Eagles, Constructive Geometry of Plane Curves (1886); geometric investigations primarily based on the relation of the conic sections to a cone are given in Hugo Hamilton's De Sectionibus Conicis (1758); this method of treatment has been largely replaced by considering the curves from their definition in piano, and then passing to their derivation from the cone and cylinder.
Eagles and hawks are common, and many kinds of singing birds.
During the Hundred Days, Louis Napoleon, then a child of seven, witnessed the presentation of the eagles to 50,000 soldiers; but a few weeks later, before his departure for Rochefort, the defeated Napoleon embraced him for the last time, and his mother had to receive Frederick William III.
Eagles, Plane Curves (1885).
Among the birds, of which 172 species are described by Mr Swinhoe in his paper in The Ibis (1870), there are eagles, notably a new species Spilornis Rutherfordi, buzzards, harriers, kites, owls, goatsuckers and woodpeckers.