The item is a 6 inch transit circle. The transit circle is an instrument used to determine the declination of stellar onjects. It consists of a circular scale kept perpendicular to the rotating axis of a telescope tube.

This item was a stellar object requires two coordinates to locate it on the sky, as the sky is a two-dimensional plane. One of these coordinates known as declination. This is similar to the two co-ordinates viz. latitude and longitude, defining a point on the surface of the earth. The transit circle is an instrument used to determine the declination of stellar onjects. It consists of a circular scale kept perpendicular to the rotating axis of a telescope tube.

This item was an instrument used for measuring the intensity of a light source. It uses a light-sensing device that is calibrated to express intensity in a standard unit. Some optical elements such as lens etc. are also employed to incerase the sensitivity of the instrument.