6 E. DEGOLYER 
t 
father of the modern science of seismology, in a paper delivered be- 
fore the Royal Irish Academy—On the Dynamics of Earthquakes: 
Being an Attempt to Reduce Their Observed Phenomena to the: Known 
Laws of Wave Motion in Solids and Fluids,' said: Uae 
However well modern geologists have surveyed and mapped the 
formations constituting the land which we.can see and handle, of the 
nature of the bottom of the great ocean we know nothing; no human 
eye has or ever can behold it; we cannot even reach its deep abysses 
with the sounding line; yet the ocean covers nearly three-fourths of 
our entire globe, and of this vast area the geology is an utter blank. 
If, however, we are enabled hereafter to determine accurately the 
time of earthquake shocks, in their passage from land to land, under 
the ocean bed, we shall be enabled almost with certainty to know 
the sort of rock formation through which they have passed, and 
hence to trace out at least approximate geological maps of the floor 
of the ocean. For, knowing the time of transit of' the wave, :we can 
find the modulus of elasticity which corresponds. to it, and finding 
this, discover the particular species of rock formation to which this 
specific elasticity belongs. 
After further emphasis on the desirability of acquiring such in- 
formation, he continued: 
While the facility with which one class of our data may be as- 
certained will be disputed by none, it may, perhaps, occur to some 
that, as earthquakes are happily rare, and give no notice of their ad- 
vent, and moreover, are times of such consternation, so but little 
accuracy is to be hoped for in observations, as to the speed or cir- 
cumstances of the shock, made during such visitations. This might 
be partly true, were we dependent upon the nerve or watchfulness of 
individual observers; but already attention has been given to the con- 
trivance of self-acting instruments (and instruments, though by no 
means well devised nor self-registering, have been already in use in 
Scotland, and perhaps elsewhere) for the registration of earthquake 
shocks; and there can be no doubt that, by earthquake observatories 
established, with suitable instruments, at distant localities, in South 
America or Central Asia for instance, ‘where earthquakes, greater or 
less, are of almost daily occurrence, a very complete knowledge of the 
time of wave transit, and of the amplitude and altitude of the earth 
waves for given districts, would be soon obtained. No instruments for 
ascertaining the latter have been yet proposed, but they do not seem 
by any means difficult to devise. 
He minimized the apparent delays in waiting for natural earth- 
quakes, and suggested a workable substitute as follows: 
But another, and much more rapid, and perhaps even certain, 
1 Trish Acad. Trans., XXI, pp. 50-106, Dublin, 1848. 
250 
