Hobbes's model of refraction and derivation of the sine law (Q2029470)

Two examples are given to bolster the historical status of Hobbes' presentations of his derivation of the sine law for refraction of light. The first is a favorable comparison of Hobbes' theory with that of Descartes. The second is an explanation of seeming inconsistencies in Hobbes' presentations. While providing clear and detailed accounts of Hobbes' work, the author's arguments are informed by the larger issues of the time dealing with the relation between mathematics (geometry) and physics. This is exemplified in the comparison of the treatment of motion in Descartes' \textit{Dioptrique} (1637) and Hobbes' first derivation in his \textit{Tractatus opticus} (1640--42). We also see this attention to context when the author suggests that Hobbes' changed view of the meaning of ``mixed mathematics'' can provide a reasonable justification for the anomalies some commentators have observed in the second presentation of his derivation compared with the first.