132 Royal Society. 



previously been in perfect health. The febrile symptoms subsided 

 in the course of a week, but were followed by a general desqua- 

 mation of the cuticle, leaving the subjacent skin of a dingy yellow 

 hue. A month afterwards, the same process, preceded by a similar 

 febrile attack, recurred, and was followed by still greater whiteness 

 of the newly-formed skin, resulting in the complete conversion cf a 

 negro to a white man, retaining the characteristic features and hair 

 of an Ethiopian. This change was accompanied with great sensi- 

 bility in the skin to the heat of the sun and of fire, exposure to 

 which readily excited irritation, and even inflammation ; but the 

 general health soon became completely re-established. In the 

 course of three months, subsequently to this change, numerous 

 spots of a chestnut-brown colour made their appearance, first on the 

 wrists, then on the back of the arms, head and neck, and succes- 

 sively on the other parts of the body, forming by their extension 

 dark patches of various sizes; which, being scattered over the 

 whole surface, presented a singularly mottled appearance ; and as 

 the black colour became predominant, the white portions of the 

 skin seemed like patches of irregular shape formed in the natural 

 negro skin. With the colour of the skin, that of the hair, which 

 had also become white, has been gradually restored to its former 

 black hue. During this process of return to the natural colour the 

 health has been remarkably good. 



June 11. — "On the Physiology of the Human Voice." By John 

 Bishop, Esq., F.R.S. 



After premising a brief description of the system of organs which 

 are subservient to the voice, the author proceeds to consider the 

 several theories which have been devised to account for its various 

 modifications. These theories have, for the most part, been founded 

 on the laws which regulate the vibratory movements of stretched 

 membranous surfaces ; and the investigation of those laws has ac- 

 cordingly occupied the attention of many eminent mathemati- 

 cians, such as Euler, Bernoulli, Riccati, Biot, Poisson and Her- 

 schel ; but it is a subject requiring the most profound analysis, and 

 involving the resolution of problems of much greater complexity 

 than the laws of the vibrations of either strings or bars. The as- 

 sumptions which are necessary in order to bring the subject within 

 the reach of analysis, namely, that the membrane is homogeneous 

 in its substance, and of equal thickness and elasticity throughout its 

 whole extent, are at variance with the actual conditions of the vocal 

 organs, which are composed of tissues differing in thickness, density 

 and elasticity, and of which the tension is indeterminate; circum- 

 stances which present insuperable obstacles to the attainment of a 

 mathematical theory of their vibrations. 



The author, after giving a critical account of the experiments 

 made by Biot, Willis, Miiller, Cagniard la Tour and De Kempelin 

 on the vibrations of membranous lamina?, examines the various 

 actions of the vocal organs during the production of the more sim- 

 ple tones; and considers more especially the office of the vocal 

 ligaments, in regulating the pitch of the voice, which he considers 



