Domenico Troili (1766): "The true cause of the fall of a stone in Albereto is a subterranean explosion that hurled the stone skyward"

Abstract

In mid-July, 1766, a stone fell at Villa Albareto near Modena in northern Italy. A sudden explosion like a cannon shot followed by fierce whistling sounds frightened people over a wide area. Some saw a fiery body falling from the sky; others said it was dark and smoky. The ground shook when the stone plunged into the soil making a hole nearly a meter deep. The Abb Domenico Troili collected eyewitness reports, examined the stone, and reported the presence of marchesita, an old name for pyrite. A century later, this mineral, which proved to be iron sulfide (FeS), was named "troilite" in his honor. Troili's description is unquestionably that of a meteorite fall, and therefore some scientists have argued that it is Troili, rather than Ernst F. F. Chladni, to whom we should give credit as the first person to record the fall of a stone from space. However, Troili, himself, had no such an idea; he wrote that a subterranean explosion had hurled the stone high into the sky from a vent in the Earth. He stoutly defended this explanation against his opponents, including the Bishop of Modena, who believed that the stone had been hurled aloft by a bolt of lightning. Both hypotheses reflect a conviction, held well into the nineteenth century, that any rocky objects that fall from the sky must originate on the Earth or in the atmosphere. In 1794, Chladni calculated that meteors and meteoritic fireballs course down the sky at such extremely high velocities that the bodies forming them must originate in space. He listed all the falls that he found credible in historic records. Partly through his efforts, meteorites had gained widespread acceptance by 1803, but the idea of their origin in space had not. For the next half century many scientists continued to argue that meteorites either consolidate in the upper atmosphere or are ejected by volcanoes on the Moon. Recent efforts to transfer honors from Chladni to Troili for being the first to describe meteorites as bodies falling from space are unwarranted.