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.

The document was sent from the Director General of Observatories to Thomas Royds in 1913. The Director General of Observatories inquired about the order of the new screw for the Ponna micrometer in response to John Evershed's letter dated 18th August 1913.

Letter to the Director-General of Observatories regarding the specification of a new Micrometer for the Madras Transit Instrument

This letter to Dr. Walker informs that the Director will arrange to despatch the necessary fittings for the new screw for the Poona micrometer to Hilger by next mail by next March

This letter states that the Photomeasuring micrometer is not yet finished and also mentions that they installed a special grinding machine

This Letter is from W. Butler, the Director General of Stores to The Director about the forward of Microphotometer which had been received from Mr. Toepfer

This letter is from Meteorological Department to the Director of Kodaikanal and Madras Observatories regarding a payment for one spectrum comparing Micrometer supplied to the Kodaikanal Observatory

This letter is from the Director of Kodaikanal and Madras Observatories to the Director General of Observatories, Simla regarding the micrometer eyepiece which was rebooked to Madras unopened as desired by the Deputy Director, Madras Observatory

This letter from Major S.G. Burrard to the Government Astronomer mentioning that Lenox Conyngham is dissatisfied with his Zenith Telescope results and with determinations of the Micrometer value, so he asked for sparing Dehra Zenith sector till next September.

This letter is from John Evershed to the Director General of Stores regarding the photo micrometer, referred to as his private property. Still, it would be mainly employed in research at the Kodaikanal Observatory.