"We sought for nothing," continues Voltaire, "in this delicious retreat, except to cultivate our understandings, without taking any trouble to inform ourselves about what was passing in the rest of the world. Our chief attention for a long time was given to Leibnitz and Newton. Madame du Chatelet at first attached herself to Leibnitz, and gave an explanation of a part of his system in a work written with great ability, which she called 'Institutions de Physique.' She did not seek to decorate this philosophy with ornaments foreign to its nature; no such affectation belonged to the character of her mind, which was masculine and true. Clearness, precision, and elegance were the constituents of her style. If it has ever been found possible to give any plausibility to the notions of Leibnitz, it is in that book that it has been done." The "Institutions de Physique" has received high commendation from the most competent authorities as well as from Voltaire. It is described as "a series of letters, in which the systems of Leibnitz and Newton are explained in a familiar style, and with a degree of knowledge of the history of the several opinions, and of sound language and ideas in their discussion, which we read with surprise, remembering that they were the production of a Frenchwoman, thirty years of age, written very few years after the introduction of the Newtonian philosophy into France. She takes that intermediate view between the refusal to admit the hypothesis of attraction and the assertion of it as a primary quality of matter, from which very few who consider the subject would now dissent. At the end of the work is an epistolary discussion with M. de Mairan, on the principle of _vis viva_--the vital energy, the metaphysical part of which then created much controversy." Her translation of Newton's "Principia" was published at Paris in 1759. It stands so high that it has been used by Delambre in his "History of Astronomy," whenever he has to make a quotation from Newton. Madame du Chatelet had been dead for ten years when the work appeared. Her life is supposed to have been shortened by her close application in preparing it, and she died at the age of forty-three. LADY HUNTINGDON. [BORN 1707. DIED 1791.] ISAAC TAYLOR.