> 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!
Very interesting, how do you get hold of an old british patent?
Not much through Google thus far.
