27(> Vvoi\ G. Wiedemann on the Magnetic 



jyortio mollis, no decussation like that of the optic nerves ; 

 the former do not intersect after leaving the fourth ventricle, 

 in which they have their common origin, and from which 

 they diverge right and left. There is in health a possible 

 communication between the ears across the pharynx, through 

 the Eustachian tubes. Moreover the bone of the skull itself 

 is capable of conveying sonorous tremors, which might account 

 for both ears hearing a sound entering by one only. In 

 either of these latter cases, however, there would be no reason 

 why combinational tones should not be equally audible in 

 binaural as in monaural audition ; so that we are driven to 

 the hypothesis that any means of comparison which may 

 exist in the nerve systems of the ears exists deep-seated in 

 the actual structure of the brain. This may be the reason 

 why dissonances are in binaural audition so excessively dis- 

 agreeable, and why even ordinary consonant intervals become 

 harsh. They evoke a discontinuous sensation when there is 

 no opportunity of their blending previously to acting upon 

 the sensitive mechanism of the nerve-structures. The dis- 

 continuity of the sensation produces an intensity of effect 

 exceeding that of a continuous one. Hence sounds all but in- 

 audible themselves may yield, as noted in No. 2, very w^ell- 

 marked beats, enabling the ear thus to detect the most deli- 

 cate differences of tone. Thus, for example, I have, in a still 

 room, hu ig up a fork with its resonant box, and, after exci- 

 ting its vibrations with a bow, have made it swing like a pen- 

 dulum at the end of a string. On retiring to the further end 

 of the room, and listening to its tones with a resonator in the 

 ear, I have, by holding to the other ear a fork vibrating 

 accurately in unison with the first, been able to pronounce 

 by the audible fluctuations of tone whether the swinging 

 fork were advancing or retreating — that is to say, whether 

 the motion of translation at any given moment were in the 

 same direction as, or in an opposite direction to, the propa- 

 o-ation of the sonorous waves. 



XXXVII. On the Magnetic JBehaviour of Chemical Com- 

 jjowuls. By Professor G. Wiedemann. 



[Concluded from p. 173.] 



11. WfA GJSETISMS of the Oxides of the Magnetic Metals. 



^ — The oxides, havino- been heated to redness, in- 



vestigated directly in the flat flasklet, show in general a much 



feebler magnetism than the corresponding salts or hydrates. 



