Die Werke von Daniel Bernoulli

The first part of this volume centers on Daniel Bernoulli's two prize-winning essays sent to the Paris Académie des Sciences in the 1740s. The first of these papers deals with the improvement of inclination compasses, giving a detailed analysis of the reasons for the great deviations observed in conventional instruments and suggesting alternative constructions; the second, written in collaboration with Daniel's brother Johann II Bernoulli, expounds a theory of magnetism based on Cartesian vortices of subtle matter. In addition, a prospectus in which Bernoulli recommends a Basel craftsman's horseshoe magnets, and several manuscripts relating to magnetism are printed and commented on. An appendix collects the few sources that mention Daniel's occupation with the theory of electricity. Because he did not publish his views on this subject, his conjecture of the 1/r2 law of electrical attraction ("Coulomb's Law") remained largely unknown. The second part of the volume is dedicated to Daniel Bernoulli's work on the technology of time measuring, especially in connection to the determination of longitude at sea - a subject of great practical importance. Also this section contains two prize essays submitted to the Paris Academy. The first one from 1725 tries to improve on the regularity of hourglasses, a device already obsolete at the time. The second essay from 1745 suggests new methods for the construction of pendulum clocks and for their application to the problem of longitude; its main importance lies, again, in the systematic investigation, based on mechanical first principles, of the sources of error.