Henry Cavendish's notes from his work on astronomy including his work for committees of the Royal Society, his observations and his calculations of orbits. In particular, HY/8/26 - HY/8/32 are in relation to the transits of Venus in 1761 and 1769; and HY/8/37 - HY/8/54 are in relation to comets, in particular to determining their orbit.
Some items in this grouping are mentioned in Thorpe, Sir Edward "The Scientific Papers of the Honourable Henry Cavendish, F.R.S" (1921; Cambridge, Cambridge University Press) Vol II, pp433-5 by Sir Frank Watson Dyson (1868-1939, F.R.S. and Astronomer Royal). He notes and comments on the records in the following order: HY/8/1-10, HY/8/35, HY/8/26-27, HY/8/43, HY/8/46, HY/8/44, HY/8/47, HY/8/41 and HY/8/53. He then makes "four short extracts from the papers" which are in order HY/8/26, HY/8/9, HY/8/10 and HY/8/52 (pp435-7).