How to look backward and forward through backsight
Needless to say, for the practical purpose of laying a foundation, some sort of sightline on the ground would have to have been established, perhaps using a front and backsight
of some kind, but as a means of gauging the location of the pole the kind of device I am positing could conceivably have been employed.
It had a heavier barrel that was exposed at the muzzle, a different front sight block, two-piece striker mechanism, longer stock, more robust backsight
In the laser rangefinder interface, backsight
and foresight functions were added for enhanced data collection in obstructed situations.
Tenders are invited for Supply of Ic Ramp Backsight
Fundamental is that the exact position of the backsight structure must itself have been chosen, after careful observation of the celestial phenomenon concerned, in relation to the horizon mark.
A third hypothesis is that Maeshowe, unlike Newgrange, might in addition have had a useful working alignment with the capacity to detect midwinter's day itself; the tomb would then have been built in a spot where it could serve as the backsight for a long alignment towards some distant mountain peak or horizon notch.
A reassessment of the high precision megalithic lunar sightlines, 1: backsights
, indicators and the archaeological status of the sightlines, Archaeoastronomy 4: S21-S40.