Sector, by William Collier, London, Early 18th Century

Brass six inch sector with folding support. The signed side has sectoral scales of Sin, Tan (to 45), tan (to 75) and Poly[gons] (6-12) with single logarithmic scales of tan (to 45), Sin (to 90) and Numb[ers] (more than double length at 1-1-35, ie 1-10--350). The other side carries sectoral scales of Lin[es] (to 10), Cho[rds] (to 60) and sec[ants] (to 75, with single scales of Hou[rs] (to VI), Cho[rds] (to 90), Lat[itude] (to 90) and In[clination of] Me[ridian] (to 90). The outer edge has a decimally-divided scale of 12".