Mathematicians Of The Day

28th September

On this day in 1695, after fitting several comets data using Newton's proposal that they followed parabolic paths, Edmund Halley tested his own measurements of the 1682 comet against an elliptical orbit. He wrote to Newton,
I am more and more confirmed that we have seen that Comet now three times since the year 1531.

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Quotation of the day

From Ismael Boulliau
As for the power by which the Sun seizes or holds the planets, and which, being corporeal, functions in the manner of hands, it is emitted in straight lines throughout the whole extent of the world, and like the species of the Sun, it turns with the body of the Sun; now, seeing that it is corporeal, it becomes weaker and attenuated at a greater distance or interval, and the ratio of its decrease in strength is the same as in the case of light, namely, the duplicate proportion, but inversely, of the distances that is, 1d2\Large\frac {1}{d^2}.