The fourth edition of this highly readable and well-received book presents the subject of measurement and instrumentation systems as an integrated and coherent text suitable for a one-semester course for undergraduate students of Instrumentation Engineering, as well as for instrumentation course/paper for Electrical/Electronics disciplines. Modern scientific world requires an increasing number of complex measurements and instruments. The subject matter of this well-planned text is designed to ensure that the students gain a thorough understanding of the concepts and principles of measurement of physical quantities and the related transducers and instruments. This edition retains all the features of its previous editions viz. plenty of worked-out examples, review questions culled from examination papers of various universities for practice and the solutions to numerical problems and other additional information in appendices. NEW TO THIS EDITION Besides the inclusion of a new chapter on Hazardous Areas and Instrumentation (Chapter 15), various new sections have been added and existing sections modified in the following chapters: Chapter 3 Linearisation and Spline interpolation Chapter 5 Classifications of transducers, Hall effect, Piezoresistivity, Surface acoustic waves, Optical effects (This chapter has been thoroughly modified) Chapter 6 Proximitys sensors Chapter 8 Hall effect and Saw transducers Chapter 9 Proving ring, Prony brake, Industrial weighing systems, Tachometers Chapter 10 ITS-90, SAW thermometer Chapter 12 Glass gauge, Level switches, Zero suppression and Zero elevation, Level switches Chapter 13 The section on ISFET has been modified substantially.