An Italian brass plane-table alidade
by Petrus Galland, 17th century
each side of the square divided to 1, numbered by 10 and cut with holes by 5, 0-50 in both directions, lines along divisions of 5 indented at intervals on the ½s, signed Petrus Galland, the alidade 15.5cm. long with pair of slit sights, engraved with scale divided by 1, numbered by 10, 5-70, underneath mount affixed with two screws and thread for mount (not present) and scrolled screw for hinge of alidade
4½in. (11.5cm.) side
An Italian brass plane-table alidade
by Petrus Galland, 17th century
each side of the square divided to 1, numbered by 10 and cut with holes by 5, 0-50 in both directions, lines along divisions of 5 indented at intervals on the ½s, signed Petrus Galland, the alidade 15.5cm. long with pair of slit sights, engraved with scale divided by 1, numbered by 10, 5-70, underneath mount affixed with two screws and thread for mount (not present) and scrolled screw for hinge of alidade
4½in. (11.5cm.) side
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