When the ten minutes are up, as signified by the ding of an egg timer, a piece of nautical equipment as pedigreed as an astrolabe or a sextant .
The eleven wooden vessels were powered by the wind and guided by the celestial bodies, thanks to that remarkable scientific instrument, the sextant .
He was sure he was on the right trail, for being no fool he measured by sextant and compass; he was now in New Mexico territory.
With only a sextant and a compass, they navigate for 16 days.
Selecting five of the hardiest men, he took a single boat on a journey of 800 miles, across a raging sea, with a sextant the only navigation tool, to the island of South Georgia.
We fitted the trucks with air wheels - balloon tires, we would say now - and kept going, navigating like mariners, by sextant and compass and dead reckoning.
The sextant goes with the nautical theme - she's trying to find where she's going, where she's been.
Suffering appalling hardships and risking dreadful tortures and death if caught, they walked for thousands of miles recording distances, altitudes and bearings with measured paces and concealed thermometers and sextants .
His other instruments still worked fine - sextants , reflecting circle, artificial horizon, telescope, chronometer, several compasses and probably a couple of thermometers - and he continued recording latitudes and longitudes.
These units incorporated mechanical gyroscopes and while the aircraft were fitted with sextants , it was the INUs that became the primary means of navigation.