It is therefore a particular form of Cassini's oval (see Oval).
Of the Austrian Netherlands, Count Joseph de Ferrari published a chorographic map on the same scale as Cassini's Carte de la France (1777).
Hachures of a rude nature first made their appearance on David Vivier's map of the environs of Paris (1674), and on Cassini's Carte de la France.
Cassini's new method of parallaxes was inserted in the Ada Eruditorum of Leipzig in 1685.
In the case of a biaxal plate perpendicular to the bisector of the acute angle between the optic axes, the curves of constant retardation are approximately Cassini's ovals, and the lines of like polarization are equilateral hyperbolae passing through the points corresponding to the optic axes.