What is bifocal lens? Bifocal lens was invented by whom? Maybe some of you have known the answers, I still want to explain it to those who don’t know.
Definition: Bifocal lens are a type of eyeglasses that allow the individual to view close objects and distant objects through separate lenses. These eyeglasses date back to the 18th century. Today, bifocals are still a commonly used invention.
Inventor Benjamin Franklin: Benjamin Franklin is widely credited as the inventor of bifocals. According to the Antique Spectacles and Other Visual Aids museum, curated by Dr. David A. Fleishman, an archived political cartoon dated 1764 and held by The Library Company of Philadelphia, which was co-founded by Franklin, shows Franklin wearing an “unusual pair of eyeglasses” that resemble bifocals. A paper published by Dr. Charles Letocha in 1990 also substantiated claims of Franklin’s invention of the bifocals.
Origin of Name: The term “bifocal lens” was not coined by Franklin himself. Rather, John Isaac Hawkins, who invented the trifocal, was the first to use the term in 1826 when referring to Franklin’s work, according to the “Notes and records of the Royal Society of London” Volumes 27-28, which were published in 1973.
History: The inventor of the first wearable eyeglasses is often cited as Salvin D’Amato, an Italian. In “Scientific American’s Inventions and Discoveries” published in 2004, Rodney P. Carlisle writes that a tombstone in Venice once read “Here lies Salvino D’Amato of the Armati of Florence, inventor of spectacles.” However, this tombstone no longer exists and this claim has not yet been verified.
Identification: Bifocal lenses were first identifiable by the distinct separate lens within the eyeglasses. These were usually small rectangle-shaped lenses located on the lower portion of the lens such that an individual would look through them when looking downwards at a book or something else at close range.
Today’s technology allows bifocals to be manufactured without a discernible line. However, these glasses still retain the benefits of earlier bifocals.
The Franklin Split: According to a the sixth issue of a newsletter published by Benjamin Franklin House of London (a Franklin museum located in one of his former residences), Benjamin Franklin first described his bifocal lenses in great detail in two letters on Aug. 21, 1784 and May 23, 1785. In these letters, it was revealed that John Dollond had been making these double spectacles–known then as the “Franklin Split”–for several customers, including painters Benjamin West and Sir Joshua Reynolds. While, Dollond, an English optician, manufactured the glasses, a Nov. 15, 1784 letter written to Benjamin Franklin refers to “your invention of double spectacles,” according to information from the aforementioned Antique Spectacles and Other Visual Aids museum, which implies that Franklin indeed invented them.
After reading this article, I am sure everyone has known bifocal lens was invented by whom. So don’t forget to say thanks to Benjamin Franklin when you are enjoying bifocal lens.
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Address:http://www.visioncarehome.com/bifocal-lens-was-invented-by-whom.html
