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Vitruvian Man by Leonardo da Vinci (circa 1487)

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“Then again, in the human body the central point is naturally the navel. For if a man be placed flat on his back, with his hands and feet extended, and a pair of compasses centred at his navel, the fingers and toes of his two hands and feet will touch the circumference of a circle described therefrom. And just as the human body yields a circular outline, so too a square figure may be found from it. For if we measure the distance from the soles of the feet to the top of the head, and then apply that measure to the outstretched arms, the breadth will be found to be the same as the height, as in the case of plane surfaces which are perfectly square.” - De Architectura, Vol 3.Unlike earlier depictions of the “Vitruvian Man”, in Leonardo’s version, the center of the circle and the center of the square do not coincide.

When the legs are spread and the arms are lifted, can you estimate how much would the center-of-gravity would move?

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Center-of-gravity for the human body is located below the navel.3

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Vitruvius

1st century BC. Roman writer, architect, engineer.

Wrote De Architectura - Ten Volumes on Architecture.

Dedicated to Caesar Augustus, heir to the famous Julius Caesar…

Lunar crater Vitruvius

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Volume 7, Chapter 8

“If the quicksilver is poured into a vessel, and a stone weighing one hundred pounds is laid upon it, the stone swims on the surface, and cannot depress the liquid, nor break through, nor separate it. If we remove the hundred pound weight, and put on a scruple of gold, it will not swim, but will sink to the bottom of its own accord. Hence, it is undeniable that the gravity of a substance depends not on the amount of its weight, but on its nature.”http://www.gutenberg.org/files/20239/20239-h/29239-h.htm#Page_215

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Brahe - Kepler

Kepler’s Laws: elliptical orbits, sweep equal areas in equal times, T2∝a3

1609-1619

Copernicus, 1543: De revolutionibus orbium

coelestium6

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http://astro.unl.edu/naap/pos/animations/kepler.swf7

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Hooke-Wren-Halley

1684 - A bet for 40 shillings worth of books.

1675ceiiinosssttuv:

Ut tensio, sic vis

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