地学雑誌
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
論説
伊能忠敬の求めた1度あたり子午線長と測量の不確かさ
─測地度説のデータに基づいて─
海津 優
著者情報
ジャーナル フリー

2020 年 129 巻 2 号 p. 275-283

詳細
抄録

 In 1880, Inoh Tadataka surveyed the meridian arc length corresponding to one degree of latitude difference. A record of calculations is contained in a handwritten manuscript titled “Sokuchidosetsu” or “On Meridian Arc Length Corresponding to One Degree.” The uncertainty of latitude for a short arc is dominant and is estimated to be about 0.42 minutes. This uncertainty is in accord with the rounding latitude at half a minute in many documents that refer to Inoh's work on coordinates. Some points were used for astronomical observations of latitude in two successive years. A comparison of those results suggests some bias in the results and a standard deviation around the mean of about 1.3 minutes. This is obviously much more than the uncertainty estimated from the scatter of one degree meridian arc length against the N–S component of a great circle connecting the ends of a route. Data sets of astronomical latitude observations surveyed independently help clarify the uncertainty associated with Inoh's latitude observations obtained from field surveys. The scatter of distance and latitude difference data around the linear trend suggests that the uncertainty of the N–S distance is about 7.3/10,000.

著者関連情報
© 2020 公益社団法人 東京地学協会
前の記事 次の記事
feedback
Top