Royal Institution of Great Britain. 457 



of modelling in clay, to the last touch required to complete his sub- 

 ject in marble ; and the various operations of modelling, casting, 

 chiseling, and the use and theory of the different instruments used, 

 were explained and illustrated by examples. For these purposes 

 clay-models, .plastQr-casts, and blocks of marble in different pro- 

 gressive states, were placed upon the table, upon which the work- 

 men carried on their several operations. 



May 9. — Mr. Faraday gave a lecture on the production of musi- 

 cal sound, with an explication of the principles of action in some 

 new musical instruments. He stated his information to be derived 

 altogether from Mr.Wheatstone, to whom, of course, the new facts 

 brought forward belonged. The nature of the pitch of sounds was 

 first explained, and stated to be the quality by wnich musical sounds 

 are distinguished from mere noise. The credit of the first philoso- 

 phical account of this quality was attributed to Gallileo, who proved 

 that it depended altogether upon the number of impulses in a given 

 time. An experiment by that philosopher, apparently forgotten in 

 modern times, but described in his Dialogues, was repeated : — it con- 

 sisted in drawing the point of a blade over a metal plate so as to 

 produce sound, and counting or comparing the dots which are al- 

 ways produced upon the plates, and which are the records of the 

 number of vibrations necessary to the pitch of sound produced. 



Hook's experiment, in which the teeth of a revolving wheel were 

 made to beat against a card, was repeated, and the pitch of sound 

 shown to correspond with the number of impulses in a given time. An 

 extension of this experiment by Mr.Wheatstone was also described, 

 in which the harmonics of a stretched string were produced by 

 holding it against the wheel ; the string producing sound whenever 

 the velocity of the wheel was such that the impulses of the teeth 

 corresponded in frequency with the vibrations of the string or of 

 any of its aliquot parts. 



Robison's mode of producing musical sounds by air passing 

 through a stop-cock rapidly revolving, was then explained and il- 

 lustrated ; afterwards, Cagniard de la Tour's syren was set in ac- 

 tion j and from these were drawn the explanation of the principles 

 of two new musical instruments from Germany, the Munt-harmonica 

 and the Acol-harmonica. 



May 2 and 16. — On these evenings Mr. Knowles, of the Navy 

 Board, gave an account of the rise, progress, and present state 

 of naval architecture. To make his historical observations more 

 clear, he first stated the elements concerned in the structure of 

 ships, as stability, floatation, masts and yard, &c.&c, and then traced 

 the state of the navy from the reign of Alfred to the present day ; 

 pointing out the times and progression of its increase ; the period 

 when any improvement had taken place ; and more minutely en- 

 tering into the important alterations introduced of late years by Sir 

 W. Rich, Sir Robert Seppings, and others. All the observations 

 relating to construction were fully illustrated by numerous models 

 from the magnificent collection belonging to the Navy Board. 



New Series. Vol. 3. No. 1 8. June 1 828. 3 N LX VIII. In- 



