61, p. 444), and the instrument contains many elegant mechanical and optical details due to Horace Darwin and Messrs Zeiss respectively.
In the apparatus of type B as made by Zeiss there are two microscopes attached to a base-plate, one of which views the spectrum-plate (or other object) to be measured, while the other views a scale that moves with the slide on which the spectrumplate is mounted.
After experiments in the Zeiss works, the erecting of Porro's prisms simultaneously permitted a convenient adaptation to the eye-distance of the observer.
The refractometer constructed by C. Pulfrich (of the firm of Zeiss, in Jena) has been successfully used by G.
Zeiss made a periscope 7 metres long, main tune 150 mm.
Zeiss and Steinheil's monocentric eye-pieces and the Cooke single achromatic eye-piece (fig.
The collection of the scientific staff of Carl Zeiss at Jena, edited by M.