Stichting De Traditie -
Cultural
Heritage
Utrecht - Science
Collateral Damage 1944 - 'Sonar' Manuscript burnt
s
In 1946, Sven Dijkgraaf published a paper: Die Sinneswelt der Fledermäuse, Experientia 2, 438-448; an article on the echolocation of bats, based on Dijkgraaf's own research in wartime and the classical studies of Spallanzani and Jurine. An earlier version of the manuscript was submitted to the Zeitschrift für vergleichende Physiology, but burned in 1944/5 due to the intensive visits by the Allied Forces. The Zeitschrift was suspended between June 1944 and August 1948. Publication in Experientia followed on the invitation of the editor H.Mislin, who explained in a letter dated March 23, 1946, to have received an inside tip from "Prof. Tinbergen". A preliminary study of this work appeared as Dijkgraaf-S 1943: Over een merkwaardige functie van den gehoorzin bij vleermuizen. Verh. Ned. Akad. Wet., Afd. Natuurk. 52, 622-627 (in Dutch). It is Dijkgraaf's merit that in spite of the absence of ultrasound equipment, he nevertheless came to the conclusion that bats orient themselves and find their food using echolocation. His written heritage justifies the suspicion that, forced by the circumstances of war, his studies on the Ferntastsinn in fish had to be interrupted, to make place for the investigation of the Ferntastsinn in bats and flies. Assistance in obtaining bats he received from the brothers L. and P. J. Bels .