London: Taylor and Sons. 1st Edition. FIRST EDITION OF JOSEPH LOCKYER'S DISCOVERY OF HELIUM, an important extract enclosed in a handsome, leather bound, clamshell case.
Lockyer discovered helium in 1868 when he adapted his 6-inch telescope to utilize a spectroscope and while using it to carry out electromagnetic spectroscopic observations of the sun during an eclipse, he discovered a yellow line never seen before in the laboratory. Unable to reproduce the line in his lab, Lockyer made the bold suggestion that the line was the 'fingerprint' of an element, an element he named 'helium' for Helios, the Greek God of the Sun. Lockyer's finding -- the only element to be discovered in space before it was discovered on Earth -- was the first element to be discovered by spectroscopy.
As Lockyer tried to make sense of his initial discovery of a yellow line, he reasoned that "because the bright yellow line was close to the D1 and D2 lines of sodium, it [should be] designated D3. In order to identify the lines in his spectral data, Lockyer enlisted the help of the prominent British chemist, Edward Frankland. Their laboratory work showed that the majority of the observed solar lines were due to hydrogen, though often modified by changes in temperature and pressure. The D3 line, however, could not be reproduced in the laboratory" (Jensen, "Why Helium Ends in 'ium'?)... While Lockyer was ridiculed for his discovery for many years, in 1895, twenty-five years after Lockyer's initial discovery, William Ramsay confirmed the existence of Helium when he managed to isolate it from another mineral.
In 1897, Lockyer was finally knighted for his discovery of helium. Item #295
CONDITION & DETAILS: London: Taylor and Sons, 1870. No wrappers as extracted from the Philosophical Transactions, Vol. 159, 1869 - Part I. Small folio (13 x 10 inches; 325 x 225mm). The extract is enclosed in a handsome clamshell box covered in half-calf over marbled paper boards. The spine of the case has five rasied bands and is both gilt-tooled and gilt-lettered. The paper is accompanied by two plates, one depicting a spectrum of helium, one depicting Lockyer's spectroscope. The clamshell case is pristine and the extract itself is in very good to near fine condition.