Figure 14. W. F. Ewald's and K. Grein's photometer. Left: view of theapparatus. Right (from top to bottom): messenger container; removable photographic plates; removable filters. This instrument was designed byWolfgang F. Ewald with the aid of Kl
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Photographer: P. Roggero
Credit: Oceanographic Museum of Monaco
Subject: Oceanography
Subject: Historical instruments