The mail/supplies in the bucket trick goes back farther than that. IIRC the
"bucket trick" was the inspiration for the AC-47 development for holding the
fire on the target in a steep banked turn.

In addition to the Amazon, the technique was used by missionaries in Borneo,
both sometime in the late twenties or early thirties.

Oxmoron1
Don't ask me where I read it,but it was a long time ago.