Mark Dominus shares an excerpt from Robert Recorde’s The Whetstone of Witte, which includes the world’s first use, in 1557, of the equals sign:
Howbeit, for easie alteration of equations. I will propounde a fewe exanples, bicause the extraction of their rootes, maie the more aptly bee wroughte. And to avoide the tediouse repetition of these woordes : is equalle to : I will sette as I doe often in woorke use, a pair of paralleles, or Gemowe lines of one lengthe, thus: =====, bicause noe .2. thynges, can be moare equalle.
He recommends reading it aloud:
The only tricky things are the spelling and the word “Gemowe”. Reading aloud will solve the spelling problem. “Gemowe” means “twin”, like in the astrological sign of Gemini.
He notes that he learned something surprising by going back to the original document:
I knew that the German “umlaut” symbol was originally a small letter “e”. A word like schön (“beautiful”) was originally spelled schoen, and then was written as schon with a tiny “e” over the “o”, and eventually the tiny “e” dwindled away to nothing but two dots. I have a German book printed around 1800 in which the little “e”s are quite distinct.And I had recently learned that the twiddle in the Spanish ñ character was similarly a letter “n”. A word like “año” was originally “anno” (as it is in Latin) and the second “n” was later abbreviated to a diacritic over the first “n”. (This makes a nice counterpoint to the fact that the mathematical logical negation symbol ~ was selected because of its resemblance to the letter “N”.) But I had no idea that anything of the sort was ever done in English.
Recorde’s book shows clearly that it was, at least for a time. The short passage illustrated above contains two examples. One is the word “examples” itself, which is written “exãples”, with a tilde over the “a”. The other is “alteration”, which is written “alteratiõ”, with a tilde over the “o”. More examples abound: “cõpendiousnesse”, “nõbers”, “denominatiõ”, and, I think, “reme~ber”. (The print is unclear.)
I had never seen this done before in English.