Guillaume Hähner to Faraday   31 May 1854¹

Monsieur le Professeur,

Ayant soumis à Monsieur Herbert, Secretaire de l’honorable Board of Trinity house les avantages de ma méthode d’Illumination des Phares, moyennant la lumière Electrique, et ayant été engagé par le susdit Board de le soumettre à Votre éxamen², j’ai l’honeur de Vous rémettre ci-joint la description du susdit procédé, accompagné d’un dessin de l’Appareil.

J’espère que cette description sera suffisante pour Vous mettre en état de porter un jugement sur ma méthode. J’ai fait construire un petit appareil dont le susdit dessin est une Copie exacte, et qui fonctionne parfaitement et serait presque suffisant pour un petit Phare. Il est à Votre disposition si Vous croyez en avoir besoin.

J’espère avoir l’honneur de Vous faire ma visite au mois de Juillet prochain; en attendant, si Vous aviez des éclaircissemens à me demander ou des Communications à me faire, veuillez me les diriger directement par lettre.

En tout cas, soit que l’invention Vous semble digne d’être prise en consideration, ou non, je compte, Monsieur, sur Votre entière discrétion, parcequ’il me serait d’un grand prejudice si l’invention fut rendu publique avant que j’ai pris les arrangements nécessaires.

Je saisis avec plaisir cette occasion pour Vous éxprimer la haute estime avec laquelle j’ai l’honeur d’être | Monsieur le Professeur | Votre très dévoué et obst. servr. | Guillme. Hähner | Consul de S.M. le Roi de Saxe³

Livourne en Toscane | ce 31 Mai 1854

A Monsieur le Professeur Faraday a Londres

Lighthouse Illumination by Electric Light

Till now no one has succeeded in using Electric light for lighthouses’ illumination, because of the difficulty of obtaining the duration of the light; for it is well known how easily Electric light extinguishes, and what a care it affords to conserve it alighted for some time. This way of Illumination gives a light of great beauty, and is visible at a greater distance than any other artificial light.

Through the following apparatus this Illumination can be obtained in a very favorable way.

Two disks of coke, graphit, or some other similar stuff formed as toothed wheels are fixed strongly on two pegs or pins (pennies) of metal and turn on opposite sides with a very slow movement caused by a watch mechanism[.] In this way the disks move regularly and end their movement in a fixed time. - The two poles of the pile are in communication with the pegs of metal and in consequence with the two disks of coke.

In the movement of rotation the teeth of the disks find themselves in contact with each other, and in removing themselves slowly from the luminous arc which finishes suddenly when they are too far, but then two other points come in contact and renew the same phenom [sic] regularly. This way of illumination instead of being inconvenient presents the advantage of having a perfect eclipse, which is not to be obtained by the ordinary systems. The elements of the Pile could be plunged in sea water, which could serve as exciting liquid.

Explanation of the drawing:

a.b. Toothed Disks of coke

c.c.d. Wheels which move the said Disks of coke

e.e. Metallic bars which communicate with the pins or pegs, on which the disks of coke are fixed.

f.f. Wires or poles of the pile

g. Spirail [sic] which strains the wire

Wm Hähner

Endorsed by Faraday: Received June 6th 1854 | MF

TRANSLATION

Dear Professor,

Having submitted to Mr Herbert, Secretary of the Honourable Board of Trinity House the advantages of my method of lighthouse lighting using electric light, and having been asked by the said Board to submit it to your examination⁴, I have the honour of enclosing the attached description of the said procedure, together with an illustration of the Instrument.

I hope that this description will be sufficient for you to form a judgement on my method. This is an exact copy of the apparatus that I have had built, which works perfectly and would be almost sufficient for a small Lighthouse. It is at your disposal if you think you might need it.

I hope to have the honour to visit you next July; in the meantime, if you would like any further information or would like to write to me, please do so directly by letter.

In any case, should the invention seem to you worthy of consideration or otherwise, I count, Sir, on your complete discretion, since it would prejudice me greatly if the invention became known before I had made the necessary arrangements.

I take this opportunity with pleasure to express to you the high esteem with which I have the honour of being | Professor | Your very devoted and obedient servant | Guillme Hähner | Consul of His Majesty the King of Saxony⁵

Livorno in Tuscany | this 31 May 1854

To Professor Faraday in London