Object-glass of 90ft. focal length which belonged to Flamsteed. Presented to the R.S. by James Hodgson, F.R.S., in 1737. R.S. no.25, no case. Diameter varies from about 9 3/4"to 9 7/8". Chipped at edge and badly scratched on one face 5/16" thick. Thought to be the object glass from Flamsteed's well telescope.