and the other Azores. 261 
would ask Dr. Webster whether he is warranted in infer- 
ring that his supposed primitive specimens, “ could not have 
been subjected to a very elevated temperature,” because 
they retain “ their lustre and translucency,” for the: glassy 
felspar which he mentions as being found so commonly in 
the lava and even in the obsidian and pumice of St. Michael 
is still more remarkable for lustre and translucency, and in 
- the lava of Vesuvius, we often find transparent and brilliant 
erystals of leucite, not to mention the beautiful olivia which 
abounds so much in the lava of the Azores. 
The author next adverts to the occurrence of fragments 
of similar rocks, in the vicinity of volcanoes now active, 
and states his opinion that the specimens observed by him 
could not. have: been carried up the mountain, | or baracpnie 
there b 
+ These stones were not found in the immediate vicin vicinity 
of any buildings, near the sea shore, nor at the base of the 
mountain, but at an elevation of not less than one thousand 
feet above the level of the sea, and in a ‘ira probably, 
never before trodden by human being.” We freely assent 
to the author’s observation that “ in examining any tract of 
country, the geologist cannot too often call to mind the re- 
mark of Humboldt that ‘ he is exposed to a thousand er- 
rors if he loses sight of the changes, which the intercourse 
The \ : | ? 
as tuff,” which also forms a small island, or more properly 
crater in the sea in front of the town of Villa Franca. This 
islet appears from its structure to have beew ere a 5 an 
eruption like that of 1811. Hot springs occur in 
places in St. Mishrabarthone of * the valley of the Fe umnas” 
are most interesting and ¢ 
; ‘is nearly circular, but its surface has egnsicerabile teregu- 
here 
larity, rising and there into small hills. A part of it 
is under — cultivation, and it is inhabited by a few 
The Portuguese word “* Furnas’? means caverns. 
Yen. Vv... No. 2. - 
