How was this pocket ammeter used?

[Sparky]

I came across this ammeter in my father-in-law's tool collection. He got it from his father who had a Model A back in the day.

I did a quick search and found several for sale on eBay, mostly described as an "antique automotive tool." This one is missing a short electrical lead that attaches to the top terminal post.

So did this have a specific use, like checking generator output, or is it a general purpose tool?

 

[Ray64]

I have one just like it and i have the same question ,i do have the wire though

 

[1930artdeco]

I think I have one as well. I will follow this one...

 

[JoeCB]

Looks like a simple series connection via the two (male and female) connections... insert meter in a circuit and read the current draw in Amps. Labeled American Ever-ready... that is the battery company, I believe. Perhaps was originally for battery powered radios or such inthe early days .
Joe B

 

[katy]

Watch polarity. Any polarity markings on it, next to the terminals?