CHAPTER XXII.
RETROSPECTS AND CONCLUDING WORDS.
The method of seismic investigation in this Report developed, indicates, that it is now in our power, more or less, to trace back, wherever we can find buildings or ruins, fissured or overthrown by ancient earthquakes, the seismic centres from which these have emanated, in epochs even lost perhaps to history.
In the ancient churches of Southern Italy, that nine centuries ago were founded by Lombard or Norman hands, in the massive walls of the Coliseum, the arches of the Campagna, the shattered columns of the Forum, we can still ascertain the direction, in which the shocks were delivered, and even approach to measure the forces, by which, while England was receiving its first Norman lords, these churches were ruined, and centuries before that, and the edifices of the Imperial city, were overturned and destroyed. We can, therefore, in Italy, perhaps still more perfectly in Mexico and elsewhere, even yet, more or less recover the ancient fluctuations of position, of these centres of seismic intensity, and compare the intensity itself in past historic and at the present time.
It is, therefore, no longer true to say (if it ever were so) with Humboldt, that "these waves of succussion can be measured as to their direction and force, but can in no way
