...; transferred from the Ministerie van Marine (Department of the Navy), The Hague, to the museum, 1883

Object number: NG-MC-885

Log timer in the shape of a stoppable hour glass. The top section contains the sand glass in a round brass casing. A valve can be operated by means of a small handle, to open the neck of the upper glass. The sand then pours into the lower section, which is a long glass with a scale on the side. Once the measurement is made, the valve is shut.

The instrument was used to establish the ship’s speed in conjunction with an ordinary log or by means of foam floating by, normally done by counting out loud.¹¹J.M. Obreen, Catalogus der verzameling modellen van het Departement van Marine, The Hague 1858, no. 885.

Rasmus Dekker repeatedly tried to sell his inventions to the Dutch and French governments between 1791 and 1815, but was turned down on each occasion. They were tested by Hendrik Willem Lantsheer in 1810 and a number of instruments were bought for further testing in 1814, but in 1817 the Navy definitively declared Dekker’s inventions unsound for the service. In 1812, Dekker received 16 ducats for his log timer.

J.M. Obreen, Catalogus der verzameling modellen van het Departement van Marine, The Hague 1858, no. 885; G. Doorman, Het Nederlandsch octrooiwezen en de techniek der 19de eeuw, The Hague 1947, p. 94; C.A. Davids, Zeewezen en wetenschap. De wetenschap en de ontwikkeling van de navigatietechniek in Nederland tussen 1585 en 1815, Amsterdam/Dieren 1985, pp. 247-50

J. van der Vliet, 2016, 'Rasmus Dekker, Log Timer, Amsterdam, c. 1795 - c. 1812', in J. van der Vliet and A. Lemmers (eds.), Navy Models in the Rijksmuseum, online coll. cat. Amsterdam: https://data.rijksmuseum.nl/20054021