Copy letter from Robert William Frederick Harrison, to Dr M Wilderman, Davy-Faraday Laboratory, Albemarle Street, W. Asks him once more to kindly answer the query about the printing of the expression at top of slip three of the proof of his abstract. Enquires if the I at the end mean intensity of light or does it mean K is a function of I and I', but A a B are independent of it. Or should it be removed entirely? 20 February 1902