64 



REPORT— 1000. 



The numbers given in the preceding table have been plotted on 

 squared paper, degrees being measured horizontally and minutes vertically. 

 From the curves thus obtained the average times for preliminary tremors 

 to travel distances of 20°, 30°, 40°, &c. have been determined, and are 

 shown diagrammatically in fig. 1. The initial velocity is taken at 

 2-2 km. per second. A glance at the table on which this curve is founded 

 indicates that the same can for the present only be regarded as provisional. 

 The incurvation between 50 and 80 degrees is evidently due to errors in 

 observation. 



•"), Larye Waves. 



The construction of the following table is similar to that given for the 

 preliminary tremors. Following the initial letter of each station, in the 

 position of a numerator, the number of minutes is given which large waves 

 occupied in travelling to that station from the origin or from the isoseist 

 of the locality, the initial letter of which is followed by a zero. The 

 figures corresponding to denominators are the distances of the localities 

 beneath which they appear from the origins of the different earthquakes. 



The times at the birigin lor thtee tn-o earthquakes were 21 and 23 min. before Tiiitbrlai 



