A remarkable and rare late 18th century folding magnifier dating to approximately 1790, composed of a natural horn case enclosing a biconvex magnifying glass of between 4x and 5x power (approximately 20 diopters). Folding magnifiers with horn cases were a common and practical optical accessory in the late 1700s, carried by scholars, merchants, naturalists, and gentlemen alike for reading fine print and examining small objects.
The instrument is an elegant piece of early optical engineering, held together by three brass studs — two at the base passing through a horn separating piece, and one at the opposite end serving as a hinge. This five-component construction consists of two side pieces of horn, a central separating base piece, a surround piece that contains the glass lens, and the biconvex lens itself. When closed, the horn case completely protects the lens; when open, the lens is held securely in position for use.
Due to its considerable age, a small piece of the lens support on one side is missing, though this does not appear to affect the optical function of the instrument in any way and could likely be repaired by a skilled jeweler. This minor wear only adds to the authenticity and character of a genuinely rare survival from the Georgian era.
A wonderful example of pre-industrial optical craftsmanship and a highly collectible piece of optical and scientific instrument history.
