The rare edition of XVIII is "Lettres à une Princesse d'Allemagne sur divers sujets de physique et de philosophie. Tome Second. Year of publication: 1768 Place of publication: St. Petersburg, printing house of the Imperial Academy of Sciences Language: French Description: The second part of the famous scientific work addressed to the German princess. The book contains letters with discussions of physical and philosophical issues of the Enlightenment. The publication, published in St. Petersburg, has historical and collectible value due to its origin and high scientific level. Ideal for collectors of rare books, antique literature and materials of the Enlightenment. Letters to the German princess on various topics of physics and philosophy. «Lettres à une princesse d'Allemagne sur divers sujets de physique et de philosophie») - This is a collection of 234 letters. It was written by the eminent mathematician and physicist Leonard Euler between 1760 and 1762. The recipients of these letters were Princess Frideric Charlotte of Brandenburg-Sweden and her younger sister Louise. Contents of the book: In his letters, Euler sought to explain complex scientific concepts in accessible language. He discussed a wide range of topics, including: Fundamentals of Physics and Mechanics Astronomy and structure of the solar system Optics and nature of light Philosophical Reflections on Nature and Knowledge The first letter begins with a discussion of the concept of "size", where Euler defines units such as foot and mile, and then goes on to discuss the size of the Earth and the distances to the planets of the solar system. Publication and translations: The first two volumes of the letters were published in French in St. Petersburg in 1768, and the third volume was published in Frankfurt in 1774. The book quickly gained popularity and was translated into many languages, including English, Spanish and German. The first English translation was made by Scottish priest Henry Hunter in 1795. Value: “Letters to the German Princess” is considered an outstanding example of popular science literature of the XVIII century. Euler was able to present complex scientific ideas in an understandable form, which made science more accessible to a wide audience. The book remains an important historical document reflecting the methods of teaching and disseminating scientific knowledge in the Enlightenment.