**Serie VII; Plaster models of surfaces of order three**

Number | Title | Date of Design | Dimension (cm) | Material |

Serie VII, nr. 2 | Surface with four real double points (A_{1}). |
1881 | 13-15 | Plaster |

Serie VII, nr. 4 | Surface with 4 real ordinary double points. | 1881 | 13-15 | Plaster |

Serie VII, nr. 5 | Surface with 4 real ordinary double points. | 1881 | 13-15 | Plaster |

Serie VII, nr. 6 | Surface with 4 real ordinary double points. | 1881 | 13-15 | Plaster |

Serie VII, nr. 7 | Surface with 3 real ordinary double points. | 1881 | 11-15 | Plaster |

Serie VII, nr. 8 | Surface of the same kind, considered from the inside, for the formation of the
D_{4} double point. |
1881 | 11-15 | Plaster |

Serie VII, nr. 9 | Surface with three real A_{2} double points. |
1881 | 11-15 | Plaster |

Serie VII, nr. 10 | Surface with an A_{2} double point, whose tangent planes at that point intersect
the surface in three lines. The model is also valid for the transfer of the A_{2} into a
D_{4} double point. |
1881 | 10-15 | Plaster |

Serie VII, nr. 11 | Surface with an A_{2} double point, whose tangent planes at that point are
imaginary conjugated. |
1881 | 12-15 | Plaster |

Serie VII, nr. 12 | Surface with an A_{3} double point and two real ordinary (A_{1})
double points. The tangent planes at the A_{3} double point are real. |
1881 | 13-15 | Plaster |

Serie VII, nr. 14 | Surface with an ordinary A_{1} double point and an A_{4} double
point. |
1881 | 13-15 | Plaster |

Serie VII, nr. 15 | Surface with an ordinary A_{1} double point and an A_{5} double
point. |
1881 | 12-15 | Plaster |

Serie VII, nr. 16 | Surface with a D_{4} double point, whose tangent plane intersects the surface in
three real lines. |
1881 | 12-15 | Plaster |

Serie VII, nr. 17 | Surface with a D_{4} double point, whose tangent plane intersects the surface in
one real line. |
1881 | 12-15 | Plaster |

Serie VII, nr. 18 | Surface with a D_{5} double point. |
1881 | 12-15 | Plaster |

Serie VII, nr. 19 | Surface with a E_{6} double point. |
1881 | 12-15 | Plaster |

Serie VII, nr. 20 | A ruled surface, whose double straight line is completely surrounded by a real sheet of the surface. | 1881 | 13-15 | Plaster |

Serie VII, nr. 21 | Ruled surface, with a double line limited by two cuspidal points at finite distance. | 1881 | 13-15 | Plaster |

Serie VII, nr. 23 | Cayley's ruled surface with a cuspidal point (at finite distance). | 1881 | 13-15 | Plaster |

Serie VII, nr. 24a | Hessian surface for models VII, 2 and VII, 5. | 1881 | 21-25 | Plaster |

Serie VII, nr. 24b | Star shaped part of the preceding for a pentaeder, which consists of the infinitely far plane and a regular tetrahedron. | 1881 | 13-16 | Plaster |

Serie VII, nr. 25 | Hessian surface for model VII, 7. | 1881 | 21-25 | Plaster |