On the back
1.75F + 1.25F + 1.00F +10c +10c = 4.20 F
But the UPU registered rate = 3.50 F
The Puzzle: On first glance, this appears to be a souvenir cover sent by the PTT to Japan on December 19, 1936, with a four-color franking of the 1936 FIP Congress commemoratives. But since the four stamps overpay the 3.50F UPU registered rate by 60c, why was a second 10c stamp affixed to the back of the cover, resulting in a total overpayment of 70c? And why was the stamp on the back canceled one hour later than the stamps on the front and with a different device? Strange stuff!
Mysteries like this confuse, confound, and annoy postal historians. Was the cover overweight? (No, an additional 20g would have cost one franc.) Was a return receipt requested but not indicated? (No, the receipt would have cost 1.75F.)
The solution: The cover enclosure, happily still in the envelope, is a receipt for stamps purchased by the Japanese sender. It explains the 4.20F (over)franking.
The sender paid for the stamps he ordered with 20 International Reply Coupons, each worth 1.75 LFr, for a total payment of 35 Luxembourg francs. Thus, the following arithmetic:
|Diverse timbres|| |
|Montrant le 20 coupons |
réponse @ 1.75 F
The PTT rounded up the 3.50F UPU rate to 4.20F, thereby using up the remaining 70c of value of the 20 IRCs after taking into account the stamps purchased and the shipping charge. Unlike modern philatelic agencies, the PTT preserved the souvenir value of a four-color cover by placing the second 10c denomination on the back, where it was apparently later noticed and cancelled en route to the cover being dispatched to Japan.