

on the Materials used in the city of Rome. 37 



IV. The Travertine, (corrupted from " lapis Tibertinus, 1 ') 

 was the most beautiful and durable stone used by the Romans 

 in their edifices. The old quarries are still seen beside the 

 Anio, near the Ponte Lugano. It is a substance daily form- 

 ing by the incrustation of reeds and other objects, with cal- 

 careous matter from springs, abounding with sulphuretted 

 hydrogen, especially at the little lake called the Solfatara, 

 whence the famous milky stream flows, known by the name of 

 the Aqua Albula. Several mistakes have occurred with re- 

 gard to the nature of travertine. The distinguished Simond 

 in his work on Italy, just published, shows how little of a 

 geologist he must be ; he confounds it with Peperino ; and says 

 " Peperino, espece de tuf volcanique que Ton voit se former 

 dans la campagne de Rome pres des caux souffrees? A man's 

 ideas of geognosy must be rather confused when he imagines 

 that volcanic rocks may be daily forming by the action of 

 springs ! Breislak too falls into an error, when he considers 

 that the Anio at present forms true travertine. The produc- 

 tions of its waters, called " confetti di Tivoli," n are far softer, 

 and are properly calcareous sinter, while the travertine is calca- 

 reous tufa. The former is known under the name of calcareous 

 alabaster, and is of very slight hardness. It is admirably cal- 

 culated for a building stone, as it hardens on exposure to the 

 air ; and, originally white, acquires a slight tint of orange, most 

 excellently adapted for picturesque effect in the numerous 

 ancient edifices composed of it. It was first used for the or- 

 namental parts of the edifices built of softer stones, as may be 

 seen in the Tabularium on the capital, which is perhaps the 

 earliest instance of the employment of this stone, as it was not 

 used of course till Tibur came into the possession of the Ro- 

 mans. When compact masses of the stone are chosen, not in- 

 terrupted by vegetable petrifactions, it is admirably calculated 

 for durability, as may be seen in the exquisite capitals of the 

 Temple of Vesta at Tivoli. This stone is not peculiar to 

 Rome ; a variety of it occurs at Terni, and it is found in great 

 perfection near the city of Passtum, where it is produced by 

 the impregnated waters of the river Salaro. The temples and 

 walls of that amazing city are built entirely of this stone, and 

 the admirably perfect remains of the former are a sufficient 



