638 
Earthquakes are, however, occasionally felt in England, even 
in Norfolk, and then we read of persons alarmed, or slumherers 
disturbed by the violent rattling of window-frames and pictures, 
the clatter of jugs and basins, the opening of doors, and the ringing 
of bells ; while much serious damage m.ay be done to old and decayed 
buildings. 
Similar manifestations of disturbance are sometimes afforded to 
those who reside near a railway, or in a road along which much 
heavy traffic passes. The vibration of the house is felt, and this 
shaking due to the passage of heavy bodies on the earth’s surface, 
is naturally not very unlike that which would be caused by the 
passage of the equivalent to a heavy body acting on the earth's 
crust from beneath. 
Earthquakes are due to internal pressure, which acts either in a 
wave-like form, commencing feebly in one place, attaining a 
maximum force further on, and finally dying away, as if the energy 
were exhausted ; or again, the pressure acts on a centre, the force 
dying away in ripples in continually widening circles. 
Such earthquake waves are of a very varied nature. Those 
which make themselves known to us are no doubt, and fortunately 
so, of a comparatively mild form ; but others are often sufficiently 
violent to rupture the earth’s surface; and if they undulate beneath 
the sea-bottom, the waters are violently agitated, and may cause 
much destruction of life and property when the waves are forced 
over the land. 
These phenomena are indeed catastrophic, and although this 
term has been much abused, there is a tendency now-a-:days to 
admit, that while uniformity has prevailed in the laws regulating 
life and matter, yet catastrophic effects are ever and anon produced 
by agents governed by these same laws. Thus, as the Kev. 0. Eisher 
has pointed out, any pressure affecting the earth’s crust might 
accumulate enormously before the crust yielded, but when ruptured 
a sudden movement might take place.* 
While earthquakes accompany and often precede volcanic 
eruptions, so they sometimes cease to occur when the outburst takes 
place ; but it is remarkable that they are felt in our own country, 
and ill other lands far away from active volcanoes. Hence, if duo 
* Quart. Journ. Geol. Soc. vol. xvii. p. 4. 
