Six autograph letters signed ('Silv. P Thompson', 'S.P.T.', 'Silvanus P.T. Magnetiser'), to H[enry] C[urrie] Marillier, 1865-1951, formerly a friend and correspondent and possibly lover of Oscar Wilde, journalist, expert on tapestries and scientific correspondent, and Managing Director of Morris & Co., about X-rays: that success depends on the degree of exhaustion, that only the highest exhaustion is used and that x-rays do not emanate exclusively from phosphorous patches on the glass ('...I have seen cases of double shadows cast from one tube where the stronger shadow cast as by rays emanating straight from the Kathode, with a weaker shadow cast as by rays originating at the phosphorescent patch...'); reports that he has found diamond to be more opaque than black carbon, that in wood the dark streaks are more transparent than the lighter coloured tissue, that a specimen of flies in amber shows no shadows of the flies and that he has found no difference in the degree of opacity of magnetized and non-magnetized iron; he relates [Oliver] Lodge's agreement with him regarding x-rays as 'rather of nature of sound waves than of light' and Hicks's 'ingenious corpuscular theory' which he considers 'magnificent'; Thompson also tells Marillier that he has located his old enemy C.B. Harness; discusses the theft of Lodge's invention of a 'jigger'; asks for a set of his own and Swinton's prints [?of x-ray photographs]; and suggests various names that Marillier might adopt on becoming a member of the Odd Volumes Club, 16 pages, 8vo and a letter-card addressed to Marillier at Kelmscott House, Hammersmith, which he owned, Morland, Chislett Road, Hampstead, 1896-1903 where dated