Galileo Galilei

“ To find a beam whose maximum stress has the same value when a constant load moves from one end of the beam to the other. The second problem—the one which Salviati proceeds to solve—is the following: To find a beam in all cross-sections of which the maximum stress is the same for a constant load in a fixed position. ”

“ The “tangent ec” is a line which touches the parabola at c; but the “tangent eb” is the side of the right-angled triangle which lies opposite the angle ecb, a line whose length is proportional to the numerical value of the tangent of this angle. ”

“ Galileo here proposes to employ as a standard of velocity the terminal speed of a body falling freely from a given height. [Trans.]
[* ] In modern mechanics this well-known theorem assumes the following form: The speed of a projectile at any point is that produced by a fall from the directrix. ”