36 The American Geologist. January, i897 
ing to their age and the superposition of the strata in which 
they are found was the French abbe. Giraud-Soulavie, who in 
1777 published this new principle in his works on the south 
of France, and particularly on the geology of Vivarais. (Ilis- 
foire iiatvrel/e (Je la France 3Ieridionale, 7 vol. 8vo, Paris, 
1780-1784. The Chapter VIII, in the first part, containing 
the chronology of fossil animals, according to the strata in 
which they are found, was written in 1777, and read before 
the Academy of Sciences of Paris, the 14th August, 1779.) 
Without knowing the researches and discoveries of the 
abbe Giraud-Soulavie, William Smith, in England, from 1794 
to 1799, derived identical principles; and in 1799 he wrote a 
tabular view entitled. "Order of the strata and their imbed- 
ded organic remains in the vicinity of Bath, examined and 
proved prior to 1799," which, although it remained manuscript 
until 1844, was copied and largely circulated among English 
geologists. It was not until 1815 that Strata Smith, as he is 
called, was able to issue his "Geological map of England and 
Wales, with part of Scotland"; and only in 1817, 1818 and 
1819 that finally he published his two works, "A stratigraph- 
ical system of organized fossils," and " Strata identified by 
organized fossils." 
Curiously enough, both Ckivier and Alexandre Brongniart 
did not know the discovery of Giraud-Soulavie, a Frenchman 
like them, nor of William Smith; and in their studies of the 
Paris basin they came to the same conclusion, of strata iden- 
tified by organized fossil remains — a remarkable coincidence, 
which, although the question of priority is unquestionably in 
favor of Giraud-Soulavie, show^s that the progress of knowl- 
edge of strata and fossil remains had arrived at that period 
when a new and most important step was to be taken. 
Cuvier and Brongniart came at a most opportune moment; 
and their capital work, " Essai sur la geographie mineralo- 
gique des environs de Paris-," written and presented to the 
Council of Mines, in Paris, in 1807, was issued first in the 
Journal des Mines, 1808, and two years after as a separate 
volume in 4to, Paris, 1810. It is called by a brother geolo- 
gist and a contemporary, J. J. d'Omalius d'Halloy, " I'ouvrage 
le plus capital de notre siecle (au point de vue de la geologie), 
puis qu'il contient le premier germe de la revolution qui a 
