Which of two weights sits nearer the balance's pole
Two rules comparing the outer weights against twice the middle weight
Three diagrams of the triangular balance — each a circle divided by radii above a graduated beam hung with boxed weights — illustrate two complementary rules. If the greatest and smallest weights together sum to less than double the middle weight, the smaller weight lies nearer the pole; if their sum exceeds double the middle, the greater weight lies nearer. Worked weight-triples (2-1-3, 5-1-6 and a further numeric set) accompany the drawings.
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When the outer weights sum to less than twice the middle
If the greatest and the smallest weight together are of a smaller sum than double the middle weight, the smaller weight will be nearer the pole than the greater. The accompanying scheme is labelled with the weights 2, 1, 3.
When the outer weights sum to more than twice the middle
But if the greatest and the smallest weight joined together exceed double the middle weight, the greater weight will be nearer the pole than the smaller. This scheme carries the weights 5, 1, 6.
Numeric values for the third scheme
A third balance drawing is labelled only with numbers rather than a stated rule. These give the weights and derived values for that case of the triangular balance.