Among the accessories of the parallactic telescope by Dollond [file 38], the 1843 inventory mentions this annular micrometer built by Amici - whose date of manufacture and purchase are, however, missing - as follows:
"An annular micrometer by Amici with astronomical eye-piece".
The fact that among the accessories of Amici’s Herschelian telescope of focal length 266 cm [file 46], mention is also made of a tube to be screwed on to the eye-piece holder, so that the eye-pieces of Dollond’s parallactic telescope could also be used, would seem to suggest that the micrometer was ordered from Amici together with the telescope itself.
For Amici see file 46, regarding the Herschelian telescope purchased by the Specola in 1813.

E. Baiada, A. Braccesi (1983), p. 122.
R.C. Brooks (1991).
M. Daumas (1953).