Posted by: episystechpubs | July 26, 2013

Editor’s Corner: The Obelus

Welcome to all of you who’ve just signed up for Editor’s Corner! At the request of one of our co-workers, I’ve been exploring the history behind some of the different symbols and punctuation marks we have on our keyboards. Today’s symbol is the division sign, which is technically called the obelus and was historically used to represent something other than division.
From our friends at Wikipedia, “An obelus (symbol: ÷, plural: obeli) is a symbol consisting of a short horizontal line with a dot above and below. It is mainly used to represent the mathematical operation of division. It is therefore commonly called the division sign. The symbol represents a fraction with dots in place of the denominator and numerator.”
Here’s where it gets interesting. The word obelus comes from Greek “ovelos” which is the word for a lance, spit, or pointed pillar. (The word obelisk also comes from this root word.)
Obelisk in Place de la Concorde, Paris

The symbol was originally used as an editing mark to note passages in ancient manuscripts that were suspected of being written by someone other than the stated author, or that were corrupted (in particular, the texts of Homer). Obelism is the practice of editing manuscripts using marks, symbols, and abbreviations in the margins. The practice was developed by Aristarchus of Samothrace, an ancient grammarian and scholar of Homeric poetry. Though some of the symbols have changed, editors still use similar marks and some of the same abbreviations (such as the Latin word stet for “let it stand”). It was not until 1659 that the obelus was used to symbolize division in an algebra book, and it is still not universally used for that purpose.

Have a great weekend!

Kara Church
Senior Technical Editor

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