Robert Hooke and Gustav Robert Kirchhoff, both physicists, asserted that light travels as waves. The debate had been running since the debates between Robert Hooke and Isaac Newton began via the Royal Society of London.
Hooke used the principle of diffraction to show that sound could bend around corners in 1672, therefore acting as a wave. Kirchhoff worked with Bunsen to found the field of spectrum analysis. He measured distinct characteristics of elements via light waves and discovered two new elements in 1860 and 1861. Both men used the measurements of the observable spectrum of light as the light passed through a prism.