228 BEPOBT— 1887. 



This year Las been less favourable for addiug to our knowledge of 

 tbe subterranean structure of this volcanic district. The artesian well at 

 Russo's factory at Ponticelli, which was in progress at the date of the 

 last report, is now completed, and M. Chartier, the engineer who super- 

 intended the boring, has kindly placed at my disposal the working 

 records and specimens, which I hope to describe in detail elsewhere. 

 Marine sand, tuff, and other clastic materials were traversed to a depth 

 of 58 metres, and from that point to 103'4 metres beds of rather coarse 

 doleritic lava were met with. The lavas repose on strata of ash, lapillo, 

 and pumice, and at a depth of 180'6 metres sand and leucitic (?) breccia were 

 met with. The importance of this well cannot be overrated, showing as 

 it does the interlapping of the trachytic ejections of the Campi Phlegrese 

 with the Vesuvian lavas, tuffs, and breccias, and proving undoubtedly 

 that the site of the valley of the Sebeto was a deep bay of the sea long 

 after the fires of Vesuvius had commenced to burn, and that this bay 

 was in great part filled up by the fragmentary deposits from the Neapo- 

 litan volcanoes, or others washed down the slopes of Vesuvius, and above 

 all the lavas of that volcano that poured as fiery torrents into the placid 

 prehistoric bath of the Siren long before that mythical goddess or even 

 the ancient Paleopolia were thought of by human mind. At San Giovanni 

 di Teduccio, in a direct line from the last well to the seashore, and near 

 the latter, another boring has been made by M. Chartier. After passing 

 through 18 metres of sand with shells 8 metres of marl were met with, 

 with tuff and sand to 34 metres. It is regrettable that no greater depth 

 was reached, as it might also have struck the Vesuvian lava, as in the 

 former case. 



At PisciarelH, on the N.B. flank of the Solfatara, once the site of the 

 alum- water rivulet, an attempt has been made to dig a well and re-find 

 the alum water. The well has reached a depth of 25 metres, and the 

 water is at boiling-point ; and even with two hand-fans the atmosphere 

 has risen above 90° C, so that the day before writing this report 

 (Aug, 17, 1887) the workmen refused to continue work ; and as it is 

 necessai-y to excavate another 10 metres the fight between human in- 

 genuity and volcanic heat may afford us some interesting facts. The 

 water found is an alkaline sulphur water, and not aluminous, as the re- 

 porter had forewarned the engineer, who would not believe that alum is 

 a surface product of the higher oxidation of the sulphurous acid and the 

 action of the resulting sulphuric acid upon the trachytic rocks. 



The railway works at the back of Naples have been suspended for 

 some months from financial difficulties, and the new drainage works have 

 not brought anything new to light. At the Armstrong works at Pozzuoli 

 only facts that confirm what is already known have been met with. 



The reporter spent over a month of the early summer in studying the 

 volcanic group of the Eolian Islands. The state of Vulcano afler the late 

 eruption seems to be very similar to what it is under oi'dinary conditions. 

 The bottom of the crater is now inaccessible without a rope, as the lower 

 half of the path was blown away by the late eruptive action. Stromboli, 

 however, showed the most remarkable quiescence, explosions being only 

 few and far between; and during a stay of 4| hours at the crater only 

 three were sufficiently strong to project a few fragments of pasty 

 lava. 



It is the reporter's wish, as soon as the geological map of Vesuvius 

 and Monte Somma is finished, to commence a series of experiments upon 



