KRAYENHOFF

NETHERLANDS (see also List of Individuals)

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2.6.1758 Nijmegen/NL - 24.11.1840 Nijmegen/NL

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Cornelis Krayenhoff gradated in science from the College of Harderwijk in 1780. He mounted the first lightning rod on the bell tower of Doesburg in 1782. He also gained a diploma in medicine two years later. When the French army occupied - or liberated - Holland in 1795 the patriot Krayenhoff was persuaded to give up medicine for a military career. After having been appointed general of engineers, he became minister of war under King Louis Bonaparte. Krayenhoff studied fortification and strengthened the defenses of Amsterdam until Napoleon ordered the Dutch King to cease further extensions. Napoleon admired in 1811 Krayenhoff's defense works during a visit to the Dutch Kingdom.

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Besides triangulation works for an accurate map of Holland, Krayenhoff rendered an example of his inventiveness in gauging the average stream velocity. A hollow cylinder, partly emergent and held in a vertical position by lead disks, floats along at mean velocity in a certain tract, when the adjusted load keeps its lower end just clear from the bottom. The float method was developed during the 19th century but later rejected because of serious errors and disadvantages. In 1813, he published a comprehensive set of hydrographic and topographic tables for Holland. This early work is of considerable value as it gives detailed records of discharge using the slope of the water surface. Under King William I, Krayenhoff was occupied with fortifications and with hydraulic engineering, relating to large rivers and draining lakes. Pensioned in 1830, he devoted his time to physics and astronomy. An auto-biography was published in 1844.

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_{Bergh, F. van den (2006). Portrait of Cornelius Rudolphus Theodorus Krayenhoff. P}

_{Krayenhoff, C.R.T. (1813). Hydrographische en topographische waarnemingen in Holland}

_{door den Oud-minister van Oorlog Krayenhoff. Amsterdam.}

_{Krayenhoff, C.R.T. (1823). Proeve van een ontwerp tot scheiding der rivieren de Whaal en de Maas, en het doen afloopen dezer laatste, over hare oude bedding. Vieweg: Nijmegen. Krayenhoff, C.R.T. (1844). Levensbijzonderheden van den Leutenant-Generaal Baron Krayenhoff, door hem zelven in schrift gesteld en op zijn verlangen in het licht gegeven door Mr. H.W. Tydeman: Nijmegen.}

_{Nieuwenkamp, W. (1973). Krayenhoff, Cornelis Rudolphus Theodorus. Dictionary of scientific biography 7: 499-501.}

_{Tydeman, H.W., Krayenhoff, C.R.T. (1844). Levensbijzonderheden van den luitenant-generaal baron C.R.T. Krayenhoff. Vieweg: Nijmegen.}