Prop. III. Pr.
To estimate the direction of a line.
Example. Prove that the definition of a line, according to Walton, coincides with that of Salmon, only that they begin at opposite ends. If such a line be divided by Frost's method, find its value according to Price.
Prop. IV. Th.
The end, (i. e. 'the product of the extremes,') justifies (i.e. 'is equal to' see Latin 'æquus,') the means.
No example is appended to this Proposition, for obvious reasons.
Prop. V. Pr.
To continue a given series.
Example. A and B, who are respectively addicted to Fours and Fives, occupy the same set