Faraday to Thomas Stevenson   25 October 1860

Royal Institution | 25 Octr. 1860

My dear Sir

I hasten to return you my sincere thanks for your kindness in remembering me; and for the data both oil - & photometric¹ -

In photometry I am always puzzled about the standard of light - the eyes of the same person vary so much & so rapidly - and the appreciation varies so greatly with change of colour & difference of intensity - I think Your telescopic apparatus is excellent in its arrangement - but it is only by trial one learns to know the circumstances[.]

Ever My dear Sir | Most Truly Yours | M. Faraday

Thomas Stevenson Esqr | &c &c &c