Benjamin Franklin believed that lightning was a form of static electricity, on a huge scale. In the Kite Experiment, he flew a kite into the storm clouds and conducted electricity down the kite string, attempting to see if an electrical charge was produced.
Robert Brown, a botanist and biologist, discovered brownian movement by accident, when he was looking at a sample of suspended pollen grains under a microscope. This discovery led to a series of important physics experiments.
J.J. Thomsons Cathode Rays
J.J. Thomson's innovative cathode ray experiment greatly contributed to our understanding of the modern world. It improved our understanding on magnetism and atoms and was a great example of slowly building a theory.