2 REPORT—1850. 
guiding hypothesis, of any distinct idea of what an earthquake really is, of 
any notion of what facts might have been of scientific importance to observe, 
and what were merely highly striking or alarming, but only secondary ac- 
cidental circumstances due to changes of surface, or the complication (never 
attempted to be disentangled) of all these with the facts of closely adjacent 
volcanic eruption,—in the want of all these, as well as of any calmness or 
unexaggerative observation during such alarming visitations, few facts of the 
character and precision requisite to render them of value to science can be col- 
lected with certainty. The true observation of earthquake phenomena is 
yet to be commenced and the required facts are to be collected, the most im- 
portant of them by methods not dreamed of until very recently. 
In collating the multitudinous and vague accounts of earthquakes, there- 
fore, I have been compelled to reject vast numbers of statements, either for 
want of the necessary conditions to scientific value, or of sufficient authen- 
ticity (as when given, not as an eye-witness, but upon common hearsay by 
the narrator), or of the facts given having any real bearing upon the scien- 
tific question. 
The staple of earthquake stories, in fact, consists of gossip made up of the 
most unusual, violent or odd accidents that befel men, animals or structures, 
rather than of the phenomenon itself. Very few of these narratives state 
even the precise direction or duration of the shock, and the chief value of a 
complete discussed catalogue of earthquakes, from such accounts as we have, 
would be to present some indications as to the nature of their diffusion over the 
earth’s surface, and of their distribution in time ; such catalogues have been 
prepared for limited districts by M. Perrey, by Von Hoff, and by some few 
others, and a much more extensive one will form a future part of this Report. 
In the succeeding Report, I have not thought it necessary to refer to author- 
ities except in cases of rarely noticed and important facts ; in other instances 
the references might be innumerable. 
As it is impessible to observe facts to any good purpose, so is it equally 
impracticable to select them from the records of others for any useful scien- 
tific end without some guiding hypothesis ; in this respect I have been guided 
by that theory of earthquake dynamics, which I have enunciated*, and which 
defines an earthquake to be “ the transit of a wave of elastic compression in 
any direction from vertically upwards to horizontally in any azimuth, through 
the surface and crust of the earth from any centre of impulse, or from more 
than one, and which may be attended with tidal and sound waves dependent 
upon the impulse, and upon circumstances of position as to sea and land.” 
It is unnecessary, I would hope, for me to add, that I have not selected the 
following facts to suit any theory, but have impartially taken note of all that 
I could find that appeared of importance to science, whether at first sight 
making for or against my own views. Let me add, that in this course of ex- 
tensive research through earthquake narrations, I have not met with a 
single fact recorded that was not resoluble upon my theory, or equally irre- 
soluble upon any, and of doubtful credence. 
Before proceeding it may be desirable to take a very brief survey of the 
several other theories (if such they may be called) which have been at dif- 
ferent times promulgated, in a word, of the literature generally of earth- 
quakes, omitting those views now palpably absurd, such as the ancient Mon- 
golian and Hindoo notion, that the earth rests upon a huge frog, which, when 
he scratches his head, produces an earthquake, &c. 
As the best and most rapid mode of doing this, I shall give in the order of 
time, and as nearly as possible in each author’s own words, the peculiar 
* Trans. Roy. Irish Acad. vol. xxi. part 1. 
