Faraday to Peter Henry Berthon   14 March 1862

Royal Institution, 14 March 1862

Sir,

I have received your communication¹ & the copy of Mr Prossers letter of the 3rd instant²[.]

As regards the lime light placed by Mr Prosser in the lighthouse I have nothing to change in my report of the 30 Septr 1861³.

As regards Mr. Prossers two points 1st and 2nd especially the first, I have only to remark that he placed the lamps in the lighthouse for the very purpose of shewing the superiority of the lime light over the oil light - did every thing according to his own wish & desire - and was quite satisfied with the arrangement. If it was not fit for the purpose why was it not? I never heard a word of objection to it during the trial[.]

As to Mr Prossers reference to my statement regarding the lime light he should quote my words & their place for I know of no such statement. I have heard that the lime light employed by Lieut Drummond⁴ in the survey was seen 95 miles off⁵ but I did not see it and believe the lime light was then not under “similar circumstances” to Mr. Prossers lime light or to an oil lamp flame in a reflector. It was I think a single small ball of lime ignited on every side by five oxy hydrogen jets exerting their united power on it:- this small ball being placed accurately in the focus of a reflector⁶[.]

I am Sir | Your Very Obedient Servant | M. Faraday

P.H. Berthon Esqr | &c &c &c