Catalogue Page from Exhibition Catalogue: 1909 Fifty-fourth Annual Exhibition of the Royal Photographic Society of Great Britain

showing (E09A027) Exhibit no. 395 396 397: Frame I: Specimens of plates taken for determination of standards of wave lengths. 2nd and 3rd order, 1 Angstrôm Unit = 1 or 1,5 mm. by Prof. H. Kayser ()