Nicol
Full Name: William Nicol
Achievement: Discovered the prismatic effect of light diffraction.
Born: 1768; Edinburgh, Scotland
Died: September 2, 1851; Edinburgh, Scotland
Field & Discipline: Science; Optics; Geology; Paleontology
Language: English
Father: Unknown
Mother: Unknown
Spouse: Unknown
Siblings: Jean
Children: Unknown
Education: University of Edinburgh, Scotland
Life & Times:
Little is known about Nicol’s early life, and indeed about his early years at Edinburgh University, where he lectured in natural philosophy (general science), because he published nothing until he was fifty-eight.
His first known work was on the structure of crystals. It may have been during this work that around 1815, after learning from Edinburgh stone expert George [taught rock-slicing by] Sanderson*, he developed a new geology technique for examining the structure of crystals and rocks, which involved cementing a geological sample onto a glass plate, then grinding the sample down to extreme thinness, so that he could examine the almost-transparent material with a microscope.
This technique, which made possible the investigation of the innermost structures of rocks and crystals, became known as “thin section,” and is used all over the world today by petrologists. However, it didn’t come into public use till 1851, when Henry [his work publicized by] Sorby* published Nicol’s slides and described the process.
Nicol found that the same technique could be used in studying fossil forms of wood in order to examine the most minute wood cell-structure with a microscope. This made possible the classification of such woods by their cell structures. Nicol’s work in this area was described in detail in “Observations on Fossil Vegetables,” by [his work publicized by] Witham*. Here, again, Nicol didn’t get the recognition due.
Nicol’s fame rests, above all, on his 1828 prism. He split a crystal of calcite spar and cemented the halves together with Canadian balsam. The crystal split any ray of light entering it into two rays.
One (the “ordinary” ray), went straight through the balsam and the rest of the crystal. The other (the ‘extraordinary” ray), was bent by the balsam and emerged from the crystal at an angle to the ordinary ray. This angle was wide enough for the two rays to be used separately.
Key to all this was the fact that the crystal also polarized the light. A ray of normal light is an emission of electromagnetic radiation moving in a certain direction. At right angles to this, in random directions (up, down and sideways) the ray generates electric fields.
Polarization causes all these random right-angle radiations to come together into a single field either sideways to the main ray, or up-and-down. In this form the light is said to be “plane”-polarized.
The value of this effect lies in the fact that when polarized light strikes certain materials the plane of polarization is altered, depending on the material.
Initially, Nicol’s prism was used by the French chemist [his prism used by] Biot* so as to measure the amount of sugar in a solution. The more the plane of the polarized light was rotated, the more sugar was in the solution.
Extra Connections: He disagreed with the fossil views of Alexandre [ disagreed with fossil ideas of] Brongniart*
He fell out with [fell out with] Murchison*
His techniques aided the work of [his work helped] Neilson*
His work was used by German rock expert [his work helped] Kirkel*
His polarization work was influenced by [his polarization work influenced by] Christiaan Huyghens*
Assessment: William Nicol’s discoveries in the study of microscopic analysis and light refraction were the building blocks for the work of many later scientists.
Oneliner: William Nicol, Scots inventor of the Nicol polarizing prism
Bibliography:
- Dictionary of Scientific Biography.