Faraday to William Crane Wilkins   13 October 1862

Royal Institution | 13 Octr. 1862

Dear Sir

I have received the tracing but it does not convey what is wanted by the Trinity house; without which they will be unable to verify the adjustment of the different parts of the apparatus when erected. The data required are

The distance of the burner beneath the horizontal focal plane

The quantity by which this distance has been diminished because of the depression of the line proceeding to the sea horizon

The proposed inclination of the lenses i.e the angle of a line to the sea horizon with a line to the true horizon or dead level

The distance of the focal point or points above the burner or aside from its axis in relation to the sea horizon.

- for the lens part of the apparatus

- for the upper reflectors

- for the lower reflectors

I write to you of course as the person representing the manufacturer though I am very glad to see M. Sautters hand writing¹ to whom present my best compliments[.]

Very Truly Yours | M. Faraday

Wilkins Esqr