36 Transactions. — Miscellaneous. 
and being served out again through the many springs occurring on the road to 
the Whau (the Western Springs), at Onehunga beach, Lake Takapuna, and 
other places. "These springs are merely the overflow of what is a natural 
subterranean reservoir. To prove this, one must consider how volcanic rocks 
occur, especially those at Mount Eden and its vicinity, and their physical 
construction. 
Dr. Hochstetter remarks about these volcanoes that “the first outbursts, 
as a closer observation shows, were probably submarine; they took place at 
the bottom of a shallow, muddy bay, little exposed to waves and wind, and 
consisted of flowing mud mixed with loose masses, such as fragments of sand- 
stone and shale, lava debris, cinders, and scoria (lapilli), which now form beds 
of volcanic agglomerate or tuff. The eruptions occurred, no doubt, at intervals, 
for in this manner alone can the fact be accounted for that the ejected 
material has been deposited round the point of eruption in layers one above 
the other, forming low hills gradually rising, and with a circular basin or dish- 
shaped crater in the middle; a cross section presents clearly the different 
layers which usually slope inwards towards the bottom of the crater, as well 
as outwards down the sides.” Further on, he says :—‘ A complete volcanic 
system accordingly consists of three parts: a tuff cone the base and pedestal of 
the whole frame, a lava cone, the chief mass of the mountain, and a scoria or 
cinder cone forming the top, with the crater." 
These violent outbursts and ejection of such large quantities of scoria and 
lava would undoubtedly produce very important effects on the surrounding 
country and on the rocks immediately below and through which the eruptions 
occurred. Before a vent could have been made through the earth’s crust, it 
must have been somewhat upheaved and cracked to emit the molten materials 
below, which, as they ascended, would have enabled the crust to subside, and 
this it would continue to do as long as material was ejected, for the earth's 
crust, by its own weight and that of the piled-up scoria and lava above, would 
necessarily sink down and occupy, in a measure, the place of the ejected 
materials. Thus, below a volcanic mountain of any considerable extent, there 
must be a basin-like depression immediately beneath capable of holding а 
large quantity of water, which, combined with the water in the mountain 
above, retained in it as if it were a large sponge, may probably be made 
available for a water supply. But as the quantity in the basin and above it 
may be inadequate for a large supply, we must consider whether this may be 
helped by the adjacent waters stored up all around. An inspection of lava 
and scoria beds prove that they are able to hold a large amount of water from 
their porosity, dependent upon the amount of resistance to dam the waters 
back. | 
Before it can be decided whether a sufficient quantity of water could be 
