Isaac Newton (1642–1727) is often described as the greatest of all scientific thinkers. He is most famous, perhaps, for having formulated the universal law of gravitation, as well as the laws of motion. However, his interests also included alchemy, theology, mathematics, and the branch of physics known as optics.

Optics is the science of light and how light behaves. Newton conducted optical experiments for several decades before he published Opticks in 1704. His achievement was twofold. He developed a theory of light and then proved his theory through experimentation and observation. Newton’s experimental method was a new approach to science, and it helped to propel scientific investigation into the modern era. Thus, at the very outset of Opticks, he makes clear to the reader that “my design in this book is not to explain the properties of light by hypotheses, but to propose and prove them by reason and experiments. . . .”

The glass prism was indispensable to these experiments. With it, Newton separated natural white light into the spectrum of primary visible colors, which could be refracted to differing degrees and combined again to re-form white light. Opticks was Newton’s statement on the nature and properties of light, but the glass prism extended his discoveries to color.

The prism was an elegantly simple instrument, and the quality of glass used in its manufacture was essential to the success of the experimental process. Glass figured prominently in many aspects of scientific inquiry. Inferior glass could invalidate or even thwart experimentation altogether. Although glass made in 17th-century England was considered to be of a higher quality than that produced elsewhere, Newton, like many of his colleagues, often ground his own glass.

By the time Newton had published Opticks, his stature and authority had peaked, and his accomplishments brought him honors. He was elected president of the prestigious Royal Society in 1703, a position he maintained until his death, and he was knighted by Queen Anne at Cambridge in 1705.

Diane Dolbashian

This essay is part of a series on Treasures in the Rakow Research Library.

Newton, Isaac. Opticks: Or, a Treatise of the Reflexions, Refractions, Inflexions and Colours of Light. Also Two Treatises of the Species and Magnitude of Curvilinear Figures. London: printed for Sam[uel] Smith, and Benj[amin] Walford, printers to the Royal Society, at the Prince’s Arms in St. Paul’s Church-yard, 1704.

Published on January 6, 2014