Stereoscope ‘Alternascope’

The Alter­nascope is a mul­ti-view stere­o­scope. It’s a vari­ant of the Edu­ca stere­o­scope, designed for edu­ca­tion­al use and man­u­fac­tured by Mat­tey. The instru­ment was pro­duced exclu­sive­ly by Mat­tey on behalf of the Edu­ca company.
(from: Com­pendi­um of Stereoscopes)

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