t has been argued that physics and astronomy served the international geopolitical interests of European powers during the nineteenth century. This notion can be applied to the situation in the Dutch East Indies around this time, and provided a beneficial situation for J.A.C. Oedemans who was able to pursue his interest in astronomy. During his stay in the Dutch East Indies, from 1857 to 1875, Oedemans carried out a range of astronomical observations, including variable stars and the 1868 and 1871 total solar eclipses. He also tried to observe the 1874 transit of Venus. But his primary task was to co-ordinate the trigonometrical survey of the Dutch East Indies. In this chapter we will briefly explore his astronomical activities while in the Dutch East Indies and show how he tried to contribute to science by observing the 1868 and 1871 total solar eclipses, both of which were important for the advancement of solar physics.

The total solar eclipse of 18 August 1868 was one of the most important eclipses in the history of solar physics, and observations of it led to a new understanding of the nature of the chromosphere, prominences and the corona. Among other places, this eclipse was visible from the Dutch East Indies (present-day Indonesia). Soon after the 1868 event came the total solar eclipse of 12 December 1871, which also was visible from the Dutch East Indies and offered a further opportunity to build on the achievements of 1868. Both solar eclipses were observed from the Dutch East Indies by teams led by J.A.C. Oudemans, and in this chapter we provide biographical details of Oudemans before examining the scientific instruments used and observations made in 1868 and 1871 by Oudemans and other local observing teams. We end by assessing the international importance of Oudemans’ published scientific results.