Cigar Box Viewers
A number of different small box viewers were produced between 1860 and 1880. W. J. Gibbons of England was a large producer. Most if not all are unmarked. They were used for early flat mount views.
Gibbons Viewers, one with slotted adjustments in center and one with adjustments on box sides.
Patent #3153 in England, December 24, 1860.
Early Gibbons Viewer, not adjustable for focus but folds nearly flat.