THE GEOLOGICAL TOURIST IN EUROPE. 225 



in the neighborhood. Not far off to the south are the borax 

 springs that supply Europe, the nearest being at Monte Arboli. 

 Returning to the main line a little farther south is San Vincenzo, 

 where a cordierite trachyte occurs, and in the works for lead and 

 zinc near by toward Campiglia fine specimens of botryoidal bus- 

 tamite are to be found. 



Soon another line goes off to our left to Monte Amiata, an ex- 

 tinct volcano, whose lava contains interesting glass balls. It has 

 recently been thoroughly described by an American, J. F. Will- 

 iams (" Neues Jahrbuch," 1887). Half-way from here to Rome 

 the volcanic tufa of the Campagna (25) comes in, and soon we 

 are in sight of St. Peter's. There are collections in the univer- 

 sity, but more modern ones at the rooms of the " Comitate Geo- 

 logico," not very far from the railway-station in the modern 

 quarter. On the Campagna the Roman cement — pozzuolana — 

 diggings should be noticed, and we should go far enough on the 

 Appian Way to visit the quarries in the melilith basalt of the 

 Capo di Bove, whose cavities abound in tiny crystals of melilith, 

 apatite, nepheline, etc. Monte Mario is well known for Pliocene 

 fossils, and from Tivoli comes the famous travertine building- 

 stone of Rome. The region of the Alban Lake affords pretty 

 excursions. The workmen have leucite crystals. 



Lago Bolsena is interesting but hard to get at. So on to 

 Naples, where an Englishman, Dr. Lavis, is the present author- 

 ity (23) on Vesuvius and Monte Somma, and has a fine collection. 

 We should not fail to notice that east of Naples is another vol- 

 canic district, in type, time, and products of eruption quite dis- 

 tinct from Vesuvius, the Phlegrsean fields, the front garden of 

 the infernal regions, according to Virgil. 



Armed with a permit from the palace at Naples, we visit the 

 beautiful park crater of Astroni. The way leads past the famous 

 Grotto del Cane, along the Lago d'Agnano, once a lake, now 

 drained. On the road to Pozzuoli, where the Serapeum has had 

 literally so many ups and downs, is the Solf atara, another smaller 

 but livelier crater. A steam-tramway also connects Pozzuoli and 

 Naples, and this may be made the starting-point of a second ex- 

 cursion among further craters. Lake Avernus, etc., which should 

 certainly include a climb up Monte Nuovo, newest of mountains. 

 May you be more fortunate than I, and have a chance to go 

 farther and visit Etna and Sicily ! But most of us must now re- 

 turn. Before we leave, one last warning : don't lay out too much 

 for a day's work near Naples, Water is scarce and bad, wine is 

 not good for walkers, and the climate is relaxing. 



On the way back from Rome we will follow the central trough 

 of the Arno and Tiber, which, near the water-shed where the 

 water was dubious which way to go, was for a long time very 



VOL. XXXIII. — 15 



