Horn and steel bow spectacles in red shagreen case (now faded). Designed by Benjamin Martin in 1756 and termed ‘Visual Glasses’. The distinctive thick-rimmed design and violet or green tinted lenses (which do not survive in this example) were ridiculed by some contemporaries but ultimately proved popular and were copied by other makers. Thus the maker of this pair is unknown. Martin used the glasses as his trademark; an image of them appears on his trade cards and receipts.

Benjamin Martin (bap. 1705–1782) was one of London’s best-known instrument-makers in the second half of the 18th century. His shop, located in Fleet Street, close to the meeting place of the Royal Society, was known to be well-stocked and was frequented by natural philosophers, wealthy clientele and customers with more limited means.

He originally devised the Visual Glasses for his own use as his eyesight began to fail when he was in his fifties. But despite initial criticism, they proved popular both with his customers and with other makers, who imitated the design.