The airmail letter rate to France was 15 cents for each quarter ounce. The Canadian post office taxed the letter "90 centimes", which tells us that this was a letter whose weight was greater than one quarter ounce and equal to or less than one half ounce. The correct rate was 30 cents. The French postage due was 135f.
The Karsh Definitives
The Karsh definitives (so-called because the design was based on a photograph by Karsh) were not viewed with much favour by the general public and were replaced in 1954 by the Wilding issue.
Canadian Taxation
T 90 centimes handstamp
Analysis of Canadian taxation
Correct rate 1/2 oz. air mail letter to Europe......................................................30c
Amount prepaid...............................................................................................15
Amount shortpaid............................................................................................15
The tax was double the deficiency
Tax................................................................................................................30c
Conversion to gold centimes
The UPU monetary unit
was a gold standard. The UPU monetary unit was the gold franc of 100
centimes of a weight of 10/31 of a gramme and of a fineness of 0.900.
The gold franc was a notional currency. No country actually minted the
UPU franc. Nations converted their currencies to gold centimes to
calculate postage due in centimes.
1 cent Canadian (c) = 3 gold centimes
30c = 30c X 3 gold centimes/c = 90 gold centimes
French Postage Due
The French post office affixed postage due stamps totaling 135 f.
The conversion factor applied by the French post office to arrive at 135f would have been 30f = 20 gold centimes
90 gold centimes = 90 gold centimes X 30f/20 gold centimes = 135f
90 gold centimes = 90 gold centimes X 30f/20 gold centimes = 135f