A full account of the experiments using two clocks by Shelton, the same clocks used on Captain Cook's circumnavigation of the globe.
Clocks were set up in four different locations;
Brassa (Shetland Islands)
Hare Island (Greenland)
Melville Island ("in the Polar Sea")
Thus the clocks were tested between latitudes 51.31 and 74.47 and the length of a pendulum vibrating seconds in each was recorded.
Two chronometers were also used in these tests; Arnold No.112 and Parkinson & Frodsham No. 259.