The Elements of Hydrostatics

be dried. Their quality is to make short, clear, and obvious *propositions, not only for the students but also for the Inventors themselves, in order to openly observe the progress of one thing from another. If you desire another example of this beyond the present book, then take from among some Conic sections. propositions of the first of the *Conic Books of Apollonius the 11th, which was translated from Greek into Latin by Fredericus Commandinus (whose name I gladly remember with reverence, as that of a star among the *Mathematicians of his time, and by whose diligence many things that lay hidden in Greek have been brought to light) as follows:

If a cone is cut by a plane through the axis; and it is also cut by another plane cutting the base of the cone according to a straight line, which is perpendicular to the base of the triangle through the axis: and the diameter of the section is made equidistant to one of the sides of the triangle through the axis: the straight line, which is drawn from the section of the cone equidistant to the common section of the cutting plane and the base of the cone, up to the diameter of the section, shall be equal to the space contained by the line, which is cut off from the diameter between itself and the vertex of the section, and another line which has the same proportion to the line between the angle of the cone and the vertex of the section, as the square of the base of the triangle through the axis has to that which is contained by the other two sides of the triangle. And let such a section be called a parabola.

In contrast, we shall say it much more shortly and clearly in the first of those conic books that we intend to publish in Dutch: