De la Rive electric egg Demonstration apparatus for Hertz's experiments Densimeter Despretz - d'Arsonval galvanometer Despretz's apparatus for the propagation of the heat Direct vision spectroscope Double cone with inclined plane Double cylinder for the Archimedean principle Drum armature with bipolar winding Duhamel's cylinder Dutch tears Dutrochet's endosmometer Dynamo-electric machine Dynamometer