It is known that objects observed through transparent materials have their images shifted from their original position. The experience of the coin hidden in the bottom of the container and which becomes visible with the placement of a certain amount of water inside it is a common example. What few people know is that this procedure would have been described by Ptolemy in the second century when he presented his method of analyzing the phenomenon of refraction in his book of Optics, one of the oldest books in the history of physics. We present in this work the Ptolemy's method and discuss a quantitative variation of its procedure: we determine the degree of curvature that the boundary between two transparent materials produces in the image location of an object and we establish the mathematical relationship between its real angular position and the corresponding angle of curvature.
Keywords:
Refraction; experiment; scientific method; Ptolemy
