422 Transactions. — Geology. 



V. : Greymouth, Hokitika, Westport, Christchurch. 



IV. -V. : Auckland, Eotorua, Ashburton, Timaru. 



IV. : Dunedin, Queenstown. 



The significance of this grouping will appear from the 

 Rossi-Forel scale, which I make no apology for quoting at 

 length, as I believe it has never yet appeared with the abso- 

 lute equivalents in any New Zealand publication. The Arabic 

 figures express the equivalents on the absolute scale — that 

 is, the maximum acceleration of the earth's surface in milli- 

 meters per second per second, the acceleration due to gravity 

 being about 9,600 mm. /sec. 2 



Absolute 

 Rossi-Forel Scale of Intensity. Scale. 



mm. /sec.' 2 



I. Eecorded by a single seismograph, or by some 



seismographs of the same model, but not by 

 several seismographs of different kinds ; the 

 shock felt by an experienced observer ... 20 



II. Recorded by seismographs of different kinds ; 



felt by a small number of persons at rest ... 40 



III. Felt by several persons at rest ; strong enough 



for the duration or the direction to be 

 appreciable ... ... ... ... GO 



IV. Felt by persons in motion ; disturbance of mov- 



able objects, doors, windows, cracking of 

 ceilings ... .. ... •■• BO 



V. Felt generally by every one ; disturbance of 



furniture and beds, ringing of some bells... 110 



VI. General awakening of those asleep ; general 



ringing of bells, oscillation of chandeliers, 

 stopping of clocks ; visible disturbance of 

 trees and shrubs ; some startled persons 

 leave their dwellings ... ... ... 150 



VII. Overthrow of movable objects, fall of plaster. 



ringing of church bells, general panic, 

 without damage to buildings ... ... 300 



VIII. Falls of chimneys, cracks in the walls of build- 



ings ... ... ... ... 500 



IX. Partial or total destruction of some buildings... 1200 



X. Great disasters, ruins, disturbance of strata, 



fissures in the earth's crust, rock-falls from 

 mountains ... ... ... ... ? 



The Milne horizontal pendulum seismograph at Wellington 

 gave a good record, and nearly all the phases were also 

 recorded on the Milne instrument at the Perth Observatory, 

 West Australia, to the Director of which I am indebted for a 

 copy of the seismogram. 



