Terrestrial globes with equators, poles, eliptics and quadrants mb-code LMG142833 The circular tool is shown

The circular tool is shown suspended on gimbals from a pulley

to whom Sam House is holding up a tankard

To prove Him of the true Duncean Line

with the entrance to Swallow Street

Terrestrial globes with equators, poles, eliptics and quadrants mb-code LMG142833 The circular tool is shownPlate 6 figures 1 6 from the paper "Demonstrations of the late Dr. Maskelyne's formulae for finding the longitude and latitude of a celestial object from its right ascension and declination; and for finding its right ascension and declination from its longitude and latitude; the obliquity of the eliptic being given in both cases", by Abram Robertson, Philosophical Transactions of the Royal Society, vol. 106 (1816), pp. 138 148. Original: ink on paper.