The Unis France Métascope is one of the stereoscopes from the very extensive product range of A. Mattey. Mattey sold its products using different trademarks. The more high-quality products were sold with the Unis France brand.

The Métascope was introduced in the early 1920s[2]. The model in this post is suitable for viewing 45x107mm glass stereoviews and is referred to as Métascope Spéciale in the 1936 catalog. The Métascope Universel supported interchangeable trays for 45x107mm slides and 6x13cm / 7x13cm slides to view multiple formats with a single device[1]. The Métamagasin included a storage compartiment for storing slide trays[2]. Storage cabinets were optionally available for the other models and the largest cabinet could store up to 1350 slides. The Métascope could be equipped with a projection lantern or electric illuminator.

The front panel shows a copper plate with Unis France Métascope. Serial number 656 is engraved on the inside of the viewer on the mechanism. The brand name Pennard & Fouquet is visible above this number. Perhaps the inclusion of this brand name must emphasize the exclusivity of this stereoscope.
The two achromatic lenses[2] can be focussed and the distance between the lenses is adjustable. The eyepieces with lenses can be removed for cleaning. The frosted glass at the back is used to illuminate the glass slides. It can be removed to attach an optional projection lantern or electric illuminator [2]. In this case a larger frosted glass is mounted inside the device to replace the original glass plate.

A slide tray can hold 25 glass slides. To place the tray, the lid on the top and the front panel must be opened. The lever that loads the slides is in down position and locked. After inserting the slide tray, the lever is unlocked and the lever moves upwards. The first stereo image is shown. The images are displayed one by one by pushing the lever down repeatedly. An indicator on the right side of the device shows which slide is loaded. With the lever in locked position, the indicator can also be used to navigate to a specific image. If a caption on the slide is present, it can be read by moving a small lever on the front panel to the left.
References
- Stereoscopes, Stéréoscopes A. Mattey, 1936
- Wing, Paul. Stereoscopes: the first one hundred years, 1996