154 Transactions. 



of tte In ortliern, and in the soutliern portion of this Island. Consequently, 

 a broad belt running in a N.E. and S."W. direction across New Zealand, and 

 folloAving 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 plutonic 

 nature— the transversal earthquake — which, if admitted in this instance, 

 will satisfactorily 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 K'ew Zealand occurrences. Let us therefore 

 draw a line passing through New Zealand, so that Napier, Waipukurau, 

 Grreytown, Featherston, (White's Bay?), and Blenheim, in Avhich 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 ; Ave shall then find 

 that the other stations, such as Wellington, 9.56, Nelson, 9.57, Christchurch, 

 9.56|, 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 Avhich 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. 



It is 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 volcanic eruption cannot account. 



Thus the abysso-dynamic forces, or tides, may have acted upon the 

 earth's crust 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 volcanic eruptions of unusual magnitude took place on the 15th, and 

 probably on the following days. But such a catastrophe could not happen 

 Avhere the crust of the earth Avas too solid : nevertheless, at many of such 

 localities, the fluid magma below the former Avas sufficiently disturbed to 

 act upon the interior of the shell by vibratory jars, and principally in those 

 lines Avhere, as along the axis of the longitudinal mountain chains or their 

 declivities, weaker zones Avere exposed to that influence, 



