ON THE EARTHQUAKE AND VOLCANIC PHENOMENA OF JAPAN. 297 



direction about N. 60 E. At my own home the range of motion was 

 folly 12 millimetres, and the direction of motion was between N.N.E. and 

 N.E. At the Meteorological Observatory the range of motion was 20 

 millimetres with a period of 2*2 seconds. The period of vibration recorded 

 by Professor Sekiya was ID second. From these quantities it appears 

 that the least maximum velocity was 165 millimetres, whilst the maximum 

 acceleration per second per second was 546 millimetres. 



At the Imperial Observatory these quantities wei-e respectively 29 and 

 83 millimetres. For two minutes the motion was severe, and Professor 

 Sekiya's instruments recorded a continuous motion for 8 minutes 6 

 seconds. The greatest vertical motion was 1'4 millimetre, and it was 

 simultaneous with the greatest horizontal motion. Its period was one 

 second. Between the time of occurrence of the first shock and 10 A.M. 

 there were four minor disturbances. 



In Yokohama, which is sixteen miles distant from Tokio, and which 

 in all probability is sixteen miles nearer to the origin of the shock than 

 Tokio, several buildings sustained injury. A number of chimneys were 

 overthrown, several were turned ; on several roofs tiles were shaken up 

 and dislodged, while several walls were cracked and fractured. There are 

 no records from seismographs with which this damage may be compared, 

 but from previous observations made in Yokohama and Tokio, I am of 

 opinion that the maximum acceleration experienced in Yokohama was 

 almost 100 or more millimetres per second per second. Reports were ob- 

 tained from many towns in the country ; but although the shock was 

 severe no damage occurred. 



To compare this earthquake with others relatively to the effects they 

 have produced on buildings, the following two records from seismographs 

 placed in Tokio are reproduced. 



On January 15, 1887, an earthquake occurred which had a maximum 

 acceleration of 66 millimetres per second per second in soft ground, and 

 36 millimetres per second per second on hard ground. In Tokio a few 

 brick walls were slightly cracked ; bat in Yokohama, which was about ten 

 miles from the origin, it destroyed several chimneys and slightly shat- 

 tered a few buildings. 



On February 22, 1880, an earthquake occurred, when in Tokio several 

 chimneys fell, and here and there tiles were dislodged, and a few walls were 

 cracked. In Yokohama the destruction was considerable ; windows were 

 broken, grave-stones rotated, chimneys were overturned, and several 

 homes were unroofed. In Tokio it seems that the acceleration was about 

 90 or 100 millimetres per second per second. 



In connection with the earthquake of February 18, I may mention 

 that I was called upon to join in an official inspection of several public 

 buildings. One building inspected, which is probably the largest brick 

 building in Tokio, rises with free sides from a basement. In this 

 building there was no damage whatever. Another heavy brick building 

 very near to this, which rises from ordinary foundations, and without a 

 free area, showed cracks in almost every room. 



On the Distribution of Earthquake Motion in a small Area. 



In the report of last year it was mentioned that experiments had been 

 commenced to approximately determine how far earthquakes were felt in 

 different parts of Tokio. To do this I distributed through the city of 



