The world at the time was a Ptolemaic World. The then current explanation for these fast and slow motions was that the circular orbit of the sun about the earth was eccentric, that the earth was not in the exact center of the sun's orbit. The first English publication to detail and illustrate the Copernican system was by Thomas Digges in 1576. It was, however, of no practical use to the navigator. When Edward Wright published his "amended" tables of solar declination in 1599, he based it on his observations with a 6 1/2-foot quadrant. The actual number of noon observations he was able to make in the course of a year in English weather was only about eighty. For the remaining days, it was necessary to interpolate the declinations. In doing so, however, he would have been interpolating for an elliptical system as if it were a circular one.