50 A-rt. 7. — S. Hirayama. 



1 WAS A KI. 



Long. 139° 54' E., Lat. 40° 35' N. 



As one of the permanent observatories belonging to tlie Land 

 Survey Department of the Army, this was established in the year 

 1882 in a small islet very near the town of Ivvasaki. The exact 

 site in the islet is indicated in the map. The first observatory 

 was opened on July 7th, 1892, and the registrations were con- 

 tinued for nearly four years. At the end of this time it was 

 decided to move the observatory about ten metres southwards 

 from the old site, and the registrations were resumed on the first 

 of September, 1896. 



The six series of marigrams obtained from 1902 to 1907 have 

 been completely reduced and their results are gathered in the ac- 

 companying table. 



The highest high-water recorded in the years which we have 

 reduced was 4.52, referred to the zero-point of the instrument, and 

 occurred on December 21, 1907. The lowest low- water recorded 

 was 5.90, referred to the same origin, and occurred on April 22, 

 1605. Thus the extreme range is 1.38 metres. 



The height of the mean sea-level, referred to the zero-point 

 of the instrument, is obtained as follows for each year-series: — 



1902 5.235 



1903 5.218 



1904 5.193 



1905 5.203 



1906 5.218 



1907 5.230 



