1896.] NEW YORK ACADEMY OF SCIENCES. 31 



cence." It appears from an elaborate series of observations that 

 when fluorescent screens are made of calcium tungstate of differ- 

 ent sized crystals, the color of the fluorescent light depends 

 upon the size of the crystals, the large crystals being more yel- 

 lowish, and the smaller ones more bluish in appearance. It was 

 also observed that though the luminosity of the screens made of 

 the smaller crystals was very much less than that of those made 

 of larger crystals, still the actinic effect of the fine screen was 

 quite as great as that of the first. This last observation would 

 rather indicate that the fine screen sends out a large proportion 

 of ultra-violet ra3's. 



The paper was discussed b}- Drs. Piffard, Hallock and Wood- 

 ward. 



The second paper of the evening was by C. C. Trowbridge. 

 It described "A New Research Fluoroscope," which consists es- 

 sentiall}' of a fluoroscope so constructed that between the eye 

 and the screen a bar or plaie ma}- be introduced, enabling the 

 observer to decide ver}- sharply whether a fluorescence of the 

 screen is reall}^ taking place or whether the apparent effect is 

 subjective. 



The appai'atus is mounted on a stand, and is supplied with va. 

 rious appliances which will render it very useful for accurate 

 observations. He proposes the name of " X-ra}^ Detector " for 

 the instrument. 



The third paper of the evening was by F. S. Muckey and Wm. 

 Hallock, and was entitled " Some Peculiar Observations in the 

 Acoustics of Articulation." 



After a brief explanation of the fundamental principles of ar- 

 ticulation, a number of photographic records of the anal3^ses of 

 vowels were shown, illustrating the great variety in the results 

 obtained by the analysis of what is intended to be the same 

 vowel spoken by different people. 



By request. Professor Hallock exhibited upon a screen a series 

 of old photographs of sound waves, showing ordinar}^ propaga- 

 tion, reflection and refraction. 



