The Migno­scope was dis­trib­uted by Mat­tey under the Unis France label, but is not list­ed in the company’s cat­a­logues. The view­er is a vari­ant of the Alter­nascope and essen­tial­ly con­sists of the Alternascope’s lens pan­el with­out the wood­en stand.
The view­er was designed to accom­mo­date wide 3 x 13 cm glass slides on which two stereo pairs are print­ed side by side.
(from: Com­pendi­um of Stereoscopes)

Fur­ther read­ing: Stere­oscopy His­to­ry Series — Mat­tey (A. Ruiter)

The illus­trat­ed view­er was pro­duced exclu­sive­ly for the Inter­na­tion­al Exhi­bi­tion in Barcelona in 1929.