The 'Vacuum Cap' invented by Edward J Artis

I've had a number of Airstreams with these caps installed. Some have been rusty tin, others like this one made from Aluminium Alloy.

Once I get a clue then it's pretty simple to find a bit of the history. In this case the Pat. number was all I needed.

I considered this to look art deco, and indeed it is

 

More of his inventions can be found by clicking here.