A new and easy method of finding the latitude on sea or land, having two altitudes of the sun and the time elapsed between the two observations, measured by a watch or other time-keeper. By Samuel Dunn, ...
Dunn, Samuel,-1794.
London : printed, for the author,
1778.
ESTC
Also reproduced on microfilm. Woodbridge, CT: Research Publications, Inc., 1986. The Eighteenth Century ; reel 1569, no. 16.