Serie XXV; Seven string models of a cone of order three

Number Title Date of Design Dimension (cm) Material
Serie XXV, nr. 3 Cone of genus zero, with a return side. 1899 17 String
Serie XXV, nr. 4 A cone of genus one. I. Existing of one converged and one diverged sheet. Or II. Consisting of a only one divergated sheet. 1899 17 String
Serie XXV, nr. ? Cone of genus one. 1899 17 String
Serie XXV, nr. ? Cone of genus one. 1899 17 String