Degrees of Time, Motion and Velocity in Free Descent
Three short notes divide time into degrees like a musician's measure, each degree adding one more of motion and of velocity.
Three short notes headed "On motion" set out Leonardo's kinematic rule for free fall: in every degree of time a descending body gains one degree of motion, and in every degree of motion one degree of velocity. He concedes that time cannot truly be divided into degrees the way a body's motion can, but says the necessity of the case forces him to divide it as musicians divide their measure. He then works the scheme out numerically: one degree of time yields one of motion and one of velocity, the second degree two and two, and so on successively. A curved pen-stroke braces the lines of the first note and a diagonal stroke cancels the middle one.
On this page
The basic rule of free descent
A freely descending heavy body acquires, in every degree of time, one degree of motion, and in every degree of motion, it acquires one degree of velocity. The lines of this first note are gathered together by a curved stroke of the pen.
Time divided into degrees, as musicians do
Although the motion of time cannot be divided into degrees as can the motion made by bodies, the necessity of the case constrains Leonardo to make degrees of it. He does so, he says, in the manner used in the domain of musicians.
The successive doubling of the degrees
In the first degree of time the body acquires one degree of motion and one degree of velocity. In the second degree of time it acquires two degrees of motion and two of velocity, and so it continues successively.