Housed in its original mahogany case, this late 19th or early 20th-century precision drafting instrument is an exceptional piece of engineering history. The "Trigonometer," as indicated by the intact instruction paper pasted inside the lid, features a heavy steel blade, an integrated brass and steel protractor arc assembly with a vernier scale, and an array of delicate spring steel drafting clips. Devices like this were vital for surveyors, engineers, and cartographers to accurately plot angles and calculate trigonometric relationships directly onto drawing boards. The piece shows age-appropriate wear, including scratches, minor scuffs, and fading on the wooden exterior, with some tarnish and surface oxidation present on the metal components. Note that the case is missing several components, evidenced by one or two empty mounting brackets and vacant recesses designed to hold ancillary parts. H 2", W 35", D 6.75". Please see photos for condition . From the Dale Beeks collection.