MARKETING LONGITUDE.

The article presents discussion of three 17th-century publications written by the Dutch mathematician Christiaan Huygens related to the development and use of th pendulum clock. The writing and publishing of the "Horologium" in 1658, the "Kort Onderwijs," or "Brief Instructions," of 1665, and the "Horologium Oscillatorium" of 1673 are each described in turn. Discussion is given outlining the contents of each monograph as well as information on the initial printing and early recipients of the work. Further commentary is provided discussing the context and significance of the works within the history of clock design and nautical navigation.