Q: Where does light come from?
Light sources are generally created by the combustion of different types of fuel. For example, fuels can be:
solid: coal or wood;
liquid: oils: animal oils such as sperm whale oil; vegetable oils such as linseed, rapeseed; mineral oils such as paraffin;
gas: vapourised oil or acetylene.
In the early days of lighthouse history, the most important property of a light source was for it to be continuous and uninterrupted over a period of time, that is, the light must not go out through lack of fuel or inefficient activities by the keepers, and there must be no obscuration because of smoke or dirty equipment. The keepers were kept very busy during their period of duty, ensuring a constant supply of fuel to the light and keeping everything clean and in good working order. As we shall see below, another aspect of a lighthouse is to keep the optic rotating and this required a constant, period winding up of the clockwork mechanisms that performed this task. Today, with automatic systems, modern electronic perform all the control functions for the light source.