Robert Edward Anderson, Dictionary of National Biography… (1890)
“ In 1824, when only a second year's student, Hamilton read before the Royal Irish Academy a 'Memoir on Caustics,' and being invited to develop the subject, he some time after produced a celebrated paper on systems of rays, and predicted 'conical refraction.' Applying the laws of optics he proved that under certain circumstances a ray of light passing through a crystal will emerge not as a single or double ray but as a cone of rays. ”
