438 Report of the Progress of the Sciences in France. 
tries, with fossils of quadrupeds, whales, &c. ; they seem to have 
been heaped together by local circumstances. 
Fossil vegetables are also very abundant. All the species of 
vegetables and animals now in existence may not have com- 
menced their existence at the sam epoch and in the same coun- 
tries: thus the animals of the continents have begun to exist 
long before the sea animals; but nothing shows that the human 
species began to exist after the ape and monkey, species, &c. 
Epochs at which Fossils have been deposited.—It is difficult 
to assign these epochs; but it may be asserted in general, that 
a. The fossils which are found in calcareous, gypseous, schis- 
tous, or bituminous stones, were deposited when these stones 
were formed, and consequently are the most ancient of fossils. 
b. Ravines (breches) having been formed subsequently to 
stones, the fossils of ravines are therefore posterior to those of 
stones. 
c. Coal and peat moss are also posterior to secondary stones. 
The fossils which exist in coal and peat moss are therefore also 
posterior to those of stenes. 
d. Alluvial strata are also posterior to the above; consequently 
the fossils contained in these soils are in general more modern. 
e. Caverns have never been discovered until after the sea had 
retired. The troglodyte animals could only have retired thither 
at very recent periods, and left their remains there. Fossils of 
sea animals have never been found there. 
Volcanoes.—The city of Caraccas in South America has been 
destroyed by an earthquake, and various parts of Europe have 
experienced similar visitations ; but they were not so violent, nor 
"attended with any new phenomena. There has also been an 
eruption of volcanic substances from the sea near the Azores, 
Earthquakes may be occasioned by volcanic eruptions: the gases 
which are emitted from inflamed substances pass throygh the 
chinks of the strata with rapidity, and produce shocks more or 
less violent. But other earthquakes, such as those which take 
place without any appearance of volcanic eruptions, seem to be 
occasioned by the galvanic action of different heterogeneous 
particles of the globe, particularly metallic substances. 
| In order to measure the intensity of earthquakes, an instru- 
ment called the Elkysmometer has been invented. This in- 
“strument makes oscillations when it is shaken. We estimate the 
intensity of subterranean commotions by the size and number 
of the oscillations of the instrument. 
GEOGRAPHY, 
Gosselin, in his Inquiries into the Geography of the Ancients, 
has shown that the Greek geographers, Eratosthenes, Hippar- 
: chus, 
~ 
ne 
