It is a refractor with an equatorial mount supported by a cast iron column, with 13.5 cm of aperture and 175 cm of focal distance. The telescope tube is made of walnut wood, while the objective holder and the eyepiece holders are made of brass. Defined as the Comet Seeker it was mainly used as a guide scope for the Cooke photographic camera (16.5 cm aperture), and in practice it proved not sufficiently robust to hold the complex stably. It is with this instrument that Cerulli discovered a new planet "Interamnia" and found the "Comet 1910 e". In 1955 the second Cooke photographic camera (8 cm aperture) was applied with the necessary modifications in order to obtain an ensemble with the necessary stability. Later, in the late 1960s, the "Cooke" cameras were replaced with a Zeiss astrograph (20 cm aperture 144 cm focal distance)