Faraday to George Biddell Airy   4 May 1846

R Institution | 4 May 1846

My dear Sir

I have just made the experiment with the Polarizing Nicoll piece in eight positions and find the effect the same in every position¹. Again taking the polarizing & eye pieces in any given position I then revolved the square prism of heavy glass on the ray passing through it as axis but without the slightest trace of effect on the ray i.e the ray being affected by the magnet & glass suffered no further change of any kind by the rotation of the prism[.]

Ever Truly Yours | M. Faraday

G.B. Airy Esq | &c &c &c