92 PROCEEDINGS OF THE ROYAL SOCIETY OF QUEENSLAND. 
gives off steam. All the evidence points to the fact that 
Matupithaven is a submarine crater, but it is impossible 
to observe its relation to the other craters except that it 
appears to be associated with the rift system. 
(d) Vulcan Island (Fig. 2).—This is another sub- 
marine crater and it was active in the earlier stages of the 
1878 eruption. At that time vast quantities of pumice and 
mud were thrown up, building the low island now known 
as Vulean Island. On the edge is a small lagoon which is 
apparently part of the crater proper. The water is very 
hot, as is the adjacent mud. 
All these eraters are explosive in type and there is no 
sign anywhere of lava-flows or dykes, except one very small 
outerop of dioritic rock at the base of Mount Mother. There 
is only a very small exposure, and it is impossible to give 
any opinion as to its nature. 
(11) Fumarotes—Along the western margin of the 
South Daughter craters and in the Cinder Cone, around 
the shores of Matupithaven and at Vulcan Island, there 
are numerous fumaroles. They are continuously active. 
Some build up small sulphur cones and pipes, some are 
merely holes. The steam comes out in puffs at regular 
intervals. The steam is probably composed of water vapour 
and H,S and SO,, as clusters of delicate crystals of yellow 
sulphur are deposited around the vents. The sulphur fumes. 
arise In such a quantity that, when the S.E. winds blow, the 
atmosphere is distinctly disagreeable in Rabaul over two 
miles away, and even strong enough to discolour silverware. 
On closer examination, these vents are seen to follow 
two fairly definite Lines—one in a north-and-south direction 
extending from the Cinder Cone to the old crater at the 
foot of Mt. Mother, and the other, commencing in Towur- 
wur, can be traced along a small gully in a south-west 
direction to the water’s edge, and is in a direct line with 
Vulean Island and passing through Matupithaven. This 
latter is in fact the old line along which steam arose imme- 
diately preceding the 1878 eruption. Where these two 
lines intersect, there is quite a cluster of fumaroles and 
the rocks are very hot. Between the town of Rabaul and 
Matupithaven, on a plantation formerly owned by the 
Hamburg Siidsee Aktien Gesellschaft, there is a series of 
hot sulphur springs. 
