Geoscience Reference
In-Depth Information
mission, consisting of calling on the observations of the public, can, as it
develops, give excellent results.” More specifically, he deemed the majority
of reports “very authentic,” while only twelve were “imprecise, rather doubt-
ful,” marked by a lack of coincidence in the reported times. one of the
“best” observations was that of a Monsieur Clement, a butcher in Yverdon.
Indeed, as forel's report for the following year would point out, observa-
tions came from “all the classes of society.” To his satisfaction, moreover,
the public was making progress: “A particularly interesting fact is that the
relative value of these observations has notably risen, and that, after two
years of collecting these documents, we recognize a very evident superiority
in those that were sent to us most recently: the public is learning to observe
earthquakes.” Still, forel urged a critical attitude: “Let us not however go too
far, and let us not overestimate the precision of our documents.”
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forel did not place the burden of improvement solely on the public:
scientists themselves needed to learn to interpret the observations of lay-
people. Thus forel judged “there are very few of them, even among the most
simple and modest, from which an intelligent comparison and critique can
not draw something useful.” Not only would the public need to learn how
to report to scientists; scientists would have to learn how to listen to the
public. In this vein, forel began, “I have, first of all, some definitions to
make, which will spare us fruitless repetition and simplify description.”
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These definitions would lay the foundation for a dialogue between scien-
tists and lay observers.
on one hand, forel picked up on phrases that observers themselves were
using. “The tremor [
secousse
] can be composed of several distinct move-
ments that I will call, according to circumstances:
oscillations,
when there is
a predominance of swaying movement;
vibrations,
when the movement has
the character of a vibration;
shocks,
when there is a violent, brief, sudden
impulse, etc.” on the other hand, he offered new terms that members of
the commission could use to compare the reports of different observers. for
instance, descriptions of an event as “violent,” “brief,” or “sudden” could
now be classed together and labeled as a single “shock.” With the exception
of the term
sismique,
which forel derived from the Greek for earthquake, all
the terms he used were drawn from “familiar language.”
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forel did not deny that the reports were colored by the subjectivity of the
observers. for instance, reports of the wavelike movement of fixed objects
were likely a “subjective illusion.” Yet such reports were not insignificant.
They could not be dismissed as the bias of observers familiar with theories
of seismic waves. More likely, the slight movement of the observer's body
during the earthquake produced the apparent wavelike motion of other
