a Theory of the Earth . 
335 
CHAP. XIX. 
Researches to he made in regard to Earthquakes . 
1 . The historical part : the greatness, extent, and 
chronology of their ravages in different countries. 
2 . Does it appear that some countries are more ex- 
posed to them than others ; are there some absolutely 
exempted ; and how far is this connected with the local 
situation of the country ? 
3. To observe the extent, duration, and direction of 
the vibrations experienced by the earth when it shakes. 
4. Are there any meteorological phenomena that an- 
nounce or accompany earthquakes ; such as extraordina- 
ry heat, calms, storms, movements of the barometer, elec- 
tricity, vapours dispersed throughout the atmosphere, 
paleness or peculiar colour of the sun and stars ? 
5. Other phenomena ; such as subterranean noise, ex- 
traordinary movement of the sea, the water of springs 
increased or dried up, any particular smell, symptoms of 
terror among domestic animals. 
6. Are there any indications that some earthqakes may 
have been the effects of electricity, and that such con- 
vulsions might be prevented by conductors ? 
7. Are there not some also which immediately depend 
on subterranean fires, and which. are preceded by or ac- 
companied with volcanic eruptions ? 
8. Are there any which exhibit indications of the ef- 
fects of water converted into steam ? 
9. To ascertain the simultaneous or at least astonish 
ing rapidity of the effects of earthquakes at very great 
distances. 
10. Are there any instances that, during the moment 
of an earthquake, some pretty considerable tract of land, 
or a mountain, has been raised to a great height above its 
