Cardan's Suspension in China 



By Berthold Laufer 



HE mechanical contrivance commonly styled "gimbal M1 is 

 known in the history of science under the term "Cardan's 

 suspension". Although named for the celebrated Italian 

 mathematician Jerome Cardan (Girolamo Cardano, or 

 Latinized Hieronymus Cardanus; 1501-76), both the prin- 

 ciple and its application were revealed and practised ages before his 

 day. In fact, Cardan himself lays no claim to originality in this in- 

 vention, but in his work De subtilitate rerum, first published in 1551, he 

 merely describes a chair constructed for an emperor, which permitted 

 him to sit in it during a drive without experiencing the least jolting, 

 and on this occasion observes that the same arrangement had been 

 used previously in connection with oil lamps. 2 



As intimated by Berthelot, Cardan must have encountered the 

 invention bearing his name in the writings on the secret processes of 

 magic, to which he was not foreign. Not only was he a philosopher, a 

 physician, and a devotee of science, but also an astrologer, charlatan, 

 and gambler. 3 We now even possess a clew to this magical document 

 presupposed by Berthelot, as will be seen farther on. 



The nearest predecessor of Cardano was Leonardo da Vinci (1452- 

 I 5 I 9). who left a design showing the suspension of a body, said to be 

 capable of turning itself around three axes perpendicular one to 

 another. 4 This construction, however, is not due to Da Vinci's genius 

 either, for, as first shown by M. Berthelot, 5 the great French his- 

 torian of chemistry, it was well known during the early middle ages. 

 The document on which Berthelot's opinion is founded is contained 

 in a curious Latin manuscript, the Mappce clavicula (that is, "Key 



1 Derived from Old French gemel. which is based on Latin gemellus, diminutive of geminus 

 ("double", "twin"). The New Oxford English Dictionary gives the following definition of the 

 term: "A contrivance by means of which articles for use at sea (esp. the compass and the chrono- 

 meter) are suspended so as to keep a horizontal position. It usually consists of a pair of rings 

 moving on pivots in such a way as to have a free motion in two directions at right angles, so as to 

 counteract the motion of a vessel." 



2 Compare F. Cajori, A History of Physics, p. 24, New York, 1899. 



3 As is also well known, the solution of the cubic equation known as Cardan's method is not due 

 to his merit, but was the discovery of his countryman Tartaglia, who communicated it to Cardan 

 in 1541, whereupon the latter published the solution under his own name. 



4 E. Gerland, Geschichte der Physik, p. 250. 



6 First in Comptes-rendus de V Academie des Sciences, vol. cxi, 1890, p. 940; then in La Chimie 

 au moyen age, vol. I, pp. 176, 177, Paris, 1893. 



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