Friction and Lubrication in Medieval Europe: The Emergence of Olive Oil as a Superior Agent Author(s): John Muendel Source: Isis, Vol. 86, No. 3 (Sep., 1995), pp. 373-393 Published by: The University of Chicago Press on behalf of The History of Science Society Stable URL: http://www.jstor.org/stable/235019 . Accessed: 07/09/2011 20:31 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact
[email protected]. The University of Chicago Press and The History of Science Society are collaborating with JSTOR to digitize, preserve and extend access to Isis. http://www.jstor.org Friction and Lubrication in Medieval Europe The Emergence of Olive Oil as a SuperiorAgent By John Muendel* W HEN DEALING WITH THE HISTORY of overcoming friction in medieval ma- chines, one cannot help but be struck by the investigations of Leonardo da Vinci. The Codice Atlantico, in particular,demonstrates that by measuring friction's force on both horizontaland inclined surfaces, he was able to introducethe concept that the coef- ficient of friction is the ratio of its force to the weight or load applied (u = FIW). His quantitativeexperiments eventually allowed him to conclude that "every frictional body has a resistance of friction equal to one-quarterof its weight," an approximationthat is close to modem standards.'In orderto reduce such resistance,Leonardo went so far as to devise self-oiling systems for lubricatingjournals, or axle-ends, and a variety of roller- bearingarrangements, one of which had balls enclosed in a cage or retainerthat anticipated recent schemes.