610 
PROFESSOR FORBES ON THE TEMPERATURES 
IV. Pfeffers. Canton of St. Gall. 
A. Geological Position. — Issues from limestone in a very remarkable fissure, often 
described by travellers. Dr. Daubeny has dwelt upon the appearances of convulsion 
presented by this site # ; and such no doubt there are, though I am of opinion that 
the chasm in which the spring itself occurs is one of erosion. The perpendicular pre- 
cipice above it, however, seems to indicate fissure; nor have I the slightest doubt 
that the course of the Rhine in this neighbourhood has been determined by a very 
extensive local disruption of the strata. 
B and C. Specialties , Temperature , fife. — There is, I believe, only one spring at 
Pfeifers. I took its temperature at its point of rise from the rock. It is insipid, and 
moderately copious. Its elevation is 2251 feet above the sea. I made particular in- 
quiries of a resident priest as to its constancy of temperature and volume. He assured 
me that the former varied but little throughout the year, and estimated it at 29f° R. 
(= 98°'7 F.), but that its quantity was by no means so constant; its discharge in 
summer being 29°8 Paris cubic feet per minute, and always diminishing towards 
winter, when occasionally (as in winter 1831-2) he declared that it became quite dry . 
This is a singular and important fact, and would almost force us to suppose that this 
thermal water owes its origin to the neighbouring glaciers. 
Troughton. Reduced. 
1832, October 1 1. — Pfeffers . . 98 0, 1 9/ 0- 9 
V. Baths of Nero, near Naples. 
A. Geological Position. — The baths of Nero, commonly called Sudatorij di Tritoli, 
occur close to the shore of the bay of Baja near Pozzuoli. They consist of vapour 
baths cut from the solid tufaceous rock of volcanic formation. Perhaps the most re- 
markable fact connected with their geological position, is the proximity of the Monte 
Nuovo, elevated by volcanic explosion in 1538. It is singular that the spring imme- 
diately to be mentioned should not have been affected by that circumstance ; for 
there is every reason to believe that it has flowed since the time of the Romans. 
B. Specialties , 8$c. — I have very fully described the origin and circumstances of 
this remarkable spring in my series of papers on the Bay of Naples in the Edinburgh 
Journal of Science-f'. I there also quoted the curious mistakes into which travellers 
have been led from the supposed difficulty and danger of reaching the hot spring. I 
am led to conclude that the observation I then published is perhaps the only accurate 
one which has been made upon this, one of the most curious, and I believe the hottest 
spring on the continent of Europe. It is reached by a low excavated passage, the 
latter half of which dips rapidly, and having a sharp turn about the middle of its 
length, which is about 120 paces in all. At the extremity (which is difficultly reached 
from the heat and oppressive nature of the atmosphere) rises the spring. I took the 
* Edinburgh New Philosophical Journal, January 1832. 
f New Series, vol. ii. p. 88. 
