Vibraciones

national academy of sciences

JacoB Pieter den HartoG

1901—1989

A Biographical Memoir by
stePHen H. crandall

Any opinions expressed in this memoir are those of the author(s) and do not necessarily reflect the views of the National Academy of Sciences.

Biographical Memoir Copyright 1995 NatioNal aCademies press washiNgtoN d.C.

JACOB PIETER DEN HARTOG
July 23, 1901–March 17,1989
BY STEPHEN H. CRANDALL

A

his book Mechanical Vibrations in 1940 when I was an undergraduate at Stevens, I did not meet Professor Den Hartog until the fall of 1946 when I joined the faculty of the mechanical engineering department at MIT. Den Hartog had himself come to MIT only a year earlier after ser ving in the navy during the war. Twenty years my senior and already world famous, hewas both an inspiring role model and a gracious mentor. He was internationally famous as a vibration consultant with an uncanny ability to identify and explain the cause of a mysterious vibration. But, above all, Den Hartog was a consummate teacher. He could hold the attention of a single colleague or a class of a hundred students as he explained a particular mechanism and wrapped his audience inthe sheer fun of imagining how it would move and why. He taught dynamics by creating vivid images of particular cases that dramatized generic concepts. Generations of students were enriched by his ver ve, wit, and captivating physical insight. Jacob P. Den Hartog was born in Ambarawa on the island of Java in the Dutch East Indies on July 23, 1901. His father, Maarten, had been a school teacher inAmsterdam until he was dismissed because of radical activity. Maarten had been
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an outspoken supporter of Alfred Dreyfus in the early phases of that famous affair when the popular view was strongly against Dreyfus. The family was forced to go to the Indies, and Maarten taught school in the colonial system in Ambarawa, Makassar, andBatavia. Young “Jaap” grew up speaking Dutch and Malay. He attended elementary school and took violin lessons. When it was time for Jaap to enter high school, it was decided that he, his two younger sisters, Wilhelmina and Clara, and his mother, Elizabeth, would return to Amsterdam, while Maarten would remain in Java. Because Holland was a neutral country during the First World War, their ship couldsail, brightly lit, without interference from submarines, although it was necessary in 1916 to bypass the Suez Canal and sail down around the southern tip of Africa and up around Iceland to reach Holland. The following eight years were difficult for the Den Hartog family. Maarten, the father, died in Java soon after the family returned to Holland, and his widow was left with three children tosupport. Jaap was such an outstanding high school student that some of his relatives undertook to pay his expenses at the Technical University of Delft. Entering Delft in 1919, young Den Hartog decided to become an electrical engineer after seeing a dramatic physics demonstration in which a bolt of lightning jumped from one charged sphere to another. He was a good student, but because of his limitedfinancial situation he was unable to participate in sports or social activities. He compensated for this by developing a strong prejudice against the rich. Economic conditions in Holland were sufficiently bad in 1924 when he graduated that even the best Delft students could not be sure of finding a job. For some reason, Den Hartog did not tr y very hard. He made only two applications, and when hewas rejected, he impulsively decided to leave Holland to seek his fortune in the United States.

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Arriving in New York without connections and essentially penniless, Den Hartog took to America with great enthusiasm. He worked briefly at a sequence of temporary jobs until he learned that Westinghouse was hiring electrical engineers in Pittsburgh. Luckily he was...