Objective lens of 5.9-inches aperture made by Charles Tulley of Islington for a refracting telescope on an English type equatorial mounting made by Dollond. Both elements of the achromatic lens are notched for alignment in the brass cell while the flint rear lens has numerous small air bubbles.

The 5.9-inch objective lens for the Smyth Telescope was made by Charles Tulley (the elder) of Islington, London. It is probably his finest work and was judge first class when it was tested in 1929 by Dr W.H.Steavenson. The large flint blank for the Tulley lens was obtained by Sir James South from the Optician Cauchoix in Paris.