368 Scientific Intelligence—Geology. 
sure means of learning the approach of an earthquake. According 
to this gentleman, the earthquake indicator is nothing more than a 
magnet, to which is suspended, by magnetic attraction, a little 
fragment of iron. Shortly before the occurrence of an earthquake, 
the magnet temporarily loses its power, and hence the iron falls. 
According to M. Ratio-Menton, the accuracy of this indicative sign 
has been thoroughly tested by a highly educated Argentine officer, 
Colonel Epinosa, during a residence of many years at. Arequipa, a 
region where earthquakes are very frequent. Independently of the 
authority of the communication, arising from the respectability of 
the communicator, and from its being published in the Transactions 
of the French Academy of Sciences, the result is nothing more than 
might have been suspected, from theoretical considerations of the 
alliance between electricity and magnetism. A disturbance of elec- 
tric power has long been known to be associated with earthquakes. 
8. The quantity of Solid Matter carried annually to the Sea.— 
Mr A. Taylor, in endeavouring to calculate the probable quan- 
tity of solid matter carried annually to the sea, either in a state 
of suspension or in a state of solution, by rivers or rivulets, or 
by other agents, has arrived at the conclusion that this quantity 
of sediment spread on the bottom of the sea, is capable to dis- 
place sufficient water to raise the level of the ocean three inches in 
10,000 years. This is an important statement, and ought to be borne 
in mind, when calculating on the changes that our earth has under- 
gone during its formation. He has also calculated the denudation 
of sediment over 100,000 square miles of North America, spread 
by the Mississippi, ought, if its river has always been charged with 
sediment as it has always been in our days, to have lowered the 
surface of the earth one foot in 9000 years, and that the Ganges 
produced the same effect in its hydrographic basin in 1794 gh — 
(L’ Institut, No. 1067.) - 
9. Origin of the Bitumen of Stratified Rocks.—Table showing 
the Geological position of Petroleum Springs,— 
The super-cretaceous rocks of South America, the cretaceous of 
Syria, the oolite of France, and the lias of Europe, furnish 15 
instances. 
The coal series and carboniferous rocks, 3 les PR 
The Devonian rocks, : : . : 13 
The Silurian, . : : 12 
The metamorphic and magnesian, a : 6 
Total, é 54 
of these 54, 31 are below the carboniferous and coal-producing rocks ; 
and 283 are in or above the coal series; of the number of 23, 15 are 
due to the rocks from the lias upward; 8 only belonging to the coal- 
bearing strata, 
