Board gave a spirited support to this enterprise, and negotiations
were entered into with the most eminent instrument-maker of those
days. This was Jesse Ramsden (1735-1800), famous as the improver of
the sextant, as the constructor of the great theodolite used by
General Roy in the English Survey, and as the inventor of the
dividing engine for graduating astronomical instruments. Ramsden had
built for Sir George Schuckburgh the largest and most perfect
equatorial ever attempted. He had constructed mural quadrants for
Padua and Verona, which elicited the wonder of astronomers when Dr.
Maskelyne declared he could detect no error in their graduation so
large as two seconds and a half. But Ramsden maintained that even
better results would be obtained by superseding the entire quadrant
by the circle. He obtained the means of testing this prediction when
he completed a superb circle for Palermo of five feet diameter.
Finding his anticipations were realised, he desired to apply the same
principles on a still grander scale. Ramsden was in this mood when
he met with Dr. Ussher. The enthusiasm of the astronomer and the
instrument-maker communicated itself to the Board, and a tremendous
circle, to be ten feet in diameter, was forthwith projected.

Projected, but never carried out. After Ramsden had to some extent
completed a 10-foot circle, he found such difficulties that he tried
a 9-foot, and this again he discarded for an 8-foot, which was
ultimately accomplished, though not entirely by himself.
Notwithstanding the contraction from the vast proportions originally
designed, the completed instrument must still be regarded as a
colossal piece of astronomical workmanship. Even at this day I do
not know that any other observatory can show a circle eight feet in
diameter graduated all round.