facility in the use of the Latin language and his skill in reporting the opinions of others. He remained in office till 1699, when he was succeeded by Fontenelle. It was eminently fitting that he should write a history of the academy as he had known it. Couplet was the first treasurer and the keeper of the instruments used in experiments, an office in which he was followed by his son; Couplet had been a mechanical engineer. Early in 1667, Perrault prepared a room in a laboratory placed at his disposal for the study of physics. By careful experiment he fitted himself for the study of comparative anatomy and vegetable physiology. The motive to these studies was curiosity rather than the thought that the knowledge obtained would be of profit to any one. The problems deemed most important were those of astronomy and geometry. Hence for a long time astronomical studies received the greatest honor in the academy, and outside of it. It is, therefore, not strange that the men who devoted themselves to these studies should consider themselves superior to their fellows. They were zealous for their department and paid little attention to what was done in other departments than their own. For a full generation there v/as ill feeling between members of the academy caused chiefly by differences of opinion in reference to scientific subjects. Yet advance was made in other departments than those of astronomy and mathematics.
Du Clos and Bourdalin analysed certain salts and observed the changes constantly taking place in many bodies. Mineral bodies were carefully examined. Denis Dodort sought to determine the virtue of plants by chemical analysis. Vegetables he tested by fire and obtained what he and others called caput mortuum. The worthlessness of this method was pointed out by Mariotte in 1679 in his essay on vegetation. Many abortive efforts were made by the academy to obtain fresh water from the salt water of the ocean. Special attention was given to a study of the vacuum, de la Hire studied the chemistry of color, du Clos and Dodort the history of plants, the result of which, as has been said, published in 1676, brought great honor upon the academy. Dodort showed much skill in all his observations. His errors were only those of his time.
The plans of the authors of this volume embraced a complete history of plants. The great lack was knowledge of the physiology and chemistry of vegetables. All naturalists were what are now called amateurs. They gave attention to many subjects. Thus Frenicle read a paper in 1660 on insects, pointing out in particular some changes observed in the caterpillar. Mariotte brought out a theory of vision which was strongly opposed as unscientific by Pacquet and Perrault. He wrote on hydrostatics also. Strenuous efforts were made, for a number of years, to measure the height of the pole at Paris. It was observed that the pendulum beat with differing degrees of rapidity at