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1874 Pierre Jules César Janssen - Passage de Venus (practice disc?)

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Published on May 5, 2012

Because of the astronomic subject it seems extra remarkable that this 1874 photo sequence of the rare passage of Venus over the face of the sun was one of the first chronophotographic sequences. It was made several years before Muybridge published his first sequences of the horse in motion (in 1878). Despite the problem that light-sensitive emulsions needed relatively long exposure times in 1874, it was possible to create a proper sequence of the passage of venus: it took much longer than a horse galloping past a camera. Photographic sequences made of the passage are basically time-lapse recordings!

It seems like none of several discs of the actual passage of Venus have survived. The presented video is based on a sequence that was probably made to test the technique with a model of the planet and a light source standing in for the sun. This may seem less impressive, but it also means that this recording is a bit older than the (lost) results that captured the actual passage on 9 December 1874.

The 1874 passage 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. French inventor Janssen came up with the idea for a "revolver photographique". 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 went to Nagasaki, Japan and on 9 December his crew made 47 photographs of the first contact of the transit. These were weak because of the hazy weather, but quite visible. Five English parties had also taken pictures with their own "Janssen revolvers" and had good to excellent results.

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. His work directly influenced Etienne-Jules Marey who later managed to record animal movements with chronophotographic systems, including a photographic revolver. One of his photographic sequences is a portrait of Janssen. Janssen would later also appear in two very early Lumière films, recorded on 11-06-1895 for the Congres de Photographie in Lyon. When one of the titles, "M. Janssen causant avec M. Lagrange" was shown to the Congress the next day, Janssen and Lagrange were secretly behind the screen to re-voice their dialogue for the audience. It took over 6 months before the first commercial public screening of the Lumière's cinématograph films on 28-12-1895 took place in Paris, traditionally marked as the birth date of the movies.

Much more info:
http://articles.adsabs.harvard.edu//f...

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