Chapter I: Preface

The chapters composing this book originally appeared as a series of articles in _The Engineer_ during January, February, and March of the current year. The articles were written in the belief that many readers would welcome a clear and full, non-mathematical exposition of the gyroscopic compass, its theory and practical construction. The gyro-compass represents at once the most involved and abstruse and the most important and valuable of all the practical applications to which the gyroscope, so far, has been put. As a navigational instrument it is now in practically universal use in all the chief war navies of the world, and is to-day being adopted by several important representatives of the mercantile marine. Remarkable figures were shown to the author recently which demonstrated that not only was navigation by the gyro-compass much more accurate than by the magnetic compass, but that the increased accuracy reduced the length of the voyage of a mercantile vessel to an extent that resulted in saving a quantity of fuel the value of which on a single trip would go a considerable way towards meeting the extra first cost of the gyro-compass. Bearing these facts in mind the author from the outset endeavoured not only to dispense with mathematics but to avoid introducing anything except the most familiar physical principles and conceptions, for his object was to explain the mode of action of the gyro-compass for the benefit primarily of the navigating officer--naval and mercantile. If some readers should find the treatment in places unduly prolix, the author trusts they will exercise leniency and regard the fault as being caused by the author’s unwillingness to take any risks in expounding a subject, no part of which can be understood incompletely without grave hurt to the understanding of the whole.

T. W. C.

LONDON, _May, 1920_.

CONTENTS

CHAP. PAGE
I. INTRODUCTION 1

II. ELEMENTARY GYROSCOPIC PHENOMENA 4

III. THE GYROSCOPE AND THE ROTATION OF THE EARTH 15

IV. DAMPING THE VIBRATIONS OF THE GYRO-COMPASS 29

V. THE DAMPING SYSTEM OF THE ANSCHÜTZ (1910) COMPASS 42

VI. THE DAMPING SYSTEM OF THE SPERRY COMPASS 52

VII. THE DAMPING SYSTEM OF THE BROWN COMPASS 59

VIII. THE LATITUDE ERROR 65

IX. THE NORTH STEAMING ERROR 71

X. THE BALLISTIC DEFLECTION 81

XI. THE QUADRANTAL ERROR 91

XII. THE ELIMINATION OF THE QUADRANTAL ERROR 107

XIII. CENTRIFUGAL FORCES DURING QUADRANTAL ROLLING 130

XIV. THE ANSCHÜTZ (1910) COMPASS 138

XV. THE SPERRY COMPASS 142

XVI. THE BROWN COMPASS 148

XVII. THE ANSCHÜTZ (1912) COMPASS 154

INDEX 165

LIST OF ILLUSTRATIONS

FIG. PAGE
1. Model gyroscope with three degrees of freedom 4

2. Model gyroscope with three degrees of freedom 7

3. Model gyroscope, frictional transmission of turning moment 9

4. Model gyroscope, one degree of freedom lost 11

5. Model gyroscope, second degree of freedom lost 12

6. Model gyroscope, lost degrees of freedom restored 13

7. Elementary gyroscope at equator 15

8. Gyroscopic clock 16

9. Elementary gyro-compass 18

10. Elementary compass at equator 20

11. Elementary compass at 55 deg. N. Lat. 24

12. Compass at equator and near North Pole 26

13. Pendulum and compass 32

14. Damped and undamped vibrations 35

15. Damped pendulum 37

16. Air-blast damping system of Anschütz (1910) compass 43

17. Free and damped motion of axle 49

18. Damping curve from Anschütz (1910) compass 50

19. Damping system of Sperry compass 53

20. Action of excentric pin in Sperry compass 55

21. Action of excentric pin in Sperry compass 57

22. Gyro-pendulum with axle tilted 60

23. Damping system of Brown compass 62

24. The north steaming error at 0 deg. and 60 deg. N. 72

25. Sperry correction mechanism for latitude and north steaming
errors 76

26. Ballistic force on compass when ship’s speed changes 83

27. Ballistic force on compass when ship’s speed changes 84

28. Ballistic deflection 86

29. Effect of rolling on due north course 93

30. Effect of rolling on due west course 94

31. External gimbal mounting 97

32. Effect of rolling on a due north course (simple
mounting) 98

33. Effect of rolling on a due north course (external gimbal
mounting) 99

34. Ship rolling on N.W. course 101

35. Sperry compass on N.W. course 108

36. Sperry ballistic gyro 111

37. Stabilised excentric pin (Sperry compass) 112

38. Diagram of Brown compass 113

39. Oil control bottles (Brown compass) 115

40. Brown compass on west course 117

41. Diagram of Anschütz (1912) compass 121

42. Plans of gyros (Anschütz compass) 122

43. Centrifugal forces on a pendulum 131

44. The Anschütz (1910) compass 139

45. The Sperry compass removed from binnacle 143

46. The Sperry compass 144

47. The Brown compass removed from binnacle 148

48. The Brown compass removed from binnacle 149

49. The Brown compass 150

50. Plan of Anschütz (1912) compass 155

51. Sectional elevation of Anschütz (1912) compass 159

THE GYROSCOPIC COMPASS:

A NON-MATHEMATICAL TREATMENT