You can measure the distance and direction between 2 dots inside Tokyo, with child calculation of the eye, the map of Tokyo.

摘要

(57) Abstract Objective As for this device, in map of former Tokyo, three circlesBy piling up, distance and direction between 2 dots inside TokyoIt tried to be able to measure with child calculation of the eye without requiring the skill,It is the thing. Constitution As for this device, in map 1 of former Tokyo, the Imperial PalaceCircle in most Nisibata of 2 of the radius 15km which is centered and this circle 2Circle it touches to most Nisibata of 3 of the radius 15km which touches and this circle 3To repeat three circles of circle 4 of ru radius 15km, inside Tokyo 2Distance and direction between the dots, without requiring the skill, child calculation of the eyeSo it is something which it tries to be able to measure.