Already noted by Manfredi in Instrumenta quibus observationes peraguntur in hoc observatorio (scilicet Marsili Observatory), this quadrant is accurately described in the 1712 Instrumentum donationis:
"Quadrans Astronomicus pendulo instructus, semidiametro pedum trium, Lusvergo Artifice. Structura quadrantis ferrea; sed limbo, & centro auricalcea lamina inducta est, limbusque Tychonice divisus. Pendulum intra tubum e’ bractea auricalcea factum simul cum ipso pendulo volubilem custoditur, ne’ venti agitatione turbetur. Pro pinnulis adsunt Dioptrae Telescopicae duae, altera ad Instrumenti latus apposita, eaque immobilis, quae per cochleas quadratis loculamentis duobus adstringitur; altera volubilis circa cilindrum, qui quadrantis centro immittitur. Ferreum Instrumenti suppedaneum pedibus quatuor solo insistit, singularisque adiecta est cochlea, cujus motu quadrans tantisper inclinetur. Ipse tum verticaliter, tum horizontaliter convertitur circa axes duos, quorum alter intra arundinem ferream volvitur, quae e’ suppedaneo assurgit, alter e’ quadrantis postico exit, priori axi ad perpendiculum occurrens, cochleisque duabus ad hujus superiorem partem adstringitur. Adest & tertius axis amovibilis, cujus ope Instrumentum in omnem inclinatam positionem componitur, atque ita non modo ad altitudines, sed & ad syderum distantias captandas usum habet. Umbilicum ejus tenet lamina auricalcea, cui Marsiliae gentis insigna insculpta sunt. Telescopia filis in regione foci decussatis praedita sunt, deficentibus lentibus, oculari scilicet, & objectiva."
Missing are the movable telescope, at least as of 1746, the lenses of the fixed telescope, as already reported in 1712, the pendulum which in 1849 still existed and the swivel junction or third axis which made it useable as an astronomical sextant, already missing in 1843. The scale engraved on the brass limb shows the arcminute.
The vertical support arm is made with a gun-barrel and the Marsili coat-of-arms is engraved on a central brass escutcheon crowned with the words Aloysius Ferdinandus Comes Marsigli.
The first of a series made at the work-shops of the Lusvergs [files 12 and 16], this instrument was built under the supervision of the Parisian astronomer Maraldi - at Rome for many months in 1702 - using the Paris model of instruments.
From a letter of Maraldi to Manfredi dated 25 July 1702 (Univ. Bo. Library, Mss. Marsiliani 80B) we learn in fact that Francesco Bianchini and Maraldi itself were overseeing the actual making of the instrument in Rome, urging the craftsman to take all the necessary precautions so that the result would be like that of the quadrants made in Paris which Picard had used for the triangulation of France. This instrument, however, fell short of expectations on account of its somewhat irregular gradation (Reg. Oss. Marsiliano, Vol. 1 dated 23 May and 17 November 1703, Arch. Dept. Astron. Bo.). One of the causes of this quadrant’s imperfection - besides the fact that the technique for building it and engraving the tychonic scale was rougher than for the other two instruments - is that it was the first instrument of this size made by the young Domenico. His uncle Giacomo Lusverg, craftsman of proven skill, had died and the buyers had thus had to entrust construction of the quadrant to the less expert nephew (for information on the Lusverg family of craftsmen see Tabarroni and P. Todesco,op. cit.).
A subsequent letter of Manfredi to Marsili on 26 December 1702 (Univ. Bo. Library, Mss. Marsiliani 80B) signaled the arrival of the instrument in Bologna.
Restoration was carried out by Giovanni Morigi (Bologna) in 1979.
E. Baiada, A. Braccesi (1983) p. 86.
M. Daumas (1953) p.91.
E. Miotto, G. Tagliaferri, P. Tucci (1990) pag. 95 e seg.
G. Tabarroni (1954) p.43.
P. Todesco (1995).