Ruechat, Abraham, a theologian and historical writer of Switzerland, was born Sept. 15. 1678, at Grandcour in the canton of Vaud. He early manifested a taste for archaeological and historical inquiry, and also great facility in the acquiring of languages, so that he was able to apply for a professorship of Greek and Latin at Berne when twenty-one years of age; and soon afterwards mastered English and German, attending for the purpose of perfecting himself in the latter tongue, various universities, e.g. Berlin and Leyden. On his return he was made pastor of Aubonne and Rolle, then professor of belles lettres and president of the Upper Gymnasium at Lausanne (July, 1721), and finally professor of theology in the same institution, which latter station he occupied until his death, Sept. 29, 1750.
Ruechat distinguished himself chiefly as a historian of the Church in his native land. In 1707 he published an Abregi de l'Histoire Eccl. du Pays-de- Vaud. His principal work, Histoire de la Reformation de la Suisse (Geneva, 6 vols.), appeared in 1727 and 1728. It was placed on the Index at Rome, and was assailed by Jesuit priests, to whom Ruechat replied in a letter addressed to the editor of the Biblioth. Germanique, 20, 213. His work had been published no farther than 1537, the remainder not being given to the public until more than a century after the first issue. The first complete edition is by Valliemin (Lausanne and Paris, 7 vols.), with Notioe sur Abraham Ruechat appended. Of Ruechat's works a number have not yet been printed. The list of his printed works includes a Hebrew Grammar (Leyden, 1707): — Examen de l'Origenisme (against M. Huber [q.v.]): — a translation of the epistles of the apostolical fathers Clement, Ignatius, ansd Polycarp (1721): — a treatise on Bible weights and measures (1743): — and various dissertations.