Letter from John Welsh, Kew Observatory to Edward Sabine Discussion regarding the anemometer. Welsh thinks they can get an ‘observatory bifilar’ from the materials they have [at Kew]. The vertical force magnet returned by Mr Blakiston will work well for Father [Angelo] Secchi, however, Welsh is not sure if this instrument belongs to the [British Association]. Reference to sending a bifilar. 7 December 1857