Proving instruments credible in the early nineteenth century: The British Magnetic Survey and site-specific experimentation

For several decades now, many histories of science have sought to emphasize the important role of instruments and other material objects in the operation of science. Many, too, have been attentive to ideas of space and place and the different geographies which are visible in the historical practice of science. This paper draws on both traditions in its interpretation of a heretofore neglected aspect of Britain's nineteenth-century geomagnetic story: that of the British Magnetic Survey, 1833-38. Far from being a footnote to the more expansive geomagnetic projects then taking place in mainland Europe or to the later British worldwide magnetic scheme, this paper argues that the British Magnetic Survey represents an important instance in which magnetic instruments, their users and their makers, were tested, developed and ultimately proved credible.