Stereosette By Stereosette Limited Circa 1920's Optician Eye Test Tool Equipment

Stereosette by Stereosette Limited. 
Circa 1920's.  £185.00 
Box measures H7" W14.5" D8.5" 
One box hinge damaged (See photos). 
This is a very unique English optical stereometer to test visual perception. A collapsible instrument that folds down to fit neatly into the original wooden box that also accommodates the instruction booklets and 18 visual testing plates (stereograms). 
It is emphasised that the stereosette is not an instrument to enable Glasses to be prescribed. Its function is to effect a rapid sorting out of those likely to benefit from a detailed eye examination. 
Ref/01108