Davy, Sir Humphry, appointed professor at the Royal Institution,
174;
letter of, to Faraday, 244.
Declaration of American Independence signed, 113.
Defence of the American Colonies against France and Spain, 62.
Degree of electrification, 137.
De la Rive's invitation to Faraday, 249.
Density of the earth, determinations of the mean, 146.
Desaguliers on electrics and non-electrics, 4.
Diagram of colour, Young's, 215;
Maxwell's, 295.
Diamagnetism discovered by Faraday, 274.
Diamonds burned by Davy, 250.
Dichroism of _Lignum nephriticum_, 30.
Discharge, electrical, difference between positive and negative, 87.
Dissipation of energy, principle of, 326.
Distilled water, resistance of, 142.
Double refraction explained by Huyghens, 219.
Dufay showed that all bodies could be electrified, 4.
Dynamical nature of heat, suggested by Bacon, 2, 32;
maintained by Boyle, 32;
investigated by Rumford, 189;
established by Joule, 193, 324.
Dynamical top, Maxwell's, 285.
Dynamo, constructed by Wheatstone, 318;
action of, 319;
essential feature of, 319.