Navigational GUNTER Ruler. Rare Item. Circa 1840s

Rare item
Gunter rule - (Gunter scale)
Navigational equipment
Circa 1840-1850s

Maker = “I. P. Cutts, Opticians to Her Majesty, Sheffield". I. P Cutts specialized in production of optical and navigational instruments in early-mid 1800s.
This 24 inch example is inscribed with linear and logarithmic scales and trigonometric functions (front and back) to help with maritime navigational calculations.

Include a linear scale in inches and half inches, a diagonal scale, scales of leagues, chords, rhumbs, sines, tangents, semi-tangents, miles of longitude, sines of rhumbs, tangents of rhumbs, log-sines, meridional lines and equal parts etc.

[rum, cho, sin, tan, s*t. S*r, t*r, num, sin, v*s, tan, mer, e*p, lea, rum, m*l, cho]

Origianlly devised by Edward Gunter in 1623, a Gunter’s scale was a key piece of equipment for charting navigational courses in sea voyages.
The 24″ Gunter’s scale was then the most widely used ruler to navigate the sea up to the time when slide rulers or discs became available.