34. Bar micrometer by D. Lusverg
Rome, 1744
Domenico Lusverg (1669 - fl.1744)
length 12 cm, width 12 cm
[Inv. MdS-38]

This micrometer, signed Dominicus Lusverg F. 1744, was an accessory for a parallactic telescope which had been solicited as gift by Eustachio Zanotti from Benedict XIV in a letter of 17 June 1744 (Arch. Dip. Astron. Bo., busta LX), which explained how a previous wooden parallactic telescope, built by Manfredi - of which there is no trace in the inventories but which does show up in the records on 15 September 1727 - had become utterly unusable. The same Zanotti suggested the name of the craftsman in this letter.
It is a bar micrometer modeled on the instrument Philippe de La Hire (1640-1718) had described in his 1685 work, L’E’cole des Arpenteurs. The 1843 inventory by Ceschi mentions "a metal-bar micrometer by Domenico Lusverg of 1744", though it almost certainly is not the micrometer mentioned in the 1799 inventory as "a filar micrometer of Mons. De La Hire", which formed part of "a case covered with gilded damask brocade", together with compasses and mathematical instruments, that today have been lost.
A micrometer modeled on the same lines but built before and signed Jacopus Lusverg mutinensis / fa.at Romae anno 1677 can be found at the seminary of Treviso (Piero Todesco, in preparation).

E. Baiada, A. Braccesi (1983), p. 120.
J.A. Bennett (1987), p. 63.
R.C. Brooks (1991).
A. Chapman (1990), p. 40.
M. Daumas (1953), p. 69.
E. Miotto, G. Tagliaferri, P. Tucci (1989), p. 97.
J.A. Repsold (1908), Fig. 55.