Trinity House had carried out an extensive testing and selection process over five years and included comparison with oil lights and examination of equipment in Britain and France.

The 800,000 candle power light was generated using carbon arcs and not an incandescent light bulb, and could be seen for up to 26 miles.
The optics were designed and built by James Chance in 1870.
The main lens array consisted of a third-order fixed catadioptric optic surrounded by a revolving assembly of eight vertical condensing-prisms which produced one flash every minute.

In addition to the main light a red/white sector light shone from a window in the tower below the lantern, to highlight hazardous rocks to the south; it was powered using light diverted (through a set of mirrors and lenses) from the landward side of the main arc lamp.

Carbon arc lights for lighthouses were pioneered by Professor Frederick Hale Holmes with experiments in (1857-60) at Blackwell and South Foreland Lighthouse off the Kent coast (described in a lecture  by Michael Faraday at the Royal Institution) and a test installation at Dungeness in 1862 and complete installation at Souter in 1870.
 Electricity  was provided by two of Holmes' own magneto electric generators for which he took out a series of patents during those years.
One of the Holmes generators built in 1867 and used at Souter is now on display at the Science Museum, London.
The generators were driven by one of a pair of 3 hp steam engines, located in the engine-house, which also drove an air-pump to feed the pressure tank of a foghorn. (
The engines were worked alternately: one week on, one week off.)
Trinity House had carried out an extensive testing and selection process over five years and included comparison with oil lights and examination of equipment in Britain and France.
The 800,000 candle power light was generated using carbon arcs and not an incandescent light bulb, and could be seen for up to 26 miles. The optics were designed and built by James Chance in 1870. The main lens array consisted of a third-order fixed catadioptric optic surrounded by a revolving assembly of eight vertical condensing-prisms which produced one flash every minute.
In addition to the main light a red/white sector light shone from a window in the tower below the lantern, to highlight hazardous rocks to the south; it was powered using light diverted (through a set of mirrors and lenses) from the landward side of the main arc lamp.
Carbon arc lights for lighthouses were pioneered by Professor Frederick Hale Holmes with experiments in (1857-60) at Blackwell and South Foreland Lighthouse off the Kent coast (described in a lecture  by Michael Faraday at the Royal Institution) and a test installation at Dungeness in 1862 and complete installation at Souter in 1870.  Electricity  was provided by two of Holmes' own magneto electric generators for which he took out a series of patents during those years. One of the Holmes generators built in 1867 and used at Souter is now on display at the Science Museum, London. The generators were driven by one of a pair of 3 hp steam engines, located in the engine-house, which also drove an air-pump to feed the pressure tank of a foghorn. (The engines were worked alternately: one week on, one week off.)
Souter Lighthouse