…; collection Jochem Pietersz Asmus (1765-1837), Amsterdam, 1807;¹¹HNA 2.01.29.02 Dept. Marine, Aanhangsel I, inv. no. 20, La. F no. 7. Ministerie van Marine (Department of the Navy), The Hague, 1837;²²After the death of Asmus in 1837 models from his private collection remained in the Navy Model Room in The Hague and were henceforth considered an integral part of the collection of the Department of the Navy. transferred to the museum, 1883

Object number: NG-MC-806

Model of an artificial reef.

Seen from above, the model is a star-shaped wooden framework with sharp points in eight directions. On a metal circle in its centre, another eight points face upwards. From the side, it looks like an upturned pyramid with an eye for anchoring at the tip; the lower section is an inversed pyramid with a square base, the sides closed with planking. A king post in the centre connects all the construction elements.

This model carried the number 805 instead of 806. The measurements, however, agree with the catalogue entry of Obreen for model number 806.³³J.M. Obreen, Catalogus der verzameling modellen van het Departement van Marine, The Hague 1858, no. 806. This particular design had a diameter of 50 feet and the king post was 22 feet long.

It is probably the model mentioned in the private collection of Jochem Pietersz Asmus (1755-1837) in 1807.⁴⁴HNA 2.01.29.02 Dept. Marine, Aanhangsel I, inv. no. 20, La. F no. 7. Artificial reefs were an invention by Hendrik Aeneae (1743-1810), member of the Central Committee for the Navy of the Batavian Republic. Anchored and floating slightly beneath the surface of the water, they were designed to defend harbours against enemy fleet.

One was tested in the harbour of Den Helder. When, during a storm, a hospital ship drifted towards the contraption, the reef was damaged, but not the ship. The chains to which the cannon, serving as anchors, were attached, did not hold and the reef had to be towed on to the beach.

Swedish Admiral Carl Olof Cronstedt (1756-1820) was interested in the design for the defence of the Sound and the Danish Belts and obtained drawings and a description, as did the Italian engineer Salvini.

Scale (derived) 1:12.

J.P. Asmus, Verzameling der verhandelingen over de defencie der zeegaten ... , s.l. 1800, manuscript in HSM, inv. no. B.0216(0322); J.C.J. de Jonge, Geschiedenis van het Nederlandsche zeewezen, 5 vols. and index, Haarlem 1858-62, vol. 5, pp. 509-11; J.M. Obreen, Catalogus der verzameling modellen van het Departement van Marine, The Hague 1858, no. 806; R.M. Haubourdin et al., De physique existentie dezes lands. Jan Blanken, inspecteur-generaal van de waterstaat (1755-1838), exh. cat. Amsterdam (Rijksmuseum) 1987, no. 45; M. Marzari, Progetti per l’imperatore. Andrea Salvini ingegnere a l’arsenal 1802-1817, Trieste 1990, p. 84, possibly pl. XLVI; A.A. Lemmers, ‘De kunstklip van Aeneae (1800) en de leugen van Asmus’, Tijdschrift voor Zeegeschiedenis 12 (1993), no. 2, pp. 111-27; H. Stevens (ed.), The Art of Technology: The Navy Model Collection in the Amsterdam Rijksmuseum, Amsterdam/Wormer 1995, pp. 38-41; A.A. Lemmers, Techniek op schaal. Modellen en het technologiebeleid van de Marine 1725-1885, Amsterdam 1996, pp. 100-15; A.J. Hoving, Message in a Model: Stories from the Navy Model Room of the Rijksmuseum, Florence, OR 2013, pp. 108-11

J. van der Vliet, 2016, 'anonymous, Model of an Artificial Reef, Netherlands, 1799 - 1800', in J. van der Vliet and A. Lemmers (eds.), Navy Models in the Rijksmuseum, online coll. cat. Amsterdam: https://data.rijksmuseum.nl/20053976