LOL! - Tubes, really?
It works exactly because it cannot move with the earth.
The Earth jiggles and wobbles, and the inertia of the coil is forced to cut magnetic lines of force.
A small sealed battery, a large coil, and preferably a bridge rectifyer, and a small light bulb, all in series will work, but refinements can be made to make it work better with one extra diode to place the bulb across the leads of the coil.
The tubes part was a joke.
Do you have a schematic? I’ll breadboard it this weekend, I no doubt have all the parts already and I’ll let you know its performance.
I should be able to leave it in my office and just let it light the bulb, while at the same time have the exact same type and voltage battery hooked up to the exact same light (with just the battery and light) to form a control. If the circuit you provide lasts longer than the control, it works. Hopefully both lights will burn at the same brightness.