Prosper, a learned bibliographer, born about the year 1675, at Guise, in Picardy, studied at Paris with much success, and was then placed with a bookseller, to qualify him for engaging in the same line of business. Having, from his infancy, been passionately devoted to books, he soon acquired the requisite knowledge, and, in 1698, was admitted into the corporation of booksellers. He then opened, in the Rue Saint Jacques, a shop under the sign of the Phoenix, which soon became the rendezvous of all the lovers of books in Paris. An eager collector of literary anecdotes, he transmitted them to Jacques Bernard, who then conducted in Holland the Nouvelles de la République des Lettres; and he at the same time made for the use of that person collections which proved very serviceable to him. In 1711, Marchand passed into Holland, that he might be more free to profess the reformed religion, which he had embraced. He established himself at Amsterdam, and there continued for some time the business of bookselling; but being disgusted with the want of good faith on the part of his brethren of "the trade," he abandoned it altogether, in order to devote himself exclusively to study. The editions of different works which he successively published made him advantageously known; and he was consulted by most of the learned men of Europe who were engaged in similar pursuits. The habits of a frugal life had fortified his constitution, which was naturally robust, and he seldom quitted his cabinet; but there received all who had recourse to him, and freely communicated to them the information they required. In the midst of these peaceful occupations, he attained a very advanced age, and died on the 14th of June 1758. By his will he bequeathed the fruits of his economy to the society for the relief of the poor at the Hague, and left his rich library to the university of Leyden. Marchand had a share in the ingenious satire, Le Chef-d'œuvre d'un Inconnu; he furnished notes to the satire called Monippée; and he was a principal conductor of the Journal Littéraire (Hague, 1713–1737, in twenty-four vols. 12mo), one of the best periodical works printed in Holland. Besides these, we have of his, 1. Catalogues of different libraries, particularly that of Joachim Faultrier, 1709, in 8vo, now exceedingly scarce, which is preceded by his new system of bibliography (epitome systematis bibliographici); 2. Histoire Critique de l'Anti-Cotton, a satire composed by César de Plaix, an advocate; 3. Histoire de la Bible de Sixte-Quint, inserted in the Amantites Litterarie of Schellion (tom. iv.); 4. Histoire de l'Origine et des premiers Progrès de l'Imprimerie, Hague, 1740, in 4to; 5. Dictionnaire Historique, or Critical and Literary Memoirs of different distinguished persons, particularly in the republic of letters, Hague, 1758, 1759, two volumes folio in one. This last work, which the author left in manuscript, forms a sort of supplement to the Dictionaries of Bayle and of Chaufé; and, though too minute perhaps, contains many interesting facts and curious anecdotes. We may add, that Marchand rendered important services to letters by the publication of a great number of useful works, which he enriched with prefaces, letters, notes, and instructive remarks. To him we are indebted for an edition, with remarks, of the Lettres Choisies of Bayle, Rotterdam, 1714, in three volumes 12mo, which is not surpassed by that of Desmaeux; and he likewise published the most beautiful and the most esteemed edition of the Dictionary of that famous critic.