Data Reconstruction of the Gore-shaped Global Map Drawn by Astronomer Harumi Shibukawa in 1670 and His Early Knowledge of World Geography

Abstract

Harumi Shibukawa (1639-1715), the first Shogunal astronomer who succeeded in the Jokyo calendar reform of 1684, is well known for his various astronomical achievements. Among other things Shibukawa drew a gore-shaped global map in 1670 probably with intent to construct a terrestrial globe; it is unknown whether or not he could actually complete it. The map has long been regarded as a product based largely upon the Chinese world map Kunyu Wanguo Quantu (Earthly World Map) published in 1602 in Beijing by the Jesuit missionary Matteo Ricci. A German diplomat then in Japan published an article regarding this Shibukawa's map as early as in 1873, including German translation of all the descriptions in it, and a Japanese historian discovered and photographed in 1911 a replica of the map made by the German diplomat, at a museum in Leipzig, Germany. Until now, however, due to poor resolution of the photographic prints, one could not read in detail the explanatory sentences abundantly written in the map.

 In 2019 I happened to find out some new prints of the map with a high resolution and could decipher almost all the written characters in it. The primary purpose of this paper is to report all the reproduced sentences consisting of 184 items, and thereby to pursue Shibukawa's new aspect as a geographer.

 This paper demonstrates that, contrary to the belief by the past researchers, Shibukawa took a considerable number of the above explanatory items from unknown materials other than Ricci's map. Oversea city names written in the map suggest that he widely utilized geographical and trade books, documents, and information brought about by European and Chinese people. Analysis of the nautical distance list to major foreign ports given in the map, in particular, indicates that Shibukawa was allowed to refer to the official reports prepared by the Nagasaki magistrate for the Shogunal government. These facts show that he was not only the first eminent astronomer but also the most talented worldwide geographer of the pre-modern times in Japan. I hope that the materials reported in this paper will help encourage further investigations of Shibukawa's forgotten greatness as a geographer.