It is probably to play some 12 volt accessory such as a tape deck or CB
radio.
Subject: Re: IML: Gadget for the Day
> Hi
>
> My 1955, which is pretty much an original car has no such device. If there
> is no 12 volt equipment, ie battery, maybe it was used to allow jumping
from
> a 12 volt without frying the car, God knows they needed planty of jumping.