190 THE ANTARCTIC MANUAL. 
C. Congs, CRATERS, ETC. Wherever the lavas present a fresh 
appearance, an attempt should be made to trace them up to their 
points of origin. 
a. If any great volcanic mountain be met with, all details con- 
cerning the lava-streams, fragmentary matters, and dykes of which 
it is built up will be of great interest. Failing these, however, 
sketches of the mountain, and of specially interesting portions of it, 
accompanied by such rock-specimens as can be obtained, will be of 
service to geologists. 
b. Cinder-cones on the flanks of a volcano, or scattered around it, 
should be examined and sketched. Note if they originate streams of 
lava, 
c. The craters, both of volcanic mountains and of cinder-cones, 
should be examined. Note if they are breached by lava-streams, or 
contain bosses of lava in their interiors, or buttress-like masses 
adhering to their sides. 
d. Note specially the arrangement of the smaller and larger cones 
in respect to one another. Furnish, if possible, plans to illustrate this 
point, or failing these, as many general outline sketches as possible. 
e. In and around the craters look for fwmaroles, and, if possible, 
record the nature of the gases evolved from them. Collect the 
interesting minerals found in the crusts which are deposited round 
the vents, and in the rocks traversed by the vapours and gases. 
J. Hot springs, geysers, ete., often occur in the vicinity of active or 
recently extinct volcanoes. These the observer should be on the 
look-out for (their vapours often render them conspicuous at great 
distances), and their phenomena should be carefully recorded. Speci- 
mens of hot and mineral water should be sealed up in bottles, and 
brought home for examination and analysis. 
gy. Deposits of siliceous sinter, travertine, ete. These, besides 
yielding interesting varieties of minerals and illustrations of their 
mode of formation, often contain incrusted cr mineralised remains of 
plants or animals, which may be of great interest. 
h, On the flanks of volcanoes ejected blocks of limestone and 
other rocks, often much altered, are found. These sometimes contain 
interesting minerals, and should be very carefully collected. 
(In the event of the observer being so fortunate as actually to 
witness an eruption of a volcano, every detail that he can supply may 
be of scientific value. Especially should he note the appearances 
presented by the ascending column of vapour and fragmentary 
materials issuing from the crater, the height to which this rises, the 
nature, sequence, and rate of the explosions to which it is due, and 
