American Scientist

To the Editors:

In “Herschel and the Puzzle of Infrared” (May–June 2012), Jack White mentions that it is not known who coined the term “infrared.” This mystery caught my attention. A Google Books search for “infra-red” finds two articles published in April 1874, both of which use the term in the context of Edmond Becquerel’s treatise on light. In that work, La Lumière (1867, vol. 1, p. 141), the French infra-rouge is used. One of the articles appeared in The Photographic News for Amateur Photographers (18:176), and is by M. de St. Florent; the other is uncredited but appeared in The British Journal of Photography (21:160) and is attributed to de St. Florent elsewhere in the volume. I have not been able to trace de St. Florent’s full name, but he published contemporaneously in Bulletin de la Société française de photographie. This author appears to be the coiner of “infra-red,” having translated it from French.

There are two curious sidelights to this story: Becquerel was the father of Henri Becquerel, for whom the unit of radioactivity was named; and the term “ultraviolet” was coined by William Herschel’s son John Herschel in 1840.

Gary Rosenberg
Academy of Natural Sciences
Drexel University
Philadelphia, PA

Mr. White responds:

Gary Rosenberg did some very nice Internet detective work pushing the earliest known usage of the word “infrared”—or the French “infra-rouge”—back at least into the 1860s. Becquerel uses “infra-rouge” casually and frequently, which likely indicates the term was in common usage at that time. I would consider “infrared,” “infra-rouge,” and the German “infra-rot” as equivalent and give credit to the first usage in any of those forms.

My mention of the 1880s in the article came from E. S. Barr’s 1960 article in the American Journal of Physics, in which he wrote:

In an 1873 paper, Abney refers to “ultra red,” but in another in 1881 he used the term “infra-red.” It is a matter of personal vexation that I have not been able to determine the exact origin of the modern term!

This article is well researched and I recommend it highly, but it was written in the dark ages before the Internet. Rosenberg’s find is a reminder of the Internet’s amazing, growing power to search original works in different languages.