Yesterday in Mekeel's: Viewing the Jennings "Half" Collection.

The bottom cover was described as "caught by alert postal employee, returned to sender (address on back) for postage due of .01-1/2 to make .02 first class rate, credit given for only one of the half-cent stamps." Top shows former .01 third class envelope uprated to new .01-1/2 rate, no date in cancel required. Alton postmaster on instructions from D.C., held each one for 1/2 cent due, but not having new postage due half-cent used his regular half-cent stock.". [Extracted from the article]