298 EEPOET — 1889. 



Tokio and its suburbs, or over an area measuring about 6 miles by 7 

 miles, 134 bundles of postcards. Each card, which was addressed to 

 myself, had upon it in English and Japanese the following request : — 

 *If you or your neighbours feel an earthquake, kindly post this card, 

 giving the date and the time of the shock, and saying whether it was 

 short, long, a tremor or a jerk ; were you upstairs or downstairs ? ' With 

 each bundle, in which there were 20 cards, there was a letter of more 

 detailed instructions. Great care was taken in the distribution of these 

 cards ; and they were all held by persons competent, and who expressed 

 a desire to make the necessary observations. Seventy-five observers 

 were situated on high ground and fifty-nine on low ground. The high 

 ground is from 50 feet to 100 feet above sea-level, on the western and 

 northern sides of the city, and it overlooks the lower part of the city 

 from bluff-like scarps. It consists of 30 or 40 feet of loam, thin bands of 

 clay, and 60 or 80 feet of sand and gravel. Below this there is a clay-like 

 tuff rock. The low ground, which is flat almost to sea-level, consists of 

 mud, clay, and sand, after which comes tuff. The thickness of these 

 materials lying on the tuff is anything between 20 and 500 feet. In 

 addition to the postcard observers there were many who communicated 

 with me by letter. I also received the records of the Imperial Meteoro- 

 logical Observatory, from which I could determine the area over which 

 any earthquake extended, and the records from two observatories under 

 the direction of Professor Sekiya, and the observations made by myself. 

 Altogether, within the 30 square miles whei'e I made observations I had 

 about 150 correspondents. The general results of the observations were 

 as follows : — 



Out of 2,010 postcards which were distributed between November 15, 

 1887, and May 6, 1888, a period of nearly six months, 103 observers 

 sent in 496 records. Thirty-one observers, 14 of whom lived on the high 

 ground, and 17 lived on the low ground, although it seems impossible 

 that they should not have felt at least one of the 69 shocks recorded, 

 did not return a single card. 



The balance of unused cards amongst actual observers up to May 5 

 was 1,064. Many of these since that date have been returned, but they 

 have not been used in the following investigations, inasmuch as other 

 observers had by May 5 exhausted the stock of cards with which they 

 were provided. 



The 496 records were made as follows : — 370 came from 61 observers 

 living on high ground — that is, upon the western and northern side of 

 Tokio ; while 126 records came from 42 observers living on the low ground. 



The average number of records per observer on the high gi-ound was 

 6, while upon the low ground the average was 3. 



The greatest number of earthquakes were therefore observed by 

 residents on the high ground. 



The disturbances which were only felt in Tokio were at least 25 in 

 number. In 8 other cases, as the shock was only recorded by one 

 observer, it is possible that a mistake may have been made in observation. 

 All these earthquakes, with the exception of one which is said to have 

 been felt upon the east side of the city, were only felt upon the hilly hard 

 ground upon the western and north-western side of the city. 



The disturbances which were felt in Tokio, and which ia addition also 

 shook a large tract of country surrounding the city — in some cases the 

 whole coastline for at least 200 miles — were 36 in number. 



