Ip2 TRAVELS THROUGH 



Hones be thrown into it. It is faid to be fifty 

 feet deep, and is celebrated for its fmall floating 

 ifiands, which are grown over with grafs and reed. 

 A fmall brook running from the Lago de' Eagni 

 forms by its incruftations the Lujus natur<2^ called 

 Confetti di Tholi, From the Lago di Zolfo to 

 Tivoli the country is flat ; but here it afcends to 

 the city, which is fituated on a calcareous hill of 

 the Apennines. This hill is towards the valley 

 covered by a large calcareous incruftation, pro- 

 duced by the waters, which, defcending from the 

 Apennines, run over this hill in the valley, and 

 have incruflated the whole ground as far as Cafteir 

 Arcicne. The ir.cruflations flicking to. the deep 

 fides of the Tivoli hill, are wave-like and twilling, 

 lamellated like the fprudel-ilone at Caclfbad.. They 

 often contain inclofed large lumps of ofteocolla or 

 incruftated roots and branches of trees, which ei- 

 ther are penetrated by the calcareous water and 

 petrified, or have left impreflions rilled with a 

 calcareous fubflance. 



From 2rz;0# to Villa d\ Adriano the road de- 

 fcends the hill, and runs afterwards over volcanic 

 tufo, which lies bare and uncovered. This ground 

 continues to the Villa d' Adriano, whofe antique 

 Walls are built of its ferruminated afhes, in a me- 

 thod which the Ancients called Opus, reticulatum. 

 Volcanic tufo is likewife ; feen inferior to the cal- 

 5 careous 



