290 ANNUAL OF SCIENTIFIC DISCOVERY. 



It must be noticed as one of the incidents of this eruption, that the 

 most striking display of the Aurora, witnessed in the United 

 States during the year 1852, took place on the 20th of February, dur- 

 ing the progress of this great eruption. 



A letter from Mr. Fuller published in Silliman's Journal, Sep- 

 tember, gives the following picture of the intensity of the eruption. 

 There played a fountain of liquid fire of such dimensions and such 

 awful sublimity, shaking the earth with such a constant and deafening 

 roar, that no picture can give any adequate conception of its grandeur. 

 A few figures may assist the imagination in its attempts to paint the 

 scene. I made the following calculations, after careful observations 



^j 



during nearly twenty-four hours, from different points within a mile 

 of the crater. The diameter of the crater, which has been entirely 

 formed by this eruption is about 1,000 feet, its height from 100 to 150. 

 One part of the crater was raised fifty feet during our presence on 

 the spot. The height of the column of red hot liquid lava, constantly 

 sustained above the crater, varied from 200 to 700 feet, seldom falling 

 below 300. Its diameter was from 100 to 300 feet, rarely perhaps 

 reaching 400 feet. The motions of this immense jet of fire were beauti- 

 ful in the extreme, far surpassing all the possible beauties of any water 

 fountain which can be conceived ; constantly varying in form, in 

 dimensions, in color and intensity ; sometimes shooting up and taper- 

 ing off like a symmetrical Gothic spire, 700 feet high ; then rising in 

 one grand mass, 300 feet in diameter, and varied on the top and sides 

 by points and jets, like the ornaments of Gothic architecture. The 

 New Yorker, as he gazes on the spire of Trinity Church, can imagine 

 its dimensions increased three-fold, and its substance converted into 

 red hot lava, in constant agitation, may obtain a tolerable idea of one 

 aspect of this terrific fire fountain. But he should stand at the foot 

 of Niagara Falls, or on the rocky shore of the Atlantic when the sea 

 is lashed by a tempest, in order to get the most terrific element in this 

 sublime composition of the great artist. For you may easily conjecture 

 that the dynamical force necessary to raise 200,000 to 500,000 tons 

 of lava at once into the air, would not be silent in its operations. 



A NEW MINERAL AND EARTH. 



DR. D. D. OWEN, U S. Geologist, gives the following communi- 

 cation respecting a supposed new mineral and a new earth, discovered 

 by him, in Silliman's Journal, May, 1852. 



While examining, in the summer of 1848, the north shore of 

 Lake Superior, situated in Minnesota, particularly in the vicinity of 

 Baptism River, I observed a peculiar, soft green mineral diffused in 

 the amygdaloidal traps. Though not in large masses, the mineral was 

 so abundantly disseminated in some of these rocks, that the least blow 

 of the hammer indented the rock, and left a whitish-green mark from 

 the easily crushed particles of the soft green mineral in question. 

 Chemical analysis of the mineral showed it to be essentially a hydrated 

 silicate of magnesia, and what appeared to be a new earth, interme- 



