Snell-Descartes Law/Historical Note

Historical Note on Snell-Descartes Law
made his discovery in $1621$.

was first to publish it, which he did in $1637$. 's own work did not appear until $1703$ when included it in his Dioptrica.

However, it appears that ' own statement was stated incorrectly as $\dfrac {\sin \alpha_1} {\sin \alpha_2} = \dfrac {v_2} {v_1}$, and proved inadequately.

It may well indeed be that himself learned it from, who now generally holds the credit for its discovery.

It needs to be noted that this law had previously been discovered by several other scientists, including in $984$ and  in $1602$.

In France this law is called la loi de Descartes or loi de Snell-Descartes, while elsewhere it tends to be known as Snell's law, or Snell's Law of Refraction.