Phenomena of induction by currents, by magnets. Phenomena of magnetism in motion. Induction of a current upon itself. Induction of different orders. Interrupted currents. Clarke’s machine. LESSON 11.   5. _Calorific Properties._ Influence of the nature of the interposed conductor; of its section; of the intensity of the current. Unequal temperatures at the different junctions of a heterogeneous circuit. 6. _Luminous Properties._ Incandescence of solid conductors. Spectrum of the electric light. Voltaic arc. Transfer of ponderable matter. Action of the magnet upon the Voltaic arc. 7. _Physiological Action of Currents._ Some words on this subject. Muscles and nerves. Actions of discontinuous currents. Reotomic contrivances. _Reometry._ Compass of sines, of tangents. Experimental graduation of galvanometers. The dynamical intensity of a current diminishes when the length of a current increases. Reostat. Laws of the dynamical intensity of a current in a homogeneous circuit. Reduced length and resistance of a circuit. Specific co-efficients of resistance. Laws of the dynamic intensity of a current in a heterogeneous circuit. The intensity of currents is in the inverse ratio of the total reduced length, and proportional to the sum of the electromotive forces. Formula of the pile. Discussion of the case of hydro-electric piles-- thermo-electric piles. Conditions for the construction of a pile, with reference to the effects to be produced. Conditions for the construction of a galvanometer with reference to its intended application. Laws of secondary currents in the simplest cases. The chemical intensity of a current is proportional to its dynamical intensity. ACOUSTICS. LESSONS 12-15. Noise, sound, quality of the sound, pitch, intensity, _timbre_. A state of vibration in a solid, liquid, or gaseous body is accompanied with the production of sound. The pitch depends on the number of vibrations. Unison. Instruments for counting the vibrations:--1st. Graphic method. 2nd. Toothed wheels. 3rd. Lever. Feeling of concord. Musical scale. Gamut. Limit of appreciable sounds. Study of vibrating motions in solids. Vibrating cords. Vibrations transversal, longitudinal. Experimental laws. Sonometer. Spontaneous division of a cord into segments. Fundamental sounds. Harmonic sounds. Straight and curved rods. Transversal and longitudinal vibrations. Experimental laws. Division into segments. Nodes. Ventral segments. Membranes. Plane and curved plates. The vibrations divide them into “_concamerations_.” Nodal lines. Harmonic sounds. Study of the vibrations in liquids and in gases.