The hat fastener actually works quite well.

Not because I know he invented it, or anything of the like. More that a paperclip & upside-down comb taped to the inside of a hat was a trick we used in media.

Apparently it got patented in the US [0]... Which probably means the patent is still valid. (Incidentally, going through those that reference it, you can see patent-files' transition from mostly-technical to mostly-legal.)

[0] https://www.google.com/patents/US715600

Valid, perhaps. No longer enforceable. The typical patent expires after 20 years.

My understanding was that the bullets that were successful against WWI Zeppelin raids were the incendiary Buckingham round not the explosive rounds. Explosive rounds refused to detonate on the canvas hull. And if you manged to hit an internal girder it was too deep inside to be near sufficient oxygen.

As I recall, the successful bullet was filled with phosphorus and had a small hole that was re-opened as it ran down the barrel when fired. Thus it spewed flame along its whole flight and as it penetrated the Zeppelin hull where hydrogen and oxygen where a good ratio.

But as I can find no citation, I must take my own memory with a grain of salt.

It's surprising that firing a chunk of dynamite from a rifle consistently won't detonate it, but it detonates when it hits the target. I think I'd be very nervous firing those from a machine gun the first time.

I know how you all feel about clickbait titles but this one's charming and we're leaving it.