Optician more important and dignified. Far-sighted or aging colonial Americans imported spectacles from Europe. Spectacles were primarily for the affluent and literate colonists, who required a valuable and precious appliance. Benjamin Franklin in the 1780s developed the bifocal. Bifocal lenses advanced little in the first half of the 19th century. The terms bifocal and trifocal were introduced in London by John Isaac Hawkins, whose trifocals were patented in 1827. In 1884 B. M. Hanna was granted patents on two forms of bifocals which become commercially standardized as the "cemented" and "perfection" bifocals. Both had the serious faults of ugly appearance, fragility,
The Black Spectacles The Black Spectacles The Black Spectacles (published in the US as "The Problem of the Green Capsule", with the subtitle "Being the psychologist's murder case"), first published in 1939, is a detective story by John Dickson Carr featuring his series detective Gideon Fell. This novel is a mystery of the type known as a locked room mystery (or more properly a subset of the locked room mystery called an "impossible crime" story). In the small English village of Sodbury Cross, pretty Marjorie Wills is suspected of having poisoned some chocolates in the local tobacco-and-sweet shop, using a method pioneered by