Formosa (Taiwan) was incorporated into the Japanese Postal Service after the Sino-Japanese war of 1894/5. Medium Single Circles of varying sizes were used.
 

11Tamsui: Foreign Mail Postcard FC11 (the reply part was used), from Tamsui via Hong Kong to Halle in Germany.  Maruichi in brown, Taiwan type, Amano #104: 30 / 1 / 4 (Jan. 4, 1897) Tamsui Medium Single Circle with Taiwan in brown: 4 JAN 1897 Hong Kong transit Arrival mark: Halle 14. 2. 97 Remark: This Tamsui cancellation is the earliest known type of Taiwan cancels under Japanese postal authority. While all other Taiwan types show Japan combined with either Taiwan or Formosa, this one has Taiwan alone. According to Bishop it has been reported from Tamsui and Anping only. I found one from Takow - see below.

 

11Tamsui2:  Cover with 5 Sen UPU Koban, from Taipei via Tamsui to Amoy.  Domestic Taipei, Daitotei Maruichi cancel (Amano type 104): 30.05.01 Domestic Tamsui Maruichi in brown: 30/05/02 Tamsui Medium Single Circle with Taiwan in violet: 2 MAY 1897 Amoy arrival mark: May 3 97 on backside of cover  This is another example of the a.m. Tamsui cancellation but this time in violet.

11Takow: 10 Sen new Koban Takow Medium Single Circle with Taiwan in violet: 6 May 1898 This cancellation is a recent find. It is not mentioned by John Gordon Bishop.

 

11Tamsui3: 10 Sen new Koban on piece  Tamsui Medium Single Circle with Taiwan, Japan and 4 figure year in violet: 15 JUL 1900

 

11Twatutia: 10 Sen new Koban Twatutia Medium Single Circle with Japan, Taiwan and 4 figure year in black: 8 1900 MAR The year and month line is reversed (year in the middle)

 

11Hobei:  10 Sen new Koban on piece Hobei (Tamsui) Medium Single Circle with Taiwan, Japan and 4 figure year  in violet: 8. MAR 1901

 

11Anping:: 20 Sen new Koban Anping Medium Single Circle with Taiwan, Japan and 4 figure year in violet: 6 NOV 1901 This type of marking had been recorded for Tainan, Taipeh and Twatutia. Is my Anping cancellation unique?

 

11Twatutia2:  20 Sen new Koban Twatutia Medium Single Circle with Taiwan, Japan and 2 figure year in black: 8 FEB 03

 

11Takow2: Postcard with 4 Sen new Koban from Takow via Tamsui and Hong Kong to Geisenheim in Germany. Takow Medium Single Circle with Taiwan, Japan and 2 figure year in violet: 13. 1. 05 Tamsui, Taiwan,  Japan in violet: no date is visible Hong Kong: 25 JA 05 Geisenheim: 24. 2. 05 Mr. Bishop did not mention this cancellation, but Mr. Fisher in his addenda did. His addition mentions the year 05 but without month and day details.