Faraday to James Clerk Maxwell   23 May 1861

[Royal Institution embossed letterhead] | 23 May 1861.

My dear Sir

I am greatly obliged to you for your kindness¹. It was the amount of the variation & its determination which has caught my mind & which I thought had been recently ascertained but I dare say my imperfect memory has taken up imperfectly what you said[.]

Ever faithfully Yours | M. Faraday

J.C. Maxwell Esqr | &c &c &c