MICHELANGELO BUONARROTI (1475-1564). Autograph diagram and measurements (six words), of a rectangular block of marble, n.p. [Florence], n.d., in pen and ink on a fragment of paper, 52 x 104 mm (minor old damp staining; inscribed in pencil 'B 26'), mounted on the 2nd leaf of a bifolium (4to) inscribed by Cosimo Buonarotti (the underlying paper restored after minor damp damage). Provenance: autograph presentation inscription by Michelangelo's last direct collateral descendant, Cosimo Buonarotti, to Monsignor Cosimo dei Conti Spada, September 1832: 'Questo saggio del carattere del divino Michelangiolo estratto da un foglio contenente le note e le misure di diversi marmi che si trovavano nella sua casa di Roma offriva nel S[ettem]bre del 1832 all'Egregio Monsig[nore] Cosimo dei Conti Spada in segno di particolare stima et affettuosa rimembranza Il suo Aff[ettuos]o Servitore Cosimo Buonarotti'.
The drawing shows the outline of a rectangular block of marble, giving its measurements in 'braccia' as 'braccia tre' by 'u[n] braccio', and 'dua terzi' (two thirds) in depth. Cosimo Buonarotti's note describes the fragment as coming from a leaf containing measurements of various blocks of marble in Michelangelo's house in Rome.
The Archivio Buonarotti, bequeathed by Cosimo Buonarotti to the City of Florence on his death on 1858, includes numerous examples of complete sheets of block drawings (Vol.I ff.108-156), which are published by C. de Tolnay, Michelangelo (1954), vol.IV, plates 124-164, together with a few other dispersed examples (though not the present drawing). Two of these (plates 168 & 185) bear inscriptions by Cosimo Buonarotti: the second, with an inscription dated 1852, is in the Stefan Zweig collection at the British Museum. De Tolnay divides the block drawings, which he notes are 'not without aesthetic quality', into two groups, with those bearing the three circles of Michelangelo's impress intended for the Medici Chapel and the remainder (of which the present example would be one) probably for architectural purposes in the façade of San Lorenzo. In spite of Cosimo Buonarotti's assertion, the sketchy nature of the present diagram makes it more likely to have been part of an order-sheet for a block to be quarried, rather than a record of a block already existing (see Wallace, 'Drawings from the Fabbrica of San Lorenzo during the Tenure of Michelangelo', Studies in the History of Art. 33. Michelangelo Drawings, 1992, pp.117-141).