LIGHTS & THE FRESNEL LENS - CIBSE Heritage Group_the... · Augustin-Jean Fresnel 1788-1827 Fresnel...
Transcript of LIGHTS & THE FRESNEL LENS - CIBSE Heritage Group_the... · Augustin-Jean Fresnel 1788-1827 Fresnel...
LIGHTS & THE FRESNEL LENS
These postage stamps show the different lights used over nearly three
centuries by the Alderney lighthouse and are typical of many other
lighthouses. From the left:
1725 coal fire
1779 oil lantern
1790 Argand lamp
(Oil lamp with tank and tin cylinder over the flames)
1818 a revolving apparatus
1952 electrification
While this Danish stamp of 1960 illustrates a 16th
century “swinging fire
which was hoisted to high level by a lever arm. In England the device was
called a swape.
Augustin-Jean Fresnel 1788-1827
Fresnel was a French physicist who made significant contributions to the
theory of wave optics. He invented the Fresnel lens which was widely
adopted for use in lighthouses. In 1819 he became Commissioner of
Lighthouses. In 1823 he was elected a member of the Academie des
Sciences in Paris. In 1825 he became a member of the Royal Society of
London and in 1827 they awarded him the Rumford Medal. Fresnel died of
tuberculosis at the age of 39.
The idea of a thin light lens in separate sections is often attributed to Georges-
Louis Leclerc, Comte de Buffon.
(Lighthouses, F Ross Holland, 1995)
An oil lamp and Fresnel lens combination
The Fresnel lens (terrypepper.com)
Example of six orders of Fresnel lenses (michiganlights.com)
A first order Fresnel lens originally used at Cape Canaveral
2nd order Fresnel lens
By comparison, a 6th
order Fresnel lens
A Fresnel lens and light source
The electric light at the South Foreland lighthouse was provided by a
steam-driven magneto-electric generator (The Graphic, 3 February 1872).
The generator was developed by Professor Frederick Hale Holmes.
The first electrically lit light was at the South Foreland lighthouse in
December 1858. The candle-power was over 1500 and the light source was of
manageable size for optic control of the beam. It was only an experimental
installation and it was not until 6th
June 1862 that the apparatus was in
service in its final form. In France, M. Reynaud was responsible for the arc-
lights at La Heve in the last days of 1863. They were a combination of the
Serrin Arc lamp and the magneto-electric machines of Nollet. The French
light was steadier than that of Holmes and many of its features, including the
use of alternating current, were adopted in later British installations.
(Lighthouses, Patrick Beaver, 1971)
Exhibit of the US Lighthouse Board at the Chicago’s World Fair, 1892-93,
included (on the right) a 1st Order Fresnel lens (Holland)