[Footnote:  The leaf on which this passage is written, is headed with the words Casi 39, and most of these cases begin with the word ‘Come’, like the two here given, which are the 26th and 27th. 7. Sughero.  In the Codex Antlanticus 377a; 1170a there is a sketch, drawn with the pen, representing a man with a tube in his mouth, and at the farther end of the tube a disk.  By the tube the word ‘Channa’ is written, and by the disk the word ’sughero’.]

The preparation of the MSS. for publication.

2.

When you put together the science of the motions of water, remember to include under each proposition its application and use, in order that this science may not be useless.—­

[Footnote:  A comparatively small portion of Leonardo’s notes on water-power was published at Bologna in 1828, under the title:  “Del moto e misura dell’Acqua, di L. da Vinci".]

Admonition to readers.

3.

Let no man who is not a Mathematician read the elements of my work.

The disorder in the MSS.

4.

Begun at Florence, in the house of Piero di Braccio Martelli, on the 22nd day of March 1508.  And this is to be a collection without order, taken from many papers which I have copied here, hoping to arrange them later each in its place, according to the subjects of which they may treat.  But I believe that before I am at the end of this [task] I shall have to repeat the same things several times; for which, O reader! do not blame me, for the subjects are many and memory cannot retain them [all] and say:  ’I will not write this because I wrote it before.’  And if I wished to avoid falling into this fault, it would be necessary in every case when I wanted to copy [a passage] that, not to repeat myself, I should read over all that had gone before; and all the more since the intervals are long between one time of writing and the next.

[Footnote:  1.  In the history of Florence in the early part of the XVIth century Piero di Braccio Martelli is frequently mentioned as Commissario della Signoria.  He was famous for his learning and at his death left four books on Mathematics ready for the press; comp.  LITTA, Famiglie celebri Italiane, Famiglia Martelli di Firenze.—­In the Official Catalogue of MSS. in the Brit.  Mus., New Series Vol.  I., where this passage is printed, Barto has been wrongly given for Braccio.

2. addi 22 di marzo 1508.  The Christian era was computed in Florence at that time from the Incarnation (Lady day, March 25th).  Hence this should be 1509 by our reckoning.

3. racolto tratto di molte carte le quali io ho qui copiate.  We must suppose that Leonardo means that he has copied out his own MSS. and not those of others.  The first thirteen leaves of the MS. in the Brit.  Mus. are a fair copy of some notes on physics.]

Suggestions for the arrangement of MSS treating of particular subjects.(5-8).