A fine pair of 19th century French made "double binoculars" with their original case circa 1860-1870

Probably made by Lemaire of Paris, this outstanding pair of Civil War era double binoculars provide an awesome 20 power. They come complete with the original leather case. The binoculars allow one to fold them to individual eye sight. There is an engraved scale from 58-70 which I am not familiar with. the only markings are 'Bte S.D.G.D.' which means that they are patented in France. Length closed: 11 1/2" Length extended: 17"