**Heinrich Suter**'s father was a farmer who also kept post horses. This was the era when carriages for long-distance travel were pulled by horses that were changed at intervals at posts (stations). In 1863 Suter entered the high school for Zürich Canton where he studied Latin and Greek. He then entered both the Eidgenössische Technische Hochschule and the University of Zürich where he was taught by Christoffel, Reye, Geiser and Wolf. He then studied at Berlin under Kronecker, Kummer and Weierstrass. As well as mathematics he also studied history and philology in Berlin which were important for his research. He obtained a doctorate from the University of Zürich in 1871 on the history of mathematics. His thesis was entitled *Geschichte der mathematischen Wissenschaften . I; Von den ältesten Zeiten bis Ende des 16. Jahrhunderts* Ⓣ. Hofmann writes [1]:-

... in[his thesis]the significance of mathematics for cultural history was emphasized. Although Suter set forth the goal of treating the history of mathematics in terms of the history of ideas, he was prevented from attaining it because of the paucity of available data.

Suter taught mathematics and physics in Swiss schools and became the leading expert on Muslim mathematics. His first appointment after the award of his doctorate was to Wettingen Teachers' training College in Aargau Canton where he was appointed to a temporary position. He was then employed part-time at the Gymnasium in Schaffhausen in 1874, then moved to a similar post in the Gymnasium in St Gall in 1875. This was the year in which Suter married Hermine Frauenfelder. She was the sister of Eduard Frauenfelder who was a well-known philanthropist and preacher at Schaffhausen cathedral. Heinrich and Hermine Suter had three daughters.

In the year 1876 Suter received a full-time appointment in the cantonal school of Aargau as a teacher of mathematics and physics. He remained in this position for ten years before moving to the cantonal school of Zürich, again as a teacher of mathematics and physics. He remained in this position until he retired in 1918.

Suter's doctoral dissertation *Geschichte der mathematischen Wissenschaften. I; Von den ältesten Zeiten bis Ende des 16. Jahrhunderts* Ⓣ was revised and published in 1873. As can be seen from the title, this was the first part of a two part work, the second part *Geschichte der mathematischen Wissenschaften. II; Vom Anfange des 17. bis gegen Ende des 18. Jahrhunderts* Ⓣ was published in 1875. For around ten years after this Suter produced no research papers but he began to publish on the history of mathematics again in 1884. It was only when he went to the cantonal school of Zürich in 1886 that he began to learn Arabic from two Orientalists there. He then began to publish important work on the history of medieval Islamic mathematics and astronomy. The two volumes of [3] contain two books and 41 articles on that topic that Suter wrote between 1892 and 1922.

The most important of Suter's works is the book *Die Mathematiker und Astronomen der Araber und ihre Werke* Ⓣ (1900). Rosenfeld and Ihsanoglu write in [2]:-

... in1900, Swiss historian of mathematics and astronomy Heinrich Suter published the bio-bibliographical survey Die Mathematiker und Astronomen der Araber und ihre Werke. Suter's book contained information on scholars not only in the Arab countries but in all the Islamic countries from the8th to the17th centuries. Die Mathematiker und Astronomen der Araber und ihre Werke contains information on approximately500scholars whose time of life was known and100with unknown dates.

Other work by Suter includes *Die Mathematiker auf den Universitäten des Mittelalters* Ⓣ (1887), and *Das Mathematiker-Verzeichnis im Fihrist des ... an-Nadim* Ⓣ (1892). There were two versions of al-Khwarizmi's main astronomical work the *Sindhind zij* but the Arabic originals of both are lost. A Latin translation of one version has survived and was published by Suter in 1914 in *Die astronomischen Tafeln des Muhammad ibn Musa al-Khwarizmi*. One of his last works was *Beitrage zur Geschichte der Mathematik dei den Griechen und Arabern* (1922).

Suter was awarded an honorary doctorate from the University of Zürich in the final year of his life.

**Article by:** *J J O'Connor* and *E F Robertson*