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This item was a optical instrument named as Stereoscope. Stereoscopes are apparently those optical devices that help to view the two images separately and with relaxed eyes. There are two types of stereoscopes as: lens or pocket stereoscopes and mirror stereoscopes. Lens or pocket stereoscopes are great for viewing the whole overlap area of prints up to 9 cm × 13 cm or parts of larger patterns. On the other hand, mirror stereoscopes were designed to accept standard 23 cm × 23 cm metric air photos and work well with A4/US letter-sized prints. Most models come with magnifying options up to eight times, which is pretty impressive. One cool thing about mirror stereoscopes is that they are large enough to allow the analyst to draw beneath them, so it is possible to trace objects identified in the stereoview with a pen onto one of the images or a transparent overlay. However, it's important to remember that this sketch wouldn't have the geometric properties of a map as it contains all distortions present in the base image.

This fond encompasses materials centred around the achromatic telescope and its diverse mountings. It features detailed figures of the telescope and incorporates a comprehensive catalogue of instruments crafted by Troughton and Simms.

The fond contains Results of observations of the fixed stars made with the Meridian Circle at the Government Observatory , Madras

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 in surveying land, alignment, testing, and calibrating optical Instruments. It is basically a refracting telescope. Whose optical elements tilt angles with high accuracy of the order of arcsecs.

The book Traite experimental of de L'electricite et du Magnetisme transalates to Experimental Treatise of Electricity. M.Becquerel, of the Academy of Sciences of the Institute of France, wrote this book. It is published in 1840

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.