International Encyclopaedia of Science and Technology is an outstanding attempt to keep pace with recent developments and expanding vocabularies in all branches of science and technology. This encyclopaedia is more or less encyclopaedic in its contents and style of representation. Throughout the process of compilation a sincere effort has been made to include all those entries which serve as a ready reference for undergraduate and postgraduate students of science, technology and engineering. This may also prove useful for those appearing for competitive examinations, research scholars, teachers and authors. The entries included in this set have been written in a clear and elegant style to provide both straight forward definition and invaluable background information. At certain suitable places the line diagrams have been included wherever the meaning of a term can be best conveyed by means of a diagram. An extensive cross reference system makes the reader to place the each entry into a broader scientific context. The main aim maintained in compiling this set is to sustain the interests of readers while enriching their vocabulary and comprehension of technical terms and expressions of various branches of science. This set will prove to be of immense value to the students of science and engineering, and to scientists, technologists and research scholars working on science projects. It is expected that many readers will use this set not merely for reference but also as a readable material. The editing of this set has been based on the vast research and teaching experience of editors who have been actively engaged in the different aspects of science and technology. Their valuable experience has been carefully' condensed in compiling this set.