16 



THAT S IT ! 



distance by the wind. In 1845 

 an eruption occurred in Iceland, 

 and some of the ashes were, in 

 ten hours afterwards, deposited 

 upon the Scottish islands. Vol- 

 canoes are sometimes wonderfully 

 powerful : a block of stone weigh- 

 ing two hundred tons was pro- 

 jected to a distance of nine miles 

 from the crater from which it 

 was thrown out. The city of 

 Pompeii was swallowed up by an 

 eruption of Mount Vesuvius, 

 accompanied by an earthquake, 

 in the Christian year 79. Many 

 of the citizens had assembled to 

 witness public spectacles at a 

 theatre when the eruption com- 

 menced, and streams of fire ran 

 down the sides of the mountain 

 and buried the whole city and 

 the country for miles around. 

 Fifteen hundred years passed 

 away before any traces of the 

 lost city were found ! Another 

 terrific eruption occurred in 

 Iceland in 1783. It was accom- 

 panied by a violent tempest, and 

 the whole island seemed likely 

 to be destroyed. Three cra- 

 ters, opened upon Mount Skapta 

 and poured forth a torrent of 

 lava which continued flowing for 

 six weeks, and ran sixty miles 

 into the sea, forming a rugged 

 bank nearly twelve miles broad ; 

 twelve rivers were dried up ; 

 twenty-one villages destroyed ; 

 and thirty-four others injured. 



Connected with volcanic action, 

 in mountainous regions, is another 

 remarkable phenomenon, the gey- 

 sers, or hoiling springs of Iceland, 

 17. About twenty-five miles from 

 Mount Hecla, lying northward, 

 there is a great number of these 



145. 



hot springs. The eruptions of 

 the geysers occur at irregular 

 intervals, and 

 seldom last 

 more than a 

 few minutes at 

 a time. The 

 basin of the 

 largest of these 

 boiling foun- 

 tains, called 

 the Great Gey- 

 ser, has the ap- 

 pearance,when 

 quiescent, of 

 a circular pool 

 of water. Pri- 

 or to the up- 

 heaving of the waters a dull 

 rumbling noise is heard ; then 

 the pond becomes troubled, and 

 soon jets of water and steam 

 are projected, with great force 

 and noise, to a height of a hun- 

 dred feet, frequently accompanied 

 with large masses of stone. The 

 earth is slightly shaken, and 

 sounds proceed from beneath the 

 surface like the firing of cannon. 

 The eruption terminates by the 

 emission of jets of steam, and by 

 a violent gurgling of the waters 

 in the crater, 18. These dis- 

 charges sometimes occur three 

 or four times in twenty-four 

 hours. The hottest springs in 

 Great Britain are those of Bath, 

 which have a temperature of 160°; 

 those at Clifton, 74° ; Buxton, 

 82° ; Matlock, 69° ; the Carls- 

 bad springs reach 167°, and those 

 of Coguinas, in Sardinia, 198°. 

 The three volcanoes most known 

 are Mount Etna, in Sicily, Vesu- 

 vius, in the Bay of Naples, and 

 Hecla, in Iceland. 



