23 
action of current ; electro-plating, &c. ; light and heat produced 
by the current ; connection between heat and resistance ; induced 
currents ; measurement of electric currents ; laws of Ohm ; the 
electric telegraph. 
IY. One Lecture on Diamagnetism and the Magnetic Proper- 
ties of Crystals . 
V. Two Lectures on the Mechanical Properties of A ir and 
Water . — Constitution of gases ; pressure of the atmosphere ; 
Magdeburgh hemispheres ; experiments with the air-pump ; the 
common pump ; law of Mariotte ; hydrostatic bellows ; hydrostatic 
press; hydraulic ram ; cohesion of water ; deviation of projectiles 
in air. 
YI. Four Lectures on Sound . — Mode of generation and propa- 
gation ; velocity through various media ; echoes ; noise and 
music ; musical notes of strings, plates, and tubes ; longitudinal 
and transverse vibrations ; modes of vibration rendered visible ; 
cause of harmony ; the gamut ; harmonic division of strings and 
tubes ; resonance ; interference of sound; singing flames. 
VII. Eight Lectures on Light — Velocity and intensity of light, 
how measured ; reflection and refraction ; action of lenses ; sphe- 
rical aberration ; the eye and vision ; principle of the stereoscope ; 
irradiation ; composition of light ; the solar spectrum ; electric 
spectra ; absorption of light ; doctrine of colours ; chromatic 
aberration ; optical instruments ; theories of emission and undu- 
lation ; analogies with sound; interference of light; colours of 
iridescent films ; Newton's rings ; diffraction ; polarization of 
light, by reflection, refraction, and by its passage through crys- 
tals ; chromatic effects ; effects of heat, strain, pressure, and 
magnetism on transparent media. 
VIII. Eight Lectures on Heat. — Principle and construction of 
thermometers ; expansion of bodies by heat ; exceptions to this 
law ; conduction and convection ; boiling points ; specific heat ; 
latent heat ; evaporation, condensation, congelation ; spheroidal 
state ; heat regarded as a mode of motion ; radiant heat ; modes 
of measurement ; the air thermometer ; the thermo-electric pile ; 
reflection, refraction, and polarization of heat ; diathermancy 
doctrine of thermal colours ; terrestrial radiation and its effects. 
