Explorer's Alidade

Image: Explorer's Alidade

Detailed Description

Manufactured by Keuffel & Esser, New York & New Jersey. In this type of alidade, as opposed to the high standard, the telescope mounted close to the straightedge, producing a more compact instrument. A right-angle prism is attached to the eyepiece and permits viewing by looking down. A cylindrical bubble and magnetic compass needle are attached to the base; these are used to level and orient the plane table to its proper position. Object ID: USGS-000161

Details

Image Dimensions: 1752 x 612

Location Taken: US