In n 1861 Oliver Wendell Holmes created and deliberately did not patent a handheld, streamlined, much more economical viewer than had been available before. The stereoscope, which dates from the 1850s, consisted of two prismatic lenses and a wooden stand to hold the stereo card. This type of stereoscope remained in production for a century and there are still companies making them in limited production currently.
There a several themed slides , family life , weeding and some geographique view.
7x7 x 5 in  ,  slides  7 x 3.5 in , most in good condition some fading about 20