CONTENTS. 



Part I. 



Page 



Introduction 3 



Detailed description of the bicycle ergometer 5 



General considerations regarding method of use 7 



Method of calibration 9 



Part II. 



Calibration tests 11 



The technique of a calibration experiment 12 



Calibration tests of Ergometer I 14 



Earlier calibration tests 14 



Calibration tests of 1911 15 



Friction tests with Ergometer I 21 



Calibration tests of Ergometer II 22 



Friction tests with Ergometer II 29 



Part III. 



The magnetic reactions produced by a copper disk rotating between the poles 



of a magnet 31 



Measurement of magnetic field by means of a bismuth spiral 33 



Comparison of results with theory 37 



Further experiments with the eddy currents 39 



Influence of temperature on the constancy of the bicycle ergometer 42 



The design of electric brakes 42 



ILLUSTRATIONS. 



Page 

 Fig. 1. Side and top views of Ergometer II 5 



2. Electro-magnet and copper disk of Ergometer II 6 



3. Scheme for calibration of the ergometer in a respiration chamber 13 



4. Heat per revolution of Ergometer I for currents of 0.7 and 0.8 ampere 



through the field 18 



5. Calibration curve of Ergometer I for magnetizing current of 0.9 ampere. 19 



6. Calibration curve of Ergometer I for magnetizing current of 1.1 am- 



peres 19 



7. Calibration curve of Ergometer I for magnetizing current of 1.25 



amperes 20 



8. Calibration curves of Ergometer I for magnetizing current of 0.7 to 1.25 



amperes 21 



9. Calibration curve of Ergometer II for magnetizing current of 0.95 



ampere 24 



10. Calibration curve of Ergometer II for magnetizing current of 1.10 



amperes 24 



11. Calibration curve of Ergometer II for magnetizing current of 1.35 



amperes 25 



12. Calibration curve of Ergometer II for magnetizing current of 1.50 



amperes 26 



13. Calibration curves of Ergometer II for magnetizing current of 1.25 



amperes 27 



14. Calibration curves of Ergometer II for magnetizing current of 0.95 to 



1.50 amperes 28 



15. Magnetic induction across the air-gap 35 



16. Magnetic lines and current loops on surface of rotating disk 40 



iii 



