An explanation of a new construction and improvement of the sea octant and sextant, containing, a ... method of adjusting and rectifying those instruments for use both at sea and land .... Illustrated by four copper-plates. By B. Martin.
Martin, Benjamin,1705-1782.
London : printed for the author,
[1775?]
"The public are indebted solely to my son, J.L. Martin, for the invention .." (Preface); he was awarded patent no. 1088 in 1774.
ESTC