Views, cross-sections, floor plans and details for the purpose of strengthening the foundations of the châtelet (strengthening the tower base), with a drawing: "Pressure line vault bridge 'Kasteel De Haar' (useful load = 600 kg per square meter)," quoting specification number 621, signed by J.Th.J. Cuypers, stamped by N.V. Gewapend Betonbouw DE KONDOR of Amsterdam, 1932 and 1933, scale 1 in 50, 1 in 100.