To the Italian school of astronomers, however, we owe the persistent and systematic study of the prominences. Among them the three greatest names are _Angelo Secchi_ (1818-1878), _Lorenzo Respighi_ (1824-1889), and _Pietro Tacchini_ (1838-1905). After the death of Secchi, the recognised head of spectroscopy in Italy was Pietro Tacchini. Born at Modena in 1838, he was appointed director at Modena in 1859, assistant at Palermo in 1863, and director at Rome in 1879. In 1870 he commenced to take daily observations of the prominences, noting their sizes, forms, and distribution, and these observations were continued for thirty-one years, until within four years of Tacchini’s death, which took place on March 24, 1905. Tacchini did for the study of the prominences what Schwabe did for the spots. The Italian spectroscopists found that the prominences increased and decreased every eleven years in harmony with the spots. Tacchini demonstrated that the streamers of the solar corona originate in regions where the prominences are most numerous, and that the shape of the corona, on the whole, varies in sympathy with the prominences. The researches of Lockyer indicated that the prominences originated in a shallow gaseous atmosphere which he termed the chromosphere. Formerly astronomers had to observe only isolated prominences, but in 1892 an American astronomer, _George Ellery Hale_ (born 1868), formerly director of the Yerkes Observatory, and now director of the Solar Observatory in California, succeeded in photographing, by an ingenious process, the whole of the chromosphere, prominences, and faculæ visible on the solar surface. Another solar envelope was discovered in 1870 by Dr Charles Augustus Young, who from 1866 to 1877 directed the Observatory at Dartmouth, New Hampshire, and from 1877 to 1905, that at Princeton, New Jersey. During the eclipse of December 22, 1870, Young was stationed at Tenez de Frontena, Spain. As the solar crescent grew apparently thinner before the disc of the Moon, “the dark lines of the spectrum,” he says, “and the spectrum itself gradually faded away, until all at once, as suddenly as a bursting rocket shoots out its stars, the whole field of view was filled with bright lines, more numerous than one could count. The phenomenon was so sudden, so unexpected, and so wonderfully beautiful, as to force an involuntary exclamation.” The phenomenon was observed for two seconds, and the impression was left on the astronomer that a bright line had taken the place of every dark one in the solar spectrum, the spectrum being completely reversed. Hence the name which was given to the hypothetical envelope—“the reversing layer.” For long the existence of the reversing layer was disputed by numerous astronomers. In 1896 photographs taken during the solar eclipse of that year finally demonstrated the existence of the “flash spectrum” as seen by Young.