164 Miscellaneous Intelligmce. 



3. On the Use of the Tympanum and the External Ear. — In con- 

 sequence of very extensive, and apparently, accurate researches 

 on the use and mode of action of the membrane of the tympanum, 

 and the parts of the external ear, M. Savart has been conducted 

 to the following conclusions : 



i. That the communication of vibrations by means of the air 

 appears to take place, at least, for small distances, according to 

 the same laws as those which take place in solid bodies. 



ii. That it is not necessary to suppose, as has been done, the 

 existence of a particular mechanism, intended to act on the mem- 

 brane of the tympanum, and make it vibrate in imison with the 

 bodies which affect it, but that it is always so conditioned as to 

 be readily influenced by any number of vibrations. 



iii. That its tension does not appear to vary except to augment 

 or diminish the amplitude of its vibrations, as Bichat has already 

 supposed; but that his opinion is the reverse of the result of ex- 

 periments, inasmuch as he imagined the tension to be diminished 

 for strong impressions and increased for weak ones. 



iv. That the vibrations of the membrane are communicated 

 without alteration to the labyrinth by means of the small bones, 

 as the vibrations of the upper table of an instrument are commu- 

 nicated to the lower table by the intervening piece. 



V. That the bones have also the office of modifying the extent 

 of the excursions of the vibrating parts of the organs contained in 

 the labyrinth. 



vi. Finally, that the cavity of the drum appears to be intended 

 to preserve an air constant in its physical properties near the 

 apertures of the labyrinth, and against the internal face of the 

 membrane of the tympanum. — Ann. de Chim. xxvi. 38. 



4. Temporary Weighing Machines. — Mr. Bevan suggests the 

 following expedient in those cases where a balance, or proper 

 machine for weighing forces cannot be obtained. If the weight 

 to be found, or force to be measured, does not much exceed twenty 

 pounds, take two pieces of deal, or oak, or any stiff wood, about 

 one inch in diameter and three feet in length, and with a piece of 

 packthread, bind them together at one end for about three or 

 four inches in length ; to the other end of one of the rods fasten 

 the weight to be ascertained, or the force to be measured, while 

 the corresponding end of the other rod is securely held : the 

 mutual deflection of the rods by the weight or force may then be 

 measured by a common rule and noted down, and when oppoi-- 

 tunity serves, the value of the observed deflection may be correctly 

 ascertained by proper weights. If the weight, or force, amount to 

 80 or 100 pounds, the diameter of the rods should be something 

 more than one inch and a half, or the former rods may be bound 

 together at each end for about two inches, and the deflections 



