9:30 AM - 9:45 AM
[SEM17-03] Analyzing the early 19th century’s geomagnrtic declination in Japan from Tadataka Inoh’s Santou-Houi-Ki The 12th report
Keywords:geomagnetic declination, Tadataka Inoh, national treasure "Santou-Houi-Ki", survey reference point, survey target point, interdisciplinary simultaneous anaysis of literature and science
I restarted the analysis in 1999,by interdisciplinary simultaneous analysis across geomagnetism,land survey science,historical cartography and local history, after stopped only one analysis in 1917 byProffesor Ryoukichi Ohtani Kyoto University, done about the magnetic compass survey azimuth data at known position of the retirement home Tadataka Inoh at Fukagawa in Edo (Tokyo) in 1802-1803. (1) Interdisciplinary simultaneous analysis: We can increase precise evidence to verify the real azimuth, geomagnetic declinationand the reference point where magnetic compass survey was excuted, or survey target points recoded Santou-Houi-Ki,than traditional way of study separated in each field. (2) Procedure of analysis: Use the recreation software of scenery and digital map of GSI Japan Chiriin Chizu to know the latitude and longitude accuracy sec of particular survey targets,and the ouline position of survey reference point to grasp the outline of each real azimuth from the the survey reference point to survey target points. Geomagnetic declination =Real azimuth-Magnetic compas survey azimuth recorded in Santou-Houi-Ki.Calcurate backward the precise position of the survey reference point should be adjusted to the position in acucracy 0.001 sec,in latitude and longitude,where all of geomagnetic declination unit of 0.001 sec. Calcurate from the magnetic compass survey azimuth to each different survey target points at the reference point are approximately equal to each other. Calcurate the average value of each declination unit of 0.001 sec ,and express it as the geomagnetic unit of 1 min,on the day and the refrernce point Tadataka Inoh's magnetic compass survey was excuted. To develop consecutive formula of Excell for speed up and keep accuracy. If it possible to go to the field of the survey reference point,confirm the real scenery and the longitude and latutude by GPS transmitter and rrecalculate the value of geomagnetic declination. (3)The outline of isogonic line in Japanese archipelago and the distribution of the declination in every 15 min in western Japan coast in those days are begin to appear. Compare the isogonic line of declination in those year's Japanese archipelago by analysis of Santou-Houi-Ki.with the Historical declination viewer by NOAA(1800,1805,1810,1815) is the NOAA's pace of variation West is almost 5 years later than the analysis from Santou-Houi-Ki in western Japan. (4)However,from the analysis of Santou-Houi-Ki,we can recognise the magnetic declination supposed as the local geomagnetic declination anomaly in southern coast of eastern Hokkaido,some part of Noto Peninsular, Mt Asama in Ise,NobeoKa city in Kyushu,etc. and revealed in the long western coast of Tsushima island etc.,it impossible to drew in historical declination viewer by NOAA. The analysis is developed from the coast area of Japanese archipelago to the inland area of Honshuu island. (5) It is able to restore the precise position of survey reference points where Tadataka Inoh's magnetic compass survey was excuted the accuracy of less than sec in latitude and longitude,valuable in local history.
It is so accurate as impossible to achieve by other way of study. (6) Itis able to change Japan as the concentrated area of data in erly 19th Century from insufficient area of data and supply data to north
east Asia. Total number of analyzed points exceeded 207. (7) We started the discussion to compile those analysis to the data base available toJapan Archeo-magnetism Data Base, or NOAA's Historical Declination Viewer.