I have read, and seen it claimed in another old thread, that Galileo was the first to measure the free fall acceleration near earth's surface. I have not found any source that explains how he did so or what his result was. I've skimmed through most of his Discorsi and have not seen it there. In K. Simonyi's A Cultural History of Physics the author claims that Galileo's measurement was 5m/s2, but does not give the explicit source for this (only saying that "in his single surviving note, the numerical value for the terrestrial acceleration is quite far (5m/s2) from the correct value, which is difficult to reconcile with his painstaking process of measurement." Does anybody know what 'note' that might be or know of any other resource that gives more information? If it is somewhere in the Discorsi and I have overlooked it would you please direct me to the page number?