174 Heilbron
preneurs, and the military—also fi gured in the transformation of natu-
ral philosophy into classical physics. The lower fl are of the hourglass is
framed by the Seven Years’ War (1756–1763) and the revolutionary and
Napoleonic wars, which made greater demands on applied natural philos-
ophy and mathematics than earlier confl icts had done. This period, and
especially the transition around 1770, is the focus of the hints and indica-
tions in this paper. It coincided with the so- called age of the democratic
revolution, with which it had ties not merely coincidental.^1
Reformers of the age, whether of government or natural philosophy,
emphasized control, effi ciency, and utility, and rejected traditional catego-
ries, customs, and privileges that did not meet their test of rationalization.
A confl uence of the two sorts of reforms and a symbol for their relation-
ship was the metric system of weights and measures, designed by the
leading academicians of France, defi ned by the most exact instruments
and experimental techniques of the day, and imposed by the Revolution
on a people slow to celebrate the marriage of democracy and decimaliza-
tion. Here we have rationalization in both a political and mathematical
sense, and a resistance to its imposition by people who preferred familiar
practices and attitudes. As in political theory and government, so in natu-
ral philosophy and its applications, the old persisted as the new gained
strength. The cross sections of the hourglass were not homogeneous. For
example, John Locke’s Elements, composed in 1706 as “an abstract or sum-
mary of whatever is most material in natural philosophy,” was reprinted
in both England and France as an introductory text long after its concep-
tion of the subject was outmoded.^2 The historian takes account of these
survivals by presenting counterexamples to his or her thesis, and by argu-
ing that they represent a diminishing trend.
If the fi gure of the hourglass be allowed for the development of natural
philosophy, that of a string gradually closing into a circle may do for the
relationships among natural philosophers. In the middle of the string are
the leading members of the leading academies; on their right, proceeding
clockwise, professors, then other teachers, public lecturers, booksellers,
and instrument makers; on the left of the high academicians, proceed-
ing counterclockwise, come lesser academicians, habitués of intellectual
salons, cameralwissenschaftler, agriculturalists, manufacturers, and inven-
tors with claims or connections to natural philosophy. According to this
superstring theory, as the eighteenth century proceeded, gaps along it
fi lled and the ends joined. The fi lling intensifi ed after 1770. The joining
of the ends may be expressed symbolically by the investigation and de-
velopment of the steam engine with separable condenser by the former
instrument makers James Watt and Matthew Boulton.