[ 289 ] 



LIT. Letter from Br. OlberS of Bremen to Baron Yos 

 Zach, on the Stones whidy have fallen from the Hta.. 

 vens "" . 



You know that in a le(3;ure wh'icti. I delivered in the 

 Mufeum of Bremen In the year 1795, on the (liower of 

 ftones, as it is called, which fell at Siena in Italy, I ex- 

 prefled the fame idea which 1 lately read with muchfatis- 

 faftion in a letter of Laplace, in which he fays: *' It is not 

 ihipoffible that large mafles, detached frorri fome of the ce- 

 leftial bodies, and particularly from the hiopn, may have 

 fometimes been projeft'ed to the earth." As you require a 

 more circumftantial illuftration of this fubje6l, I embrace 

 the prefent opportunity of gratifying your wifhes. 



I nnift readily acknowledge, that when I viTOte the before- 

 mentioned eday on the Ihower of ftones which fell at Siena,- 

 I confidered thefe ftones to be of a volcanic origin. The 

 ftones found at Siena fell at the diftance of fixty miles from 

 Vefuvius, only eighteen hours after the commencement of 

 the great eruption which deftroyed the unfortunate Torre' 

 del Greco, and of which fo elegant a defcription has been, 

 given by fir William Hamilton. I was acquainted with the 

 principles of Zolner and Lichtenberg, according to which 

 thefe (tones could not be afcribcd to Vefuvius ; but to me 

 thefe principles did not appear fatisfaftory. The great ve- 

 locity which would be neceflary to make a mafs projected 

 from Vefuvius to proceed to fo great a diftance, was not fpf- 

 ficient to induce me to abandon my opinion. By calculation 

 I found that it was not fo great as what might be fuppofed 

 to be produced by the dreadful convulfion which takes 

 place on fuch occafions. What tended chiefly to confirm 

 •me in my idea was, that fir William Hamilton then be- 

 lieved that he had often found at Vefuvius ftones which had 

 a great rcfcmblance to thofe which fell at Siena t- I alfo 

 fuppofed that Vefuvius might have proje£ted from one of its 

 mouths a half-fufed mafs at an an8;ie of from forty to fifty 

 degrees, whiehj like every thins: eUe proceeding from the 

 crater, was in a high degree ele8;ric; that this mafs had 



• From Algemeene Konjl en Lctio-Bode, No. 17, IS03. 



t Stones of the fame n-iturc, at kalV as far as the eye can judge of 

 them, are frt-qucntly fcuud on Monni Vefuvius: ;tnd when I was on th« 

 mount-tin lately 1 I'circhcd for inch ftones iie^r the new mouths ; but as 

 the foil around tlicnn has been covered with a thick bed of ;i(hes, \vhatevcr 

 was thrown up durin,i the force of the tru^^tion lies bttfied under ihofo 

 afties, &c. — Philolophical Tfaiif..ftions 1795, P- '"4* 



VoZ7XV7N^r6o: U crater^ 



May 1803. 



