366 Biographical Notice of Haiiy. 
broken from the group, presented the appearance of a new 
and regularly formed crystal, with smooth surfaces. Haiy 
discovered with surprise that this form was precisely that 
of rhomboidal crystals of Iceland spar. ‘: The mystery is 
explained,” cried he. In fact, his whole theory of erys- 
tallography, a2 monument as imperishable as the truths of 
geometry, is founded on this observation; but because this 
discovery was altogether geometrical, it was necessary that 
it should be explained and perfected through the medium of 
geometry. Haiiy felt on this occasion also, that his studies 
had been imperfect. But he was not discouraged. He 
perceived what he stood in need of in order to continue his 
researches upon the structure of crystals; invented a meth- 
ed of measuring and describing them, and not till then did 
he venture to speak of his discoveries to his master, to 
whose lessons he had modestly and silently attended. It 
may readily be conceived that Daubenton was eager to ac- 
cept and to make known such valuable labours. M. de 
Laplace, to whom he communicated them, hastened to en- 
courage the author to bring them before the Academy of 
Sciences. Butit was not easy to induce the modest Hatiy 
toleave his happy obscurity to shew himself at the house 
where the Academy held its sittings, and in the midst of 
this society of distinguished men. He yielded, however, 
fo the solicitation, and went to the house as to an ecclesi- 
astical ceremony, clothed with the costume prescribed by 
the canons. It was found necessary to have recourse to the 
authority of a doctor of the Sorbonne, to persuade him that 
he might, with a safe conscience, wear the same garb as the. 
other ecclesiastics of that day. It is probable, however, 
that the Academy would have received him, whatever 
dress he might have chosen to appearin. On the 12th of 
February, 1783, he was admitted as an adjunct in the class | 
of Botany. 
While Hatty was pursuing these peaceful labours, the 
Revolution burst upon the nation. The Bastile was de- 
stroyed, and the monarchy soon after shared the same fate: 
but all this did not disturb the naturalist from the train of 
his occupations, nor induce him to participate in the gener- 
al movements. As he refused to take the oath to the ec- 
clesiastical constitution prescribed at that period, he was 
deprived of all his perquisites, and found himself as poor as 
