GEOLOGY. 299 



the fixed conductor; "and, during the fall of the ashes," he says, "I verified 

 a curious fact, which I have observed during the fall of rain, also, that while 

 with the movable conductor we had positive electricity, with the fixed con- 

 ductor a faint, negative electricity was observed." This eruption is described 

 as having been extremely grand, and many interesting observations were 

 made respecting it. A correspondent of the London Athenaeum thus de- 

 scribes the course of lava: "It was pent within the deep banks of a wide 

 bed, and was flowing down, not like a fluid, which is the ordinary motion of 

 it, but like a mountain of coke, or at times like highly gaseous coal. It split, 

 and crackled, and sparkled, and smoked, and flamed up, and ever moved on 

 in one vast compact body. Pieces, detaching themselves, rolled down, leaving 

 behind a glare so fierce, that I could have imagined myself at the mouth of 

 an iron furnace ; and as every mass fell down with the noise of thunder, or 

 rolled sideways from the upper surface into the gardens and vineyards, the 

 trees flamed up, and the crowds uttered shouts of admiration and regret. 

 Following the course of the stream, or rather tracing it back to its source, we 

 walked by the side of that huge leviathan, through highly-cultivated grounds, 

 now trodden under the feet of multitudes, until we arrived at the edge of a 

 precipice, whence we looked into the boiling flood, fed by the cascade of 

 lava, which was pouring down from above. The sublimity of that spectacle 

 is indescribable ; and, were I to live the life of Methusellah, the impression it 

 made upon me would never be obliterated. I can- think of nothing else ; 

 and when I close my eyes, still the stream of fire dazzles my sight. Full 

 1000 feet fell that glowing, flaming Niagara, in one unbroken sheet, over the 

 precipice at the back of the Hermitage and the Observatory. Forming, at 

 first, two cascades, the interval between had been filled up by the immense 

 masses of scorise, which the mountain had thrown out ; and now it majes- 

 tically rolled down one continued stream into a lake of boiling fire, and then 

 descended into the plains which it had left. There were times when pro- 

 jection.^ in the face of the lava seemed to impede its course, or when the 

 adhesive character of it appeared to bind it up in a temporary rigidity ; then, 

 behind those projections, accumulated tons upon tons of material. It was a 

 moment of breathless expectation ; all eyes were fixed upon that one black- 

 ened spot. There was a slight movement ; one heard a click ; a few ashes 

 and stones fell down like avant-couriers, and down went a mountain of solid 

 fire into the boiling, smoking abyss, with the noise of thunder." 



EARTHQUAKE INDICATOR. 



Dr. Kreil, formerly Director of the Observatory at Prague, has invented an 

 ingenious instrument to measure the force, duration, and direction of earth- 

 quakes. It consists of a pendulum, so contrived that, while it can move in 

 any direction, it can not return. A perpendicular cylinder is attached, which, 

 by means of clock-work, turns on its vertical axis in twenty-four hours. A 

 pole, with a thin elastic arm, is fixed near the pendulum ; this arm points 

 toward the cylinder, and presses on it gently a pencil, by which means an 

 unbroken line is formed on the surface of the cylinder as long as the pendulum 



