Displacement Interferometry By The Aid Of The Achromatic Fringes, Part 4 (1919) : Kessinger Publishing : 9781168046802 : 1168046807 : 10 Sep 2010 : ""Displacement Interferometry By The Aid Of The Achromatic Fringes, Part 4"" is a scientific book authored by Carl Barus, which was first published in 1919. The book focuses on the concept of displacement interferometry, a technique used to measure small displacements or changes in length, which is achieved by observing the interference fringes produced by a light beam that has passed through a pair of closely spaced mirrors. The book is the fourth part of a series of publications by Barus on the topic, and it provides a comprehensive analysis of the use of achromatic fringes in displacement interferometry. The author discusses the theory and principles of the technique, as well as the various instruments and methods used to achieve accurate measurements.The book is written in a technical style, with a heavy emphasis on mathematical equatio