1880. ] The Island of Dominica. T oz 
by generation of heat. Such action will be facilitated and accel- 
erated by the extremely small size of the individual pyritic parti- 
cles. The postulated reagents are abundantly supplied at the 
locality in question, In addition to the ferric compound the 
feldspathic portions of the trachyte are attacked, yield to altering 
agents, and by increase of volume accompanying chemical 
change, add their share to the generation of heat. At the same 
time the decomposing mass is physically disintegrated and then 
easily removed by natural causes, thus permitting a repetition of 
the same process, until the supply of unstable chemical com- 
pounds may become exhausted. Irregularities of either chemical 
or physical character within trachytic rocks are by no means of 
rare occurrence. Should their nature be such as to yield more 
readily to active reagents than the portions surrounding them, 
decomposition will progress at a higher rate of speed along cer- 
tain lines or in certain directions. Thus vents may be formed 
which besides serving as outlets for gases and liquids, will allow — 
fresh supplies of moisture and air to reach points as yet com- 
paratively intact. 
Returning to our darkies we found them unfeignedly surprised 
to see us still alive, but they evidently concluded that we were 
reserved for some fate even worse than “having rocks thrown 
at us.” 
“Wotten Waven” is another point deserving of special study. 
A morning ride aldng the left bank of the Roseau, which led 
through flourishing lime plantations, brought us to the undisturbed 
timbered slopes of a subtropical zone. Huge tree ferns over- 
shadowed the narrow path cut into a steep face of trachytic con- __ 
glomerate, over which we were gradually winding our way 
upward. It would be impossible to furnish a pen picture capa- — 
ble of giving even a faint idea of the beauty inherent in such a 
forest. The cool moist atmosphere is refreshing, and every step — ; i 
taken forces admiration from those whose eyes are accustomed to 
the more sombre grandeur of northern climes. A column re ae 
steam slowly wreathing skyward betrayed the presence of Wot- 
ten Waven. These “ thermal springs” lie about 1600 feet above- 
sea level, but not within pyritiferous trachyte. A short distance 
from the timber edge we found a creek flowing cold water. Fol- 
lowing this down, the first hot springs were soon encountered. 
Here the water issued from small apertures in trachytic rock =~ 
