Begun in Florence, 1508: preface and weights on the balance
Leonardo's dated foreword to the collection, with lever-and-weight calculations
Folio 1r opens with Leonardo's famous dated foreword, stating that on 22 March 1508, in the Florence house of Piero di Braccio Martelli, he began a collection 'without order' copied from many sheets, and apologising to the reader for the repetitions memory will cause. The rest of the leaf treats a heavy body suspended from the arms of a balance by a doubled cord (its 'potential appendage'), and gives worked lever-and-counterweight calculations that multiply the divisions of the lever by the weight and divide by the counter-lever. The facing folio 14v appears blank. Further untranscribed writing and balance diagrams are present on the sheet.
On this page
The dated preface of 22 March 1508
Leonardo records that he began this collection in Florence, in the house of Piero di Braccio Martelli, on 22 March 1508. He calls it a gathering without order, copied from many sheets, and asks the reader not to blame him for repeating the same thing, since the matters are many and memory cannot hold them, especially as he writes at long intervals.
Heavy body on a doubled cord
A heavy body suspended from the arms of the balance by a doubled cord will always have its appendage, which will be wholly or in part a potential appendage. The note underlies the calculations that follow.
The lever-and-counterweight rule
Multiply the divisions of the lever by the pounds of the weight attached, and divide by the divisions of the counter-lever; the result is the counterweight that resists the descent. As an example: the 2 of n m times the weight b,1 makes 8; divided by the 4 of m o gives 2, and this 2 placed at o s resists the descent of the 4 placed at n d.
The same rule worked in reverse
Conversely: 2 times 4 is 8; divided by the 2 of m n gives 4; and thus you have 4 for the weight d, so the rule always comes out right.