The balance rule for finding a counterweight
Counterweight arithmetic, numbers, geometric sketches and a note on the eye and the sun
Several small sheets are mounted together and dominated by a worked example on balances: a rule 'for finding the counterweight to a given weight on one of the arms of the balance,' followed by a numerical demonstration for equal arms a b and b c. Around it are columns of numbers (27, 54, 81), crossed-out lettered figures and, inverted at the foot, a few geometric sketches including an irregular pyramid. A closing line turns to optics, noting that the eye retains the more images of the sun the more often it has gazed at it.
On this page
Rule for the counterweight on a balance arm
To find the counterweight, multiply the counterweight's arm by the given weight as many times as its arm contains the opposite arm, divide the weight by that sum, then multiply the result back by the weight. For equal arms a b and b c the given weight of 4 at c is balanced by 4 at a, since equal weights on equal arms resist each other's descent.
Columns of numbers: 27, 54, 81
At the upper left stand figures 54, 27 and 81 (multiples of 27) set out in columns, with abbreviated references 'for p c, for p i, for p K.'
Irregular pyramid and geometric sketches
Inverted at the foot of the sheet are a few small geometric figures, among them an irregular pyramid, one bearing the number 16.
The eye retaining images of the sun
A single line observes that the eye will keep within itself the more images of the sun, the more times it has looked at the sun.