Uber Bunsen's Geysertheorie," ibid., 1850, vol. 79).

[Illustration]

The principal difference between the artificial and the natural geyser-tube is that in the latter the effect is not necessarily produced by two distinct sources of heat like the two fires of the experimental apparatus, but by the continual influx of heat from the bottom of the shaft, and the differences between the boiling-points of the different parts of the column owing to the different pressures of the superincumbent mass. This may be thus illustrated: AB is the column of water; on the right side the figures represent approximately the boiling-points (Fahr.) calculated according to the ordinary laws, and the figures on the left the actual temperature of the same places. Both gradually increase as we descend, but the relation between the two is very different at different heights. At the top the water is still 39 deg. from its boiling-point, and even at the bottom it is 19 deg.; but at D the deficiency is only 4 deg. If, then, the stratum at D be suddenly lifted as high as C, it will be 2 deg. above the boiling-point there, and will consequently expend those 2 deg. in the formation of steam.

GEZER (the Kazir of Tethmosis [Thothmes] III.'s list of Palestinian cities and the Gazri of the Amarna tablets), a royal Canaanite city on the boundary of Ephraim, in the maritime plain (Josh. xvi. 3-10), and near the Philistine border (2 Sam. v. 25). It was allotted to the Levites, but its original inhabitants were not driven out until the time of Solomon, when "Pharaoh, king of Egypt" took the city and gave it as a dowry to his daughter, Solomon's wife (1 Kings ix. 16). Under the form Gazera it is mentioned (1 Macc. iv. 15) as being in the neighbourhood of Emmaus-Nicopolis ('Amwas) and Jamnia (Yebnah). Throughout the history of the Maccabean wars Gezer or Gazara plays the part of an important frontier post. It was first taken from the Syrians by Simon the Asmonean (1 Macc. xiv. 7). Josephus also mentions that the city was "naturally strong" (_Antiq._ viii. 6. 1). The position of Gezer is defined by Jerome (_Onomasticon_, s.v.) as four Roman miles north (_contra septentrionem_) of Nicopolis ('Amwas). This points to the mound of debris called _Tell-el-Jezari_ near the village of Abu Shusheh. The site is naturally very strong, the town standing on an isolated hill, commanding the western road to Jerusalem just where it begins to enter the mountains of Judea. This identification has been confirmed by the discovery of a series of boundary inscriptions, apparently marking the limit of the city's lands, which have been found cut in rock--outcrops

## partly surrounding the site. They read in every case in [Hebrew: nur]

[Hebrew: taham][1], "the boundary of Gezer," with the name _Alkios_ in Greek, probably that of the governor under whom the inscriptions were cut. The site has been partially excavated by the Palestine Exploration Fund, and an enormous mass of material for the history of Palestine recovered from it, including remains of a pre-Semitic aboriginal race, a remarkably perfect High Place, the castle built by Simon, and other remains of the first importance.

See R. A. S. Macalister's reports in _Palestine Exploration Fund Quarterly Statement_ (October 1902 onwards). Also _Bible Sidelights from the Mound of Gezer_, by the same writer. (R. A. S. M.)

FOOTNOTE:

[1] So written, with a medial _mem_ ([Hebrew: mem]) instead of the final ([Hebrew: mem]).

GFRORER, AUGUST FRIEDRICH (1803-1861), German historian, was born at Calw, Wurttemberg, on the 5th of March 1803, and at the close of his preliminary studies at the seminary of Blaubeuren entered the university of Tubingen in 1821 as a student of evangelical theology. After passing his final examinations in 1825, he spent a year in Switzerland, during part of the time acting as companion and secretary to C. von Bonstetten (1745-1832); the year 1827 was spent chiefly in Rome. Returning to Wurttemberg in 1828, he first undertook the duties of repetent or theological tutor in Tubingen, and afterwards accepted a curacy in Stuttgart; but having in 1830 received an appointment in the royal public library at Stuttgart, he thenceforth gave himself exclusively to literature and historical science. His first work on Philo (_Philo u. die judisch-alexandrinische Theosophie_, Stuttgart, 1831) was rapidly followed by an elaborate biography, in two volumes, of Gustavus Adolphus (_Gustav Adolf, Konig von Schweden, und seine Zeit_, Stuttgart, 1835-1837), and by a critical history of primitive Christianity (_Kritische Geschichte des Urchristenthums_, 3 vols., Stuttgart, 1838). Here Gfrorer had manifested opinions unfavourable to Protestantism, which, however, were not openly avowed until fully developed in his church history (_Allgemeine Kirchengeschichte bis Beginn des 14ten Jahrhunderts_, Stuttgart, 1841-1846). In the autumn of 1846 he was appointed to the chair of history in the university of Freiburg, where he continued to teach until his death at Carlsbad on the 6th of July 1861. In 1848 he sat as a representative in the Frankfort parliament, where he supported the "High German" party, and in 1853 he publicly went over to the Church of Rome. He was a bitter opponent of Prussia and an ardent controversialist.

Among his later historical works the most important is the _Geschichte der ost- u. westfrankischen Karolinger_ (Freiburg, 1848); but those on the pseudo-Isidorian Decretals (_Untersuchung uber Alter, Ursprung, u. Werth der Decretalen des falschen Isidorus_, 1848), on the primitive history of mankind (_Urgeschichte des menschlichen Geschlechts_, 1855), on Hildebrand (_Papst Gregorius VII. u. sein Zeitalter_, 7 vols., 1859-1861), on the history of the 18th century (_Geschichte des 18ten Jahrhunderts_, 1862-1873), on German popular rights (_Zur Geschichte deutscher Volksrechte im Mittelalter_, Basel, 1865-1866) and on Byzantine history (_Byzantinische Geschichten_, 1872-1874), are also of real value.

GHADAMES, GADAMES or RHADAMES, a town in an oasis of the same name, in that part of the Sahara which forms part of the Turkish vilayet of Tripoli. It is about 300 m. S.W. of the city of Tripoli and some 10 m. E. of the Algerian frontier. According to Gerhard Rohlfs, the last form given to the word most correctly represents the Arabic pronunciation, but the other forms are more often used in Europe. The streets of the town are narrow and vaulted and have been likened to the bewildering galleries of a coalpit. The roofs are laid out as gardens and preserved for the exclusive use of the women. The Ghadamsi merchants have been known for centuries as keen and adventurous traders, and their agents are to be found in the more important places of the western and central Sudan, such as Kano, Katsena, Kanem, Bornu, Timbuktu, as well as at Ghat and Tripoli. Ghadames itself is the centre of a large number of caravan routes, and in the early part of the 19th century about 30,000 laden camels entered its markets every year. The caravan trade was created by the Ghadamsi merchants who, aided by their superior intelligence, capacity and honesty, long enjoyed a monopoly. In 1873 Tripolitan merchants began to compete with them. In 1893 came the invasion of Bornu by Rabah, and the total stoppage of this caravan route for nearly ten years to the great detriment of the merchants of Ghadames. The caravans from Kano were also frequently pillaged by the Tuareg, so that the prosperity of the town declined. Later on, the opening of rapid means of transport from Kano and other cities to the Gulf of Guinea also affected Ghadames, which, however, maintains a considerable trade. The chief articles brought by the caravans are ostrich feathers, skins and ivory and one of the principal imports is tea. In 1845 the population was estimated at 3000, of whom about 500 were slaves and strangers, and upwards of 1200 children; in 1905 it amounted in round numbers to 7000. The inhabitants are chiefly Berbers and Arabs. A Turkish garrison is maintained in the town.

Before the Christian era Ghadames was a stronghold of the Garamantes whose power was overthrown in the days of Augustus by L. Cornelius Balbus Minor, who captured Ghadames (Cydamus). It is not unlikely that Roman settlers may have been attracted to the spot by the presence of the warm springs which still rise in the heart of the town, and spread fertility in the surrounding gardens. In the 7th century Ghadames was conquered by the Arabs. It appears afterwards to have fallen under the power of the rulers of Tunisia, then to a native dynasty which reigned at Tripoli, and in the 16th century it became part of the Turkish vilayet of Tripoli. It has since then shared the political fortunes of that country. In the first half of the 19th century it was visited by several British explorers and later by German and French travellers.

See J. Richardson, _Travels in the Great Desert of Sahara in 1845-1846 ... including a Description of ... Ghadames_ (London, 1848); G. Rohlfs, _Reise durch Marokko ... und Reise durch die Grosse Wuste uber Rhadames nach Tripoli_ (Bremen, 1868).

GHAT, or RHAT, an oasis and town, forming part of the Turkish vilayet of Tripoli. Ghat is an important centre of the caravan trade between the Nigerian states and the seaports of the Mediterranean (see TRIPOLI).

GHATS, or GHAUTS (literally "the Landing Stairs" from the sea, or "Passes"), two ranges of mountains extending along the eastern and western shores of the Indian peninsula. The word properly applies to the passes through the mountains, but from an early date was transferred by Europeans to the mountains themselves.

The Eastern Ghats run in fragmentary spurs and ranges down the Madras coast. They begin in the Orissa district of Balasore, pass southwards through Cuttack and Puri, enter the Madras presidency in Ganjam, and sweep southwards through the districts of Vizagapatam, Godavari, Nellore, Chingleput, South Arcot, Trichinopoly and Tinnevelly. They run at a distance of 50 to 150 m. from the coast, except in Ganjam and Vizagapatam, where in places they almost abut on the Bay of Bengal. Their geological formation is granite, with gneiss and mica slate, with clay slate, hornblende and primitive limestone overlying. The average elevation is about 1500 ft., but several hills in Ganjam are between 4000 and 5000 ft. high. For the most part there is a broad expanse of low land between their base and the sea, and their line is pierced by the Godavari, Kistna and Cauvery rivers.

The Western Ghats (Sahyadri in Sanskrit) start from the south of the Tapti valley, and run south through the districts of Khandesh, Nasik, Thana, Satara, Ratnagiri, Kanara and Malabar, and the states of Cochin and Travancore, meeting the Eastern Ghats at an angle near Cape Comorin. The range of the Western Ghats extends uninterruptedly, with the exception of a gap or valley 25 m. across, known as the Palghat gap, through which runs the principal railway of the south of India. The length of the range is 800 m. from the Tapti to the Palghat gap, and south of this about 200 m. to the extreme south of the peninsula. In many parts there is only a narrow strip of coast between the hills and the sea; at one point they rise in magnificent precipices and headlands out of the ocean. The average elevation is 3000 ft., precipitous on the western side facing the sea, but with a more gradual slope on the east to the plains below. The highest peaks in the northern section are Kalsubai, 5427 ft.; Harischandragarh, 4691 ft.; and Mahabaleshwar, where is the summer capital of the government of Bombay, 4700 ft. South of Mahabaleshwar the elevation diminishes, but again increases, and attains its maximum towards Coorg, where the highest peaks vary from 5500 to 7000 ft., and where the main range joins the interior Nilgiri hills. South of the Palghat gap, the peaks of the Western Ghats rise as high as 8000 ft. The geological formation is trap in the northern and gneiss in the southern section.

GHAZALI [Muhammad ibn Muhammad Abu Hamid al-Ghazali] (1058-1111), Arabian philosopher and theologian, was born at Tus, and belonged to a family of Ghazala (near Tus) distinguished for its knowledge of canon law. Educated at first in Tus, then in Jorjan, and again in Tus, he went to college at Nishapur, where he studied under Juwaini (known as the Imam ul-Haramain) until 1085, when he visited the celebrated vizier Nizam ul-Mulk, who appointed him to a professorship in his college at Bagdad in 1091. Here he was engaged in writing against the Isma'ilites (Assassins). After four years of this work he suddenly gave up his chair, left home and family and gave himself to an ascetic life. This was due to a growing scepticism, which caused him much mental unrest and which gradually gave way to mysticism. Having secured his chair for his brother he went to Damascus, Jerusalem, Hebron, Mecca, Medina and Alexandria, studying, meditating and writing in these cities. In 1106 he was tempted to go to the West, where the Moravid (Almoravid) reformation was being led by Yusuf ibn Tashfin, with whom he had been in correspondence earlier. Yusuf, however, died in this year, and Ghazali abandoned his idea. At the wish of the sultan Malik Shah he again undertook professorial work, this time in the college of Nizam ul-Mulk at Nishapur, but returned soon after to Tus, where he died in December 1111.