Rotavating the garden yesterday, and apart from the usual bits of broken china, I found a few interesting objects (including a Browning M2 machine gun shell casing), a couple of which I have no idea what they are.

One's large, the others are smaller, but the construction is the same - a ceramic-like outer with a bore containing what looks like a graphite rod. There's a touch of copper corrosion visible of the end of the larger item, and with graphite being a conductor, leads me to believe they are electrical components of some type.

Everything I'm pulling out of the ground is 1940's / 1950's, so assume these are of the same vintage, whatever they are.