Paris: J. Duboscq. We are pleased to offer an early didactic instrument by the famed firm J. Duboscq of Paris. This instrument is a huge demonstration prism (6 cm on a side and 7.5 cm high) mounted on a large brass base. There is a knurled dial below the prism that can be used to rotate the prism around it's center point. There is a inclination mechanism that can be used to move the prism assembly from a horizontal to a vertical position. And finally there is a quadruple knurled ring that can be used to loosen the stand allowing the prism assembly to be raised and lowered. The base is marked with the previous institutional owner information.
We've had plenty of small prisms over time, but this one is impressive. It is damaged (you can see one upper and one lower corner are damaged but nearly 5 cm in the middle of the prism is in working condition. This example is 19th century though what time period I'm not sure. The base is weighted (see the images) so that it is stable when being used. Large philosophical instruments are usually relegated to schools where having a larger example is necessary for teaching multiple students at one time. They rarely enter the secondary market, especially when they have a great presence like this one.
The Duboscq name and location is stamped just below the prism assembly.
We often have a wide range of instruments for sale from $100 to $5000. Please inquire.
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