GEOLOGY AND MINERALOGY. 255 



ERUPTION OF VESUVIUS. 



The Correspondent of the Athenceum writes, March 20 and 21 : — 



" At 1 a.m. the mountain threw out fire and burning stones, at the same 

 time uttering a loud noise, as of thunder. At the bottom of the crater several 

 smoke holes have been formed, in which fire may be seen, and from which a 

 noise continually issues. At the foot of the mountain three small craters were 

 formed ; ' and I counted this night,' says the guide, 'thirty-two currents of lava, 

 one of which was full sixteen palms in width, and travelled rapidly in the direction 

 of San Salvadore, whilst the others went towards the Piano della Ginestra. As 

 I stood and looked, I saw the earth open and currents of lava issue.' All the 

 proprietors of laud in the direction of Torre del Greco are in a state of great 

 apprehension, as their estates are threatened. ' On going up the mountain,' 

 says the cautious and learned Cozzolino, ' take care of the smell of muriatic 

 acid.' " 



In the same journal of April 14, we find : — 



" The eruption of Vesuvius continues and increases," writes a friend from 

 Naples ; " and during the last week the surface of the mountain has undergone 

 great changes. On Friday night last the discharges were so loud and strong 

 that the whole neighbourhood shook ; and these were followed by a hissing 

 sound, as of a rapidly flowing river. Looking into the crater, one sees a body of 

 liquid fire; and on one occasion a tri-coloured jet was thrown up; so that it is 

 generally expected that Commendatore Ajossa will send up a body of police to 

 take note of and suppress this treasonable demonstration. The three colours — 

 blue, violet, and black — were not, it is true, the Italian colours; but we do not 

 stand to trifles here : number is as suspicious an element as colour. As these 

 variegated circles of fire made their appearance, the crater shook with the 

 violence of the elt'ort. From the foot of the mountain a stream of water and of 

 lava issued, and ran so rapidly, that in one hour it advanced a mile ; its course 

 was then slower, and always in the direction of Torre del Greco. Towards 

 Eesina the guides counted twenty currents ; and in the midst of them had been 

 formed a lake of lire, full forty feet in circumference. The appearance of the 

 mountain from Naples is, of course, very striking." 



In the journal of May 12 : — 



" I send you the following report of the state of Vesuvius, which has just been 

 brought in by the guide. The crater still sends out its thunders, followed by 

 red-hot stones. At the bottom of it one sees a mass of fire, from which ri3e up 

 fiery circles like carriage-wheels. The exhalations of muriatic acid are so strong 

 that it is diilicult to approach. At the foot of the mountain there are full a 

 hundred currents of liquid lava, which have arrived at the ' Piano delle Ginestre.' 

 At present the numerous craters are no longer visible ; the whole ground seems 

 id forth lava, and the small proprietors are in great apprehension. The 

 currents have been flowing over the old bed of 1701, when Torre del Greco was 

 swept away, and the lava went half a mile into the sea." 



NEW SEISMOMETER. 



Professor Cavalleri has constructed in the College at Monza a 

 new Seismometer, for recording',the shocks and convulsions to which 

 the surface of our globe is subject ; and Mr. 11. Mallet has commu- 

 nicated to the Philosophical Magazine, No. 125, Professor Cavalleri'.s 

 memoir upon seismology, in which he describes this new instrument. 



Earthquake waves, says M. Cavalleri, as far as I can remember, 

 in three distinct cases, which I have present to my mind, appeared 

 very rapid and almost isochronous, liecalling these shocks, it does 

 not appear to me far from the truth to assign about three undula- 

 tions per second as the rate, at least in our Lombardy Plains. The 

 instrument which I have constructed with this view will note the 

 duration of these undulations, and consequently whether they are 

 different in various countries and in different earthquakes. 



