Astrolabes were first invented in the ancient Greek world in ... a string tied to the center of the plate to get the angle.

He travelled all over the world and was away for months at a time - he would have used this sextant for navigation. Later on in life he became a river pilot in Gravesend. Comments are closed for ...

The fact is often overlooked that as the sextant is a double-reflecting instrument ... The attachment is the invention of Capt. Henry A. Gadsen, of 6 Binden Road, Raves-court Park W., ...