Page:The American Cyclopædia (1879) Volume VII.djvu/799

 GEYSERS 783 commanded by musketry and artillery. To advance, retreat, or stand still was alike im- possible. The men flung themselves on the ground, holding up their hands in token of sur- render. Of the whole number, not one in four escaped ; the others were dead or prison- ers. The attacking column being thus utterly routed in the centre, Meade ordered his right to advance and drive back the division of Hood, which had been held in check upon the ridge they had won the preceding day. This was easily done, arid many prisoners were captured. The confederate loss this day was about 16,000 in killed, wounded, and prisoners ; the Union loss was about 3,000. During the night Lee concentrated his force behind the crest of Seminary ridge, awaiting and probably desiring an attack. In the morning Meade called a council of war, by which it was decided to " remain a day and await the development of the enemy's plan." Before night a heavy storm set in, under cover of which Lee began his re- treat to the Potomac, leaving a strong rear guard to defend the passes through the moun- tains. He reached the river, 40 m. distant, on the 7th. The stream, which he had crossed almost dry-shod a fortnight before, was now swollen by unusually heavy rains and unford- able. A bridge which he had flung across had been destroyed by a cavalry dash from Harper's Ferry, and he had no alternative but to intrench himself and await an attack or the falling of the waters. Meade advanced slowly by a much longer route, and on the 12th came in front of the confederate intrenchments. He called a council of war, which, against his opinion, voted to postpone the attack until reconnoissances had been made. On the evening of the 13th an order was issued for an advance the next morn- ing ; but when day broke the tnemy had dis- appeared. A slight bridge had been construct- ed, and the river had fallen so as to be fordable at a single point. Swell's corps crossed by the ford, the others by the bridge. The remains of the confederate army stood safe on the other side ; and the invasion of the north, upon which so much had been staked, was at an end. The Union loss at Gettysburg, was 23,190, of whom 2,834 were killed, 13,713 wounded, and 6,643 missing. The confederate loss has never been officially stated ; but by the best estimates it was about 36,000, of whom about 5,000 were killed, 23,000 wounde.d, and 8,000 unwounded prisoners. The entire number of prisoners, wounded and unwounded, was about 14,000. At almost the same moment when the final action at Gettysburg took place, the negotia- tions for the surrender of Vicksburg were con- cluded. These twin disasters mark the epoch of the decline of the confederacy. GEYSERS (Icelandic, geysa, to burst forth violently), intermittent hot springs found in various parts of the world. In Iceland the principal geysers are in the S.- "W. part of the island, about 35 m. N". W. of Hecla, and 70 m. from Reykiavik. the chief town. In a circuit 357 VOL. vii. 50 of about two miles are more than 100 springs which send forth hot water, 50 or more in the space of a few acres. These are on the lower slope of a small hill of trappean rock, and above them in the steeper part of the hill under the cliffs of this rock are banks formed by the in- crustations of ancient and now nearly extinct geysers. The springs are of different dimen- sions, and exhibit various degrees of activity ; some are uniformly full and quiet, others are constantly boiling, and others only at intervals, with explosive discharges of water and steam. The vapors rising from them form clouds that are seen miles away. They are attended with sulphurous odors ; and the geysers of other lo- calities on the island deposit sulphur derived from the decomposition of the iron pyrites in the clays through which the hot waters pene- trate. The chief spouting springs of the group are the Great geyser and the Great and Little Strokr. The Great geyser when quiet presents the appearance of a circular mound of silicious incrustations, enclosing a pool, with sides slo- ping inward at an average angle of 13, and out- ward at a mean inclination of 8. The height of the mound is about 20 ft. on the lower side, but only half as much on the upper side. The di- ameter of the basin varies from 50 to 60 ft., and its average depth is 4 ft. In its centre is the mouth of the vertical tube which connects it with the subterranean passages. This tube is about 9 ft. in diameter at its mouth, and 70 ft. in depth. "When the geyser is inactive, the ba- sin is filled to the edge with clear water, which has a mean temperature of 185 F. and runs gently down the mound, emitting clouds of steam ; but for several hours after an eruption the tube is empty to the depth of 4 or 5 ft. At intervals of about an hour and a half a rum- bling noise is heard, and the water heaves up in the centre, throwing an increased quantity over the margin. The great eruptions take place at irregular intervals, sometimes exceed- ing 30 hours. At these times loud explosions 'are heard beneath the surface, the water is thrown into violent agitation, it boils furious- ly, and at last is suddenly sent forth in a suc- cession of jets, which increase in force till they become an immense fountain that is lost to view in the clouds of steam in which it is en- veloped. The heights reached by these jets have been variously estimated by different trav- ellers. The lowest estimate is 60 or 70 ft. ; that of Von Troil in 1772 is 92 ft. ; of Sir John Stanley in 1789, 96 ft. ; of Lieut. Ohlsen, a Danish officer, in 1804, determined by a quad- rant, 212 ft. ; of Sir George Mackenzie in 1810, 90 ft. ; and of Henderson in 1815, 150 ft. La- ter visitors, Lord Dufferin, Mme. Ida Pfeifier, J. Ross Browne, and others, estimate the height at from 60 to 70 ft. The eruptions appear to be diminishing in force and frequency, and it is not improbable that they will cease altogeth- er before the lapse of another century. The discharge continues only about five minutes, when the geyser subsides to a state of tranquil-