NATURAL PHILOSOPHY. 135 



its probable arrival in the Black Sea might have been telegraphed 

 some forty-eight hours in advance. 



VERTICAL MOVEMENTS OF THE ATMOSPHERE. 



At the British Association, 1862, Prof. Hennesy stated as the 

 result of his observations, that non-horizontal movements of the air 

 are more prevalent, upon the whole, about mid-day, than at any 

 other diurnal period. Their sudden and abrupt commencement is 

 usually a precursor and always accompanies great horizontal disturb- 

 ances. Their gradual and regular diminution in energy seems to 

 point to a steady tendency in the air towards a state of convective 

 equilibrium, and frequently precedes fine weather. In general the 

 motion of the air is not strictly horizontal, but imdulatory ; and the 

 mingling of such undulations with the effects of convection seems to 

 point out the value of the study of the atmospherical pulse as a test 

 of the changes of the weather. 



MECHANISM OF THE HUMAN VOICE. 



By means of the laryngoscope, Mr. John Bishop has succeeded in 

 watching the movements of the larynx during the utterance of vocal 

 sounds. When the lower tones are made, the vocal cords vibrate 

 through their whole length. As the pitch rises, the vibrating length 

 diminishes, and the cords are pressed more closely together. In fal- 

 setto notes, it is only the extreme end of the cord that vibrates. 

 Moreover, the vocal cords form a kind of valve, which is situated in 

 a tube, and, acts like a reed. Thus, the organs of the voice perform 

 the double office of reed and string. Proc. Royal Soc. 



Taking advantage of the laryngoscope, Prof. Czermak has succeeded 

 in photographing the glottis, its condition during vocalization, and the 

 changes which take place in the cords during the different chest and 

 falsetto notes. 



THE SOUNDING PROPERTIES OF ROOMS. 



A correspondent of the London Builder presents the following 

 ideas on the proportions of rooms for propagating sound. He says: 

 A building of a certain height, length, breadth, and form, is required 

 to enable an assemblage of persons to hear clearly and distinctly in 

 every part of the room. I only know of one room in Great Britain 

 (and I have examined many) which is as near perfection as possible, 

 and this a concert room at Harrowgate. The following are its dimen- 

 sions : 



Length of room inside 86 feet 6 inches. 



Width 33 " 



Height to the ceiling line 22 " 7 



Height to centre of ceiling . ... 24 " 2 " 



The ceiling is the segment of a circle rising one foot in seven 

 inches. There are nine sunken panels in the length of the ceiling 

 and seven in width, each nine inches deep. There are nine large 

 windows along the north wall, three at the east and three at the 



