### A symbol for continuous proportionality

I first met the symbol while working with Emanuel Swedenborg's mathematical manuscripts and then in his book on Algebra, Regelkonsten. A more detailed use of the symbol is presented in Daedalus Hyperboreus, the first Swedish scientific journal, edited by Swedenborg in 1716 - 1718. Later I found the symbol in William Oughtred's and William Jones's texts printed in 1647 and 1706. These observations let me dare to give a talk on this forgotten symbol.

Präsentation Staffan Rodhe