Details For Cover ID# 29418

2c green on white postal entire (U305, scarcer die type) with 1890 5c chocolate Small Bank Note (223) tied by "San Francisco, Cal. Dec 10, 91" duplex postmark, to Honolulu, Hawaiian Islands. Underpaid letter, "40/CTMS/T" postage due marking probably applied in San Francisco, which is 40 French gold centimes = 8 Hawaiian cents. "Honolulu, H.I. Dec 17 1891" backstamp.

Hawaii was a member of the UPU from 1882 to 1900, when annexed by the U.S.  Unpaid or underpaid letters were forwarded to their destination under UPU rules. However, the recipient was charged double the deficient postage as a penalty. In this case the letter was probably double rate, requiring 10c postage, hence 3c short (note the manuscript "3" marking at left). Double the 3c deficiency = 6c Hawaiian due. 5 French gold centimes = 1c, so this letter should have been marked 30 centimes due. It is not known why it was marked 40 centimes due instead.