Proceedings of the Royal Institution, 397 



clined plane, and elevate the pelvis, &c. without disturbing the pa- 

 tient. This, however, as well as the catheter with foramina several 

 inches down the side, and the syringe with bows, although useful 

 instruments, cannot be deemed essential to the operation ; and they 

 will, of course, be adopted or rejected, according to circumstances, 

 of which the attending surgeon can alone be the proper judgii^H*' ^^'^ 



''*'l!l the library, amongst other objects of attention, were some cal- 

 culating machines by M. Palarino of Genoa. By means of them, 

 M. Palarino, who was present, worked various arithmetical questions 

 put to him by those around, in doing which, the operations of addi- 

 tion, subtraction, multiplication, division, extraction of roots, &c. 

 were performed with great rapidity. Besides these operations, there 

 was a machine intended especially for ascertaining the interest of any 

 sum at any rate, for any time, which appeared to answer its purpose 

 exceedingly well. 



May 2Ut. 



On. the Application of a New Principle in the Construction of 

 Musical Instruments. — This was one of the series of the evenings 

 devoted to the consideration and developement of various parts of the 

 science of sound. The illustrations were given by Mr. Faraday, but, 

 with the matter, were supplied by Mr. Wheatstone. The principle is 

 the one now so well known for its popularity in the aeolina, where a 

 spring of metal being fixed by one end, in an aperture which it 

 nearly fills, is thrown into vibration by the breath or any other soft 

 current of air passing by it, and produces musical sound. 



The general laws of the vibrations of rods and springs were first 

 given, and partly illustrated by an instrument called a tonometer 

 invented by Mr. Wheatstone, in which the sound produced by any 

 length of an uniform spring could be ascertained. Then the appli- 

 cation of these springs, in a great variety of instruments, was shewn, 

 first in the mund-harmonica, or aeolina, down to those of most recent 

 construction. .^The arrangement of the single, double, and triple 

 chords in the aeolina, with the power thus given to play airs in one 

 key^ were illustrated by diagrams and practice. 



The limited capabilities of this instrument then led to the consider- 

 ation of those in which the power of fingering was introduced, and 



APRIL — JUNE, 1830. 2D 



