LA UFER— CARDAN'S SUSPENSION 



this ingenious arrangement has been forgotten by Hero and the sub- 

 sequent mechanicians; but it is not impossible, after all, that it should 

 have been forgotten. The text says that this mode of suspension was 

 utilized in the Jewish censers; some archeologist versed in Hebrew 

 antiquities might possibly deduce a date therefrom." There can be 

 no doubt that the description of the inkwell was part and parcel of 

 Philo's original Greek text, and that the Arabic translation renders 

 a correct account of it. 1 This is confirmed by the Mappce clavicula, 

 and we are fully entitled to the conclusion that the principle of Car- 

 dan's suspension was well familiar to the great Hellenic mechanicians 

 of the Alexandrian epoch. 



Whether the allusion to the Jewish censer hints at some Semitic 

 influence can hardly be decided in the present state of our knowledge. 

 What is of particular interest in this connection is the fact that in 

 China also the Cardanic principle has been applied to censers or 

 braziers. 2 Berthelot already had some vague information to the effect 

 that "suspension a. la Cardan has been employed in eastern Asia 

 probably from times immemorial, as the Chinese do not change their 

 processes." This point, however, he added, would require further 

 elucidation. 



The principle is well exemplified in a Chinese brazier obtained by 

 the writer in 1909 at Si-ngan, the capital of Shen-si Province, for the 

 Field Museum, Chicago (cat. no. 1 17679). In its outward appearance 

 it presents a hollow sphere of brass, cut out into rosette-like designs 

 in open-work, and composed of two hemispheres (see pi. 1, upper 

 figure), one fitting above the other. If the upper one is removed (lower 

 figure on the same plate), we notice in the interior a round brass bowl, 

 which may be filled with aromatic substances, incense, or burning 

 charcoal. If filled with coal, the brazier conveniently serves as a bed- 

 warmer, as the sphere may be rolled and knocked around ad libitum, 

 while the bowl swinging freely and independent of this motion will 

 never turn upside down. The contrivance consists of two brass hoops, 

 so arranged that one is within and perpendicular to the other. The 

 outer hoop is riveted to two lugs, projecting from the inner side of 

 the hemisphere and made in the same cast with it. The inner hoop 

 moves on a pivot connecting it with the outer hoop and encircles the 

 brass bowl. The bowl, accordingly, remains constantly suspended in 

 a vertical position, while the rolling motion of the sphere is not com- 



1 This, so far as I know, is the generally accepted opinion. See, for instance, J. L. Heiberg, 

 Naturwissenschaften und Mathematik im klassischen Altertum, p. 59. 



2 We still apply it to ship's lamps, the mariner's compass, and to barometers. A barometer 

 suspended a la Cardan is figured and described by E. Atkinson, Elementary Treatise on Physics, 

 13th ed., p. 145, New York, 1890. 



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