Warren De La Rue to Faraday   26 April 1861

110 Bunhill Row | E.C. | April 26 1861

My dear Faraday

You will think at last that I am boreing [sic] you with letters. I wrote you one last night¹ or rather this morning at 1o clock after I had been chasing round Saturn’s satellites which I suspect are greater in number by three than those known.

Some particulars I could not supply not having all my papers at home.

They are as follows:

Greenwich mean Time min sec

The duration being 3 .25

<->

I think that when you asked me yesterday about the meaning of a certain shaded portion on each side of the central line of Vignolles’² map³ and certain other lines parallel to the shaded zone I did not quite understand your question and hence could not have given you the fitting answer on thinking over your question I am able to answer more to the purpose.

The central zone (shaded) includes all those parts of Spain where the duration of the total eclipse was three minutes and this being a long time and only 35 seconds less than the longest duration in any part of Spain it was made prominent so that intending observers might place themselves here & there in any position convenient to themselves; it being desirable however that they should spread themselves as much as possible.

The lines parallel to most favorable zone indicates still where the Eclipse⁴ was total from the position where there was simple contact only (and duration 0) to other positions where the duration was that indicated on the particular parallel to the central line.

Yours Very sincerely | Warren de la Rue