slipstick
/ˈsɪpˌstɪk/Definitions
1. noun
a light, handheld device for calculating the rate of change of an angle, or for measuring the angle of elevation of an object, typically used in surveying and navigation
“The surveyor used a slipstick to measure the angle of the building’s slope.”
2. noun
a thin, flexible ruler, typically used for measuring angles or drawing curves
“The artist used a slipstick to draw the smooth curve of the landscape.”