About David Rittenhouse:
David Rittenhouse was a renowned American astronomer, inventor, clockmaker, mathematician, surveyor, scientific instrument craftsman and public official. Rittenhouse was a member of the American Philosophical Society and the first director of the United States Mint.
For the greater beauty of the instrument, the balls representing the planets are to be of considerable bigness; but so contrived, that they may be taken off at pleasure, and others, much smaller, and fitter for some purposes, put in their places.David Rittenhouse
In order to know the true situation of a Planet at any particular time, the small set of balls are to be put each on its respective axis; then the winch to be turned round until each index points to the given time.David Rittenhouse