Rat breeding, sun-moon-earth eclipses, and hand muscles
An exponential-breeding reckoning, astronomical orbit figures, and 26 hand muscles
The page mixes several inquiries. At the top Leonardo reckons how fast rats multiply, counting litters of six across the months of a year and running the compounding tally toward more than a hundred offspring, with a small breeding diagram marked 'mesi 3.' A run of circular sun-moon-earth figures continues the astronomical theme, describing how the moon's night sees the earth's ocean eclipsed while the earth's day sees the sun eclipsed, and noting that the two luminaries have no light of their own. At the left a labelled figure enumerates the 26 muscles of the hand and what each group does. Further untranscribed mechanical sketches, including lever and stand-like devices, occupy the lower part of the sheet.
On this page
Reckoning how fast rats multiply
In its first year a rat makes 12 litters of 6, giving 72 offspring; assuming half are females, Leonardo compounds the litters month by month toward 108 offspring. A small diagram is marked '3 months.'
Ocean and sun eclipsed (sun, moon, earth)
In this orbit figure the night side of the moon sees the earth's ocean eclipsed, while the day side of the earth sees the sun eclipsed. The bodies are marked sun, moon and earth.
The two luminaries shine only borrowed light
These two luminaries have no light of their own, and shine only insofar as the sun sees them; in this aspect the earth's eastern evening sees the moon's daytime. Leonardo also asks what difference the ocean's light makes in storm versus calm, and notes the moon has 12 days and 12 nights in the year.
The 26 muscles of the hand (26)
A labelled figure counts 26 muscles: 10 that bend the first joint of the fingers, 4 over the wrist, 2 that draw thumb and little finger together, 5 that incline the fingers to the outer side and 5 to the inner side.
Untranscribed mechanical sketches
The lower portion of the sheet carries small pen sketches of mechanisms, including lever-and-stand and wheel-like devices, that are not covered by the transcribed notes. Their function is not specified in the accompanying text.