154 Transactions, 
of the Northern, and in the southern portion of this Island. Consequently, 
a broad belt running in a N.E. and S.W. direction across New Zealand, and 
following the direction of the central chain in both islands, appears to 
have been visited simultaneously by the vibratory movement. 
There is, however, one form of propagation, and of a truly plutonie 
nature—the transversal earthquake— which, if admitted in this instance, 
will satisfaetorily explain all the apparent anomalies. 
If, therefore, we accept the hypothesis that an earthquake has reached 
the surface of the earth simultaneously along a line several hundred miles 
in length, and running parallel with the central chain in both islands, and 
through a fissure deep below the earth's crust, we shall be able to find 
sufficient explanation of all New Zealand occurrences. Let us therefore 
draw a line passing through New Zealand, so that N apier, Waipukurau, 
Greytown, Featherston, (White's Bay?), and Blenheim, in which the 
vibratory jar was experienced at the same time (9.55), are situated at an 
equal distance, either on the same or on both sides of it ; we shall then find 
that the other stations, such as Wellington, 9.56, Nelson, 9.57, Christchurch, 
- 9.565, and Hokitika, 9.58, may be grouped along with it at greater or less 
distances. Owing to the occurrence of mountain chains, across which the 
shocks have to pass, a change of rocks, &c., many other causes of retardation 
or acceleration may arise by which they may arrive at greater or lesser speed 
at the station where they have been registered; and a calculation for each 
station from such an adopted line would show that in every case the shocks 
moved from it, laterally, in a much diminished ratio, and more in accordance 
with the velocity of such class of earthquakes observed in other parts of the 
world. 
Ttis also evident, from the occurrence of an earthquake shock in Sydney, 
experienced on the 18th August, where such phenomena are of such rare 
occurrence, that a deep-seated disturbance in or below the solid crust of 
the earth must have occurred over a great portion of the globe, and for 
which a voleanie eruption cannot account. 
Thus the abysso-dynamie forces, or tides, may have acted upon the 
earth's erust at any given spot more readily, owing to its weakness, when 
compared with others. They may have been able to form a vent, from 
which voleanie eruptions of unusual magnitude took place on the 15th, and 
probably on the following days. But such a catastrophe could not happen 
where the crust of the earth was too solid: nevertheless, at many of such 
localities, the fluid magma below the former was sufficiently disturbed to 
act upon the interior of the shell by vibratory jars, and principally in those 
lines where, as along the axis of the longitudinal mountain chains or their 
-declivities, weaker zones were exposed to that influence, 
