When Kepler concluded that the orbit of Mars was not a circle, he was led to the belief that the orbit was an oval touching the circle at the apsides and lying within the circle at other points. In the definition of the oval, physical hypotheses played a primary role. Two forces were involved; a tractive force arising from the effect of the solar rays rotating with the sun, and a directing force arising from a natural instinct of the planet (...) itself. The former pushed the planet along the orbit while the latter enabled the planet to steer itself across the stream of the solar vortex in a small epicycle. In adopting this physical theory to determine the oval, Kepler was led into what he himself described as ‘a new labyrinth’. After several attempts to construct the oval, and by progressively eliminating the sources of error from his calculating procedures in order to arrive at an accurate mathematical formulation of the physical hypotheses, he was able to conclude that the oval was inconsistent with the empirical data and the physical theory in need of modification. (shrink)

When Bouvet discovered the relationship between the binary arithmetic of Leibniz and the hexagrams of the I ching—in reality only a purely formal correspondence—he sent to Leibniz a woodcut diagram of the Fu-Hsi arrangement, which provides the key to the analogy. This diagram, in a re-drawn version, was first published by Gorai Kinzō in a study of Leibniz's interpretation of the I ching and Confucianism which has been influential in providing, indirectly, the principal source for the accounts of Wilhelm and (...) Needham. Yet this pioneering study of Leibniz's interpretation of the hexagrams is virtually unknown. Even the account of Needham, who saved it from complete obscurity, contains one or two inaccuracies about it and these are repeated by Zacher in his otherwise excellent monograph on Leibniz's binary arithmetic. (shrink)

Soon after receiving Bouvet's interpretation of the hexagrams of the I ching as binary numbers, Leibniz communicated this application of his binary arithmetic to Hans Sloane in a letter published here for the first time. The letter also included a report on the observations of the variable star in the neck of the Swan by Gottfried Kirch. Sloane sent a copy of the scientific parts of the letter to Flamsteed.