Copy letter from Herbert Rix, to Dr Arthur Schuster, [Fellow of the Royal Society] 'Dear Dr Schuster, Your corona-spectrum drawing [sketch of figure 2 in the body of the text] we are going to do white on black. But will you tell me whether you prefer white on black or b. on w. [black on white] for figs [figures] 4 & 5 (the two square patches of spectra). You can have whichever you like; it will make no diffce [difference] in cost. The question is whether you would like them as drawn, or reversed (i.e. the black made into white) Yours faithfully H Rix'. 5 April 1889