I. Experiments concerning the nature of air : Pressure of the hands ; The air of the punctured ball, of the tube, and of the pump ; The making of air and the movement of projectiles ; Centrifugal force.
II. The origin of wind and breath : The formation of wind ; Breathing.
III. Movement of the clouds and the heavenly bodies : The movement of clouds ; The movement of the heavenly bodies.
IV. Water currents and movements due to weight : The waves of the lake ; The current of rivers ; The suspension of the sun and moon, and the fall of heavy bodies to the ground.
V. The child's idea of force : How the child explains movement ; Definition of the idea of force ; 3. Origin of the idea of force.
VI. The floating of boats : The first and second stages: boats float for moral or dynamic reasons ; Third stage: boats float owing to their own or to acquired movement and because they are light in relation to the total mass of the water ; Boat float for static reasons.
VII. The level of water : First stage: the water rises because of the weight of the submerged body ; Second and third stages: the role of volume is understood and made explicit ; Conclusions ; Prediction and explanation of the phenomenon of communicating vessels in children from 8 to 12 years old.
VIII. The problem of shadows : First stage: shadow is a substance emanating from the object and participating with night ; Second stage: shadow is a substance emanating from the object alone ; Third stage: shadow is a substance which flees from light ; Conclusions.
IX. The mechanism of bicycles : First stage: the cause of the movement is synthetic ; Second stage: the various parts are necessary but unrelated ; Third and fourth stages: the search for contacts and mechanical explanation.
X. The steam-engine : First stage: the wheel turns because of the fire ; Second stage: the wheel turns because of the water ; Third stage: the wheel turns because of the steam.
XI. Trains, motor-cars, and aeroplanes : Steam-engines and motor-boats ; Motor-cars and aeroplanes ; Conclusions.