Thomson's Mouse Mill Dynamo

Abstract

ALLOW me to make a slight but important correction on your description, in last week's NATURE, of Sir William Thomson's mouse-mill dynamo. In your description it is said that “at one end of the hollow drum these copper bars [the mouse-mill bars] are united to each other in pairs, each to the one opposite it.” This is not so. At one end of the hollow drum the ends of the copper bare are all united together, “metallically connected by soldering or otherwise.” The effect is electrically the same as that of the arrangement described in your article; but, in the construction of the machine, the uniting of all the bars together at one end, instead of joining them in pairs, is so much more simple and easy that the correction seems of importance.