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



drangular apartment under ground, to which we descend by 

 40 steps ; it is 230 English feet long and 97 broad, and is 

 supported by 48 square pillars in four rows, which are united 

 by small arches at top, presenting when combined with their 

 great height, a striking appearance. The walls are invested 

 with a crust which is of great hardness, and has been consi- 

 dered by Winkelman and others as a peculiar kind of plaster; 

 but this seems overthrown by the observation of other authors, 

 that the thickness of it diminishes regularly to the top of the 

 chamber, and that it has actually a true stucco under it, * in- 

 dicating that this crust was deposited by the water once ar- 

 tificially collected in this reservoir. It resembles, besides, the 

 incrustation found in the chambers called the " Sette Sale" in 

 the Baths of Titus at Rome, which is so hard that I found a 

 difficulty in breaking it with a small hammer, and which is 

 the undoubted deposition of water. The following are the 

 constituent parts of the coating of the Piscina Mirabile : 



Muriate of lime, . _ _ 5 



Muriate of soda, - - - 11 



Carbonate of lime, - _ - 75 



Alumina, . _ . _ 5 



Iron and silica, _ - » 3 



Loss, _ _ - 1 



100 



From the Piscina Mirabile f we command a view of the Mare 

 Morto, which appears anciently to have constituted the fa- 

 mous Port of Misenum. From its shores rise the swelling 

 plains which form the mythological representation of the 

 Elysian fields ; and, however they may fall short of what a 

 poetic imagination might desire, they must still be dear to the 

 classical traveller, from their intimate associations with the ex- 

 quisite description of Virgil : 



* Orloff, Memoires sur Naples^ v. 350. 



+ I ought not to omit entirely the mention of some singular excavated 

 apartments in this neighhourhood, called the Cento Camerelle, dug out of 

 tufa and plastered. They have created much antiquarian discussion, and, 

 as they do not present any peculiar physical fact, my limits do not allow 

 me to give any account of them. They were probably prisons. 



