LOUIS ELLES, doctor of the Sorbonne, and professor of philosophy in the Royal College, one of the greatest ecclesiastical critics of his time, was born at Paris in 1637. When he published the first volume of his Bibliothèque Universelle des Auteurs Ecclésiastiques, in 1686, the liberty with which he discussed the merits of some ecclesiastical writers gave so much offence that, at the instigation of Bossuet, M. de Harlay, archbishop of Paris, compelled Dupin to make a retraction, and to suppress the work. He was, however, afterwards permitted to continue it, by altering the title from Bibliothèque Universelle à Bibliothèque Nouvelle. This great undertaking was ultimately brought to a close in 47 vols., and several translations of it appeared almost immediately. Dupin was a man of prodigious reading, and had an easy, happy way of writing, with a singular talent for analysis; a quality which renders his Bibliothèque very valuable. He was for some time editor of the Journal des Savants. He was banished for a time from his chair in the Royal College for having subscribed the famous Cas de Conscience, and thus identified himself in some measure with the Jansenists. He afterwards, however, withdrew his subscription, and was restored to office. He corresponded with Archbishop Wake in regard to the proposed union of the English and French Churches, and is said to have been consulted by the czar of Russia in regard to a similar union of the French with the Greek Church. Dupin died in 1719.

DUIPLE (Lat. duplus), double. Double ratio is that of 2 to 1. Thus the ratio of 8 to 4 is double, or as 2 to 1. Sub-duple ratio is the reverse, or as 1 to 2, 4 to 8, 6 to 12, &c.