ntally the important inference
which could be drawn from the discovery of altered sandstones in the
Erebus region. He went to the shapes of volcanoes:

The massive type formed by very fluid lavas--Mauna Loa (Hawaii),
Vesuvius, examples.

The more perfect cones formed by ash talus--Fujiama, Discovery.

The explosive type with parasitic cones--Erebus, Morning, Etna.

Fissure eruption--historic only in Iceland, but best prehistoric
examples Deccan (India) and Oregon (U.S.).

There is small ground for supposing relation between adjacent
volcanoes--activity in one is rarely accompanied by activity in the
other. It seems most likely that vent tubes are entirely separate.

_Products of volcanoes_.--The lecturer mentioned the escape of
quantities of free hydrogen--there was some discussion on this
point afterwards; that water is broken up is easily understood, but
what becomes of the oxygen? Simpson suggests the presence of much
oxidizable material.

CO_2 as a noxious gas also mentioned and discussed--causes mythical
'upas' tree--sulphurous fumes attend final stages.

Practically little or no heat escapes through sides of a volcano.

There was argument over physical conditions influencing
explosions--especially as to barometric influence. There was a good
deal of disjointed information on lavas, ropy or rapid flowing and
viscous--also on spatter cones and caverns.

In all cases lavas cool slowly--heat has been found close to the
surface after 87 years. On Etna there is lava over ice. The lecturer
finally reviewed the volcanicity of our own neighbourhood. He described
various vents of Erebus, thinks Castle Rock a 'plug'--here some
discussion--Observation Hill part of old volcano, nothing in common
with Crater Hill. Inaccessible Island seems to have no connection
with Erebus.

Finally we had a few words on the origin of volcanicity and afterwards
some discussion on an old point--the relation to the sea. Why are
volcanoes close to sea? Debenham thinks not cause and effect, but
two effects resulting from same cause.

Great argument as to whether effect of barometric changes on Erebus
vapour can be observed. Not much was said about the theory of
volcanoes, but Debenham touched on American theories--the melting
out from internal magma.

There was nothing much to catch hold of throughout, but discussion
of such a subject sorts one's ideas.

_Saturday, June_ 17.--Northerly wind, temperature changeable, dropping
to -1