JOHN, was a physician in Dieppe, and died at Paris in 1674. He was physician in ordinary to the celebrated Ponquet, whom he entertained at his spare hours with some of the most amusing experiments in natural philosophy. He acquired immortal honour to himself by the discovery of a lacteal vein, which conveys the chyle to the heart; and which from his name is called le Refervoir de Pecquet. This discovery was a fresh proof of the truth of the circulation of the blood; though it met with opposition from many of the learned, particularly from the famous Roilau, who wrote a treatise against the author of it, with this title: Adversus Pecquetum et Pecquetianos. The only works which we have of Pecquet, are, 1. Experimenta nova Anatomica, published at Paris, 1654. 2. A Dissertation, De Thoracis Lacteis, published at Amsterdam, 1661. He was a man of a lively and active genius; but his sprightliness sometimes led him to adopt dangerous opinions. He recommended, as a remedy for all diseases, the use of brandy. This remedy, however, proved fatal to himself, and contributed to shorten his days, which he might have employed to the advantage of the public.