In 1638, Galileo tried to determine the speed of light.
His method was quite simple. He and an assistant each had lamps which could be covered and uncovered at will. Galileo would uncover his lamp, and as soon as his assistant saw the light he would uncover his.
By measuring the elapsed time until Galileo saw his assistant’s light and knowing how far apart the lamps were, Galileo reasoned he should be able to determine the speed of the light.
His conclusion: “If not instantaneous, it is extraordinarily rapid”.
That was just a great time to be a scientist. You could do cutting edge research with everyday things like lanterns and copper wire and corks and apples and kites and stuff.