How was parkinson's disease discovered?

The disease is named after a British physician, James Parkinson, who first described it in “An Essay on the Shaking Palsy” in 1817. In Parkinson's disease, nerve cells, also called neurons, in a region of the brain called the substantia nigra begin to malfunction or die, a process called neurodegeneration.

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.