The horizontal circle of this instrument is graduated to 2 minutes, and read by opposite verniers to 2 seconds; the vertical arc is graduated to 20 minutes, and read by vernier to 3
seconds. There are two telescopes: an upper one (which is missing), and a lower one which is attached to the central pillar, below the horizontal circle. Delamarre worked in Paris in the first half of the 19th century, making repeating circles, graphometers, etc.
Ref: Deleuil, Catalogue des Instruments de Physique, de Chimie, d'Optique et de Mathématiques (Paris, 1863), p. 69.