1From Thomas Jefferson to Andrew Gwin, 24 March 1798 (Jefferson Papers)
I wrote to mr Madison , President of the college of Williamsburg, describing to him the experiment I wished him to try with the dipping needle of that college. I did not give him the least hint of the object, but only desired him to hold the meridian of the instrument in the meridian of the place, but with the North end pointing South, and to mark the dip. I inclose you his answer, by which...