Passage of Venus (1874)

• 68%
• 1874
• Documentary
• P.J.C. Janssen

Observing the 1874 Transit of Venus over the face of the sun was very popular with scientists. Many expeditions to the best viewing points in the world were organized; at least 62 parties would visit 80 locations. In preparation, much effort was made to find the best techniques to get objective and permanent records of the event. Frenchman inventor Janssen came up with the idea for a "revolver photographic". This huge camera system used a Maltese cross-type mechanism, very similar to the system that would later be of great importance in the development of movie cameras. The revolver could take several dozens of exposures at regulated intervals on a daguerreotype disc. Janssen later suggested that his apparatus might become suitable for the study of animal movements once photographic materials would allow the very brief exposures necessary.