Milan Cathedral account: a merchant's debits and credits
A reused register leaf with two double-entry accounts, September to October
This leaf was cut from a Register of Milan Cathedral and bears two double-entry accounts, each headed 'debet dare' (debit) on the left and 'debet habere' (credit) on the right, for the merchant Steffanino Taberna. Entries run through late September into October, citing folio cross-references and sums in lire, soldi and denari, including an exchange premium (agio) on gold. The Ambrosiana catalogue notes that Leonardo later added faint geometrical and mechanical jottings to the sheet (on the lever, on antifriction, and on equal quantities taken from both sides of an equation), which are not transcribed here.
On this page
First account of Steffanino Taberna
The left column records what Taberna owes, credited to Battista Magiolino and Gabriele de Busti with folio references and September dates, one entry noted as an exchange. The facing right column records the offsetting credits, among them £4,000 and a premium on gold, closing at £4,130 19s 7d.
Second account, late September to October
A second account credits Galeazzo Mantegazio £332 10s on 27 September, its debit side reaching £2,400 by agreement and £1,300 on 9 October. All sums are given in lire, soldi and denari.