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. Müller 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 über die hauptsächlichsten Geisire Islands,” Pogg.
Ann., 1847, vol. 72; and Müller, “Über Bunsen’s Geysertheorie,”
ibid., 1850, vol. 79).
| Observed. | A | Calculated. |
| 186° | 225° | |
| 230° | 241° | |
| C | 249° | |
| 251° | 255° | |
| D | ||
| 255° | 266° | |
| 259° | ...... | 278° |
| B |
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° from its boiling-point, and even at the bottom it is 19°; but at D the deficiency is only 4°. If, then, the stratum at D be suddenly lifted as high as C, it will be 2° above the boiling-point there, and will consequently expend those 2° 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 (ʽAmwās) 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 (ʽAmwās). This points to the mound of debris called Tell-el-Jezari near the village of Abū Shūsheh. 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 נור תחמ[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.)
GFRÖRER, AUGUST FRIEDRICH (1803–1861), German historian, was born at Calw, Württemberg, on the 5th of March 1803, and at the close of his preliminary studies at the seminary of Blaubeuren entered the university of Tübingen 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 Württemberg in 1828, he first undertook the duties of repetent or theological tutor in Tübingen, 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 jüdisch-alexandrinische Theosophie, Stuttgart, 1831) was rapidly followed by an elaborate biography, in two volumes, of Gustavus Adolphus (Gustav Adolf, König 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 Gfrörer 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. westfränkischen Karolinger (Freiburg, 1848); but those on the pseudo-Isidorian Decretals (Untersuchung über 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 Rhadāmes, 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
- ↑ So written, with a medial mem (מ) instead of the final (ם).
