Initial Research

I have done a lot of research into the history and evolution of lighthouses through the years, starting with ancient times.

A lighthouse is a structure (most usually a tower of sorts) which is designed to emit light from a system of lamps and lenses to be used as a navigational aid for maritime pilots at sea or on inland waterways. Lighthouses mark dangerous coastlines, hazardous shoals, reefs, safe entries to harbours and can sometimes even assist in aerial navigation.

Ancient Lighthouses

Before the developments of ports, mariners would be guided by fires on hilltops, and since raising the fires would improve visibility, placing the fires on a platform became a practise that led to the development of the lighthouse. In these earlier times, lighthouses would function more as an entrance marker to ports rather than warning signals. The most famous lighthouse from ancient times is the Lighthouse of Alexandria (or the Pharos of Alexandria), this was between 393 and 450 ft tall (being one of the tallest man-made structures for many centuries.) and was located in the city of Pharos, Alexandria, Egypt. 

Modern construction

The modern era of lighthouses began at the turn of the 18^th century, as transatlantic commerce became more and more used. Advances in structural engineering and new and efficient lighting equipment allowed for the creation of larger and more powerful lighthouses, including ones exposed to the sea. Lighthouses were also beginning to be used to provide a visible warning against shipping hazards, such as rocks or reefs.

The Eddystone Rocks were a major shipwreck hazard for mariners sailing through the English Channel, the first lighthouse built there, in 1698 by Henry Winstanley, was an octagonal wooden structure, anchored by 12 iron stanchions secured in the rock. This was the first tower in the world to have been fully exposed to the open sea.

Advancements in Design

The civil engineer, John Smeaton, rebuilt the lighthouse from 1756-59, his tower marked a major step forwards in the design of lighthouses and remained in use until 1877, he modelled the shape of his lighthouse on that of an oak tree, using granite blocks. He also pioneered the use of “hydronic lime” which is a form of concrete that sets underwater, and developed a technique of securing the granite blocks together using dovetail joints and marble dowels, which served to improve the structural stability greatly. Smeaton also had to taper the thickness of the tower towards the top, to do this he curved the tower inwards on a very gentle gradient, this brought an advantage of allowing some of the energy of the waves to dissipate upon impact with the walls. This lighthouse was also the prototype for modern lighthouses, and therefore influenced all subsequent engineers.

One influence of this was Robert Stevenson, who created the Bell Rock Lighthouse in 1810, which was one of the most impressive engineering feats of that age. This structure was based upon Smeatons initial design, but also featured several improved features including rotating lights, which alternated between red and white.

The source of illumination for lighthouses had generally been wood pyes or burning coal, this was until Swiss scientist Aimé Argand invented the Argand lamp in 1782, revolutionising lighthouse illumination with its steady smokeless flame. Early models used ground glass which was sometimes tinted around the wick, while later models used a mantle of thorium dioxide suspended over the flame which created a bright and steady light.

South Foreland Lighthouse was the first tower to successfully use an electric light in 1875, but this did not become the generally used light source until the 1960’s, as the vaporized oil burner was much more widely available, and then the Dalén Light was developed in the 1900’s, this was the predominant form of lighting for this time. This light used Agasmassan, a substrate, to absorb the gas allowing safe storage, and hence commercial exploitation. Dalén also invented the “sun valve”, which automatically regulated and turned it off in the daytime. In the 1960’s, electric lighting had become completely dominant, and therefore was used in all lighthouses.