English philosopher and Franciscan friar Roger Bacon (c. 1219/20 – c. 1292) falsely stated in his "De Multiplicatione Specerium" (1267) that an image projected through a square aperture was round because light would travel in spherical waves and therefore assumed its natural shape after passing through a hole. He is also credited with a manuscript that advised to study solar eclipses safely by observing the rays passing through some round hole and studying the spot of light they form on a surface.