Sir William Ramsay's direct-vision spectroscope, 1880-1890.
© Science Museum / Science & Society Picture Library
Sir William Ramsay (1852-1916), the Scottish chemist, used this hand-held direct-vision spectroscope to observe the faint spectra of inert gases such as helium, neon, argon and Krypton. For this work Ramsey was awarded a knighthood in 1902 and received the Nobel Prize for chemistry in 1904. Made around 1880-1890, the compact instrument lacks the narrow slit usually found on most spectroscopes; instead light enters from the left side where it is dispersed by a series of triangular glas prisms. Cemented together apex to apex, so forming a straight bar of glas, they form a detailed spectrum that is viewed using the eyepiece on the right side of the spectroscope.