Line of Descent by its own Gravity.
- If therefore this be added to a projecting Force downward in a Perpendicular; or subducted from such projecting Force upward; that is, to or from
1-a / n f: The Descent in the first Case will be
1-a / n f +
nt - 1 + a / nn g; and the Ascent in the other Case
1-a / n f -
nt - 1 + a / nn g. And in this latter Case, when the ablative Part becomes equal to the positive Part, the Ascent is at the highest; and thenceforth (the ablative Part exceeding the positive) will descend.
- In an Horizontal or Oblique Projection, having taken 1-a / n f, in the Line of Projection, and thence (at the Angle given) nt - 1 + a / nn g, in the Line of Descent; the Point in the Curve answering to these, is the Place of the Project answering to that Moment.