Lettres a une Princesse d'Allemagne sur..Physique et de Philosophie, (3 vols.) by Leonhard Euler - 1775-1778

Leonhard Euler - Lettres a une Princesse d'Allemagne sur..Physique et de Philosophie, 3 vol., 3rd edition in French, 8vo, vol.1 Chez la Société Typographique, "Londres" [?Paris] 1775, vol.2 & 3 Chez la Société Typographique, Berne,1778 These volumes contain the series of 234 letters written by Euler between 1760 and 1762 addressed to Friederike Charlotte of Brandenburg-Schwedt and her younger sister Louise, to present explanations of science and mathematics in an educational form. For example, he began the first letter with an explanation of the concept of "size". Starting with the definition of a foot, he defined the mile and the diameter of the earth as a unit in terms of foot and then calculated the distance of the planets of the Solar System in terms of the diameter of the earth. Euler published the letters with the encouragement of his patroness, Catherine the Great. The first two volumes in French appeared in print in Saint Petersburg in 1768 and the third in Frankfurt in 1774. The letters were later reprinted in Paris. This set represents the third edition in French. The titles have woodcut ornaments. There are 19 folding engraved plates. In contemporary pink paste-paper boards, a little rubbed, spines are slightly faded. The books are protected in clear plastic covers in a modern custom cloth slip-case, and are in very good+ condition for their age. Vol. 1 – viii, 309 pp., 4 foldout plates, a small stain at the upper edge of the first few leaves but otherwise very good+ Vol. 2 – viii, 315 pp., 4 foldout plates, Very good+ Vol. 3 – x, 351 pp. , 11 foldout plates, a small crack at the top of the spine. Plate 7 is lacking a small portion of the upper outer edge just touching the image (repaired), otherwise very good. Early editions such as this are uncommon. A very attractive set, very well preserved. The Swiss mathematician Leonhard Euler (1707-1783) is considered one of the greatest mathematicians in history and the greatest of the 18th century. He was a physicist, astronomer, geographer, logician and engineer, who founded the studies of graph theory and topology and made pioneering and influential discoveries in many other branches of mathematics, including analytic number theory, complex analysis, and infinitesimal calculus. He introduced much of modern mathematical terminology and notation, including the notion of a mathematical function. He is also known for his work in mechanics, fluid dynamics, optics, astronomy and music theory. The great French mathematician, Pierre-Simon Laplace, is often quoted as having once said "Read Euler, read Euler, he is the master of us all." The eminent German mathematician, Carl Friedrich Gauss remarked: "The study of Euler's works will remain the best school for the different fields of mathematics, and nothing else can replace it." Euler is also widely considered to be a most prolific author; his 866 publications, as well as his correspondences are collected in the Opera Omnia Leonhard Euler which, when completed, will consist of 81 quarto volumes. He spent most of his adult life in Saint Petersburg, Russia, and in Berlin, then the capital of Prussia. His influence on other mathematicians was such that he essentially standardized modern mathematical notations. For example, he is credited for establishing the Greek letter π to denote the ratio of a circle's circumference to its diameter, as well as first using the notation f(x) for the value of a function, the letter i to express the imaginary square root of -1, the Greek letter Σ to express summations, the Greek letter Δ for finite differences, and lowercase letters to represent the sides of a triangle while representing the angles as capital letters. He also defined the constant e, the base of the natural logarithm, which is now known as "Euler's number". He was also the first practitioner of graph theory (partly as a solution for the problem of the Seven Bridges of Königsberg). He became famous for, among many other accomplishments, solving the Basel problem, after proving that the sum of the infinite series of squared integer reciprocals equaled exactly π2/6, and for discovering that the sum of the numbers of vertices and faces minus edges of a polyhedron equals 2, a number now commonly known as the Euler characteristic. In the field of physics, Euler reformulated Newton's laws of physics into new laws in his two-volume work Mechanica to better explain the motion of rigid bodies. He also made substantial contributions to the study of elastic deformations of solid objects.