(double click to enlarge)
Here is a map titled "JAPAN UND KOREA", which was published in Leipzig, Germany. I have two versions of the same map, I was told by a mapseller that one was published in 1897 while I was told the other was published in 1894. It seems that it is reasonable to think that the map was first published in 1894 and then it may have been reprinted in later years again, because it didn't include Taiwan (Formosa island) which Japan acquired in 1895 after the Sino-Japanese War.
Anyway, the territories are shown in colour; Japan in red, Korea in yellow, China in orange. Please take a look at the islands in the Sea of Japan (Japanishches Meer) - Ulleungdo is drawn as "Matsu-shima (Dagelet I.)" and Liancourt Rocks as "Liancourt In. (Hornet In.)". These are painted in red - the colour which indicates Japan's territory. Oki island is drawn as "Oki-shima". This map is another circumstantial evidence that Seokdo in the 1900 Ordinance #41 can't be Dokdo (Liancourt Rocks).