94 Mr Forbes's Physical Notices of the Bay of Naples. 



been fed, and which affords so remarkable a subject of specu- 

 lation in this age of geological inquiry. * It has been supposed 

 by some, that the temperature has increased greatly since the 

 day of the Romans ; -j- this, however I think, is improbable from 

 the strong expressions of Pliny ; " Tanta eis est vis ut balineas 

 calefaciant, ac frigidam etiam in soliis fervere cogant. Ob- 

 sonia quoque percoquunt." J Yet, notwithstanding the con- 

 tinuance and intensity of the heat, the water, ^s we have al- 

 ready remarked, is almost pure; it evolves no sulphuretted hy- 

 drogen, like the other springs of this neighbourhood, and ap- 

 pears to have no action on the tufaceous rock § through which 

 its vapours have circulated for hundreds or thousands of years. 

 I must not close this description without adding, that the spring 

 is not the only termination of this excavation ; various bran- 

 ches strike off from the first one, and constitute no less than 

 seven terminations. The only tolerable description I have met 

 with of these intricate passages is in a curious work, a century 

 and a half old, already alluded to, and which contains an ori- 

 ginal ground plan ||. Some of these are extremely low, not 

 above two and a half feet in height, of which the floor com- 

 posed of sand has a burning heat. One of the most inacces- 

 sible terminates in a cross, in the centre of which is a dry well, 

 from which issue vapours of high temperature. The confine- 

 ment and remoteness of this grotto occasions an extremely in- 

 supportable atmosphere, and it is said to be dangerous to visit 

 these remote recesses, though they contain no hot spring. 



Besides the Stufe de Tritoli, which, with great probability, 

 may be considered the true Baths of Nero, others of less im- 

 portance are distributed over the same neighbourhood. Baja 

 was famous for the variety and multiplicity as well as the ex- 

 cellence of its thermal springs ; 



*' Baianos sinus, et foeta tepentibus undis 



Littora. '* 



Ital. Lib. iii. 4. 



* Neither Professor Daubeny nor Mr Scrope, our two principal volcanic 

 writers, seem lo have visited these stoves. 



I Orloff, V. 332. 

 i Lib. xxxi. 2. 

 § Breislak. 



II Sarnelli, Guida ; Napoli, 1688. 



