The World Map on Bokusen's Terrestrial Portable Globe

Abstract

Numajiri Bokusen invented an epochal terrestrial globe made from wood, bamboo nd Japanese paper in 1800 and published details of it in 1855. The globe was similar to a coarse Japanese oilpaper umbrella, and in fact was called the “umberlla-like globe” later. Previously, the author has described the form of this globe.
The present paper describes the geometrical features of Bokusen's globe, especially, the shapes of shorelines and national boundaries. The world map on the 1855 globe had obviously been revised since that appearing on the globe invented in 1800, based on the latest information on the shorelines available at the time.
Since the Japan Archipelago was set in the center of the world, the axis of the globe was declined at 36 degrees. Therefore, the ground level sinusoidally rounds the globe according to its declination.
Lines of latitude were shown every 10 degrees. The interval of the lines of longitude was also 10 degrees. While the value of latitude was written, that of longitude was not shown anywhere on the globe. Between the lines of longitude, marks were inserted every one degree along the equator, resembling the symbol used for railways in recent maps.
Despite the lack of a base for the median line of the globe, the base was expected to pass through Ferro Island in the Canary Islands. Thus, it is assumed that values were intended to be written every 10 degrees according to the distance from the Island. The location of the Japan Archipelago at the center, and the declination of the earth's axis seem to have been important political matters influenced by attitudes such as reverence for the Emperor and exclusion of foreigners during the late Edo period in Japan.
On this globe, the center of the Japan Archipelago was intended to be just under the zenith, and set at 130°(actual value 132° in recent maps) E and 36 N. This location was selected as the place nearest to Miyako (Kyoto), which is placed at 135°46'E and 35°00'N. On the other hand, Edo is at 139°40'E and 35°42'N (almost equal to 36 degrees) based on values in recent maps. Therefore, the base of latitude at the center of the 1855 map seems to have been unchanged since that on the 1800 globe. If Bokusen used the value of Miyako, the inclination of the earth's axis was set at 35 degrees.
On the other hand, the base of longitude was altered to a new location near Miyako. Ne-vertheless, Bokusen could not help including some of the base of the median line of the world maps established in the western Europe. Thus, the center was not set in Miyako, but was moved to the west.
Some compass lines drawn from the center were made on assumptions, and some remarks about astronomical phenomena such as sunrise and sunset at the winter/summer solstices and the vernal/autumnal equinoxes were written on these lines and assumed lines.
Most of the shapes of the shorelines closely resembled those on recent maps. Although the Australian continent was correctly shaped, the Antarctic continent was not shown. In the Arctic region, the shape of the northern coast of the Eurasian continent was relatively correct compared with that of the North American continent. Especially, the areas in the vicinity of Hudson's Bay and the District of Franklin were obscure, and their shapes were expressed using broken lines. This seems to reflect Bokusen's scientific standpoint, which excluded any uncertainty.
Between 80°N and 80°S, the coast lines including Korea and the California Peninsula and other continents were correctly shown. On the other hand, the shapes of national boundaries of inland areas were drawn as rough lines framed by colors including blue, red, violet, yellow and black. Some of the shapes appear to be scribbled. Therefore, the decisions regarding boundaries seem to have been less confident.