308 



EEPORT UNITED STATES GEOLOGICAL SURVEY. 



As to the duration of tlie erux)tions there is more unanimity, as the 

 following shows: 



Duration of eruptions. 



Observer. 



Date. 







1789 







1815 





Dillon 



1834-'85 







1846 





Allen ; 



1855 







1856 







1859 







1867 









The following is the description of an eruption by S. Baring-Gould: 



Five strokes underground were the signal, then an overflow, wetting every side of 

 the mound. Presently a dome of water rose in the center of the basin and fell again, 

 immediately to be followed by a fresh bell, which sprang into the air full forty feet 

 high, accompanied by a roaring burst of steam. Instantly the fountain began to play 

 with the utmost violence ; a column rushed up to the height of ninety or one hundred 

 feet against the gray night sky, with mighty vohimes of white steam-cloud rolling 

 about it, and swept off by the breeze to fall in torrents of hot rain. Jets and lines of 

 water tore their way through the cloud, or leaped high above its domed mass. The 

 earth trembled and throbbed during the explosion, then the column sank, started up 

 again, dropped once more, and seemed to be sucked back into earth. 



A. J. Symington * describes his experience of an eruption of the Great 

 Geyser as follows : 



Subterranean noises, like tliunder, were waxing louder and louder, each earth-shock 

 accomxjanied by a tremor of the ground, more or less violent, but quite unmistakable. 

 Bells of water in quick succession were rising from the basin and falling again, ever 

 increasing in size, till a large one burst ; and then jets of water in successive spurts 

 rushed up in sheafs from the tube; at first about 10 feet, then the height was 15,20, 

 30, 50 feet, and so on, each effort surpassing the preceding, till it attained the height 

 of 200 feet. , The fountain did not fall down between each jet, but, nearly holding the 

 elevation once gained, the whole grew up bodily by a series of jerks, each higher than 

 the last. Dense clouds of steam enveloped the whole, and only afforded occasional 

 glimpses of the columns of water from the leeward side. White vapor also spread out 

 above the fountain, rolling away in vast curling volumes, which, condensing in the 

 air, came down like heavy dew. Tremendous sounds were continuously heard, like the 

 roaring of an angry sea broken in upon by the near discharge of minute guns. It is at 

 last what we longed to behold, a grand eruption of the Great Geyser! The vast body 

 of water from the central pipe continued jetting up, till, as I have said, it attained 

 the height of 200 feet, falling down again into the basin, which was brim full to over- 

 flowing. The subterranean rumbling sounds and reports, accompanied with vibra- 

 tion of the ground, were fearful. Jets of water rushed up in sheaf with a continuous 

 noise, such as would be produced by 500 rockets discharged into the air at the same 

 Instant. 



Even the beautiful clouds of steam which robed the geyser were regarded by us 

 with an indescribable feeling of mysterious awe and wonder, as if we had actually 

 discovered the fabled magic vapor, from which the Eastern Ufret or any other vision 

 might arise; while the sharp tinkling plash of the descending water could at times be 

 heard amidst the loud, hissing, roaring, booming, and confused Babel of all unearthly 

 sounds. The eruptive forces having now expended themselves for a time, the fountain 

 gradually subsided, in the same manner though more speedily than it had risen. The 

 whole terrific spectacle lasted about twenty minutes. We were singularly fortunate, 

 as, from what we were told, few eruptions of late have lasted more than four or five 

 minutes, or attained half the height of this which we had just witnessed. 



* In Pen and Pencil Sketches of Faroe and Iceland, 1862. 



