Hey, history lovers. I'm Mike Rosenwald with Retropod, a show about the past, rediscovered.

May 1918 was an exciting time to be alive. I mean, it's no 2018 when food is being delivered by

drone in some parts of the world. Then again, drones weren't around back then.

But the U.S. mail was, and by golly, it was about to be delivered by airplane for the very first time.

A letter from Washington, D.C. would be able to reach Philadelphia in an hour and a half.

How about that? Well, it was also an exciting time for a stamp collector

named William Roby. As thousands of people planned to watch the first flight leave Washington,

Roby, a stockbroker's clerk, went to the post office instead. The post office had released a special edition stamp

to commemorate the first airmail delivery.

It was an elegant red and blue stamp

and bore an image of the biplane

that would be used on the Washington flight.

The plane was called a Curtis JN4H, also known as a Jenny.

Roby asked the clerk for a sheet of the new 24-cent stamps. The clerk reached under the counter

and pulled out a sheet of 100. And when Roby saw it, his heart stood still.

The airplanes on this particular sheet of stamps had been printed upside down.

It was a stamp collector's dream.

Collectors were always on the alert back then for new stamps that would be printed in two colors, because multicolored stamps had to be run twice through the hand presses at the U.S. Bureau of Engraving and Printing. That increased the odds of a mistake happening. The rare sheet of inverted designs were worth a lot more

than stamps printed correctly, that's for sure. Robey quickly paid for the sheet and then asked the

clerk if he had any more. The clerk brought out three more sheets, but the Jenny was printed

correctly on those.

Roby asked for more stamps like the ones he'd already bought.

...