John Philoponus, Nicole Oresme, and Domingo de Soto
That unequal weights would fall with the same speed may have been proposed as early as by the Roman philosopher Lucretius.[195] Observations that similarly sized objects of different weights fall at the same speed are documented in sixth-century works by John Philoponus, of which Galileo was aware.[196][197] In the 14th century, Nicole Oresme had derived the time-squared law for uniformly accelerated change,[198][199] and in the 16th century, Domingo de Soto had suggested that bodies falling through a homogeneous medium would be uniformly accelerated.[200] De Soto, however, did not anticipate many of the qualifications and refinements contained in Galileo's theory of falling bodies. He did not, for instance, recognise, as Galileo did, that a body would fall with a strictly uniform acceleration only in a vacuum, and that it would otherwise eventually reach a uniform terminal velocity.
Delft tower experiment
In 1586, Simon Stevin (commonly known as Stevinus) and Jan Cornets de Groot dropped lead balls from the Nieuwe Kerk in the Dutch city of Delft. The experiment established that objects of identical size, but different masses, fall at the same speed.[37][201] While the Delft tower experiment had been a success, it was not conducted with the same scientific rigour that later experiments were. Stevin was forced to rely on audio feedback (caused by the spheres impacting a wooden platform below) to deduce that the balls had fallen at the same speed. The experiment was given less credence than the more substantive work of Galileo Galilei and his famous Leaning Tower of Pisa thought experiment of 1589.