Interesting cover!
Based on the commemorative cancels, it's a cover probably mailed from the National Taiwan Museum. The dating of the cancels in relation to the stamp will need some explaining, but from a postal perspective the mailing was sent at the domestic express mail rate on June 9, 1987. The domestic express mail receipt shows the weight and postage.
Regarding the dates, this is a bit tricky. The NT$14 stamp is from the June 9, 1981 set commemorating the centenary of railroad service in China. And yet you will notice the commemorative cancel seems to note the 100th anniversary dated 1987.
The 1981 date (postage stamp) is for the centenary of the first official railway built in China (mainland) in 1881. The 1987 date (commemorative cancel) is for the centenary of the first official railway built in Taiwan (island) in 1887. I will assume that there was a special exhibition at the museum at that time, hence the commemorative cancel, likely only provided at the post office inside the National Taiwan Museum.
EDIT --
Obviously, the post office had a stockpile of the 1981 set remaining. It's a nice touch. At that time, they had a time limit on validity of commemorative stamps, after which they would automatically be de-monetized. Back then, I thought I was told it was something like 5 years, but I was either told wrong, or remembered wrong, or the post office made an exception, or they simply ignored their rule.
re: Taiwan cover with various cancels
Interesting cover!
Based on the commemorative cancels, it's a cover probably mailed from the National Taiwan Museum. The dating of the cancels in relation to the stamp will need some explaining, but from a postal perspective the mailing was sent at the domestic express mail rate on June 9, 1987. The domestic express mail receipt shows the weight and postage.
Regarding the dates, this is a bit tricky. The NT$14 stamp is from the June 9, 1981 set commemorating the centenary of railroad service in China. And yet you will notice the commemorative cancel seems to note the 100th anniversary dated 1987.
The 1981 date (postage stamp) is for the centenary of the first official railway built in China (mainland) in 1881. The 1987 date (commemorative cancel) is for the centenary of the first official railway built in Taiwan (island) in 1887. I will assume that there was a special exhibition at the museum at that time, hence the commemorative cancel, likely only provided at the post office inside the National Taiwan Museum.
EDIT --
Obviously, the post office had a stockpile of the 1981 set remaining. It's a nice touch. At that time, they had a time limit on validity of commemorative stamps, after which they would automatically be de-monetized. Back then, I thought I was told it was something like 5 years, but I was either told wrong, or remembered wrong, or the post office made an exception, or they simply ignored their rule.