298 



Islands *. 1 shall only mention some circum- 

 stances respecting the height, to which very con- 

 siderable fragments of rocks were projected by 

 the nlbuths frf the Chahorra. Mr. Cologan l \ 

 reckoned from twelve to fifteen seconds during 

 Ihefafl s 6i ftrese stones, Ohtft is to say, beginning to 

 count from the inornent they had reached the 

 iriakimutn $f their height. This ciiritfns experi- 

 ment proves, that the mouth projected rocks 

 upwards of thrde thousand feet. 



llie whole of the eruptions recorded in this 

 chronological ^tenient belong solely to the 

 three islands 6f Palma, Teneriffe, atid Lanze- 



k Bory de St. Vinceot, p. %&6. 

 + «' Three of thes* stones/* says Mr. Bory de -St. Vincent, 

 u took from twelve to fifteen seconds to rise till they were 

 out of sight and fall back to the ground." If such was the 

 observation of Mr. Cologan, the result of the calculation 

 would differ from that I liave given $ but the observer expressly 

 Says, in the mahuscript in my possession : " Be n6dhe so 

 ob^et voces relox en mano y a muy corta distaftcia de la 

 tercera bocca del volcan tie Chahorra, el tiempo que desd« su 

 mas alto punto de elevacion hasta perderlas de vista en su 

 caida, gastaban las piedras mas faciles de distinguir y de tres 

 conque se hizo la experiencia, dos cayeron en cliez seguridas. 

 ckda ihia y la dtfa en quinze." Mr. Cologan observes, that 

 the duration of the fall Was even something more than 

 fifteen seconds, because he could not keep the stories in sight 

 till they touched the ground. This kind of observation i& 

 susceptible of great precision, as I was convinced from 

 similar experiments, which I made during the eruption of 

 Vesuvius in 1805. 



