very important fortress of Germany, seated on the banks of the Rhine, built by the French after a design of marshal Vauban, for the defence of Strasbourg. It was ceded to the empire in 1697, by the treaty of Ryswick. The French retook it in 1703, and it was restored to the empire by the treaty of Reitadt. E. Long. 7.45. N. Lat. 48.40.

Keill (Dr John), a celebrated astronomer and mathematician, was born at Edinburgh in 1671, and studied in the university of that city. In 1694 he went to Oxford; where, being admitted of Balliol-college, he began to read lectures according to the Newtonian system in his private chamber in that college. He is said to have been the first who taught Sir Isaac Newton's principles by the experiments on which they are founded: and thus, it seems, he did by an apparatus of instruments of his own providing, by which means he acquired a great reputation in the university. The first specimen he gave the public of his skill in mathematical and philosophical knowledge, was his Examination of Dr Burnet's theory of the earth, with Remarks on Mr Whiston's theory: and these theories being defended by their respective inventors, drew from Mr Keill An examination of the reflections on the theory of the earth, together with A defense of the remarks on Mr Whiston's new theory. In 1701, he published his celebrated treatise, intitled, Introductio ad veram phisicam, which only contains 14 lectures; but in the following editions he added two more. This work has been translated into English, under the title of An introduction to natural philosophy. Afterwards, being made fellow of the Royal Society, he published, in the Philosophical Transactions, a paper of the laws of attraction; and being offended at a passage in the Acta eruditorum of Leipzig, warmly vindicated, agains Mr Leibnitz, Sir Isaac Newton's right to the honour of the first invention of his method of fluxions. In 1709 he went to New-England, as treasurer of the Palatines. About the year 1711, several objections being urged against Sir Isaac Newton's philosophy, in support of Descartes's notions of a plenum, Mr Keill published a paper in the Philosophical Transactions on the rarity of matter, and the tenacity of its composition. But, while he was engaged in this dispute, queen Anne was pleased to appoint him her decipherer; and he continued in that place under king George I. till the year 1716. He had also the degree of doctor of physic conferred on him by the university of Oxford, in 1713. He died in 1721. He published, besides the works already mentioned, *Intruductio ad verum astronomiam*, which was translated into English by Dr Keill himself; and an edition of Commandinus's Euclid, with additions of his own.

Keill (James), M.D., an eminent physician, and brother of the former, was born in Scotland, about the year 1673; and having travelled abroad, read lectures of anatomy with great applause in the universities of Oxford and Cambridge, by the latter of which he had the degree of doctor of physic conferred upon him. In 1700 he settled at Northampton, where he had considerable practice as a physician; and died there of a cancer in the mouth, in 1719. He published, 1. An English translation of Lomery's chemistry. 2. An account of animal secretion, the quantity of blood in the human body, and muscular motion. 3. A treatise on anatomy. 4. Several pieces in the Philosophical Transactions.