Tallow candles made from animal fat in moulds were the cheapest but they burnt with a smoky flame which produced progressively less and less light - and they stank.
Spermaceti wax, made from whale oil, was harder than either beeswax or tallow and was least likely to soften in hot weather.
An understanding of what these changes were and when they occurred provides a valuable tool for dating early electric lamps.
This discussion will gloss over internal modifications and focus on the external appearance, as this aspect is the most useful for on-the-spot assessments.
Although Edison invented the first functional electric light bulb in 1879, more than 20 years would pass before his revolutionary device was practical enough to be embraced by the mass consuming public.
In fact, early electrical systems were exorbitantly expensive to install and to maintain, as well as subject to frustrating service interruptions and frightening power surges.
Financial backing was provided by the Deutsche Bank.
Three types of candle were commonly used at the start of the period; tallow, spermaceti and beeswax.Interior fittings included chandeliers (suspended from the ceiling) and sconces (fixed to the wall).However these were mainly used on special occasions, and most ordinary events after sunset took place using portable light sources such as candlesticks, candelabra (bracketed candlesticks) and oil lamps, and by the light of the fire.Edison acquired a controlling interest in September 1908. Mack in 1912, and the company went into receivership shortly afterwards.In 1913 the company moved its plant to Allentown, Pennsylvania, and combined with the Mack Truck Company and the Webb Fire Engine Company. Edison began litigation in July, alleging patent infringement, and a settlement agreement was signed in November 1904.