Ai Li-shan
Most collectors
of
Probably to
prevent stamp theft, some chops were used in
Since the chops are on the back of the stamps, it is certainly not identifiable on cover. I suppose it could be used to prevent theft of stamps, but once applied to a cover no one would know.
The earliest one that I have seen is on Scott 1031 the surcharge on Sun Yat-Sen issue of 1950. The illustration is dated July 6, 1950 and is on a pair of stamps. The chop reads “Taiwan Health Department”. Unfortunately, this is the only example I have at the present. Check the back of your used stamps during this period, you might just be lucky and find the complete chop on a block of four.
front of the stamps Health Department Chop
Taiwan Health Department Chop on the reverse