Sheraton, Thomas; Bensley, Thomas; Mathews, James; Bensley, Thomas [Oth.]; Mathews, James [Oth.]; Terry, George [Oth.]; Jordan, Jeremiah Samuel [Oth.]; Wayland, L. [Oth.]: The Cabinet-Maker And Upholsterer's Drawing-Book: In Three Parts (London: Printed For The Author, By T. Bensley; And Sold By J. Mathews ... C. Terry ... J.S. Jordan ... L. Wayland ... And By The Author, 1793)

Of the Line of Chords on- the Sector ~
The Chords on the fixed fcale have already been con-
fidered (fee page 29). Thefe chords are limited to one circle,
which, to fuit that fcale, muft always be drawn by the compaffes
extended to fixty degrees: but the fcale of chords on the fedor
is unlimited, becaufe the chords of circles of various radiufes
may be found according as the limbs of the inlirument are
more or lefs extended.
The line of Chords is on the fame fide of the fedor with
the Polygons, marked with c nigh to a brafs center on each
limb: and if it be required to find the chord of thirty of any
circle, take the radius of the given circle, and open the fedor
till the compafs legs coincide with thofe brafs centers at 6o.6o,
then contrading the compaffes till their legs touch 30.30, the
required chord line will be found. Th this manner proceed in
any other cafe; always obferving that the femi-diameter of
the circle muft limit the opening of the fedor at the brafs
centers..
By this line of Chords on the Sedor it is evident that a
circle may be divided into feven hundred and twenty equal parts
with confiderable difpatch and great accuracy.