The Order of Secrets
Later known as a capacitor, this device stores energy in an electric field and releases it as a flow of current. These work as primitive batteries early on, using a series of differing dielectrics between two plates of metal and kept inside some sort of box or jar.
Induction Coil Lamp
This device uses a Bunsen cell activated by potassium bichromate, which can be sealed in a watertight rubberized cloth bag. An induction coil transfers the electric current to an evacuated spiral glass lamp containing only nitrogen at low pressure. The current causes the gas to glow with a steady light and very little heat. It provides light to a 50’ area, though this is reduced to 20’ underwater. It lasts for up to 12 hours.
This instrument reads the earth’s magnetic field to find the users position. It’s used with a chronometer for full effect.