CONTENTS 



CHAPTER IV 



OBSERVATIONS OF CERTAIN MUTUAL CHANGES, COMMON TO 

 ALL KINDS OF MATTER 



PAGE 



36. Bodies displaced equally from the earth, reach it again simul- 



taneously, if allowed to fall 52 



37. Time of fall . 53 



38. A body returns to the earth with a uniformly accelerated 



speed in a straight line 53 



39. Meaning of term ' force ' 54 



40. The moveable pulley 55 



41. The lever 56 



42. The pressure of liquids . . 58 



43. The equilibrium of two liquid columns in communication . 59 



44. The internal stress of liquids 61 



45. The relation between mutual displacements . . . .64 



46. New test for equal quantities of matter ..... 66 

 Additional exercises and questions 68 



CHAPTER V 



OBSERVATIONS OF CERTAIN MUTUAL CHANGES EXHIBITED 

 BY CERTAIN KINDS OF MATTER 



47. Changes observable when certain bodies are rubbed together 



and separated 70 



48. Communication of the property to other bodies . . .71 



49. Investigation of the electric field ...... 71 



Additional exercises and questions 73 



50. Existence of electric stress indicated by the electroscope . 73 



51. The quadrant electrometer . 74 



52. Exploration of the electric field by two discs . . . .77 

 Additional exercises and questions 78 



53. Electric phenomena produced by another method . . .79 



54. Processes by which electric equilibrium is effected . . .80 



55. An eiectric circuit, conditions necessary for . . . .81 



56. The existence of magnetic stress indicated . . . .82 



57. Deflection of a magnet by a substance forming part of an 



electric circuit 84 



58. Construction of a galvanometer 85 



59. Meaning of conductivity 86 



