No. 7.] NUTRITIVE VALUES OF FISH. 407 



disturbance produced in crystalline selenium by the action of an 

 intermittent beam of light f^hould be audible in a similar manner 

 without the aid of a telephone or battery. Many experiments 

 were made to verify this theory without definite results. The 

 anomalous behaviour of the hard rubber screen su":o;ested the 

 thought of listening to it also. The experiment was tried with 

 extraordinary success. I held the sheet in close contact with my 

 ear, while a beam of intermittent light was focussed upon it by a 

 lens. A distinct musical note was immediately heard. We found 

 the effect intensified by arranging the sheet of hard rubber as a 

 diaphragm, and listening through a hearing-tube. We then tried 

 crystalline selenium in the form of a thin disk, and obtained a 

 similar but less intense effect. The other substances which I 

 enumerated at the beginning of my address were now successively 

 tried in the form of thin disks, and sounds were obtained from all 

 but carbon and thin glass. We found hard rubber to produce a 

 louder sound than any other substance we tried, excepting an- 

 timony, and paper and mica to produce the weakest sound. On 

 the whole, we feel warranted in announcing as our conclusion that 

 sounds can he produced hy the action of a variable light from 

 substances of all kinds, when in the form of thin diaj^hragms. 

 We have heard from interrupted sunlight very perceptible musical 

 tunes through tubes of ordinary vulcanized rubber, of brass and 

 of wood. These were all the materials at hand in tubular form, 

 and we have had no opportunity since of extending the obser- 

 vations to other substances. — (^Address before the American As- 

 sociation at Boston, August, 1880.) 



THE CHEMICAL COMPOSITION AND NUTRITIVE 



VALUES OF FISH. 



A paper with this title was read before the chemical sub-section 

 at the recent meeting of the American Association by Professor 

 W. 0. Atwater, of Middlcton, Ct., and gave the results of an 

 investigation made under the auspices of the Smithsonian Insti- 

 tution and the United States fish commission. They included 

 analyses of a large number of specimens of more common food 

 fishes, whose details, though quite extended, were mainly of 

 theoretical value. Some of the applications, however, were of 



