HERSCHEL, WILLIAM. - THE DISCOVERY OF INFRARED RADIATION.

Untersuchungen über die wärmende und die erleuchtende Kraft der farbigen Sonnenstrahlen; Versuch über die nichht-sichbaren Strahlen der Sonne und deren Brechbarkeit; und Einrichtung grosser Teleskope zu Sonnenbeobachtungen.

Halle, Rengerschen Buchhandlung, 1801. Without wrappers as published in "Annalen der Physik. Herausgegeben von Ludwig Wilhelm Gilbert", Bd. 7, Zweites Stück. The entire issue offered (=Heft 2). Pp. 137-264 a. 2 folded engraved plates. Herschels papers: pp. 137-156. The plate depicts Herschel's experimental arrangements.

First appearance in German of Herschel's epochal announcement of his discovery of infrared light in 1800. This was the first time that a form of light beyond visible light had been detected. The paper offered is the German translation of the main parts of Herschel's paper "An Investigation of the Powers of Prismatic Colours to Heat and Illuminate Objects".

"In 1800 he tested various portions of the sun's spectrum by thermometer to see if he could find interesting differences in the amount of heat the different colors delivered. He did, but in a rather unexpected way, for he found that the temperature rise was highest in no color at all, at a spot beyond the red end of the spectrum. He concluded that the sunlight contained invisible light beyond the red. This is now called infrared radiation. The following year Ritter was to extend the visible spectrum in the other direction."(Asimov).
Parkinson "Breakthroughs" 1800 P.

Order-nr.: 43599