After the fixed-chain mod­els came the push-and-pull stere­o­scope, in which the views pass from the sup­ply mag­a­zine to the receiv­ing mag­a­zine after a view­ing peri­od, thanks to a chang­ing rod. This sys­tem was invent­ed by Her­mann-Marie-Camille Jahn­holtz, who filed patent FR 280.799 on August 23, 1898, joint­ly with Jules Richard. The patent was sup­ple­ment­ed by an addi­tion dat­ed Feb­ru­ary 13, 1899, which pro­duced the final ver­sion of the device. This sys­tem rep­re­sents Jules Richard’s first con­cept of a hand­held stere­o­scope allow­ing the auto­mat­ic chang­ing of plates by mechan­i­cal action.
The stere­o­scope is a portable type, con­sist­ing of a var­nished mahogany case fit­ted with a large met­al han­dle for car­ry­ing and for hold­ing it dur­ing use. On the front, in the cen­ter, is the view­ing sec­tion with fixed eye­pieces and rack-and-pin­ion focus­ing con­trolled by a knob. Above and below are the access doors to the mag­a­zines. On the same right-hand side is a pull knob which, when drawn out, removes a stereo­scop­ic plate from the low­er sup­ply mag­a­zine, rais­es it into view­ing posi­tion, and then inserts it into the upper receiv­ing magazine.
The orig­i­nal patent placed the oper­at­ing knob under­neath the instru­ment. The Feb­ru­ary 1899 cer­tifi­cate of addi­tion moved it to the side, mak­ing the device eas­i­er to han­dle. This stere­o­scope requires accu­rate­ly stan­dard­ized glass plates to ensure prop­er operation.
Note: Although mar­ket­ed by Jules Richard, this mod­el does not appear in the manufacturer’s catalogs.
(from: Moulin­ier et al. His­toires de vision­neuses stéréo­scopiques français­es. Limo­ges, 2025, p. 169. Author’s translation.)