38 KEPOKT— 1891. 



existence I am aware have not so far been available for use. 

 When all are included, I anticipate that the number of shocks 

 recorded will be found to be nearly nine hundred for the years 

 in question. 



(2.) A large number of earthquakes were unobserved, 

 especially in the earlier years. Slighter shocks will escape 

 notice mitil we have seismographs in use at the chief sta- 

 tions ; but under the present system it is hardly possible for 

 a perceptible shock (felt at several places) to escape the 

 record. 



(3.) Many of the records are inexact. This fault, again, can 

 only be fully corrected by the use of instruments ; but once 

 more I may claim that the system, which I shall presently 

 describe in brief, has introduced a greater degree of exactness 

 than has (except occasionally) been possible before. Not- 

 withstanding these drawbacks, much may be learned from 

 the records as to the distribution of New Zealand earthquakes 

 in place and time, and as to the origins of disturbance. If 

 nothing else were done, it would, I venture to submit, be 

 useful to summarise our knowledge of the past, and so to place 

 ourselves in a position to see towards what points future inquiry 

 may profitably be directed. 



I. DisTiiiBUTiON IX Time. 



This is perhaps the least important part of the subject, 

 and may be dismissed in a few words. Table A shows the 

 number of shocks recorded (or, rather, included in my list) 

 per year from 1848 to the present time. Its chief value is to 

 indicate the natme of the records themselves. 



Table B shows the number of shocks recorded for each 

 month of the year from 1848 to 1890. Its accuracy is not 

 affected in any special way by the incompleteness of the earlier 

 records, which are almost as likely to fail in any one month as 

 in any other. The number of earthquakes for the months 

 October to March is 341 ; for the months April to September, 

 404 — thus confirming the general rule stated in Milne's 

 '•' Earthquakes," p. 257, namely, that "generally the greater 

 number of shocks have happened during the cooler seasons." 

 Professor Milne, indeed, remarks that the rule is not true in the 

 Southern Hemisphere ; but his table (given on the same page) 

 seems to show that it is, and our present list certainly proves 

 that the law holds as far as New Zealand is concerned. 



C is a chart (PI. III.) of the curves of Monthly Seismic In- 

 tensity (after Mallet — see Milne's "Earthquakes," p. 256) for 

 the Northern and Southern Hemispheres, with the correspond- 

 ing New Zealand curve, based upon Table B, for com]3arison. 

 The number of earthquakes is a maximum in September, with 

 two lower maxima in January and March. The minimum is 



