One of his maps was mentioned in an 1876 letter entitled "Concerning Matsushma 2," which was written by Watanabe Kouki (渡辺洪基), the Director of the Bureau of Documents in Japan's Ministry of Foreign Affairs at the time. In the letter, Mr. Watanabe said that Toda Takayoshi's survey map showed the circumference of "Takeshima" (Ulleungdo) to be about 23 ri, a measure that was calculated by adding up all the measurements of the ins and outs of the shoreline on the map. The reference to the map was as follows:
又戶田敬義ノ圖私船ノ測量ヲ總計スレハ二十三里餘トナル[尤曲屈出入ヲ合セ沿岸]I posting the map to give people an opportunity to look at it and to comment on it. I will modify the post later after reading the comments and studying the map myself, including trying to determine the circumference of the island. It looks like an interesting map. You can go to the source of the map at Mr. Tanaka's Web site HERE to find a much larger version.
Also, if you calculate all the survey measurements on Toda Takayoshi's private ship survey map, they add up to about 23 ri. (That measure includes all the ins and outs of the shoreline.)
I wonder what happened to Mr. Toda Takayoshi's third map of Ulleungdo.