[Article] Popular exposition of some scientific experiments. Part III.–Things that are invisible.–The nature of sight.–Visual deceptions Adjust Share By John William Draper, This article is only available as a PDF to subscribers. Download PDF Tags 19th century Fraunhofer lines Hallucinations and illusions Optical illusions Religion and science Research United States Vision More from John William Draper The national division The national division Franklin’s place in the science of the last century Adjust Share Close < Previous Issue | View All Issues | Next Issue > May 1877 < Previous Issue | View All Issues | Next Issue > Table of Contents Close