In article <4187ae74.2475034_at_news.ecn.ab.ca>,
jsavard_at_excxn.aNOSPAMb.cdn.invalid says...
>
>In an old book on optics, among several examples of types of prisms used
>in terrestrial telescopes to erect the image, was one called the
>Daubresse prism.
>
>It was a standard right-angle prism adjoined to a pentaprism.
>
>Some web searches for additional information indicated that Daubresse
>did in fact invent the pentaprism.
>
>British patent 7035/1900 seems to be the only likely candidate for the
>patent in which the pentaprism is described, since there is one diagram
>which shows some sort of roof prism.
>
>In addition, British patent 7650/1901 shows him as the inventor of
>something else I noted as clever! You know those machines that you run
>film through for editing: sometimes they have viewers in them so you can
>also watch the film while moving it? I noticed that one I purchased,
>instead of having a shutter, used a rotating prism with multiple sets of
>parallel sides to move the image in the opposite direction of the
>advance of the film. Achille Victor Emile Daubresse invented that as
>well!
>
>John Savard
>http://home.ecn.ab.ca/~jsavard/index.html
--
Best regards,
Steve Eckhardt
skeckhardt at mmm dot com
