He began a career in medicine, but could not stand the sight  of blood, and turned to physics after hearing of Daguerre's  discovery of photography. Prior to dying of paralysis at the age  of 48, he discovered the yellow lines in emission spectra, worked  with Fizeau on the toothed-wheel experiment, and used Arago's  equipment to show that light moves slower in water than 
He began a career in medicine, but could not stand the sight  of blood, and turned to physics after hearing of Daguerre's  discovery of photography. Prior to dying of paralysis at the age  of 48, he discovered the yellow lines in emission spectra, worked  with Fizeau on the toothed-wheel experiment, and used Arago's  equipment to show that light moves slower in water than in air.  FTP, identify this French physicist, the inventor of the gyroscope  who measured the rotation of the earth with his pendulum.
He began a career in medicine, but could not stand the sight  of blood, and turned to physics after hearing of Daguerre's  discovery of photography.
Jean Bernard Leon {Foucault}