and the other Azores. 259 
portion of the work which although highly i interesting has been 
in part published before. In this chapter is a letter from 
Captain Tillard of the British frigate Sabrina, “ describing 
the phenomena attending the eruption from the sea in 1811, 
and which was originally published in the Philosop. Transact. 
for 1812. The frigate being there at the time, Capt. 
landed on the new Telend and named it “ Sabrina,” but it 
disappeared a few days after beneath the waters of the 
ocean. ‘To the account of Capt. T. succeeds another, first 
published i in the ninth volume of Brande’s Jour. of Science 
and the Arts, of the Royal Inst. 
We observe Dr. Webster makes much use of ae won 
Trachyte, which is rather new in this country. 
is now applied very generally abroad to a pints on Be — 
or rather, to many differ eut porphyritic roche having the 
epee character of containing crystals of glassy felspar. 
n speaking of this rock, it is observed in e Edin. Ph. 
Jour. ina r of Dr. Borré’s on the volcanic rocks of 
Auvergne, that “ it is almost impossible to give a definition 
of such a rock; how could it be otherwise with a volcanic 
production, which is formed from all the different members 
of the granite formation ?” 
umice is described as occurring in vast quantity and it 
often contains bituminous wood resembling the Suturbrand 
of Iceland. A distinct transition from Pumice to Obsidian 
was often noticed. The obsidian is always found in St. Mi- 
chael, in loose pieces and is of the usual black colour, somes; 
times ‘itridescent, which Dr. Webster attributes to e 
to the air, &c. and always contains crystals of glassy eee 
In chap. XIV, an interesting account is given of a stu- 
pendous crater fifteen miles in circumference, and now em- 
soming an inland lake which covers one third of the in- 
eluded space, while the rest is occupied by vegetables and 
a thin population with a small village called by the natives, 
be we La cities, and the yale is called the valley of the sev- 
ed the XVth chapter a remarkable rock is described as 
©ccurring on the mountain of Agoa de Pao. “Some of 
pieces were Ahoet twice the size of a man’s head, and, 
‘at first sight, might easily have been mistaken for pieces of 
granite. ‘They are composed of felspar and herablands, 
and contain a few scattered grains of magnetic e 
