The lang, medial or descendin s (ſ) is a kyn o wee letter 's' whit wis uised whaur 's' occurred in the mids or at the stairt o a ward, for ensaumple ſinfulneſs ("sinfulness"). The modren letter wis cried the terminal or cuttie s.
the integral of f
The lang 's' survives in elangatit form, an wi a italic-style bowt descender, as the integral symbol ∫ uised in calculus; Gottfried Wilhelm von Leibniz based the chairacter on the Laitin word summa (sum), whilk he clarkit ſumma. This uiss first appeart for public in his paper De Geometria, publisht in Acta Eruditorum o Juin, 1686, bit he haed uised it in private manuscripts syne at least 1675.
In Scandinavian an German-speakin kintras, relics o the lang ſ haud on in signs an logaes whit uise various kynds o fraktur typefaces. Ensaumples include the logaes o the Norse newspapers Aftenpoſten an Adresſeaviſen; the packagin logae faur Finnish 'Siſu' pastilles; an the Jägermeiſter logae.
Anither survival o the lang s wis the abbreviation uised in Scots an Inglis for shillin, as in 5/-, whar the forrit slash stood in for the lang s whilk haed been lang forgotten bi aw bit antiquarians.
- Mathematics and its History, John Stillwell, Springer 1989, p. 110
- Early Mathematical Manuscripts of Leibniz, J. M. Child, Open Court Publishing Co., 1920, pp. 73–74, 80.