CONTENTS 

 PART II: PRACTICE 



19 Batteries 283 



20 Resistors 291 



21 Capacitors 297 



22 Chokes and Transformers 305 



23 Non-thermionic diodes 315 



24 Valves 319 



25 Sundries 321 



26 Forms of Mechanical Construction 327 



27 Tools and Workshop Facilities 329 



PART III : TRANSDUCERS, ELECTRODES AND INDICATORS 



28 Light Sources and Detectors 333 



F. W. Campbell 



29 Measurement and Control of Temperature 383 



/. W. L. Beament 



30 Measurement and Control of Humidity 413 



/. W. L. Beament 



31 Assay of Radioactivity 419 



R. D. Keynes 



32 Visual Indicators 446 



P. E. K. Donaldson 



33 Transducers 471 



K. E. Machin 



34 Relays and Related Mechanisms 510 



K. E. Machin 



35 Glass Microcapillary Electrodes used for Measuring 534 



Potential in Living Tissues 

 D. W. Kennard 



36 Other Electrodes 568 



/. A. Silver 



vi 



