10 июн 1752 г. - Invention of Bifocals
Описание:
In 1752, Benjamin Franklin invented bifocals. Bifocals are glasses with transitional lenses that allow people who are both farsighted and nearsighted to maintain their vision with one pair of glasses, and while they have been upgraded, they are still used today.Добавлено на ленту времени:
Дата:
10 июн 1752 г.
Сейчас
~ 273 г назад