Explores the links between science and empire in the 19th cent\ury, focusing on the mutual interactions of British imperialism and geophysical empiricism. The 19th century was a time when science was becoming global, in part due to European colonial and imperial expansion. Colonies became not just propagation points for European science, but also collection points for geophysical investigations. These "colonial observatories" influenced the type of science that could be done. Comparing the development of British and American geomagnetic research during this period shows the dependency between the two influences. Both the scientific theories and the geopolitical realities played a role in creating the tool for studying global science still in use today.