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are twelve in number, and are the summits of gigantic volcanic 
mountains rising suddenly from the bottom of the Pacific. In 
the Island of Hawaii the volcanic forces are still in operation, 
the two chief volcanoes being Mauna Loa and Kilauea. Mauna 
Loa, “the Great Mountain,” rises from the bottom of the 
Pacific to a height of about 30,000 feet. 
Captain Dutton, of the American Geological Survey, thus 
describes this mighty volcano. 
“In the aggregate of its eruptions Mauna Loa is also unrivalled. Some 
of the volcanoes of Iceland have been known to disgorge at a single out- 
break masses of lava fully equal to them. But in that land such extravasa- 
tions are infrequent, and a century has elapsed since any of such magnitude 
have been emitted, though several of minor extent have been outpoured. 
The eruptions of Mauna Loa are all of great volume, and occur irregularly, 
with an average interval of about eight years. Taking the total quantity of 
material disgorged during the past century, no other volcano is at all com- 
parable to it. A moderate eruption of Mauna Loa represents more material 
than Vesuvius has emitted since the days of Pompeii. The great flow of 1855 
would nearly have built Vesuvius, and those 1859 and 1881 are not greatly 
inferior.” * 
In 188] lava was poured out for a period of eleven months, 
and the flow reached a distance of 60 miles. The rate at 
which the lava stream advanced varied; some days its progress 
was at the rate of } to half-a-mile a day, and was described 
by the Bishop of Hilo as coming down the rocky bed of the 
ravine like the roar of a river in flood. Sometimes the sound 
was like that of distant thunder; the explosions and detona- 
tions were rapid and startling, sometimes as many as ten a 
minute could be counted. These sounds seem to have resulted 
from the rapid escape of steam and water vapour, a feature 
to be remembered in our further investigations. The volcano 
was again in eruption on January 15th of this year (1887), and 
previous to the outbreak there had been 36 hours of continuous 
earthquakes. The crater is from 2 to 3 miles across, and has 
the appearance of a lava lake, which becomes more agitated 
previous to an eruption, and is finally relieved by violent 
* United States Geol. Survey, Fourth Annual Report, p. 84, 1882-83. 
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