This book contains 5 main chapters. The first chapter is an INTRODUCTION to the temperature scales and the fog behavior in the fogging system. The second chapter is a LITERATURE REVIEW to the temperature measuring devices and the previous work , which done in the field of measuring the dry bulb temperature. The third chapter is the EXPERIMENTAL SETUP and the detailed explanation of the design and the working idea of the designed devices. The fourth chapter is the RESULTS AND DISCUSSION of all data taken by the experiments on the designed devices. The final fifth chapter is the CONCLUSIONS AND RECOMMENDATIONS for the work. Also, this book contains a brief summary about the work in the beginning of the book,a list of references contains the references used in the work after the five chapters, finally the appendices which contains the devices' design calculations, the data tables and the thermocouples' calibration.