Ivih Trans. Acad. Sci. of St. Louis. 



costal with the diaphragmatic type. Reserve force in breath- 

 ing is best attained by deep inspiration, fixation of the dis- 

 tended diaphragm and thorax, and control of these muscles 

 while tone is produced. (2) To facilitate vocalization, the 

 larynx should never be tightly contracted by the muscles of 

 the throat, especially in the production of the registers. (3) 

 On the resonating cavities, their proper conformation and 

 position in relation to the vibrating cords and larynx, depend 

 the quality and timbre of the voice, so that the careful and 

 proper placing of tones is perhaps the most essential factor 

 in voice production. 



Professor F. E. Nipher read a short communication on the 

 zero photographic plate, to which reference was made at the 

 meeting of May 7 and in his paper published as Volume X, 

 No. 6, of the Academy's Transactions. 



The zero plate is one upon which a photographic image has 

 been made, but which will develop no image in a bath placed 

 in light of given candle power, at a distance of one meter 

 from the source. For example, if the developing bath is 

 twenty centimeters from a sixteen-candle lamp, a Cramer 

 isochromatic plate, such as is called " instantaneous," held 

 for ninety seconds at a distance of one meter from the lamp, 

 will be a zero plate. With an opaque stencil over the plate 

 when placed in a printing frame, during the exposure, there 

 will develop a positive of holes through the stencil if the 

 exposure is longer, and a negative if the exposure is shorter. 



If a fresh plate is exposed in our camera, with full opening, 

 to a brilliantly lighted street scene for one minute, it will 

 develop as a positive in that same bath. This time can be 

 somewhat reduced, but the least time needed has not yet been 

 determined. It is evident that part of this minute is used in 

 producing a zero plate. It is furthermore clear that different 

 parts of the plate will arrive at the zero condition at different 

 times. The exposure may be arrested at a time when the 

 strongly lighted white background of a sign-board will develop 

 white as a positive and when the black letters will also show 

 white as a negative. 



It has been found that when a plate is uniformly exposed 

 over its whole surface to the extent that nothing would have 



